The University of Medicine and Dentistry of New Jersey (UMDNJ) owns a patent relating to the use of anti-Müllerian hormone/Müllerian inhibiting substance for predicting ovarian response in women with infertility. The patent is based in part on work that Dr. Seifer carried out while employed at UMDNJ. In accordance with UMDNJ policy, Dr. Seifer, a named inventor on this patent, assigned his interest in the invention to UMDNJ. UMDNJ has a licensing agreement with Diagnostic Systems Laboratory for the use of the claimed invention. Dr. Seifer receives a portion of the royalties, as determined by UMDNJ policy, that UMDNJ gains from this licensing agreement.

CASE: Borderline test result prompts referral

A 36-year-old nulliparous woman is seen in your office for evaluation after 6 months of infertility. She is ovulatory, and has been using an ovulation-prediction kit to time intercourse. You learn that she had Chlamydia trachomatis infection in the distant past, but elicit no other significant medical or surgical history. She reports that she smoked approximately one pack of cigarettes a day for 15 years but gave up smoking 5 years ago.

You order a hysterosalpingogram, followed by day 3 testing of follicle-stimulating hormone (FSH). The hysterosalpingogram is normal; the FSH level is 7.5 mIU/mL and the estradiol level is 30 pg/mL—both in the normal range.

The patient asks for testing of anti-Müllerian hormone (AMH; also known as Müllerian-inhibiting substance) because she has read that it is a new marker of fertility. The result is 0.5 ng/mL, a borderline value. After reviewing these results, you refer her to a reproductive endocrinologist for further management.

Was the test for AMH indicated? And is this referral appropriate?

The referral is entirely appropriate, even though the patient has not been trying to conceive for a full year. Why? The AMH value suggests that her ovarian reserve is in early decline. She would benefit from evaluation by a subspecialist who can review the entire spectrum of treatments, including aggressive options such as ovulation induction and in vitro fertilization (IVF), to optimize her reproductive success.

This article reviews the various biomarkers available to assess ovarian reserve in women who experience infertility:

• day 3 (basal) FSH
• clomiphene citrate challenge
• gonadotropin-releasing hormone (GnRH) agonist stimulation
• inhibin-B
• antral follicle count (AFC)
• AMH.

The AFC and AMH tend to detect the earliest changes in ovarian reserve, followed, sequentially, by inhibin-B, the clomiphene citrate challenge test (CCCT), and basal FSH.

The tests we describe are used primarily to assess treatment prognosis in infertile women. In time, however, appropriate population screening of ovarian reserve may be feasible to provide many more women with information about their reproductive potential and help them shape their life plan.

What makes a test valuable?

Ovarian reserve describes a woman’s reproductive potential—specifically, the number and quality of oocytes she possesses.¹ Biochemical tests of ovarian reserve emerged during the rise of assisted reproductive technologies (ART) in the late 1980s to predict both responsiveness to superovulation drugs and the odds of pregnancy with treatment.

Ideally, a test that assesses ovarian reserve should be affordable, straightforward, rapidly interpretable, and minimally invasive. It also should be able to detect changes that begin early in reproductive life. To be applicable to large populations of reproductive-age women, it should be of use anytime in the menstrual cycle, and should provide reproducible and highly accurate assessment of the reproductive aging process.

Our ability to offer tests that accurately measure ovarian reserve has a significant impact on women at risk of infertility and early menopause and on those who choose to delay childbearing for personal (nonmedical) reasons. These tests have become increasingly relevant because women are choosing to have their first child at a later age than their counterparts did 20 years ago:

• In 1980, 40% of women having their first baby were younger than 25 years, and only 5% were older than 35
• In 2000, 25% of women were younger than 25 when their first child was born, and 15% were older than 35.

Who should be tested?

Ovarian reserve is a complex clinical phenomenon that is influenced by age, genetics, and environmental variables. The decline in a woman’s ovarian reserve over time is irreversible; the trajectory of this decline is fundamental to the odds of fertility with age and the timing of the menopausal transition. At present, the markers used most often in clinical practice have some utility but also suffer from several drawbacks ( TABLE ).

For the general practitioner performing an infertility evaluation, we recommend focusing on the following groups of women for ovarian reserve testing:

• women over 30 years of age
• women with a history of exposure to a confirmed gonadotoxin, i.e., tobacco smoke, chemotherapy, radiation therapy
• women with a strong family history of early menopause or premature ovarian failure
• women who have had extensive ovarian surgery, i.e., cystectomy and unilateral oophorectomy.

Testing tends to have the highest yield in these groups. Women who have abnormal results should be referred to a reproductive endocrinologist for further evaluation and treatment.

The six tests are described below.

TABLE

How six markers of ovarian reserve stack up

1 | Basal FSH—widely used but only moderately informative

Day 3 FSH and the CCCT are the most widely used measures of ovarian reserve in ART practice. The use of early follicular-phase FSH as a marker of ovarian reserve and fertility was proposed 20 years ago with the emergence of IVF.^2-4 The test is an indirect assessment of ovarian reserve in that it measures pituitary production of FSH in response to feedback from ovarian hormones. Estradiol and inhibin-B reach a nadir early in the menstrual cycle; measuring FSH on day 3 offers a glimpse of the functioning of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise later in the cycle ( FIGURE 1 ).^5,6

FIGURE 1 The HPO axis

The FSH level opens a window onto the function of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise in the cycle. Women who have normal ovarian reserve have sufficient ovarian hormone production early in the menstrual cycle to maintain FSH levels within the normal range. Conversely, a “monotropic” elevation in FSH—one that is unaccompanied by a rise in luteinizing hormone (LH)—reflects poor hormone production from an aging pool of ovarian follicles and disinhibition of FSH production.^5,6

FSH measurements are typically combined with estradiol to enhance the sensitivity of testing ( FIGURE 2, ). Premature elevations of estradiol early in the follicular phase are driven by rising FSH levels in women with declining ovarian reserve. Abnormally elevated estrogen levels then feed back negatively on pituitary production of FSH and mask an elevation that might otherwise reveal diminished ovarian reserve. Measurement of both FSH and estradiol on cycle day 3 may therefore help decrease the incidence of false-negative testing.

Commonly cited criteria for normal ovarian reserve are:

• early follicular phase FSH, <10 mIU/mL
• estradiol, <80 pg/mL¹

It is extremely important to note, however, that these are general guidelines and that cutoffs are both laboratory- and practice-specific.

FIGURE 2 Monthly and lifetime variations in estradiol and FSH

How 17ß-estradiol and follicle-stimulating hormone levels vary over the menstrual cycle (top) and a woman’s lifetime (bottom).

2 | Clomiphene citrate—more sensitive than FSH testing

Like basal FSH testing, the CCCT is an indirect assessment of ovarian reserve. Unlike FSH testing, the CCCT is provocative. It involves administration of 100 mg of clomiphene citrate (Clomid) on days 5 through 9 of the menstrual cycle, with FSH and estradiol measured on days 3 and 10. Once clomiphene citrate is administered, FSH and LH levels rise, followed by an increase in estradiol and inhibin. Evidence suggests that the smaller follicular cohorts in women with diminished ovarian reserve produce less inhibin-B and estradiol and, therefore, less negative feedback on clomiphene-induced pituitary FSH release.^6,7 The result: persistent elevation of the day 10 FSH value and a positive screen for diminished ovarian reserve.

In some women, day 10 FSH is elevated even after a normal day 3 value. This makes the CCCT more sensitive than basal FSH testing; it can identify women who might go unrecognized if evaluated by day 3 FSH and estradiol levels alone.

More expensive and labor-intensive than the alternatives

Interpretation of the CCCT requires that FSH and estradiol both be assessed on days 3 and 10. An elevated FSH (≥10 mIU/mL) on either day indicates diminished ovarian reserve. As with basal FSH testing, elevated estradiol (≥80 pg/mL) on day 3 is considered abnormal. The day 10 estradiol value of the CCCT reflects whether or not clomiphene citrate was administered appropriately, and should be elevated. However, the significance of the day 10 estradiol level has been debated with respect to its predictive value for pregnancy in infertile populations.⁸

The addition of day 10 FSH assessment improves the sensitivity of the CCCT over basal FSH measurement, but makes it a more expensive and labor-intensive test ( TABLE ).^5,6 The CCCT involves administration of clomiphene citrate, a safe drug (though it can have side effects), and two blood draws instead of one. Nevertheless, both tests are relatively noninvasive, rapid measures of ovarian reserve.

Drawbacks of the tests

Both basal FSH testing and the CCCT are widely used, although support for their ability to predict ovarian reserve in the infertile population has been challenged recently. Newer data demonstrate that these tests are limited in their ability to predict outcome (pregnancy and response to superovulation drugs) in all but a narrow group of patients undergoing IVF. Performance is particularly limited in:

• young women
• women in the general infertility population who are not utilizing IVF.^9-13

Additional drawbacks of basal FSH testing and the CCCT include:

• significant variability of test results from cycle to cycle (intercycle variability)
• limited time frame within which the tests can be performed (intracycle variability).

The basal FSH test and CCCT have high specificity (98% to 99% for each) as an assessment of reproductive performance in infertile women and generate few false-positive results.^5,6 However, the high screen cutoffs that allow for such specificity come at a price: Few women will screen positive, and sensitivity of the tests is low (between 7% and 8% for basal FSH and between 25% and 40% for the CCCT). Such low sensitivity means that many women will not conceive after infertility treatment despite a normal test result.^5,11 Overall, the tests are not highly informative for many women who get tested.

Once abnormal, normal results are meaningless

Once an FSH level or the CCCT has ever been abnormal, the patient has diminished ovarian reserve; normal values in subsequent menstrual cycles do not improve the odds of pregnancy with treatment.¹⁴ This fact can be a significant source of confusion and frustration for patients.

3 | GnRH agonist stimulation —no better than FSH testing

This test was developed in the search for a very sensitive assessment of ovarian reserve. It was designed to uncover subtle abnormalities in pituitary and ovarian dynamics. It involves administering a gonadotropin-releasing hormone (GnRH) agonist such as leuprolide acetate (Lupron) on day 2 or 3 of the menstrual cycle and measuring pituitary and ovarian hormone responses.^5,15

One group of investigators demonstrated a correlation between stimulated estradiol levels and responsiveness during IVF,¹⁶ but other studies have shown that the test does not perform significantly better than day 3 FSH in predicting ovarian reserve.^17,18

The sensitivity of GnRH agonist testing for pregnancy is moderate (32% to 89%); specificity ranges from 79% to 97%.¹⁹

4 | Inhibin-B—not helpful when used alone

This glycoprotein hormone produced by granulosa cells of developing follicles is a direct measure of ovarian reserve when assessed in the early follicular phase of the menstrual cycle.²⁰ Women treated with IVF who have a low inhibin-B level—particularly when using cutoffs below the range of 45–80 pg/mL—have been shown to respond poorly to superovulation and have a lower pregnancy rate than women with high inhibin-B.^21,22 One group of investigators demonstrated that women with clinical evidence of diminished ovarian reserve but a normal FSH level also had low inhibin-B production, suggesting that it may be a more sensitive marker than FSH.²²

Inhibin-B testing involves a simple blood draw. However, the test has been incorporated into clinical assessment of ovarian reserve only to a limited degree, due to the lack of reliable assays and controversy concerning its prognostic value.²³

Because of these limitations, routine testing of serum inhibin-B in isolation of other markers of ovarian reserve is not recommended.

5 | Antral follicle count—good predictor of IVF outcome

Transvaginal ultrasonographic determination of the number of ovarian follicles that measure between 2 mm and 10 mm in diameter in the early follicular phase of the cycle yields the AFC. As a direct marker of the cohort of growing follicles in the early menstrual cycle, the AFC is believed to correlate strongly with the number of primordial follicles present in the ovary and, therefore, ovarian reserve. Total AFCs of less than 5 to 10 are suggestive of diminished ovarian reserve.^24,25

In IVF cycles, AFC has proven to be an accurate predictor of number of oocytes retrieved, risk of cycle cancellation, and odds of conception.^24,25 Some investigators have even suggested that, compared with other markers of ovarian reserve, AFC is the best independent predictor of outcome in IVF cycles.^7,26-27

In a group of normally cycling women with proven fertility, AFC also showed a strong correlation with age, declining slowly until age 37 and more rapidly thereafter.^28,29

AFC sensitivity for pregnancy is moderate and varies widely in published reports (8% to 60%), whereas specificity tends to be higher (33% to 96%).¹⁹

Drawbacks of AFC

• Because of the need to perform transvaginal ultrasonography, AFC is a more invasive and often more expensive test than hormonal biomarkers
• Accurate assessment of AFC requires an experienced sonographer and can be limited in patients who have had pelvic surgery or uterine fibroids and in those who are obese
• Moderate interobserver and intercycle variability of AFC determinations limits its reproducibility^29,30
• As with basal FSH measurement, the intercycle variability of AFC does not correlate well with IVF outcome in individual patients.³⁰

6 | Anti-Müllerian hormone— many advantages

The drawbacks of the tests just described— e.g., intercycle variability, lack of uniform cutoffs, and limited ability to predict IVF outcomes—make the development of more reliable measures of ovarian reserve a priority in reproductive medicine. AMH is a highly promising marker that appears to have many advantages over other tests and may have the greatest power to predict ovarian aging in women of reproductive age.

How it works

AMH is a glycoprotein growth factor and a member of the transforming growth factor-ß superfamily.³¹ It is primarily produced by the pool of early-growing follicles, which are believed to serve as a proxy for the number of primordial follicles in the ovary. The number of primordial follicles at a given point in time represents the ovarian reserve. AMH levels above 0.7 ng/mL are considered normal; values between 0.3 ng/mL and 0.7 ng/mL are consistent with borderline ovarian reserve, according to 2007 data from Reprosource Corp.

AMH has been studied as a marker of ovarian reserve for 6 years, with multiple reports describing declines in levels with age and with diminishing oocyte numbers. It is undetectable at menopause.³²

The age-related decline in AMH is gradual but measurable even in young women, consistently preceding changes in other markers of ovarian reserve such as FSH and inhibin-B.^32-35 The longitudinal changes in AMH have been demonstrated in ovulatory premenopausal women and healthy volunteers with proven fertility.^33,34 In one series of women followed over a mean of 4 years (ages 25 to 46), AMH testing was superior to day 3 FSH, inhibin-B, and AFC in its ability to predict the onset of cycle irregularity and the menopausal transition.³³

Does it predict oocyte quality?

AMH has performed well as a biomarker, comparable in most series to AFC and superior to FSH. AMH levels are strongly correlated with the number of oocytes retrieved during IVF and the odds of cycle cancellation due to poor response^35-41 —but does it accurately characterize oocyte quality, the other element of ovarian reserve?

Some reports have shown a strong association between AMH levels and surrogates of oocyte quality, including fertilization, oocyte morphology, embryo quality, and pregnancy and miscarriage rates,^36-41 but others have not.⁴² Some reports demonstrate a relationship between AMH and some but not all surrogate markers of oocyte quality.⁴⁰

Advantages of AMH

• It demonstrates minimal intracycle variability.^32,43-45 Compared with other markers of ovarian reserve, which must be measured early in the follicular phase of the menstrual cycle, AMH can be assessed at random times, making it a more convenient method for patients and physicians
• It demonstrates minimal intercycle variability^32,34
• AMH levels are not significantly affected by the hormonal changes of pregnancy, oral contraceptive use, or GnRH treatment, and can be measured in these settings.^46,47

Utility of AMH is limited in PCOS and obesity

The ability to use AMH as a marker of ovarian aging in women who have polycystic ovary syndrome (PCOS) and in women who are obese may be limited by the ovulatory dysfunction in these populations. Circulating levels of AMH are higher in women with PCOS than in unaffected women, a finding thought to be indicative of oligo-ovulation and poor follicular development in polycystic ovaries.^48-53

In a recent series investigating AMH levels in women with PCOS, AMH and the degree of insulin resistance were positively correlated, and the AMH level was negatively correlated with the number of menses in a year.⁴⁹ The consistently positive correlation between AMH and PCOS may suggest a future role for this marker as a diagnostic tool.

In obese women who do not have PCOS, AMH production may be lower than in women of normal weight. In a recent series, normally cycling obese women in the later reproductive years were shown to have an AMH level 70% lower than those in women who were not obese.⁵⁴ These differences have not been well studied in younger obese women.

Which test is best?

AMH may be preferable to the other tests to assess ovarian reserve because it can be measured any time during the menstrual cycle or between cycles. AMH measurement is also useful if a woman is taking oral contraceptives or leuprolide acetate because these medications may confound the results of the other test methods. In addition, AMH may be the earliest indicator of decline in ovarian reproductive function. As such, it may highlight cases that merit a search for other causes of infertility and make it possible to treat them in a timely manner.

Elevated AMH may reveal occult PCOS and warn of significant risk of ovarian hyperstimulation prior to ovulation induction with gonadotrophins, so that the clinician can plan smaller doses.

The University of Medicine and Dentistry of New Jersey (UMDNJ) owns a patent relating to the use of anti-Müllerian hormone/Müllerian inhibiting substance for predicting ovarian response in women with infertility. The patent is based in part on work that Dr. Seifer carried out while employed at UMDNJ. In accordance with UMDNJ policy, Dr. Seifer, a named inventor on this patent, assigned his interest in the invention to UMDNJ. UMDNJ has a licensing agreement with Diagnostic Systems Laboratory for the use of the claimed invention. Dr. Seifer receives a portion of the royalties, as determined by UMDNJ policy, that UMDNJ gains from this licensing agreement.

CASE: Borderline test result prompts referral

A 36-year-old nulliparous woman is seen in your office for evaluation after 6 months of infertility. She is ovulatory, and has been using an ovulation-prediction kit to time intercourse. You learn that she had Chlamydia trachomatis infection in the distant past, but elicit no other significant medical or surgical history. She reports that she smoked approximately one pack of cigarettes a day for 15 years but gave up smoking 5 years ago.

You order a hysterosalpingogram, followed by day 3 testing of follicle-stimulating hormone (FSH). The hysterosalpingogram is normal; the FSH level is 7.5 mIU/mL and the estradiol level is 30 pg/mL—both in the normal range.

The patient asks for testing of anti-Müllerian hormone (AMH; also known as Müllerian-inhibiting substance) because she has read that it is a new marker of fertility. The result is 0.5 ng/mL, a borderline value. After reviewing these results, you refer her to a reproductive endocrinologist for further management.

Was the test for AMH indicated? And is this referral appropriate?

The referral is entirely appropriate, even though the patient has not been trying to conceive for a full year. Why? The AMH value suggests that her ovarian reserve is in early decline. She would benefit from evaluation by a subspecialist who can review the entire spectrum of treatments, including aggressive options such as ovulation induction and in vitro fertilization (IVF), to optimize her reproductive success.

This article reviews the various biomarkers available to assess ovarian reserve in women who experience infertility:

• day 3 (basal) FSH
• clomiphene citrate challenge
• gonadotropin-releasing hormone (GnRH) agonist stimulation
• inhibin-B
• antral follicle count (AFC)
• AMH.

The AFC and AMH tend to detect the earliest changes in ovarian reserve, followed, sequentially, by inhibin-B, the clomiphene citrate challenge test (CCCT), and basal FSH.

The tests we describe are used primarily to assess treatment prognosis in infertile women. In time, however, appropriate population screening of ovarian reserve may be feasible to provide many more women with information about their reproductive potential and help them shape their life plan.

What makes a test valuable?

Ovarian reserve describes a woman’s reproductive potential—specifically, the number and quality of oocytes she possesses.¹ Biochemical tests of ovarian reserve emerged during the rise of assisted reproductive technologies (ART) in the late 1980s to predict both responsiveness to superovulation drugs and the odds of pregnancy with treatment.

Ideally, a test that assesses ovarian reserve should be affordable, straightforward, rapidly interpretable, and minimally invasive. It also should be able to detect changes that begin early in reproductive life. To be applicable to large populations of reproductive-age women, it should be of use anytime in the menstrual cycle, and should provide reproducible and highly accurate assessment of the reproductive aging process.

Our ability to offer tests that accurately measure ovarian reserve has a significant impact on women at risk of infertility and early menopause and on those who choose to delay childbearing for personal (nonmedical) reasons. These tests have become increasingly relevant because women are choosing to have their first child at a later age than their counterparts did 20 years ago:

• In 1980, 40% of women having their first baby were younger than 25 years, and only 5% were older than 35
• In 2000, 25% of women were younger than 25 when their first child was born, and 15% were older than 35.

Who should be tested?

Ovarian reserve is a complex clinical phenomenon that is influenced by age, genetics, and environmental variables. The decline in a woman’s ovarian reserve over time is irreversible; the trajectory of this decline is fundamental to the odds of fertility with age and the timing of the menopausal transition. At present, the markers used most often in clinical practice have some utility but also suffer from several drawbacks ( TABLE ).

For the general practitioner performing an infertility evaluation, we recommend focusing on the following groups of women for ovarian reserve testing:

• women over 30 years of age
• women with a history of exposure to a confirmed gonadotoxin, i.e., tobacco smoke, chemotherapy, radiation therapy
• women with a strong family history of early menopause or premature ovarian failure
• women who have had extensive ovarian surgery, i.e., cystectomy and unilateral oophorectomy.

Testing tends to have the highest yield in these groups. Women who have abnormal results should be referred to a reproductive endocrinologist for further evaluation and treatment.

The six tests are described below.

TABLE

How six markers of ovarian reserve stack up

1 | Basal FSH—widely used but only moderately informative

Day 3 FSH and the CCCT are the most widely used measures of ovarian reserve in ART practice. The use of early follicular-phase FSH as a marker of ovarian reserve and fertility was proposed 20 years ago with the emergence of IVF.^2-4 The test is an indirect assessment of ovarian reserve in that it measures pituitary production of FSH in response to feedback from ovarian hormones. Estradiol and inhibin-B reach a nadir early in the menstrual cycle; measuring FSH on day 3 offers a glimpse of the functioning of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise later in the cycle ( FIGURE 1 ).^5,6

FIGURE 1 The HPO axis

The FSH level opens a window onto the function of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise in the cycle. Women who have normal ovarian reserve have sufficient ovarian hormone production early in the menstrual cycle to maintain FSH levels within the normal range. Conversely, a “monotropic” elevation in FSH—one that is unaccompanied by a rise in luteinizing hormone (LH)—reflects poor hormone production from an aging pool of ovarian follicles and disinhibition of FSH production.^5,6

FSH measurements are typically combined with estradiol to enhance the sensitivity of testing ( FIGURE 2, ). Premature elevations of estradiol early in the follicular phase are driven by rising FSH levels in women with declining ovarian reserve. Abnormally elevated estrogen levels then feed back negatively on pituitary production of FSH and mask an elevation that might otherwise reveal diminished ovarian reserve. Measurement of both FSH and estradiol on cycle day 3 may therefore help decrease the incidence of false-negative testing.

Commonly cited criteria for normal ovarian reserve are:

• early follicular phase FSH, <10 mIU/mL
• estradiol, <80 pg/mL¹

It is extremely important to note, however, that these are general guidelines and that cutoffs are both laboratory- and practice-specific.

FIGURE 2 Monthly and lifetime variations in estradiol and FSH

How 17ß-estradiol and follicle-stimulating hormone levels vary over the menstrual cycle (top) and a woman’s lifetime (bottom).

2 | Clomiphene citrate—more sensitive than FSH testing

Like basal FSH testing, the CCCT is an indirect assessment of ovarian reserve. Unlike FSH testing, the CCCT is provocative. It involves administration of 100 mg of clomiphene citrate (Clomid) on days 5 through 9 of the menstrual cycle, with FSH and estradiol measured on days 3 and 10. Once clomiphene citrate is administered, FSH and LH levels rise, followed by an increase in estradiol and inhibin. Evidence suggests that the smaller follicular cohorts in women with diminished ovarian reserve produce less inhibin-B and estradiol and, therefore, less negative feedback on clomiphene-induced pituitary FSH release.^6,7 The result: persistent elevation of the day 10 FSH value and a positive screen for diminished ovarian reserve.

In some women, day 10 FSH is elevated even after a normal day 3 value. This makes the CCCT more sensitive than basal FSH testing; it can identify women who might go unrecognized if evaluated by day 3 FSH and estradiol levels alone.

More expensive and labor-intensive than the alternatives

Interpretation of the CCCT requires that FSH and estradiol both be assessed on days 3 and 10. An elevated FSH (≥10 mIU/mL) on either day indicates diminished ovarian reserve. As with basal FSH testing, elevated estradiol (≥80 pg/mL) on day 3 is considered abnormal. The day 10 estradiol value of the CCCT reflects whether or not clomiphene citrate was administered appropriately, and should be elevated. However, the significance of the day 10 estradiol level has been debated with respect to its predictive value for pregnancy in infertile populations.⁸

The addition of day 10 FSH assessment improves the sensitivity of the CCCT over basal FSH measurement, but makes it a more expensive and labor-intensive test ( TABLE ).^5,6 The CCCT involves administration of clomiphene citrate, a safe drug (though it can have side effects), and two blood draws instead of one. Nevertheless, both tests are relatively noninvasive, rapid measures of ovarian reserve.

Drawbacks of the tests

Both basal FSH testing and the CCCT are widely used, although support for their ability to predict ovarian reserve in the infertile population has been challenged recently. Newer data demonstrate that these tests are limited in their ability to predict outcome (pregnancy and response to superovulation drugs) in all but a narrow group of patients undergoing IVF. Performance is particularly limited in:

• young women
• women in the general infertility population who are not utilizing IVF.^9-13

Additional drawbacks of basal FSH testing and the CCCT include:

• significant variability of test results from cycle to cycle (intercycle variability)
• limited time frame within which the tests can be performed (intracycle variability).

The basal FSH test and CCCT have high specificity (98% to 99% for each) as an assessment of reproductive performance in infertile women and generate few false-positive results.^5,6 However, the high screen cutoffs that allow for such specificity come at a price: Few women will screen positive, and sensitivity of the tests is low (between 7% and 8% for basal FSH and between 25% and 40% for the CCCT). Such low sensitivity means that many women will not conceive after infertility treatment despite a normal test result.^5,11 Overall, the tests are not highly informative for many women who get tested.

Once abnormal, normal results are meaningless

Once an FSH level or the CCCT has ever been abnormal, the patient has diminished ovarian reserve; normal values in subsequent menstrual cycles do not improve the odds of pregnancy with treatment.¹⁴ This fact can be a significant source of confusion and frustration for patients.

3 | GnRH agonist stimulation —no better than FSH testing

This test was developed in the search for a very sensitive assessment of ovarian reserve. It was designed to uncover subtle abnormalities in pituitary and ovarian dynamics. It involves administering a gonadotropin-releasing hormone (GnRH) agonist such as leuprolide acetate (Lupron) on day 2 or 3 of the menstrual cycle and measuring pituitary and ovarian hormone responses.^5,15

One group of investigators demonstrated a correlation between stimulated estradiol levels and responsiveness during IVF,¹⁶ but other studies have shown that the test does not perform significantly better than day 3 FSH in predicting ovarian reserve.^17,18

The sensitivity of GnRH agonist testing for pregnancy is moderate (32% to 89%); specificity ranges from 79% to 97%.¹⁹

4 | Inhibin-B—not helpful when used alone

This glycoprotein hormone produced by granulosa cells of developing follicles is a direct measure of ovarian reserve when assessed in the early follicular phase of the menstrual cycle.²⁰ Women treated with IVF who have a low inhibin-B level—particularly when using cutoffs below the range of 45–80 pg/mL—have been shown to respond poorly to superovulation and have a lower pregnancy rate than women with high inhibin-B.^21,22 One group of investigators demonstrated that women with clinical evidence of diminished ovarian reserve but a normal FSH level also had low inhibin-B production, suggesting that it may be a more sensitive marker than FSH.²²

Inhibin-B testing involves a simple blood draw. However, the test has been incorporated into clinical assessment of ovarian reserve only to a limited degree, due to the lack of reliable assays and controversy concerning its prognostic value.²³

Because of these limitations, routine testing of serum inhibin-B in isolation of other markers of ovarian reserve is not recommended.

5 | Antral follicle count—good predictor of IVF outcome

Transvaginal ultrasonographic determination of the number of ovarian follicles that measure between 2 mm and 10 mm in diameter in the early follicular phase of the cycle yields the AFC. As a direct marker of the cohort of growing follicles in the early menstrual cycle, the AFC is believed to correlate strongly with the number of primordial follicles present in the ovary and, therefore, ovarian reserve. Total AFCs of less than 5 to 10 are suggestive of diminished ovarian reserve.^24,25

In IVF cycles, AFC has proven to be an accurate predictor of number of oocytes retrieved, risk of cycle cancellation, and odds of conception.^24,25 Some investigators have even suggested that, compared with other markers of ovarian reserve, AFC is the best independent predictor of outcome in IVF cycles.^7,26-27

In a group of normally cycling women with proven fertility, AFC also showed a strong correlation with age, declining slowly until age 37 and more rapidly thereafter.^28,29

AFC sensitivity for pregnancy is moderate and varies widely in published reports (8% to 60%), whereas specificity tends to be higher (33% to 96%).¹⁹

Drawbacks of AFC

• Because of the need to perform transvaginal ultrasonography, AFC is a more invasive and often more expensive test than hormonal biomarkers
• Accurate assessment of AFC requires an experienced sonographer and can be limited in patients who have had pelvic surgery or uterine fibroids and in those who are obese
• Moderate interobserver and intercycle variability of AFC determinations limits its reproducibility^29,30
• As with basal FSH measurement, the intercycle variability of AFC does not correlate well with IVF outcome in individual patients.³⁰

6 | Anti-Müllerian hormone— many advantages

The drawbacks of the tests just described— e.g., intercycle variability, lack of uniform cutoffs, and limited ability to predict IVF outcomes—make the development of more reliable measures of ovarian reserve a priority in reproductive medicine. AMH is a highly promising marker that appears to have many advantages over other tests and may have the greatest power to predict ovarian aging in women of reproductive age.

How it works

AMH is a glycoprotein growth factor and a member of the transforming growth factor-ß superfamily.³¹ It is primarily produced by the pool of early-growing follicles, which are believed to serve as a proxy for the number of primordial follicles in the ovary. The number of primordial follicles at a given point in time represents the ovarian reserve. AMH levels above 0.7 ng/mL are considered normal; values between 0.3 ng/mL and 0.7 ng/mL are consistent with borderline ovarian reserve, according to 2007 data from Reprosource Corp.

AMH has been studied as a marker of ovarian reserve for 6 years, with multiple reports describing declines in levels with age and with diminishing oocyte numbers. It is undetectable at menopause.³²

The age-related decline in AMH is gradual but measurable even in young women, consistently preceding changes in other markers of ovarian reserve such as FSH and inhibin-B.^32-35 The longitudinal changes in AMH have been demonstrated in ovulatory premenopausal women and healthy volunteers with proven fertility.^33,34 In one series of women followed over a mean of 4 years (ages 25 to 46), AMH testing was superior to day 3 FSH, inhibin-B, and AFC in its ability to predict the onset of cycle irregularity and the menopausal transition.³³

Does it predict oocyte quality?

AMH has performed well as a biomarker, comparable in most series to AFC and superior to FSH. AMH levels are strongly correlated with the number of oocytes retrieved during IVF and the odds of cycle cancellation due to poor response^35-41 —but does it accurately characterize oocyte quality, the other element of ovarian reserve?

Some reports have shown a strong association between AMH levels and surrogates of oocyte quality, including fertilization, oocyte morphology, embryo quality, and pregnancy and miscarriage rates,^36-41 but others have not.⁴² Some reports demonstrate a relationship between AMH and some but not all surrogate markers of oocyte quality.⁴⁰

Advantages of AMH

• It demonstrates minimal intracycle variability.^32,43-45 Compared with other markers of ovarian reserve, which must be measured early in the follicular phase of the menstrual cycle, AMH can be assessed at random times, making it a more convenient method for patients and physicians
• It demonstrates minimal intercycle variability^32,34
• AMH levels are not significantly affected by the hormonal changes of pregnancy, oral contraceptive use, or GnRH treatment, and can be measured in these settings.^46,47

Utility of AMH is limited in PCOS and obesity

The ability to use AMH as a marker of ovarian aging in women who have polycystic ovary syndrome (PCOS) and in women who are obese may be limited by the ovulatory dysfunction in these populations. Circulating levels of AMH are higher in women with PCOS than in unaffected women, a finding thought to be indicative of oligo-ovulation and poor follicular development in polycystic ovaries.^48-53

In a recent series investigating AMH levels in women with PCOS, AMH and the degree of insulin resistance were positively correlated, and the AMH level was negatively correlated with the number of menses in a year.⁴⁹ The consistently positive correlation between AMH and PCOS may suggest a future role for this marker as a diagnostic tool.

In obese women who do not have PCOS, AMH production may be lower than in women of normal weight. In a recent series, normally cycling obese women in the later reproductive years were shown to have an AMH level 70% lower than those in women who were not obese.⁵⁴ These differences have not been well studied in younger obese women.

Which test is best?

AMH may be preferable to the other tests to assess ovarian reserve because it can be measured any time during the menstrual cycle or between cycles. AMH measurement is also useful if a woman is taking oral contraceptives or leuprolide acetate because these medications may confound the results of the other test methods. In addition, AMH may be the earliest indicator of decline in ovarian reproductive function. As such, it may highlight cases that merit a search for other causes of infertility and make it possible to treat them in a timely manner.

Elevated AMH may reveal occult PCOS and warn of significant risk of ovarian hyperstimulation prior to ovulation induction with gonadotrophins, so that the clinician can plan smaller doses.

The University of Medicine and Dentistry of New Jersey (UMDNJ) owns a patent relating to the use of anti-Müllerian hormone/Müllerian inhibiting substance for predicting ovarian response in women with infertility. The patent is based in part on work that Dr. Seifer carried out while employed at UMDNJ. In accordance with UMDNJ policy, Dr. Seifer, a named inventor on this patent, assigned his interest in the invention to UMDNJ. UMDNJ has a licensing agreement with Diagnostic Systems Laboratory for the use of the claimed invention. Dr. Seifer receives a portion of the royalties, as determined by UMDNJ policy, that UMDNJ gains from this licensing agreement.

CASE: Borderline test result prompts referral

A 36-year-old nulliparous woman is seen in your office for evaluation after 6 months of infertility. She is ovulatory, and has been using an ovulation-prediction kit to time intercourse. You learn that she had Chlamydia trachomatis infection in the distant past, but elicit no other significant medical or surgical history. She reports that she smoked approximately one pack of cigarettes a day for 15 years but gave up smoking 5 years ago.

You order a hysterosalpingogram, followed by day 3 testing of follicle-stimulating hormone (FSH). The hysterosalpingogram is normal; the FSH level is 7.5 mIU/mL and the estradiol level is 30 pg/mL—both in the normal range.

The patient asks for testing of anti-Müllerian hormone (AMH; also known as Müllerian-inhibiting substance) because she has read that it is a new marker of fertility. The result is 0.5 ng/mL, a borderline value. After reviewing these results, you refer her to a reproductive endocrinologist for further management.

Was the test for AMH indicated? And is this referral appropriate?

The referral is entirely appropriate, even though the patient has not been trying to conceive for a full year. Why? The AMH value suggests that her ovarian reserve is in early decline. She would benefit from evaluation by a subspecialist who can review the entire spectrum of treatments, including aggressive options such as ovulation induction and in vitro fertilization (IVF), to optimize her reproductive success.

This article reviews the various biomarkers available to assess ovarian reserve in women who experience infertility:

• day 3 (basal) FSH
• clomiphene citrate challenge
• gonadotropin-releasing hormone (GnRH) agonist stimulation
• inhibin-B
• antral follicle count (AFC)
• AMH.

The AFC and AMH tend to detect the earliest changes in ovarian reserve, followed, sequentially, by inhibin-B, the clomiphene citrate challenge test (CCCT), and basal FSH.

The tests we describe are used primarily to assess treatment prognosis in infertile women. In time, however, appropriate population screening of ovarian reserve may be feasible to provide many more women with information about their reproductive potential and help them shape their life plan.

What makes a test valuable?

Ovarian reserve describes a woman’s reproductive potential—specifically, the number and quality of oocytes she possesses.¹ Biochemical tests of ovarian reserve emerged during the rise of assisted reproductive technologies (ART) in the late 1980s to predict both responsiveness to superovulation drugs and the odds of pregnancy with treatment.

Ideally, a test that assesses ovarian reserve should be affordable, straightforward, rapidly interpretable, and minimally invasive. It also should be able to detect changes that begin early in reproductive life. To be applicable to large populations of reproductive-age women, it should be of use anytime in the menstrual cycle, and should provide reproducible and highly accurate assessment of the reproductive aging process.

Our ability to offer tests that accurately measure ovarian reserve has a significant impact on women at risk of infertility and early menopause and on those who choose to delay childbearing for personal (nonmedical) reasons. These tests have become increasingly relevant because women are choosing to have their first child at a later age than their counterparts did 20 years ago:

• In 1980, 40% of women having their first baby were younger than 25 years, and only 5% were older than 35
• In 2000, 25% of women were younger than 25 when their first child was born, and 15% were older than 35.

Who should be tested?

Ovarian reserve is a complex clinical phenomenon that is influenced by age, genetics, and environmental variables. The decline in a woman’s ovarian reserve over time is irreversible; the trajectory of this decline is fundamental to the odds of fertility with age and the timing of the menopausal transition. At present, the markers used most often in clinical practice have some utility but also suffer from several drawbacks ( TABLE ).

For the general practitioner performing an infertility evaluation, we recommend focusing on the following groups of women for ovarian reserve testing:

• women over 30 years of age
• women with a history of exposure to a confirmed gonadotoxin, i.e., tobacco smoke, chemotherapy, radiation therapy
• women with a strong family history of early menopause or premature ovarian failure
• women who have had extensive ovarian surgery, i.e., cystectomy and unilateral oophorectomy.

Testing tends to have the highest yield in these groups. Women who have abnormal results should be referred to a reproductive endocrinologist for further evaluation and treatment.

The six tests are described below.

TABLE

How six markers of ovarian reserve stack up

1 | Basal FSH—widely used but only moderately informative

Day 3 FSH and the CCCT are the most widely used measures of ovarian reserve in ART practice. The use of early follicular-phase FSH as a marker of ovarian reserve and fertility was proposed 20 years ago with the emergence of IVF.^2-4 The test is an indirect assessment of ovarian reserve in that it measures pituitary production of FSH in response to feedback from ovarian hormones. Estradiol and inhibin-B reach a nadir early in the menstrual cycle; measuring FSH on day 3 offers a glimpse of the functioning of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise later in the cycle ( FIGURE 1 ).^5,6

FIGURE 1 The HPO axis

The FSH level opens a window onto the function of the hypothalamic–pituitary–ovarian axis before ovarian hormone levels rise in the cycle. Women who have normal ovarian reserve have sufficient ovarian hormone production early in the menstrual cycle to maintain FSH levels within the normal range. Conversely, a “monotropic” elevation in FSH—one that is unaccompanied by a rise in luteinizing hormone (LH)—reflects poor hormone production from an aging pool of ovarian follicles and disinhibition of FSH production.^5,6

FSH measurements are typically combined with estradiol to enhance the sensitivity of testing ( FIGURE 2, ). Premature elevations of estradiol early in the follicular phase are driven by rising FSH levels in women with declining ovarian reserve. Abnormally elevated estrogen levels then feed back negatively on pituitary production of FSH and mask an elevation that might otherwise reveal diminished ovarian reserve. Measurement of both FSH and estradiol on cycle day 3 may therefore help decrease the incidence of false-negative testing.

Commonly cited criteria for normal ovarian reserve are:

• early follicular phase FSH, <10 mIU/mL
• estradiol, <80 pg/mL¹

It is extremely important to note, however, that these are general guidelines and that cutoffs are both laboratory- and practice-specific.

FIGURE 2 Monthly and lifetime variations in estradiol and FSH

How 17ß-estradiol and follicle-stimulating hormone levels vary over the menstrual cycle (top) and a woman’s lifetime (bottom).

2 | Clomiphene citrate—more sensitive than FSH testing

Like basal FSH testing, the CCCT is an indirect assessment of ovarian reserve. Unlike FSH testing, the CCCT is provocative. It involves administration of 100 mg of clomiphene citrate (Clomid) on days 5 through 9 of the menstrual cycle, with FSH and estradiol measured on days 3 and 10. Once clomiphene citrate is administered, FSH and LH levels rise, followed by an increase in estradiol and inhibin. Evidence suggests that the smaller follicular cohorts in women with diminished ovarian reserve produce less inhibin-B and estradiol and, therefore, less negative feedback on clomiphene-induced pituitary FSH release.^6,7 The result: persistent elevation of the day 10 FSH value and a positive screen for diminished ovarian reserve.

In some women, day 10 FSH is elevated even after a normal day 3 value. This makes the CCCT more sensitive than basal FSH testing; it can identify women who might go unrecognized if evaluated by day 3 FSH and estradiol levels alone.

More expensive and labor-intensive than the alternatives

Interpretation of the CCCT requires that FSH and estradiol both be assessed on days 3 and 10. An elevated FSH (≥10 mIU/mL) on either day indicates diminished ovarian reserve. As with basal FSH testing, elevated estradiol (≥80 pg/mL) on day 3 is considered abnormal. The day 10 estradiol value of the CCCT reflects whether or not clomiphene citrate was administered appropriately, and should be elevated. However, the significance of the day 10 estradiol level has been debated with respect to its predictive value for pregnancy in infertile populations.⁸

The addition of day 10 FSH assessment improves the sensitivity of the CCCT over basal FSH measurement, but makes it a more expensive and labor-intensive test ( TABLE ).^5,6 The CCCT involves administration of clomiphene citrate, a safe drug (though it can have side effects), and two blood draws instead of one. Nevertheless, both tests are relatively noninvasive, rapid measures of ovarian reserve.

Drawbacks of the tests

Both basal FSH testing and the CCCT are widely used, although support for their ability to predict ovarian reserve in the infertile population has been challenged recently. Newer data demonstrate that these tests are limited in their ability to predict outcome (pregnancy and response to superovulation drugs) in all but a narrow group of patients undergoing IVF. Performance is particularly limited in:

• young women
• women in the general infertility population who are not utilizing IVF.^9-13

Additional drawbacks of basal FSH testing and the CCCT include:

• significant variability of test results from cycle to cycle (intercycle variability)
• limited time frame within which the tests can be performed (intracycle variability).

The basal FSH test and CCCT have high specificity (98% to 99% for each) as an assessment of reproductive performance in infertile women and generate few false-positive results.^5,6 However, the high screen cutoffs that allow for such specificity come at a price: Few women will screen positive, and sensitivity of the tests is low (between 7% and 8% for basal FSH and between 25% and 40% for the CCCT). Such low sensitivity means that many women will not conceive after infertility treatment despite a normal test result.^5,11 Overall, the tests are not highly informative for many women who get tested.

Once abnormal, normal results are meaningless

Once an FSH level or the CCCT has ever been abnormal, the patient has diminished ovarian reserve; normal values in subsequent menstrual cycles do not improve the odds of pregnancy with treatment.¹⁴ This fact can be a significant source of confusion and frustration for patients.

3 | GnRH agonist stimulation —no better than FSH testing

This test was developed in the search for a very sensitive assessment of ovarian reserve. It was designed to uncover subtle abnormalities in pituitary and ovarian dynamics. It involves administering a gonadotropin-releasing hormone (GnRH) agonist such as leuprolide acetate (Lupron) on day 2 or 3 of the menstrual cycle and measuring pituitary and ovarian hormone responses.^5,15

One group of investigators demonstrated a correlation between stimulated estradiol levels and responsiveness during IVF,¹⁶ but other studies have shown that the test does not perform significantly better than day 3 FSH in predicting ovarian reserve.^17,18

The sensitivity of GnRH agonist testing for pregnancy is moderate (32% to 89%); specificity ranges from 79% to 97%.¹⁹

4 | Inhibin-B—not helpful when used alone

This glycoprotein hormone produced by granulosa cells of developing follicles is a direct measure of ovarian reserve when assessed in the early follicular phase of the menstrual cycle.²⁰ Women treated with IVF who have a low inhibin-B level—particularly when using cutoffs below the range of 45–80 pg/mL—have been shown to respond poorly to superovulation and have a lower pregnancy rate than women with high inhibin-B.^21,22 One group of investigators demonstrated that women with clinical evidence of diminished ovarian reserve but a normal FSH level also had low inhibin-B production, suggesting that it may be a more sensitive marker than FSH.²²

Inhibin-B testing involves a simple blood draw. However, the test has been incorporated into clinical assessment of ovarian reserve only to a limited degree, due to the lack of reliable assays and controversy concerning its prognostic value.²³

Because of these limitations, routine testing of serum inhibin-B in isolation of other markers of ovarian reserve is not recommended.

5 | Antral follicle count—good predictor of IVF outcome

Transvaginal ultrasonographic determination of the number of ovarian follicles that measure between 2 mm and 10 mm in diameter in the early follicular phase of the cycle yields the AFC. As a direct marker of the cohort of growing follicles in the early menstrual cycle, the AFC is believed to correlate strongly with the number of primordial follicles present in the ovary and, therefore, ovarian reserve. Total AFCs of less than 5 to 10 are suggestive of diminished ovarian reserve.^24,25

In IVF cycles, AFC has proven to be an accurate predictor of number of oocytes retrieved, risk of cycle cancellation, and odds of conception.^24,25 Some investigators have even suggested that, compared with other markers of ovarian reserve, AFC is the best independent predictor of outcome in IVF cycles.^7,26-27

In a group of normally cycling women with proven fertility, AFC also showed a strong correlation with age, declining slowly until age 37 and more rapidly thereafter.^28,29

AFC sensitivity for pregnancy is moderate and varies widely in published reports (8% to 60%), whereas specificity tends to be higher (33% to 96%).¹⁹

Drawbacks of AFC

• Because of the need to perform transvaginal ultrasonography, AFC is a more invasive and often more expensive test than hormonal biomarkers
• Accurate assessment of AFC requires an experienced sonographer and can be limited in patients who have had pelvic surgery or uterine fibroids and in those who are obese
• Moderate interobserver and intercycle variability of AFC determinations limits its reproducibility^29,30
• As with basal FSH measurement, the intercycle variability of AFC does not correlate well with IVF outcome in individual patients.³⁰

6 | Anti-Müllerian hormone— many advantages

The drawbacks of the tests just described— e.g., intercycle variability, lack of uniform cutoffs, and limited ability to predict IVF outcomes—make the development of more reliable measures of ovarian reserve a priority in reproductive medicine. AMH is a highly promising marker that appears to have many advantages over other tests and may have the greatest power to predict ovarian aging in women of reproductive age.

How it works

AMH is a glycoprotein growth factor and a member of the transforming growth factor-ß superfamily.³¹ It is primarily produced by the pool of early-growing follicles, which are believed to serve as a proxy for the number of primordial follicles in the ovary. The number of primordial follicles at a given point in time represents the ovarian reserve. AMH levels above 0.7 ng/mL are considered normal; values between 0.3 ng/mL and 0.7 ng/mL are consistent with borderline ovarian reserve, according to 2007 data from Reprosource Corp.

AMH has been studied as a marker of ovarian reserve for 6 years, with multiple reports describing declines in levels with age and with diminishing oocyte numbers. It is undetectable at menopause.³²

The age-related decline in AMH is gradual but measurable even in young women, consistently preceding changes in other markers of ovarian reserve such as FSH and inhibin-B.^32-35 The longitudinal changes in AMH have been demonstrated in ovulatory premenopausal women and healthy volunteers with proven fertility.^33,34 In one series of women followed over a mean of 4 years (ages 25 to 46), AMH testing was superior to day 3 FSH, inhibin-B, and AFC in its ability to predict the onset of cycle irregularity and the menopausal transition.³³

Does it predict oocyte quality?

AMH has performed well as a biomarker, comparable in most series to AFC and superior to FSH. AMH levels are strongly correlated with the number of oocytes retrieved during IVF and the odds of cycle cancellation due to poor response^35-41 —but does it accurately characterize oocyte quality, the other element of ovarian reserve?

Some reports have shown a strong association between AMH levels and surrogates of oocyte quality, including fertilization, oocyte morphology, embryo quality, and pregnancy and miscarriage rates,^36-41 but others have not.⁴² Some reports demonstrate a relationship between AMH and some but not all surrogate markers of oocyte quality.⁴⁰

Advantages of AMH

• It demonstrates minimal intracycle variability.^32,43-45 Compared with other markers of ovarian reserve, which must be measured early in the follicular phase of the menstrual cycle, AMH can be assessed at random times, making it a more convenient method for patients and physicians
• It demonstrates minimal intercycle variability^32,34
• AMH levels are not significantly affected by the hormonal changes of pregnancy, oral contraceptive use, or GnRH treatment, and can be measured in these settings.^46,47

Utility of AMH is limited in PCOS and obesity

The ability to use AMH as a marker of ovarian aging in women who have polycystic ovary syndrome (PCOS) and in women who are obese may be limited by the ovulatory dysfunction in these populations. Circulating levels of AMH are higher in women with PCOS than in unaffected women, a finding thought to be indicative of oligo-ovulation and poor follicular development in polycystic ovaries.^48-53

In a recent series investigating AMH levels in women with PCOS, AMH and the degree of insulin resistance were positively correlated, and the AMH level was negatively correlated with the number of menses in a year.⁴⁹ The consistently positive correlation between AMH and PCOS may suggest a future role for this marker as a diagnostic tool.

In obese women who do not have PCOS, AMH production may be lower than in women of normal weight. In a recent series, normally cycling obese women in the later reproductive years were shown to have an AMH level 70% lower than those in women who were not obese.⁵⁴ These differences have not been well studied in younger obese women.

Which test is best?

AMH may be preferable to the other tests to assess ovarian reserve because it can be measured any time during the menstrual cycle or between cycles. AMH measurement is also useful if a woman is taking oral contraceptives or leuprolide acetate because these medications may confound the results of the other test methods. In addition, AMH may be the earliest indicator of decline in ovarian reproductive function. As such, it may highlight cases that merit a search for other causes of infertility and make it possible to treat them in a timely manner.

Elevated AMH may reveal occult PCOS and warn of significant risk of ovarian hyperstimulation prior to ovulation induction with gonadotrophins, so that the clinician can plan smaller doses.

The author has no financial relationships relevant to this article.

CASE: Inadvertent ureteral transection

A gynecologic surgeon operates via Pfannenstiel incision to remove a 12-cm complex left adnexal mass from a 36-year-old obese woman. When she discovers that the mass is densely adherent to the pelvic peritoneum, the surgeon incises the peritoneum lateral to the mass and opens the retroperitoneal space. However, the size and relative immobility of the mass, coupled with the low transverse incision, impair visualization of retroperitoneal structures.

The surgeon clamps and divides the ovarian vessels above the mass but, afterward, suspects that the ureter has been transected and that its ends are included within the clamps. She separates the ovarian vessels above the clamp and ligates them, at which time transection of the ureter is confirmed.

How should she proceed?

The ureter is intimately associated with the female internal genitalia in a way that challenges the gynecologic surgeon to avoid it. In a small percentage of cases involving surgical extirpation in a woman who has severe pelvic pathology, ureteral injury may be inevitable.

Several variables predispose a patient to ureteral injury, including limited exposure, as in the opening case. Others include distorted anatomy of the urinary tract relative to internal genitalia and operations that require extensive resection of pelvic tissues.

This article describes:

• prevention and intraoperative recognition of ureteral injury during gynecologic surgery
• management of intraoperatively recognized ureteral injury.

Maintain a high index of suspicion

The surgeon in the opening case has already taken the first and most important step in ensuring a good outcome: She suspected ureteral injury. In high-risk situations, intraoperative recognition of ureteral injury is more likely when the operative field is inspected thoroughly during and at the conclusion of the surgical procedure.

In a high-risk case, the combined use of intravenous indigo carmine, careful inspection of the operative field, cystoscopy, and ureteral dissection is recommended and should be routine.

Common sites of injury

During gynecologic surgery, the ureter is susceptible to injury along its entire course through the pelvis (see “The ureter takes a course fraught with hazard,”).

During adnexectomy, the gonadal vessels are generally ligated 2 to 3 cm above the adnexa. The ureter lies in close proximity to these vessels and may inadvertently be included in the ligation.

During hysterectomy, the ureter is susceptible to injury as it passes through the parametrium a short distance from the uterus and vaginal fornix.

Sutures placed in the posterior lateral cul de sac during prolapse surgery lie near the midpelvic ureter, and sutures placed during vaginal cuff closure, anterior colporrhaphy, and retropubic urethropexy are in close proximity to the trigonal portion of the ureter.

The ureter takes a course fraught with hazard

The ureter extends from the renal pelvis to the bladder, with a length that ranges from 25 to 30 cm, depending on the patient’s height. It crosses the pelvic brim near the bifurcation of the common iliac artery, where it becomes the “pelvic” ureter. The abdominal and pelvic portions of the ureter are approximately equal in length.

ILLUSTRATIONS BY ROB FLEWELL FOR OBG MANAGEMENT

The blood supply of the ureter derives from branches of the major arterial system of the lower abdomen and pelvis. These branches reach the medial aspect of the abdominal ureter and the lateral side of the pelvic ureter to form an anastomotic vascular network protected by an adventitial layer surrounding the ureter.

The ureter is attached to the posterior lateral pelvic peritoneum running dorsal to ovarian vessels. At the midpelvis, it separates from the peritoneum to pierce the base of the broad ligament underneath the uterine artery. At this point, the ureter is about 1.5 to 2 cm lateral to the uterus and curves medially and ventrally, tunneling through the cardinal and vesicovaginal ligaments to enter the bladder trigone.

Risky procedures

In gynecologic surgery, ureteral injury occurs most often during abdominal hysterectomy—probably because of how frequently this operation is performed and the range of pathology managed. The incidence of ureteral injury is much higher during abdominal hysterectomy than vaginal hysterectomy.^1-4

Laparoscopic hysterectomy also has been associated with a higher incidence of ureteral injury, especially in the early phase of training.^5,6 Possible explanations include:

• greater difficulty identifying the ureter
• a steeper learning curve
• more frequent use of energy to hemostatically divide pedicles, with the potential for thermal injury
• less traction–countertraction, resulting in dissection closer to the ureter
• management of complex pathology.

Although the overall incidence of ureteral injury during adnexectomy is low, it is probably much higher in women undergoing this procedure after a previous hysterectomy or in the presence of complex adnexal pathology.

When injury is likely

Compromised exposure, distorted anatomy, and certain procedures can heighten the risk of ureteral injury. Large tumors may limit the ability of the surgeon to visualize or palpate the ureter (FIGURE 1). Extensive adhesions may cause similar difficulties, and a small incision or obesity may hinder identification of pelvic sidewall structures.

A number of pathologic conditions can distort the anatomy of the ureter, especially as it relates to the female genital tract:

• Malignancies such as ovarian cancer often encroach on and occasionally encase the ureter
• Pelvic inflammatory disease, endometriosis, and a history of surgery or pelvic radiotherapy can retract and encase the ureter toward the gynecologic tract
• Some masses expand against the lower ureter, such as cervical or broad-ligament leiomyomata or placenta previa with accreta
• During vaginal hysterectomy for complete uterine prolapse, the ureters frequently extend beyond the introitus well within the operative field
• Congenital anomalies of the ureter or hydroureter can also cause distortion.

Even in the presence of relatively normal anatomy, certain procedures predispose the ureter to injury. For example, radical hysterectomy involves the almost complete separation of the pelvic ureter from the gynecologic tract and its surrounding soft tissue. When pelvic pathology is significant, the plane of dissection will always be near the ureter.

FIGURE 1 Access to the ureter is obstructed, putting it in jeopardy

Large tumors may limit the ability of the surgeon to visualize or palpate the ureter.

Prevention is the best strategy

At least 50% of ureteral injuries reported during gynecologic surgery have occurred in the absence of a recognizable risk factor.^2,7 Nevertheless, knowledge of anatomy and the ability to recognize situations in which there is an elevated risk for ureteral injury will best enable the surgeon to prevent such injury.

When a high-risk situation is encountered, critical preventive steps include:

• adequate exposure
• competent assistance
• exposure of the path of the ureter through the planned course of dissection. Dissecting the ureter beyond this area is usually unnecessary and may itself cause injury.

Skip preoperative IVP in most cases

The vast majority of women who undergo gynecologic surgery do not benefit from preoperative intravenous pyelography (IVP). This measure does not appear to reduce the likelihood of ureteral injury, even in the face of obvious gynecologic disease. However, preoperative identification of obvious ureteral involvement by the disease process is useful. In such cases, the plane of dissection will probably lie closer to the ureter. One of the goals of surgery will then be to clear the urinary tract from the affected area.

When there is a high index of suspicion of an abnormality such as obstruction, intrinsic ureteral endometriosis, or congenital anomaly, preoperative IVP is indicated.

A stent may be helpful in some cases

Ureteral stents are sometimes placed in order to aid in identification and dissection of the ureters during surgery. Some authors of reports on this topic, including Hoffman, believe that stents are useful in certain situations, such as excision of an ovarian remnant, radical vaginal hysterectomy, and when pelvic organs are encased by malignant ovarian tumors. However, stents do not clearly reduce the risk of injury and, in some cases, may increase the risk by providing a false sense of security and predisposing the ureter to adventitial injury during difficult dissection.

Anticipate the effects of disease

The surgeon must have a thorough knowledge of the gynecologic disease process as it relates to surgery involving the urinary tract. For example, an ovarian remnant will almost always be somewhat densely adherent to the pelvic ureter. When severe endometriosis involves the posterior leaf of the broad ligament, the ureter will often be fibrotically retracted toward the operative field.

Certain procedures have special challenges. During resection of adnexa, for example, it is important that the ureter be identified in the retroperitoneum before the ovarian vessels are ligated. During hysterectomy, soft tissues that contain the bladder and ureters should be mobilized caudally and laterally, respectively, creating a U-shaped region (“U” for urinary tract, FIGURE 2) to which the surgeon must limit dissection.

FIGURE 2 During hysterectomy, mobilize the bladder and ureter

Mobilize the soft tissues that contain the bladder and ureters caudally and laterally, respectively, creating a U-shaped region. During division of the paracervical tissues, the surgeon must remain within this region.

Intraoperative detection

Two main types of ureteral injury occur during gynecologic surgery: transection and destruction. The latter includes ligation, crushing, devascularization, and thermal injury.

Intraoperative detection of ureteral injury is more likely when the surgeon recognizes at the outset that the operation places the ureter at increased risk. When dissection has been difficult or complicated for any reason, be concerned about possible injury.

In general, ureteral injury is first recognized by careful inspection of the surgical field. Begin by instilling 5 ml of indigo carmine intravenously. Once the dye begins to appear in the Foley catheter, inspect the area of dissection under a small amount of irrigation fluid, looking for extravasation of dye that indicates partial or complete transection.

If no injury is identified, cystoscopy is the next step. I perform all major abdominal operations with the patient in the low lithotomy position, which provides easy access to the perineum. Cystoscopic identification of urine jetting from both ureteral orifices confirms patency. When only wisps of dye are observed, it is likely that the ureter in question has been partially occluded (e.g., by acute angulation). Failure of any urine to appear from one of the orifices highly suggests injury to that ureter.

During inspection of the operative field, attempt to pass a ureteral stent into the affected orifice. If the stent passes easily and dyed urine is seen to drip freely from it, look for possible angulation of the ureter. If you find none, remove the stent and inspect the orifice again for jetting urine.

If the ureteral stent will move only a few centimeters into the ureteral orifice, ligation (with or without transection) is likely. In this case, leave the stent in place. If the operative site is readily accessible, dissect the applicable area to identify the problem. Depending on the circumstances, you may wish to infuse dye through the stent to aid in operative identification or radiographic evaluation.

Intraoperative IVP may be useful, especially when cystoscopy is unavailable.

Fundamentals of repair

Repair of major injury to the pelvic ureter is generally best accomplished by ureteroneocystostomy or, in selected cases involving injury to the proximal pelvic ureter, by ureteroureterostomy.

When intraoperatively recognized injury to the pelvic ureter appears to be minor, it can be managed by placing a ureteral stent and a closed-suction pelvic drain. Also consider wrapping the injured area with vascularized tissue such as perivesical fat. Minor lacerations can be closed perpendicular to the axis of the ureter using interrupted 4-0 delayed absorbable suture.

Most injuries to the pelvic ureter are optimally managed by ureteroneocystostomy (FIGURE 3). When a significant portion of the pelvic ureter has been lost, ureteroneocystostomy usually requires a combination of:

• extensive mobilization of the bladder
• conservative mobilization of the ureter
• elongation of the bladder
• psoas hitch.

When necessary, mobilization of the kidney with suturing of the caudal perinephric fascia to the psoas muscle will bridge an additional 2- to 3-cm gap.

Major injury to the distal half of the pelvic ureter is repaired using straightforward ureteroneocystostomy.

When there is no significant pelvic disease and the distal ureter is healthy, injury to the proximal pelvic ureter during division of the ovarian vessels may be repaired via ureteroureterostomy. If the ureteral ends will be anastomosed on tension or there is any question about the integrity of the distal portion of the ureter, as when extensive distal ureterolysis has been necessary, consider ureteroneocystostomy.

FIGURE 3 When the distal ureter is injured

Most injuries to the pelvic ureter are managed optimally by ureteroneocystostomy.

Postoperative management

After repair of a ureteral injury, leave a closed-suction pelvic drain in place for 2 to 3 days so that any major urinary leak can be detected; it also enhances spontaneous closure and helps prevent potentially infected fluid from accumulating in the region of anastomosis.

The cystotomy performed during ureteroneocystostomy generally heals quickly with a low risk of complications.

Leave a large-bore (20 or 22 French) urethral Foley catheter in place for 2 weeks.

I recommend that a 6 French double-J ureteral stent be left in place for 6 weeks. Potential benefits of the stent include:

• prevention of stricture
• stabilization and immobilization of the ureter during healing
• reduced risk of extravasation of urine
• reduced risk of angulation of the ureter
• isolation of the repair from infection, retroperitoneal fibrosis, and cancer.

I perform IVP approximately 1 week after stent removal to ensure ureteral patency.

CASE RESOLVED

Exposure is improved by widening the incision and dividing the tendonous insertions of the rectus abdominus muscles. The surgeon then removes the mass, preserving the distal ureter, which is estimated to be 12 cm in length and to have intact adventitia.

The surgeon performs a double-spatulated end-to-end ureteroureterostomy over a 6 French double-J ureteral stent that has been passed proximally into the renal pelvis and distally into the bladder. The stent is removed 6 weeks postoperatively, and an IVP the following week demonstrates excellent patency.

The author has no financial relationships relevant to this article.

CASE: Inadvertent ureteral transection

A gynecologic surgeon operates via Pfannenstiel incision to remove a 12-cm complex left adnexal mass from a 36-year-old obese woman. When she discovers that the mass is densely adherent to the pelvic peritoneum, the surgeon incises the peritoneum lateral to the mass and opens the retroperitoneal space. However, the size and relative immobility of the mass, coupled with the low transverse incision, impair visualization of retroperitoneal structures.

The surgeon clamps and divides the ovarian vessels above the mass but, afterward, suspects that the ureter has been transected and that its ends are included within the clamps. She separates the ovarian vessels above the clamp and ligates them, at which time transection of the ureter is confirmed.

How should she proceed?

The ureter is intimately associated with the female internal genitalia in a way that challenges the gynecologic surgeon to avoid it. In a small percentage of cases involving surgical extirpation in a woman who has severe pelvic pathology, ureteral injury may be inevitable.

Several variables predispose a patient to ureteral injury, including limited exposure, as in the opening case. Others include distorted anatomy of the urinary tract relative to internal genitalia and operations that require extensive resection of pelvic tissues.

This article describes:

• prevention and intraoperative recognition of ureteral injury during gynecologic surgery
• management of intraoperatively recognized ureteral injury.

Maintain a high index of suspicion

The surgeon in the opening case has already taken the first and most important step in ensuring a good outcome: She suspected ureteral injury. In high-risk situations, intraoperative recognition of ureteral injury is more likely when the operative field is inspected thoroughly during and at the conclusion of the surgical procedure.

In a high-risk case, the combined use of intravenous indigo carmine, careful inspection of the operative field, cystoscopy, and ureteral dissection is recommended and should be routine.

Common sites of injury

During gynecologic surgery, the ureter is susceptible to injury along its entire course through the pelvis (see “The ureter takes a course fraught with hazard,”).

During adnexectomy, the gonadal vessels are generally ligated 2 to 3 cm above the adnexa. The ureter lies in close proximity to these vessels and may inadvertently be included in the ligation.

During hysterectomy, the ureter is susceptible to injury as it passes through the parametrium a short distance from the uterus and vaginal fornix.

Sutures placed in the posterior lateral cul de sac during prolapse surgery lie near the midpelvic ureter, and sutures placed during vaginal cuff closure, anterior colporrhaphy, and retropubic urethropexy are in close proximity to the trigonal portion of the ureter.

The ureter takes a course fraught with hazard

The ureter extends from the renal pelvis to the bladder, with a length that ranges from 25 to 30 cm, depending on the patient’s height. It crosses the pelvic brim near the bifurcation of the common iliac artery, where it becomes the “pelvic” ureter. The abdominal and pelvic portions of the ureter are approximately equal in length.

ILLUSTRATIONS BY ROB FLEWELL FOR OBG MANAGEMENT

The blood supply of the ureter derives from branches of the major arterial system of the lower abdomen and pelvis. These branches reach the medial aspect of the abdominal ureter and the lateral side of the pelvic ureter to form an anastomotic vascular network protected by an adventitial layer surrounding the ureter.

The ureter is attached to the posterior lateral pelvic peritoneum running dorsal to ovarian vessels. At the midpelvis, it separates from the peritoneum to pierce the base of the broad ligament underneath the uterine artery. At this point, the ureter is about 1.5 to 2 cm lateral to the uterus and curves medially and ventrally, tunneling through the cardinal and vesicovaginal ligaments to enter the bladder trigone.

Risky procedures

In gynecologic surgery, ureteral injury occurs most often during abdominal hysterectomy—probably because of how frequently this operation is performed and the range of pathology managed. The incidence of ureteral injury is much higher during abdominal hysterectomy than vaginal hysterectomy.^1-4

Laparoscopic hysterectomy also has been associated with a higher incidence of ureteral injury, especially in the early phase of training.^5,6 Possible explanations include:

• greater difficulty identifying the ureter
• a steeper learning curve
• more frequent use of energy to hemostatically divide pedicles, with the potential for thermal injury
• less traction–countertraction, resulting in dissection closer to the ureter
• management of complex pathology.

Although the overall incidence of ureteral injury during adnexectomy is low, it is probably much higher in women undergoing this procedure after a previous hysterectomy or in the presence of complex adnexal pathology.

When injury is likely

Compromised exposure, distorted anatomy, and certain procedures can heighten the risk of ureteral injury. Large tumors may limit the ability of the surgeon to visualize or palpate the ureter (FIGURE 1). Extensive adhesions may cause similar difficulties, and a small incision or obesity may hinder identification of pelvic sidewall structures.

A number of pathologic conditions can distort the anatomy of the ureter, especially as it relates to the female genital tract:

• Malignancies such as ovarian cancer often encroach on and occasionally encase the ureter
• Pelvic inflammatory disease, endometriosis, and a history of surgery or pelvic radiotherapy can retract and encase the ureter toward the gynecologic tract
• Some masses expand against the lower ureter, such as cervical or broad-ligament leiomyomata or placenta previa with accreta
• During vaginal hysterectomy for complete uterine prolapse, the ureters frequently extend beyond the introitus well within the operative field
• Congenital anomalies of the ureter or hydroureter can also cause distortion.

Even in the presence of relatively normal anatomy, certain procedures predispose the ureter to injury. For example, radical hysterectomy involves the almost complete separation of the pelvic ureter from the gynecologic tract and its surrounding soft tissue. When pelvic pathology is significant, the plane of dissection will always be near the ureter.

FIGURE 1 Access to the ureter is obstructed, putting it in jeopardy

Large tumors may limit the ability of the surgeon to visualize or palpate the ureter.

Prevention is the best strategy

At least 50% of ureteral injuries reported during gynecologic surgery have occurred in the absence of a recognizable risk factor.^2,7 Nevertheless, knowledge of anatomy and the ability to recognize situations in which there is an elevated risk for ureteral injury will best enable the surgeon to prevent such injury.

When a high-risk situation is encountered, critical preventive steps include:

• adequate exposure
• competent assistance
• exposure of the path of the ureter through the planned course of dissection. Dissecting the ureter beyond this area is usually unnecessary and may itself cause injury.

Skip preoperative IVP in most cases

The vast majority of women who undergo gynecologic surgery do not benefit from preoperative intravenous pyelography (IVP). This measure does not appear to reduce the likelihood of ureteral injury, even in the face of obvious gynecologic disease. However, preoperative identification of obvious ureteral involvement by the disease process is useful. In such cases, the plane of dissection will probably lie closer to the ureter. One of the goals of surgery will then be to clear the urinary tract from the affected area.

When there is a high index of suspicion of an abnormality such as obstruction, intrinsic ureteral endometriosis, or congenital anomaly, preoperative IVP is indicated.

A stent may be helpful in some cases

Ureteral stents are sometimes placed in order to aid in identification and dissection of the ureters during surgery. Some authors of reports on this topic, including Hoffman, believe that stents are useful in certain situations, such as excision of an ovarian remnant, radical vaginal hysterectomy, and when pelvic organs are encased by malignant ovarian tumors. However, stents do not clearly reduce the risk of injury and, in some cases, may increase the risk by providing a false sense of security and predisposing the ureter to adventitial injury during difficult dissection.

Anticipate the effects of disease

The surgeon must have a thorough knowledge of the gynecologic disease process as it relates to surgery involving the urinary tract. For example, an ovarian remnant will almost always be somewhat densely adherent to the pelvic ureter. When severe endometriosis involves the posterior leaf of the broad ligament, the ureter will often be fibrotically retracted toward the operative field.

Certain procedures have special challenges. During resection of adnexa, for example, it is important that the ureter be identified in the retroperitoneum before the ovarian vessels are ligated. During hysterectomy, soft tissues that contain the bladder and ureters should be mobilized caudally and laterally, respectively, creating a U-shaped region (“U” for urinary tract, FIGURE 2) to which the surgeon must limit dissection.

FIGURE 2 During hysterectomy, mobilize the bladder and ureter

Mobilize the soft tissues that contain the bladder and ureters caudally and laterally, respectively, creating a U-shaped region. During division of the paracervical tissues, the surgeon must remain within this region.

Intraoperative detection

Two main types of ureteral injury occur during gynecologic surgery: transection and destruction. The latter includes ligation, crushing, devascularization, and thermal injury.

Intraoperative detection of ureteral injury is more likely when the surgeon recognizes at the outset that the operation places the ureter at increased risk. When dissection has been difficult or complicated for any reason, be concerned about possible injury.

In general, ureteral injury is first recognized by careful inspection of the surgical field. Begin by instilling 5 ml of indigo carmine intravenously. Once the dye begins to appear in the Foley catheter, inspect the area of dissection under a small amount of irrigation fluid, looking for extravasation of dye that indicates partial or complete transection.

If no injury is identified, cystoscopy is the next step. I perform all major abdominal operations with the patient in the low lithotomy position, which provides easy access to the perineum. Cystoscopic identification of urine jetting from both ureteral orifices confirms patency. When only wisps of dye are observed, it is likely that the ureter in question has been partially occluded (e.g., by acute angulation). Failure of any urine to appear from one of the orifices highly suggests injury to that ureter.

During inspection of the operative field, attempt to pass a ureteral stent into the affected orifice. If the stent passes easily and dyed urine is seen to drip freely from it, look for possible angulation of the ureter. If you find none, remove the stent and inspect the orifice again for jetting urine.

If the ureteral stent will move only a few centimeters into the ureteral orifice, ligation (with or without transection) is likely. In this case, leave the stent in place. If the operative site is readily accessible, dissect the applicable area to identify the problem. Depending on the circumstances, you may wish to infuse dye through the stent to aid in operative identification or radiographic evaluation.

Intraoperative IVP may be useful, especially when cystoscopy is unavailable.

Fundamentals of repair

Repair of major injury to the pelvic ureter is generally best accomplished by ureteroneocystostomy or, in selected cases involving injury to the proximal pelvic ureter, by ureteroureterostomy.

When intraoperatively recognized injury to the pelvic ureter appears to be minor, it can be managed by placing a ureteral stent and a closed-suction pelvic drain. Also consider wrapping the injured area with vascularized tissue such as perivesical fat. Minor lacerations can be closed perpendicular to the axis of the ureter using interrupted 4-0 delayed absorbable suture.

Most injuries to the pelvic ureter are optimally managed by ureteroneocystostomy (FIGURE 3). When a significant portion of the pelvic ureter has been lost, ureteroneocystostomy usually requires a combination of:

• extensive mobilization of the bladder
• conservative mobilization of the ureter
• elongation of the bladder
• psoas hitch.

When necessary, mobilization of the kidney with suturing of the caudal perinephric fascia to the psoas muscle will bridge an additional 2- to 3-cm gap.

Major injury to the distal half of the pelvic ureter is repaired using straightforward ureteroneocystostomy.

When there is no significant pelvic disease and the distal ureter is healthy, injury to the proximal pelvic ureter during division of the ovarian vessels may be repaired via ureteroureterostomy. If the ureteral ends will be anastomosed on tension or there is any question about the integrity of the distal portion of the ureter, as when extensive distal ureterolysis has been necessary, consider ureteroneocystostomy.

FIGURE 3 When the distal ureter is injured

Most injuries to the pelvic ureter are managed optimally by ureteroneocystostomy.

Postoperative management

After repair of a ureteral injury, leave a closed-suction pelvic drain in place for 2 to 3 days so that any major urinary leak can be detected; it also enhances spontaneous closure and helps prevent potentially infected fluid from accumulating in the region of anastomosis.

The cystotomy performed during ureteroneocystostomy generally heals quickly with a low risk of complications.

Leave a large-bore (20 or 22 French) urethral Foley catheter in place for 2 weeks.

I recommend that a 6 French double-J ureteral stent be left in place for 6 weeks. Potential benefits of the stent include:

• prevention of stricture
• stabilization and immobilization of the ureter during healing
• reduced risk of extravasation of urine
• reduced risk of angulation of the ureter
• isolation of the repair from infection, retroperitoneal fibrosis, and cancer.

I perform IVP approximately 1 week after stent removal to ensure ureteral patency.

CASE RESOLVED

Exposure is improved by widening the incision and dividing the tendonous insertions of the rectus abdominus muscles. The surgeon then removes the mass, preserving the distal ureter, which is estimated to be 12 cm in length and to have intact adventitia.

The surgeon performs a double-spatulated end-to-end ureteroureterostomy over a 6 French double-J ureteral stent that has been passed proximally into the renal pelvis and distally into the bladder. The stent is removed 6 weeks postoperatively, and an IVP the following week demonstrates excellent patency.

The author has no financial relationships relevant to this article.

CASE: Inadvertent ureteral transection

A gynecologic surgeon operates via Pfannenstiel incision to remove a 12-cm complex left adnexal mass from a 36-year-old obese woman. When she discovers that the mass is densely adherent to the pelvic peritoneum, the surgeon incises the peritoneum lateral to the mass and opens the retroperitoneal space. However, the size and relative immobility of the mass, coupled with the low transverse incision, impair visualization of retroperitoneal structures.

The surgeon clamps and divides the ovarian vessels above the mass but, afterward, suspects that the ureter has been transected and that its ends are included within the clamps. She separates the ovarian vessels above the clamp and ligates them, at which time transection of the ureter is confirmed.

How should she proceed?

The ureter is intimately associated with the female internal genitalia in a way that challenges the gynecologic surgeon to avoid it. In a small percentage of cases involving surgical extirpation in a woman who has severe pelvic pathology, ureteral injury may be inevitable.

Several variables predispose a patient to ureteral injury, including limited exposure, as in the opening case. Others include distorted anatomy of the urinary tract relative to internal genitalia and operations that require extensive resection of pelvic tissues.

This article describes:

• prevention and intraoperative recognition of ureteral injury during gynecologic surgery
• management of intraoperatively recognized ureteral injury.

Maintain a high index of suspicion

The surgeon in the opening case has already taken the first and most important step in ensuring a good outcome: She suspected ureteral injury. In high-risk situations, intraoperative recognition of ureteral injury is more likely when the operative field is inspected thoroughly during and at the conclusion of the surgical procedure.

In a high-risk case, the combined use of intravenous indigo carmine, careful inspection of the operative field, cystoscopy, and ureteral dissection is recommended and should be routine.

Common sites of injury

During gynecologic surgery, the ureter is susceptible to injury along its entire course through the pelvis (see “The ureter takes a course fraught with hazard,”).

During adnexectomy, the gonadal vessels are generally ligated 2 to 3 cm above the adnexa. The ureter lies in close proximity to these vessels and may inadvertently be included in the ligation.

During hysterectomy, the ureter is susceptible to injury as it passes through the parametrium a short distance from the uterus and vaginal fornix.

Sutures placed in the posterior lateral cul de sac during prolapse surgery lie near the midpelvic ureter, and sutures placed during vaginal cuff closure, anterior colporrhaphy, and retropubic urethropexy are in close proximity to the trigonal portion of the ureter.

The ureter takes a course fraught with hazard

The ureter extends from the renal pelvis to the bladder, with a length that ranges from 25 to 30 cm, depending on the patient’s height. It crosses the pelvic brim near the bifurcation of the common iliac artery, where it becomes the “pelvic” ureter. The abdominal and pelvic portions of the ureter are approximately equal in length.

ILLUSTRATIONS BY ROB FLEWELL FOR OBG MANAGEMENT

The blood supply of the ureter derives from branches of the major arterial system of the lower abdomen and pelvis. These branches reach the medial aspect of the abdominal ureter and the lateral side of the pelvic ureter to form an anastomotic vascular network protected by an adventitial layer surrounding the ureter.

The ureter is attached to the posterior lateral pelvic peritoneum running dorsal to ovarian vessels. At the midpelvis, it separates from the peritoneum to pierce the base of the broad ligament underneath the uterine artery. At this point, the ureter is about 1.5 to 2 cm lateral to the uterus and curves medially and ventrally, tunneling through the cardinal and vesicovaginal ligaments to enter the bladder trigone.

Risky procedures

In gynecologic surgery, ureteral injury occurs most often during abdominal hysterectomy—probably because of how frequently this operation is performed and the range of pathology managed. The incidence of ureteral injury is much higher during abdominal hysterectomy than vaginal hysterectomy.^1-4

Laparoscopic hysterectomy also has been associated with a higher incidence of ureteral injury, especially in the early phase of training.^5,6 Possible explanations include:

• greater difficulty identifying the ureter
• a steeper learning curve
• more frequent use of energy to hemostatically divide pedicles, with the potential for thermal injury
• less traction–countertraction, resulting in dissection closer to the ureter
• management of complex pathology.

Although the overall incidence of ureteral injury during adnexectomy is low, it is probably much higher in women undergoing this procedure after a previous hysterectomy or in the presence of complex adnexal pathology.

When injury is likely

Compromised exposure, distorted anatomy, and certain procedures can heighten the risk of ureteral injury. Large tumors may limit the ability of the surgeon to visualize or palpate the ureter (FIGURE 1). Extensive adhesions may cause similar difficulties, and a small incision or obesity may hinder identification of pelvic sidewall structures.

A number of pathologic conditions can distort the anatomy of the ureter, especially as it relates to the female genital tract:

• Malignancies such as ovarian cancer often encroach on and occasionally encase the ureter
• Pelvic inflammatory disease, endometriosis, and a history of surgery or pelvic radiotherapy can retract and encase the ureter toward the gynecologic tract
• Some masses expand against the lower ureter, such as cervical or broad-ligament leiomyomata or placenta previa with accreta
• During vaginal hysterectomy for complete uterine prolapse, the ureters frequently extend beyond the introitus well within the operative field
• Congenital anomalies of the ureter or hydroureter can also cause distortion.

Even in the presence of relatively normal anatomy, certain procedures predispose the ureter to injury. For example, radical hysterectomy involves the almost complete separation of the pelvic ureter from the gynecologic tract and its surrounding soft tissue. When pelvic pathology is significant, the plane of dissection will always be near the ureter.

FIGURE 1 Access to the ureter is obstructed, putting it in jeopardy

Large tumors may limit the ability of the surgeon to visualize or palpate the ureter.

Prevention is the best strategy

At least 50% of ureteral injuries reported during gynecologic surgery have occurred in the absence of a recognizable risk factor.^2,7 Nevertheless, knowledge of anatomy and the ability to recognize situations in which there is an elevated risk for ureteral injury will best enable the surgeon to prevent such injury.

When a high-risk situation is encountered, critical preventive steps include:

• adequate exposure
• competent assistance
• exposure of the path of the ureter through the planned course of dissection. Dissecting the ureter beyond this area is usually unnecessary and may itself cause injury.

Skip preoperative IVP in most cases

The vast majority of women who undergo gynecologic surgery do not benefit from preoperative intravenous pyelography (IVP). This measure does not appear to reduce the likelihood of ureteral injury, even in the face of obvious gynecologic disease. However, preoperative identification of obvious ureteral involvement by the disease process is useful. In such cases, the plane of dissection will probably lie closer to the ureter. One of the goals of surgery will then be to clear the urinary tract from the affected area.

When there is a high index of suspicion of an abnormality such as obstruction, intrinsic ureteral endometriosis, or congenital anomaly, preoperative IVP is indicated.

A stent may be helpful in some cases

Ureteral stents are sometimes placed in order to aid in identification and dissection of the ureters during surgery. Some authors of reports on this topic, including Hoffman, believe that stents are useful in certain situations, such as excision of an ovarian remnant, radical vaginal hysterectomy, and when pelvic organs are encased by malignant ovarian tumors. However, stents do not clearly reduce the risk of injury and, in some cases, may increase the risk by providing a false sense of security and predisposing the ureter to adventitial injury during difficult dissection.

Anticipate the effects of disease

The surgeon must have a thorough knowledge of the gynecologic disease process as it relates to surgery involving the urinary tract. For example, an ovarian remnant will almost always be somewhat densely adherent to the pelvic ureter. When severe endometriosis involves the posterior leaf of the broad ligament, the ureter will often be fibrotically retracted toward the operative field.

Certain procedures have special challenges. During resection of adnexa, for example, it is important that the ureter be identified in the retroperitoneum before the ovarian vessels are ligated. During hysterectomy, soft tissues that contain the bladder and ureters should be mobilized caudally and laterally, respectively, creating a U-shaped region (“U” for urinary tract, FIGURE 2) to which the surgeon must limit dissection.

FIGURE 2 During hysterectomy, mobilize the bladder and ureter

Mobilize the soft tissues that contain the bladder and ureters caudally and laterally, respectively, creating a U-shaped region. During division of the paracervical tissues, the surgeon must remain within this region.

Intraoperative detection

Two main types of ureteral injury occur during gynecologic surgery: transection and destruction. The latter includes ligation, crushing, devascularization, and thermal injury.

Intraoperative detection of ureteral injury is more likely when the surgeon recognizes at the outset that the operation places the ureter at increased risk. When dissection has been difficult or complicated for any reason, be concerned about possible injury.

In general, ureteral injury is first recognized by careful inspection of the surgical field. Begin by instilling 5 ml of indigo carmine intravenously. Once the dye begins to appear in the Foley catheter, inspect the area of dissection under a small amount of irrigation fluid, looking for extravasation of dye that indicates partial or complete transection.

If no injury is identified, cystoscopy is the next step. I perform all major abdominal operations with the patient in the low lithotomy position, which provides easy access to the perineum. Cystoscopic identification of urine jetting from both ureteral orifices confirms patency. When only wisps of dye are observed, it is likely that the ureter in question has been partially occluded (e.g., by acute angulation). Failure of any urine to appear from one of the orifices highly suggests injury to that ureter.

During inspection of the operative field, attempt to pass a ureteral stent into the affected orifice. If the stent passes easily and dyed urine is seen to drip freely from it, look for possible angulation of the ureter. If you find none, remove the stent and inspect the orifice again for jetting urine.

If the ureteral stent will move only a few centimeters into the ureteral orifice, ligation (with or without transection) is likely. In this case, leave the stent in place. If the operative site is readily accessible, dissect the applicable area to identify the problem. Depending on the circumstances, you may wish to infuse dye through the stent to aid in operative identification or radiographic evaluation.

Intraoperative IVP may be useful, especially when cystoscopy is unavailable.

Fundamentals of repair

Repair of major injury to the pelvic ureter is generally best accomplished by ureteroneocystostomy or, in selected cases involving injury to the proximal pelvic ureter, by ureteroureterostomy.

When intraoperatively recognized injury to the pelvic ureter appears to be minor, it can be managed by placing a ureteral stent and a closed-suction pelvic drain. Also consider wrapping the injured area with vascularized tissue such as perivesical fat. Minor lacerations can be closed perpendicular to the axis of the ureter using interrupted 4-0 delayed absorbable suture.

Most injuries to the pelvic ureter are optimally managed by ureteroneocystostomy (FIGURE 3). When a significant portion of the pelvic ureter has been lost, ureteroneocystostomy usually requires a combination of:

• extensive mobilization of the bladder
• conservative mobilization of the ureter
• elongation of the bladder
• psoas hitch.

When necessary, mobilization of the kidney with suturing of the caudal perinephric fascia to the psoas muscle will bridge an additional 2- to 3-cm gap.

Major injury to the distal half of the pelvic ureter is repaired using straightforward ureteroneocystostomy.

When there is no significant pelvic disease and the distal ureter is healthy, injury to the proximal pelvic ureter during division of the ovarian vessels may be repaired via ureteroureterostomy. If the ureteral ends will be anastomosed on tension or there is any question about the integrity of the distal portion of the ureter, as when extensive distal ureterolysis has been necessary, consider ureteroneocystostomy.

FIGURE 3 When the distal ureter is injured

Most injuries to the pelvic ureter are managed optimally by ureteroneocystostomy.

Postoperative management

After repair of a ureteral injury, leave a closed-suction pelvic drain in place for 2 to 3 days so that any major urinary leak can be detected; it also enhances spontaneous closure and helps prevent potentially infected fluid from accumulating in the region of anastomosis.

The cystotomy performed during ureteroneocystostomy generally heals quickly with a low risk of complications.

Leave a large-bore (20 or 22 French) urethral Foley catheter in place for 2 weeks.

I recommend that a 6 French double-J ureteral stent be left in place for 6 weeks. Potential benefits of the stent include:

• prevention of stricture
• stabilization and immobilization of the ureter during healing
• reduced risk of extravasation of urine
• reduced risk of angulation of the ureter
• isolation of the repair from infection, retroperitoneal fibrosis, and cancer.

I perform IVP approximately 1 week after stent removal to ensure ureteral patency.

CASE RESOLVED

Exposure is improved by widening the incision and dividing the tendonous insertions of the rectus abdominus muscles. The surgeon then removes the mass, preserving the distal ureter, which is estimated to be 12 cm in length and to have intact adventitia.

The surgeon performs a double-spatulated end-to-end ureteroureterostomy over a 6 French double-J ureteral stent that has been passed proximally into the renal pelvis and distally into the bladder. The stent is removed 6 weeks postoperatively, and an IVP the following week demonstrates excellent patency.

pdnews@elsevier.com

The current limitation of the rabies vaccine supply presents an urgent, but not emergent, situation. In fact, nothing has changed regarding the indications for the vaccine's use. However, the supply issue does underscore the need for judicious use and careful attention to information gathering.

At this time, rabies vaccine is limited to postexposure prophylaxis and is not being given to travelers or individuals with occupational exposure risk. On Oct. 8, the Centers for Disease Control and Prevention announced that Novartis has collaborated with public health and government officials to provide additional supplies of RabAvert vaccine for postexposure prophylaxis without the need for a pass code or other restrictions. (Questions can be directed to Novartis customer service at 1-800-244-7668.)

A pass code is still required to receive Sanofi Pasteur Inc.'s IMOVAX. To obtain IMOVAX rabies vaccine, you must first contact your rabies state health official to conduct a risk assessment for the suspected exposure. (A list of those officials, along with the latest supply updates, is available at www.cdc.gov/rabies

The required form has specific information that should be collected so that an appropriate decision can be made for each patient. Basic information includes details regarding the animal species, the bite circumstances, and local rabies epidemiology. Even when the rabies vaccine supply is back to normal, practitioners will continue to be responsible for obtaining the relevant data that are necessary for making a decision about vaccine.

Children's Mercy Hospital has developed an easy-to-use form that practitioners can utilize now and in the future. Our infectious disease section data analyst, Josh Herigon, helped develop our current form, which can be accessed at http://www.childrensmercy.org/rabiesform

Parents of children who have had an animal bite are usually highly anxious and need to know that you are collecting all relevant information so that appropriate postexposure prophylaxis occurs in a timely fashion. In cases in which rabies postexposure prophylaxis is not recommended, parents need to understand the rationale for that decision.

Other key concepts include the following:

▸ Attempts should be made to recover the animal in all cases of exposure or possible exposure. If the animal is in a high-risk category, it should be immediately referred for rabies testing. Domestic animals that are acting normally should be observed, and referred for testing if they begin to exhibit abnormal behavior. Postexposure prophylaxis can be safely delayed for this period of time.

▸ If the animal can't be recovered, the next step depends upon the information you've gathered. If the animal is in the high-risk category and there was a bite wound, then postexposure prophylaxis—comprising both vaccine and rabies immune globulin—must be initiated.

▸ On the other hand, bites from low-risk animals that have escaped will rarely require vaccination. Indeed, the animal's ability to escape is a sign of noninfection, because a rabid animal is usually very sick and typically won't be able to make a quick getaway. Knowing whether the attack was provoked or not is also helpful, as a provoked animal is far less likely to be infected than is one that attacks for no apparent reason. Low-risk animals rarely carry rabies, and have never been documented to transmit it to a human in the United States.

▸ In an intermediate-risk situation, such as a dog bite in which the dog escapes, information such as the local rabies rates, the type and severity of the wound, and whether or not the attack was provoked will help you make the decision regarding whether or not to vaccinate. Again, consult with your local health officials or infectious disease specialist.

▸ Seeing a bat in the house commonly arouses concern about rabies. In the case of a preverbal child or an impaired (for example, drunk) adult who has no noticeable bite wound but who nevertheless may have been exposed, animal control should be called to capture the animal, and arrangements should be made with the local health department for rabies testing. If the bat cannot be captured, immunization plus rabies immune globulin is necessary. Approximately 5% of bats in the United States are rabid.

▸ Rabies vaccine is given intramuscularly on days 0, 3, 7, 14, and 28. The same dosage is used for both children and adults, but the injection is given in the deltoid in adults and in the anterolateral thigh in infants and children. Although primary care physicians don't typically administer rabies vaccine, it's important to educate patients about what's in store.

▸ Wound cleansing is extremely important. Irrigation (except in the case of puncture wounds), tetanus vaccination, antibiotic prophylaxis in appropriate cases, and wound closure when indicated are all essential. Animal studies suggest that wound cleansing reduces the chance of viral transmission.

▸ Officials at the CDC anticipate that the rabies vaccine supply will be fully restored in mid-2009, when Sanofi Pasteur's manufacturing facility in France is expected to be reopened. It was the scheduled closing of that facility in June 2007—combined with Novartis' inability to meet the remaining market demand—that resulted in the current supply problems. Hopefully, if we continue to practice judicious use of the vaccine even after the supply is restored, we can prevent a similar situation from reoccurring.

By the way, those of you practicing in Hawaii don't need to worry. Yours is the only U.S. state that has never had a documented case of rabies.

pdnews@elsevier.com

The current limitation of the rabies vaccine supply presents an urgent, but not emergent, situation. In fact, nothing has changed regarding the indications for the vaccine's use. However, the supply issue does underscore the need for judicious use and careful attention to information gathering.

At this time, rabies vaccine is limited to postexposure prophylaxis and is not being given to travelers or individuals with occupational exposure risk. On Oct. 8, the Centers for Disease Control and Prevention announced that Novartis has collaborated with public health and government officials to provide additional supplies of RabAvert vaccine for postexposure prophylaxis without the need for a pass code or other restrictions. (Questions can be directed to Novartis customer service at 1-800-244-7668.)

A pass code is still required to receive Sanofi Pasteur Inc.'s IMOVAX. To obtain IMOVAX rabies vaccine, you must first contact your rabies state health official to conduct a risk assessment for the suspected exposure. (A list of those officials, along with the latest supply updates, is available at www.cdc.gov/rabies

The required form has specific information that should be collected so that an appropriate decision can be made for each patient. Basic information includes details regarding the animal species, the bite circumstances, and local rabies epidemiology. Even when the rabies vaccine supply is back to normal, practitioners will continue to be responsible for obtaining the relevant data that are necessary for making a decision about vaccine.

Children's Mercy Hospital has developed an easy-to-use form that practitioners can utilize now and in the future. Our infectious disease section data analyst, Josh Herigon, helped develop our current form, which can be accessed at http://www.childrensmercy.org/rabiesform

Parents of children who have had an animal bite are usually highly anxious and need to know that you are collecting all relevant information so that appropriate postexposure prophylaxis occurs in a timely fashion. In cases in which rabies postexposure prophylaxis is not recommended, parents need to understand the rationale for that decision.

Other key concepts include the following:

▸ Attempts should be made to recover the animal in all cases of exposure or possible exposure. If the animal is in a high-risk category, it should be immediately referred for rabies testing. Domestic animals that are acting normally should be observed, and referred for testing if they begin to exhibit abnormal behavior. Postexposure prophylaxis can be safely delayed for this period of time.

▸ If the animal can't be recovered, the next step depends upon the information you've gathered. If the animal is in the high-risk category and there was a bite wound, then postexposure prophylaxis—comprising both vaccine and rabies immune globulin—must be initiated.

▸ On the other hand, bites from low-risk animals that have escaped will rarely require vaccination. Indeed, the animal's ability to escape is a sign of noninfection, because a rabid animal is usually very sick and typically won't be able to make a quick getaway. Knowing whether the attack was provoked or not is also helpful, as a provoked animal is far less likely to be infected than is one that attacks for no apparent reason. Low-risk animals rarely carry rabies, and have never been documented to transmit it to a human in the United States.

▸ In an intermediate-risk situation, such as a dog bite in which the dog escapes, information such as the local rabies rates, the type and severity of the wound, and whether or not the attack was provoked will help you make the decision regarding whether or not to vaccinate. Again, consult with your local health officials or infectious disease specialist.

▸ Seeing a bat in the house commonly arouses concern about rabies. In the case of a preverbal child or an impaired (for example, drunk) adult who has no noticeable bite wound but who nevertheless may have been exposed, animal control should be called to capture the animal, and arrangements should be made with the local health department for rabies testing. If the bat cannot be captured, immunization plus rabies immune globulin is necessary. Approximately 5% of bats in the United States are rabid.

▸ Rabies vaccine is given intramuscularly on days 0, 3, 7, 14, and 28. The same dosage is used for both children and adults, but the injection is given in the deltoid in adults and in the anterolateral thigh in infants and children. Although primary care physicians don't typically administer rabies vaccine, it's important to educate patients about what's in store.

▸ Wound cleansing is extremely important. Irrigation (except in the case of puncture wounds), tetanus vaccination, antibiotic prophylaxis in appropriate cases, and wound closure when indicated are all essential. Animal studies suggest that wound cleansing reduces the chance of viral transmission.

▸ Officials at the CDC anticipate that the rabies vaccine supply will be fully restored in mid-2009, when Sanofi Pasteur's manufacturing facility in France is expected to be reopened. It was the scheduled closing of that facility in June 2007—combined with Novartis' inability to meet the remaining market demand—that resulted in the current supply problems. Hopefully, if we continue to practice judicious use of the vaccine even after the supply is restored, we can prevent a similar situation from reoccurring.

By the way, those of you practicing in Hawaii don't need to worry. Yours is the only U.S. state that has never had a documented case of rabies.

pdnews@elsevier.com

The current limitation of the rabies vaccine supply presents an urgent, but not emergent, situation. In fact, nothing has changed regarding the indications for the vaccine's use. However, the supply issue does underscore the need for judicious use and careful attention to information gathering.

At this time, rabies vaccine is limited to postexposure prophylaxis and is not being given to travelers or individuals with occupational exposure risk. On Oct. 8, the Centers for Disease Control and Prevention announced that Novartis has collaborated with public health and government officials to provide additional supplies of RabAvert vaccine for postexposure prophylaxis without the need for a pass code or other restrictions. (Questions can be directed to Novartis customer service at 1-800-244-7668.)

A pass code is still required to receive Sanofi Pasteur Inc.'s IMOVAX. To obtain IMOVAX rabies vaccine, you must first contact your rabies state health official to conduct a risk assessment for the suspected exposure. (A list of those officials, along with the latest supply updates, is available at www.cdc.gov/rabies

The required form has specific information that should be collected so that an appropriate decision can be made for each patient. Basic information includes details regarding the animal species, the bite circumstances, and local rabies epidemiology. Even when the rabies vaccine supply is back to normal, practitioners will continue to be responsible for obtaining the relevant data that are necessary for making a decision about vaccine.

Children's Mercy Hospital has developed an easy-to-use form that practitioners can utilize now and in the future. Our infectious disease section data analyst, Josh Herigon, helped develop our current form, which can be accessed at http://www.childrensmercy.org/rabiesform

Parents of children who have had an animal bite are usually highly anxious and need to know that you are collecting all relevant information so that appropriate postexposure prophylaxis occurs in a timely fashion. In cases in which rabies postexposure prophylaxis is not recommended, parents need to understand the rationale for that decision.

Other key concepts include the following:

▸ Attempts should be made to recover the animal in all cases of exposure or possible exposure. If the animal is in a high-risk category, it should be immediately referred for rabies testing. Domestic animals that are acting normally should be observed, and referred for testing if they begin to exhibit abnormal behavior. Postexposure prophylaxis can be safely delayed for this period of time.

▸ If the animal can't be recovered, the next step depends upon the information you've gathered. If the animal is in the high-risk category and there was a bite wound, then postexposure prophylaxis—comprising both vaccine and rabies immune globulin—must be initiated.

▸ On the other hand, bites from low-risk animals that have escaped will rarely require vaccination. Indeed, the animal's ability to escape is a sign of noninfection, because a rabid animal is usually very sick and typically won't be able to make a quick getaway. Knowing whether the attack was provoked or not is also helpful, as a provoked animal is far less likely to be infected than is one that attacks for no apparent reason. Low-risk animals rarely carry rabies, and have never been documented to transmit it to a human in the United States.

▸ In an intermediate-risk situation, such as a dog bite in which the dog escapes, information such as the local rabies rates, the type and severity of the wound, and whether or not the attack was provoked will help you make the decision regarding whether or not to vaccinate. Again, consult with your local health officials or infectious disease specialist.

▸ Seeing a bat in the house commonly arouses concern about rabies. In the case of a preverbal child or an impaired (for example, drunk) adult who has no noticeable bite wound but who nevertheless may have been exposed, animal control should be called to capture the animal, and arrangements should be made with the local health department for rabies testing. If the bat cannot be captured, immunization plus rabies immune globulin is necessary. Approximately 5% of bats in the United States are rabid.

▸ Rabies vaccine is given intramuscularly on days 0, 3, 7, 14, and 28. The same dosage is used for both children and adults, but the injection is given in the deltoid in adults and in the anterolateral thigh in infants and children. Although primary care physicians don't typically administer rabies vaccine, it's important to educate patients about what's in store.

▸ Wound cleansing is extremely important. Irrigation (except in the case of puncture wounds), tetanus vaccination, antibiotic prophylaxis in appropriate cases, and wound closure when indicated are all essential. Animal studies suggest that wound cleansing reduces the chance of viral transmission.

▸ Officials at the CDC anticipate that the rabies vaccine supply will be fully restored in mid-2009, when Sanofi Pasteur's manufacturing facility in France is expected to be reopened. It was the scheduled closing of that facility in June 2007—combined with Novartis' inability to meet the remaining market demand—that resulted in the current supply problems. Hopefully, if we continue to practice judicious use of the vaccine even after the supply is restored, we can prevent a similar situation from reoccurring.

By the way, those of you practicing in Hawaii don't need to worry. Yours is the only U.S. state that has never had a documented case of rabies.