“IN WHICH CLINICAL SITUATIONS CAN THE USE OF THE 52-MG LEVONORGESTREL-RELEASING IUD (MIRENA) AND THE TCU380A COPPER-IUD (PARAGARD) BE EXTENDED?”

ROBERT L. BARBIERI, MD (SEPTEMBER 2016)

Extended-use IUDs and infection risk

For some time now I have been leaving hormonal intrauterine devices (IUDs) in place for 6 to 7 years, until menses returns. In my practice, long-term use of copper-IUDs has been associated with the presence of actinomycosis in the endometrial cavity, although usually without sepsis.

George Haber, MD
Montreal, Canada
 

Suppressing menses, pain with an IUD

I have a number of patients using the 52-mg levonorgestrel-releasing (LNG) IUD (Mirena) for noncontraceptive reasons, especially for reduction or elimination of menstrual flow and/or pain. Many have permanent sterilization in place (tubal sterilization, partner vasectomy) and I tell them we can leave the IUD in as long as they are satisfied with the results, since we are not concerned with pregnancy. Several have continued IUD use well past the 5-year mark.

Alan Smith, MD
Savannah, Georgia
 

LNG-IUD effective for multiple uses

In our practice, we have used the LNG-IUD Mirena off label for over a decade successfully for men-strual suppression in perimenopausal and postmenopausal women effectively for up to 8 years. We often place this device in the uterus after an endometrial ablation. We also offer it extended use as an alternative for menopausal hormone therapy when a progestin is indicated due to the presence of a uterus. Progestin delivery by this IUD is maximized in the endometrium and minimized in the breast and other systemic sites.

John Lenihan Jr, MD
Tacoma, Washington

Dr. Barbieri responds

I thank Dr. Haber for his observations. He notes that users of IUDs may have Actinomyces organisms identified on cervical cytology. These women should be informed of the finding and examined for evidence of active pelvic infection. If the women are asympto-matic and have a normal physical exam, the IUD does not need to be removed and antibiotic treatment is not recommended. If the woman has evidence of pelvic infection, the IUD should be removed and sent for anaerobic culture.

I appreciate that Drs. Smith and Lenihan shared their clinical pearls with readers. Dr. Smith notes that when an LNG-IUD is used to control bleeding in women who are sterilized, there are few concerns about the duration of its contraceptive efficacy, and adequate control of bleeding is a clinically useful end point demonstrating the IUD’s continued efficacy. If bleeding begins to increase after 5 years, the clinician might choose to remove the old device and replace it with a new one. Dr. Lenihan reports his use of the 52-mg LNG-IUD as the progestin in a regimen of menopausal hormone therapy. Of note, there are multiple reports from Finland that use of an LNG-IUD in premenopausal and menopausal women may be associated with an increased risk of breast cancer.^1,2 Conflicting reports from Finland and Germany did not detect an increased risk of breast cancer in women who used an LNG-IUD.^3,4 Clinicians should be aware that when Mirena is used past its approved 5-year time limit, it is an off-label use of the device.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

“IN WHICH CLINICAL SITUATIONS CAN THE USE OF THE 52-MG LEVONORGESTREL-RELEASING IUD (MIRENA) AND THE TCU380A COPPER-IUD (PARAGARD) BE EXTENDED?”

ROBERT L. BARBIERI, MD (SEPTEMBER 2016)

Extended-use IUDs and infection risk

For some time now I have been leaving hormonal intrauterine devices (IUDs) in place for 6 to 7 years, until menses returns. In my practice, long-term use of copper-IUDs has been associated with the presence of actinomycosis in the endometrial cavity, although usually without sepsis.

George Haber, MD
Montreal, Canada
 

Suppressing menses, pain with an IUD

I have a number of patients using the 52-mg levonorgestrel-releasing (LNG) IUD (Mirena) for noncontraceptive reasons, especially for reduction or elimination of menstrual flow and/or pain. Many have permanent sterilization in place (tubal sterilization, partner vasectomy) and I tell them we can leave the IUD in as long as they are satisfied with the results, since we are not concerned with pregnancy. Several have continued IUD use well past the 5-year mark.

Alan Smith, MD
Savannah, Georgia
 

LNG-IUD effective for multiple uses

In our practice, we have used the LNG-IUD Mirena off label for over a decade successfully for men-strual suppression in perimenopausal and postmenopausal women effectively for up to 8 years. We often place this device in the uterus after an endometrial ablation. We also offer it extended use as an alternative for menopausal hormone therapy when a progestin is indicated due to the presence of a uterus. Progestin delivery by this IUD is maximized in the endometrium and minimized in the breast and other systemic sites.

John Lenihan Jr, MD
Tacoma, Washington

Dr. Barbieri responds

I thank Dr. Haber for his observations. He notes that users of IUDs may have Actinomyces organisms identified on cervical cytology. These women should be informed of the finding and examined for evidence of active pelvic infection. If the women are asympto-matic and have a normal physical exam, the IUD does not need to be removed and antibiotic treatment is not recommended. If the woman has evidence of pelvic infection, the IUD should be removed and sent for anaerobic culture.

I appreciate that Drs. Smith and Lenihan shared their clinical pearls with readers. Dr. Smith notes that when an LNG-IUD is used to control bleeding in women who are sterilized, there are few concerns about the duration of its contraceptive efficacy, and adequate control of bleeding is a clinically useful end point demonstrating the IUD’s continued efficacy. If bleeding begins to increase after 5 years, the clinician might choose to remove the old device and replace it with a new one. Dr. Lenihan reports his use of the 52-mg LNG-IUD as the progestin in a regimen of menopausal hormone therapy. Of note, there are multiple reports from Finland that use of an LNG-IUD in premenopausal and menopausal women may be associated with an increased risk of breast cancer.^1,2 Conflicting reports from Finland and Germany did not detect an increased risk of breast cancer in women who used an LNG-IUD.^3,4 Clinicians should be aware that when Mirena is used past its approved 5-year time limit, it is an off-label use of the device.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

“IN WHICH CLINICAL SITUATIONS CAN THE USE OF THE 52-MG LEVONORGESTREL-RELEASING IUD (MIRENA) AND THE TCU380A COPPER-IUD (PARAGARD) BE EXTENDED?”

ROBERT L. BARBIERI, MD (SEPTEMBER 2016)

Extended-use IUDs and infection risk

For some time now I have been leaving hormonal intrauterine devices (IUDs) in place for 6 to 7 years, until menses returns. In my practice, long-term use of copper-IUDs has been associated with the presence of actinomycosis in the endometrial cavity, although usually without sepsis.

George Haber, MD
Montreal, Canada
 

Suppressing menses, pain with an IUD

I have a number of patients using the 52-mg levonorgestrel-releasing (LNG) IUD (Mirena) for noncontraceptive reasons, especially for reduction or elimination of menstrual flow and/or pain. Many have permanent sterilization in place (tubal sterilization, partner vasectomy) and I tell them we can leave the IUD in as long as they are satisfied with the results, since we are not concerned with pregnancy. Several have continued IUD use well past the 5-year mark.

Alan Smith, MD
Savannah, Georgia
 

LNG-IUD effective for multiple uses

In our practice, we have used the LNG-IUD Mirena off label for over a decade successfully for men-strual suppression in perimenopausal and postmenopausal women effectively for up to 8 years. We often place this device in the uterus after an endometrial ablation. We also offer it extended use as an alternative for menopausal hormone therapy when a progestin is indicated due to the presence of a uterus. Progestin delivery by this IUD is maximized in the endometrium and minimized in the breast and other systemic sites.

John Lenihan Jr, MD
Tacoma, Washington

Dr. Barbieri responds

I thank Dr. Haber for his observations. He notes that users of IUDs may have Actinomyces organisms identified on cervical cytology. These women should be informed of the finding and examined for evidence of active pelvic infection. If the women are asympto-matic and have a normal physical exam, the IUD does not need to be removed and antibiotic treatment is not recommended. If the woman has evidence of pelvic infection, the IUD should be removed and sent for anaerobic culture.

I appreciate that Drs. Smith and Lenihan shared their clinical pearls with readers. Dr. Smith notes that when an LNG-IUD is used to control bleeding in women who are sterilized, there are few concerns about the duration of its contraceptive efficacy, and adequate control of bleeding is a clinically useful end point demonstrating the IUD’s continued efficacy. If bleeding begins to increase after 5 years, the clinician might choose to remove the old device and replace it with a new one. Dr. Lenihan reports his use of the 52-mg LNG-IUD as the progestin in a regimen of menopausal hormone therapy. Of note, there are multiple reports from Finland that use of an LNG-IUD in premenopausal and menopausal women may be associated with an increased risk of breast cancer.^1,2 Conflicting reports from Finland and Germany did not detect an increased risk of breast cancer in women who used an LNG-IUD.^3,4 Clinicians should be aware that when Mirena is used past its approved 5-year time limit, it is an off-label use of the device.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

Cesarean delivery is now the most commonly performed major operation in hospitals across the United States. Approximately 30% of the 4 million deliveries that occur each year are by cesarean. Endometritis and wound infection (superficial and deep surgical site infection) are the most common postoperative complications of cesarean delivery. These 2 infections usually can be treated in a straightforward manner with antibiotics or surgical drainage. In some cases, however, they can lead to serious sequelae, such as pelvic abscess, septic pelvic vein thrombophlebitis, and wound dehiscence/evisceration, thereby prolonging the patient’s hospitalization and significantly increasing medical expenses.

Accordingly, in the past 50 years many investigators have proposed various specific measures to reduce the risk of postcesarean infection. In this article, we critically evaluate 2 of these major interventions: methods of skin preparation and administration of prophylactic antibiotics. In part 2 of this series next month, we will review the evidence regarding preoperative bathing with an antiseptic, preoperative vaginal cleansing with an antiseptic solution, methods of placental extraction, closure of the deep subcutaneous layer of the abdomen, and closure of the skin.

CASE Cesarean delivery required for nonprogressing labor

A 26-year-old obese primigravid woman, body mass index (BMI) 37 kg m², at 40 weeks’ gestation has been in labor for 20 hours. Her membranes have been ruptured for 16 hours. Her cervix is completely effaced and is 7 cm dilated. The fetal head is at −1 cm station. Her cervical examination findings have not changed in 4 hours despite adequate uterine contractility documented by intrauterine pressure catheter. You are now ready to proceed with cesarean delivery, and you want to do everything possible to prevent the patient from developing a postoperative infection.

What are the best practices for postcesarean infection prevention in this patient?

Skin preparation

Adequate preoperative skin preparation is an important first step in preventing post‑ cesarean infection.

How should you prepare the patient’s skin for surgery?

Two issues to address when preparing the abdominal wall for surgery are hair removal and skin cleansing. More than 40 years ago, Cruse and Foord definitively answered the question about hair removal.¹ In a landmark cohort investigation of more than 23,000 patients having many different types of operative procedures, they demonstrated that shaving the hair on the evening before surgery resulted in a higher rate of wound infection than clipping the hair, removing the hair with a depilatory cream just before surgery, or not removing the hair at all.

Three recent investigations have thoughtfully addressed the issue of skin cleansing. Darouiche and colleagues conducted a prospective, randomized, multicenter trial comparing chlorhexidine-alcohol with povidone-iodine for skin preparation before surgery.² Their investigation included 849 patients having many different types of surgical procedures, only a minority of which were in obstetric and gynecologic patients. They demonstrated fewer superficial wound infections in patients in the chlorhexidine-alcohol group (4.2% vs 8.6%, P = .008). Of even greater importance, patients in the chlorhexidine-alcohol group had fewer deep wound infections (1% vs 3%, P = .005).

Ngai and co-workers recently reported the results of a randomized controlled trial (RCT) in which women undergoing nonurgent cesarean delivery had their skin cleansed with povidone-iodine with alcohol, chlorhexidine with alcohol, or the sequential combination of both solutions.³ The overall rate of surgical site infection was just 4.3%. The 3 groups had comparable infection rates and, accordingly, the authors were unable to conclude that one type of skin preparation was superior to the other.

The most informative recent investigation was by Tuuli and colleagues, who evaluated 1,147 patients having cesarean delivery assigned to undergo skin preparation with either chlorhexidine-alcohol or iodine-alcohol.⁴ Unlike the study by Ngai and co-workers, in this study approximately 40% of the patients in each treatment arm had unscheduled, urgent cesarean deliveries.^3,4 Overall, the rate of infection in the chlorhexidine-alcohol group was 4.0% compared with 7.3% in the iodine-alcohol group (relative risk [RR], 0.55; 95% confidence interval [CI], 0.34–0.90, P = .02).

What the evidence says

Based on the evidence cited above, we advise removing hair at the incision site with clippers or depilatory cream just before the start of surgery. The abdomen should then be cleansed with a chlorhexidine-alcohol solution (Level I Evidence, Level 1A Recommendation; TABLE).

Antibiotic prophylaxis

Questions to consider regarding antibiotic prophylaxis for cesarean delivery include appropriateness of treatment, antibiotic(s) selection, timing of administration, dose, and special circumstances.

Should you give the patient prophylactic antibiotics?

Prophylactic antibiotics are justified for surgical procedures whenever 3 major criteria are met⁵:

1. the surgical site is inevitably contaminated with bacteria
2. in the absence of prophylaxis, the frequency of infection at the operative site is unacceptably high
3. operative site infections have the potential to lead to serious, potentially life-threatening sequelae.

Without a doubt, all 3 of these criteria are fulfilled when considering either urgent or nonurgent cesarean delivery. When cesarean delivery follows a long labor complicated by ruptured membranes, multiple internal vaginal examinations, and internal fetal monitoring, the operative site is inevitably contaminated with hundreds of thousands of pathogenic bacteria. Even when cesarean delivery is scheduled to occur before the onset of labor and ruptured membranes, a high concentration of vaginal organisms is introduced into the uterine and pelvic cavities coincident with making the hysterotomy incision.⁶

In the era before prophylactic antibiotics were used routinely, postoperative infection rates in some highly indigent patient populations approached 85%.⁵ Finally, as noted previously, postcesarean endometritis may progress to pelvic abscess formation, septic pelvic vein thrombophlebitis, and septic shock; wound infections may be complicated by dehiscence and evisceration.

When should you administer antibiotics: Before the surgical incision or after cord clamping?

More than 50 years ago, Burke conducted the classic sequence of basic science experiments that forms the foundation for use of prophylactic antibiotics.⁷ Using a guinea pig model, he showed that prophylactic antibiotics exert their most pronounced effect when they are administered before the surgical incision is made and before bacterial contamination occurs. Prophylaxis that is delayed more than 4 hours after the start of surgery will likely be ineffective.

Interestingly, however, when clinicians first began using prophylactic antibiotics for cesarean delivery, some investigators expressed concern about the possible exposure of the neonate to antibiotics just before delivery—specifically, whether this exposure would increase the frequency of evaluations for suspected sepsis or would promote resistance among organisms that would make neonatal sepsis more difficult to treat.

Gordon and colleagues published an important report in 1979 that showed that preoperative administration of ampicillin did not increase the frequency of immediate or delayed neonatal infections.⁸ However, delaying the administration of ampicillin until after the umbilical cord was clamped was just as effective in preventing post‑cesarean endometritis. Subsequently, Cunningham and co-workers showed that preoperative administration of prophylactic antibiotics significantly increased the frequency of sepsis workups in exposed neonates compared with infants with no preoperative antibiotic exposure (28% vs 15%; P<.025).⁹ Based on these 2 reports, obstetricians adopted a policy of delaying antibiotic administration until after the infant’s umbilical cord was clamped.

In 2007, Sullivan and colleagues challenged this long-standing practice.¹⁰ In a carefully designed prospective, randomized, double-blind trial, they showed that patients who received preoperative cefazolin had a significant reduction in the frequency of endometritis compared with women who received the same antibiotic after cord clamping (1% vs 5%; RR, 0.2; 95% CI, 0.2–0.94). The rate of wound infection was lower in the preoperative antibiotic group (3% vs 5%), but this difference did not reach statistical significance. The total infection-related morbidity was significantly reduced in women who received antibiotics preoperatively (4.0% vs 11.5%; RR, 0.4; 95% CI, 0.18–0.87). Additionally, there was no increase in the frequency of proven or suspected neonatal infection in the infants exposed to antibiotics before delivery.

Subsequent to the publication by Sullivan and colleagues, other reports have confirmed that administration of antibiotics prior to surgery is superior to administration after clamping of the umbilical cord.^10–12 Thus, we have come full circle back to Burke’s principle established more than a half century ago.⁷

Which antibiotic(s) should you administer for prophylaxis, and how many doses?

In an earlier review, one of us (PD) examined the evidence regarding choice of antibiotics and number of doses, concluding that a single dose of a first-generation cephalosporin, such as cefazolin, was the preferred regimen.⁵ The single dose was comparable in effectiveness to 2- or 3-dose regimens and to single- or multiple-dose regimens of broader-spectrum agents. For more than 20 years now, the standard of care for antibiotic prophylaxis has been a single 1- to 2-g dose of cefazolin.

Several recent reports, however, have raised the question of whether the prophylactic effect could be enhanced if the spectrum of activity of the antibiotic regimen was broadened to include an agent effective against Ureaplasma species.

Tita and colleagues evaluated an indigent patient population with an inherently high rate of postoperative infection; they showed that adding azithromycin 500 mg to cefazolin significantly reduced the rate of postcesarean endometritis.¹³ In a follow-up report from the same institution, Tita and co-workers demonstrated that adding azithromycin also significantly reduced the frequency of wound infection.¹⁴ In both of these investigations, the antibiotics were administered after cord clamping.

In a subsequent report, Ward and Duff¹⁵ showed that the combination of azithromycin plus cefazolin administered preoperatively resulted in a very low rate of both endometritis and wound infection in a population similar to that studied by Tita et al.^13,14

Very recently, Tita and associates published the results of the Cesarean Section Optimal Antibiotic Prophylaxis (C/SOAP) trial conducted at 14 US hospitals.¹⁶ This study included 2,013 women undergoing cesarean delivery during labor or after membrane rupture who were randomly assigned to receive intravenous azithromycin 500 mg (n = 1,019) or placebo (n = 994). All women also received standard antibiotic prophylaxis with cefazolin. The primary outcome (a composite of endometritis, wound infection, or other infection within 6 weeks) was significantly lower in the azithromycin group than in the placebo group (6.1% vs 12.0%, P<.001). In addition, there were significant differences between the treatment groups in the rates of endometritis (3.8% in the azithromycin group vs 6.1% in the placebo group, P = .02) as well as in the rates of wound infection (2.4% vs 6.6%, respectively, P<.001). Of additional note, there were no differences between the 2 groups in the composite neonatal outcome of death and serious neonatal complications (14.3% vs 13.6%, P = .63).The investigators concluded that extended-spectrum prophylaxis with adjunctive azithromycin safely reduces infection rates without raising the risk of neonatal adverse outcomes.

What the evidence says

We conclude that all patients, even those having a scheduled cesarean before the onset of labor or ruptured membranes, should receive prophylactic antibiotics in a single dose administered preoperatively rather than after cord clamping (Level I Evidence, Level 1A Recommendation; TABLE). In high-risk populations (eg, women in labor with ruptured membranes who are having an urgent cesarean), for whom the baseline risk of infection is high, administer the combination of cefazolin plus azithromycin in lieu of cefazolin alone (Level I Evidence, Level 1A Recommendation; TABLE).

If the patient has a history of an immediate hypersensitivity reaction to beta-lactam antibiotics, we recommend the combination of clindamycin (900 mg) plus gentamicin (1.5 mg/kg) as a single infusion prior to surgery. We base this recommendation on the need to provide reasonable coverage against a broad range of pathogens. Clindamycin covers gram-positive aerobes, such as staphylococci species and group B streptococci, and anaerobes; gentamicin covers aerobic gram-negative bacilli. A single agent, such as clindamycin or metronidazole, does not provide the broad-based coverage necessary for effective prophylaxis (Level III Evidence, Level 1C Recommendation; TABLE).

If the patient is overweight or obese, should you modify the antibiotic dose?

The prevalence of obesity in the United States continues to increase. One-third of all US reproductive-aged women are obese, and 6% of women are extremely obese.¹⁷ Obesity increases the risk of postcesarean infection 3- to 5- fold.¹⁸ Because both pregnancy and obesity increase the total volume of a drug’s distribution, achieving adequate antibiotic tissue concentrations may be hindered by a dilutional effect. Furthermore, pharmacokinetic studies consistently have shown that the tissue concentration of an antibiotic—which, ideally, should be above the minimum inhibitory concentration (MIC) for common bacteria—determines the susceptibility of those tissues to infection, regardless of whether the serum concentration of the antibiotic is in the therapeutic range.¹⁹

These concerns have led to several recent investigations evaluating different doses of cefazolin for obese patients. Pevzner and colleagues conducted a prospective cohort study of 29 women having a scheduled cesarean delivery.²⁰ The patients were divided into 3 groups: lean (BMI <30 kg m²), obese (BMI 30.0–39.9 kg m²), and extremely obese (BMI >40 kg m²). All women received a 2-g dose of cefazolin 30 to 60 minutes before surgery. Cefazolin concentrations in adipose tissue obtained at the time of skin incision were inversely proportional to maternal BMI (r, −0.67; P<.001). All specimens demonstrated a therapeutic concentration (>1 µg/g) of cefazolin for gram-positive cocci, but 20% of the obese women and 33% of the extremely obese women did not achieve the MIC (>4 µg/g) for gram-negative bacilli (P = .29 and P = .14, respectively). At the time of skin closure, 20% of obese women and 44% of extremely obese women did not have tissue concentrations that exceeded the MIC for gram-negative bacteria.

Swank and associates conducted a prospective cohort study that included 28 women.¹⁸ They demonstrated that, after a 2-g dose of cefazolin, only 20% of the obese women (BMI 30–40 kg m²) and 0% of the extremely obese women (BMI >40 kg m²) achieved an adipose tissue concentration that exceeded the MIC for gram-negative rods (8 µg/mL). However, 100% and 71.4%, respectively, achieved such a tissue concentration after a 3-g dose. When the women were stratified by actual weight, there was a statistically significant difference between those who weighed less than 120 kg and those who weighed more than 120 kg. Seventy-nine percent of the former had a tissue concentration of cefazolin greater than 8 µg/mL compared with 0% of the women who weighed more than 120 kg. Based on these observations, the authors recommended a 3-g dose of cefazolin for women who weigh more than 120 kg.

In a double-blind RCT with 26 obese women (BMI ≥30 kg m²), Young and colleagues demonstrated that, at the time of hysterotomy and fascial closure, significantly higher concentrations of cefazolin were found in the adipose tissue of obese women who received a 3-g dose of antibiotic compared with those who received a 2-g dose.²¹ However, all concentrations of cefazolin were consistently above the MIC of cefazolin for gram-positive cocci (1 µg/g) and gram-negative bacilli (4 µg/g). Further, Maggio and co-workers conducted a double-blind RCT comparing a 2-g dose of cefazolin versus a 3-g dose in 57 obese women (BMI ≥30 kg m²).²² They found no statistically significant difference in the percentage of women who had tissue concentrations of cefazolin greater than the MIC for gram-positive cocci (8 µg/g). All samples were above the MIC of cefazolin for gram-negative bacilli (2 µg/g). Based on these data, these investigators did not recommend increasing the dose of cefazolin from 2 g to 3 g in obese patients.^21,22

The studies discussed above are difficult to compare for 3 reasons. First, each study used a different MIC of cefazolin for both gram-positive and gram-negative bacteria. Second, the authors sampled different maternal tissues or serum at varying times during the cesarean delivery. Third, the studies did not specifically investigate, or were not powered sufficiently to address, the more important clinical outcome of surgical site infection. In a recent historical cohort study, Ward and Duff were unable to show that increasing the dose of cefazolin to 2 g in all women with a BMI <30 kg m² and to 3 g in all women with a BMI >30 kg m² reduced the rate of endometritis and wound infection below the level already achieved with combined prophylaxis with cefazolin (1 g) plus azithromycin (500 mg).¹⁵

Sutton and colleagues recently assessed the pharmacokinetics of azithromycin when used as prophylaxis for cesarean delivery.²³ They studied 30 women who had a scheduled cesarean delivery and who received a 500-mg intravenous dose of azithromycin that was initiated 15, 30, or 60 minutes before the surgical incision and then infused over 1 hour. They obtained maternal plasma samples multiple times during the first 8 hours after surgery. They also obtained samples of amniotic fluid, placenta, myometrium, adipose tissue, and umbilical cord blood intraoperatively. The median concentration of azithromycin in adipose tissue was 102 ng/g, which is below the MIC₅₀ for Ureaplasma species (250 ng/mL). The median concentration in myometrial tissue was 402 ng/g. The concentration in maternal plasma consistently exceeded the MIC₅₀ for Ureaplasma species.

What the evidence says

All women, regardless of weight, who will undergo cesarean delivery should receive a 2-g dose of cefazolin (Level II Evidence, Level 1B Recommendation; TABLE).If azithromycin is used in combination with cefazolin, an intravenous dose of 500 mg appears to provide adequate concentrations in serum and myometrium, but probably not in adipose tissue. More information is needed before we can make a firm recommendation about weight-based dosing of azithromycin.

CASE Resolved

For the 26-year-old obese laboring patient about to undergo cesarean delivery, reasonable steps for prevention of infection include removing the hair at the incision site with clippers or depilatory cream immediately prior to the start of surgery; cleansing the abdomen with a chlorhexidine-alcohol solution; and administering cefazolin (2 g) plus azithromycin (500 mg) preoperatively.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

Cesarean delivery is now the most commonly performed major operation in hospitals across the United States. Approximately 30% of the 4 million deliveries that occur each year are by cesarean. Endometritis and wound infection (superficial and deep surgical site infection) are the most common postoperative complications of cesarean delivery. These 2 infections usually can be treated in a straightforward manner with antibiotics or surgical drainage. In some cases, however, they can lead to serious sequelae, such as pelvic abscess, septic pelvic vein thrombophlebitis, and wound dehiscence/evisceration, thereby prolonging the patient’s hospitalization and significantly increasing medical expenses.

Accordingly, in the past 50 years many investigators have proposed various specific measures to reduce the risk of postcesarean infection. In this article, we critically evaluate 2 of these major interventions: methods of skin preparation and administration of prophylactic antibiotics. In part 2 of this series next month, we will review the evidence regarding preoperative bathing with an antiseptic, preoperative vaginal cleansing with an antiseptic solution, methods of placental extraction, closure of the deep subcutaneous layer of the abdomen, and closure of the skin.

CASE Cesarean delivery required for nonprogressing labor

A 26-year-old obese primigravid woman, body mass index (BMI) 37 kg m², at 40 weeks’ gestation has been in labor for 20 hours. Her membranes have been ruptured for 16 hours. Her cervix is completely effaced and is 7 cm dilated. The fetal head is at −1 cm station. Her cervical examination findings have not changed in 4 hours despite adequate uterine contractility documented by intrauterine pressure catheter. You are now ready to proceed with cesarean delivery, and you want to do everything possible to prevent the patient from developing a postoperative infection.

What are the best practices for postcesarean infection prevention in this patient?

Skin preparation

Adequate preoperative skin preparation is an important first step in preventing post‑ cesarean infection.

How should you prepare the patient’s skin for surgery?

Two issues to address when preparing the abdominal wall for surgery are hair removal and skin cleansing. More than 40 years ago, Cruse and Foord definitively answered the question about hair removal.¹ In a landmark cohort investigation of more than 23,000 patients having many different types of operative procedures, they demonstrated that shaving the hair on the evening before surgery resulted in a higher rate of wound infection than clipping the hair, removing the hair with a depilatory cream just before surgery, or not removing the hair at all.

Three recent investigations have thoughtfully addressed the issue of skin cleansing. Darouiche and colleagues conducted a prospective, randomized, multicenter trial comparing chlorhexidine-alcohol with povidone-iodine for skin preparation before surgery.² Their investigation included 849 patients having many different types of surgical procedures, only a minority of which were in obstetric and gynecologic patients. They demonstrated fewer superficial wound infections in patients in the chlorhexidine-alcohol group (4.2% vs 8.6%, P = .008). Of even greater importance, patients in the chlorhexidine-alcohol group had fewer deep wound infections (1% vs 3%, P = .005).

Ngai and co-workers recently reported the results of a randomized controlled trial (RCT) in which women undergoing nonurgent cesarean delivery had their skin cleansed with povidone-iodine with alcohol, chlorhexidine with alcohol, or the sequential combination of both solutions.³ The overall rate of surgical site infection was just 4.3%. The 3 groups had comparable infection rates and, accordingly, the authors were unable to conclude that one type of skin preparation was superior to the other.

The most informative recent investigation was by Tuuli and colleagues, who evaluated 1,147 patients having cesarean delivery assigned to undergo skin preparation with either chlorhexidine-alcohol or iodine-alcohol.⁴ Unlike the study by Ngai and co-workers, in this study approximately 40% of the patients in each treatment arm had unscheduled, urgent cesarean deliveries.^3,4 Overall, the rate of infection in the chlorhexidine-alcohol group was 4.0% compared with 7.3% in the iodine-alcohol group (relative risk [RR], 0.55; 95% confidence interval [CI], 0.34–0.90, P = .02).

What the evidence says

Based on the evidence cited above, we advise removing hair at the incision site with clippers or depilatory cream just before the start of surgery. The abdomen should then be cleansed with a chlorhexidine-alcohol solution (Level I Evidence, Level 1A Recommendation; TABLE).

Antibiotic prophylaxis

Questions to consider regarding antibiotic prophylaxis for cesarean delivery include appropriateness of treatment, antibiotic(s) selection, timing of administration, dose, and special circumstances.

Should you give the patient prophylactic antibiotics?

Prophylactic antibiotics are justified for surgical procedures whenever 3 major criteria are met⁵:

1. the surgical site is inevitably contaminated with bacteria
2. in the absence of prophylaxis, the frequency of infection at the operative site is unacceptably high
3. operative site infections have the potential to lead to serious, potentially life-threatening sequelae.

Without a doubt, all 3 of these criteria are fulfilled when considering either urgent or nonurgent cesarean delivery. When cesarean delivery follows a long labor complicated by ruptured membranes, multiple internal vaginal examinations, and internal fetal monitoring, the operative site is inevitably contaminated with hundreds of thousands of pathogenic bacteria. Even when cesarean delivery is scheduled to occur before the onset of labor and ruptured membranes, a high concentration of vaginal organisms is introduced into the uterine and pelvic cavities coincident with making the hysterotomy incision.⁶

In the era before prophylactic antibiotics were used routinely, postoperative infection rates in some highly indigent patient populations approached 85%.⁵ Finally, as noted previously, postcesarean endometritis may progress to pelvic abscess formation, septic pelvic vein thrombophlebitis, and septic shock; wound infections may be complicated by dehiscence and evisceration.

When should you administer antibiotics: Before the surgical incision or after cord clamping?

More than 50 years ago, Burke conducted the classic sequence of basic science experiments that forms the foundation for use of prophylactic antibiotics.⁷ Using a guinea pig model, he showed that prophylactic antibiotics exert their most pronounced effect when they are administered before the surgical incision is made and before bacterial contamination occurs. Prophylaxis that is delayed more than 4 hours after the start of surgery will likely be ineffective.

Interestingly, however, when clinicians first began using prophylactic antibiotics for cesarean delivery, some investigators expressed concern about the possible exposure of the neonate to antibiotics just before delivery—specifically, whether this exposure would increase the frequency of evaluations for suspected sepsis or would promote resistance among organisms that would make neonatal sepsis more difficult to treat.

Gordon and colleagues published an important report in 1979 that showed that preoperative administration of ampicillin did not increase the frequency of immediate or delayed neonatal infections.⁸ However, delaying the administration of ampicillin until after the umbilical cord was clamped was just as effective in preventing post‑cesarean endometritis. Subsequently, Cunningham and co-workers showed that preoperative administration of prophylactic antibiotics significantly increased the frequency of sepsis workups in exposed neonates compared with infants with no preoperative antibiotic exposure (28% vs 15%; P<.025).⁹ Based on these 2 reports, obstetricians adopted a policy of delaying antibiotic administration until after the infant’s umbilical cord was clamped.

In 2007, Sullivan and colleagues challenged this long-standing practice.¹⁰ In a carefully designed prospective, randomized, double-blind trial, they showed that patients who received preoperative cefazolin had a significant reduction in the frequency of endometritis compared with women who received the same antibiotic after cord clamping (1% vs 5%; RR, 0.2; 95% CI, 0.2–0.94). The rate of wound infection was lower in the preoperative antibiotic group (3% vs 5%), but this difference did not reach statistical significance. The total infection-related morbidity was significantly reduced in women who received antibiotics preoperatively (4.0% vs 11.5%; RR, 0.4; 95% CI, 0.18–0.87). Additionally, there was no increase in the frequency of proven or suspected neonatal infection in the infants exposed to antibiotics before delivery.

Subsequent to the publication by Sullivan and colleagues, other reports have confirmed that administration of antibiotics prior to surgery is superior to administration after clamping of the umbilical cord.^10–12 Thus, we have come full circle back to Burke’s principle established more than a half century ago.⁷

Which antibiotic(s) should you administer for prophylaxis, and how many doses?

In an earlier review, one of us (PD) examined the evidence regarding choice of antibiotics and number of doses, concluding that a single dose of a first-generation cephalosporin, such as cefazolin, was the preferred regimen.⁵ The single dose was comparable in effectiveness to 2- or 3-dose regimens and to single- or multiple-dose regimens of broader-spectrum agents. For more than 20 years now, the standard of care for antibiotic prophylaxis has been a single 1- to 2-g dose of cefazolin.

Several recent reports, however, have raised the question of whether the prophylactic effect could be enhanced if the spectrum of activity of the antibiotic regimen was broadened to include an agent effective against Ureaplasma species.

Tita and colleagues evaluated an indigent patient population with an inherently high rate of postoperative infection; they showed that adding azithromycin 500 mg to cefazolin significantly reduced the rate of postcesarean endometritis.¹³ In a follow-up report from the same institution, Tita and co-workers demonstrated that adding azithromycin also significantly reduced the frequency of wound infection.¹⁴ In both of these investigations, the antibiotics were administered after cord clamping.

In a subsequent report, Ward and Duff¹⁵ showed that the combination of azithromycin plus cefazolin administered preoperatively resulted in a very low rate of both endometritis and wound infection in a population similar to that studied by Tita et al.^13,14

Very recently, Tita and associates published the results of the Cesarean Section Optimal Antibiotic Prophylaxis (C/SOAP) trial conducted at 14 US hospitals.¹⁶ This study included 2,013 women undergoing cesarean delivery during labor or after membrane rupture who were randomly assigned to receive intravenous azithromycin 500 mg (n = 1,019) or placebo (n = 994). All women also received standard antibiotic prophylaxis with cefazolin. The primary outcome (a composite of endometritis, wound infection, or other infection within 6 weeks) was significantly lower in the azithromycin group than in the placebo group (6.1% vs 12.0%, P<.001). In addition, there were significant differences between the treatment groups in the rates of endometritis (3.8% in the azithromycin group vs 6.1% in the placebo group, P = .02) as well as in the rates of wound infection (2.4% vs 6.6%, respectively, P<.001). Of additional note, there were no differences between the 2 groups in the composite neonatal outcome of death and serious neonatal complications (14.3% vs 13.6%, P = .63).The investigators concluded that extended-spectrum prophylaxis with adjunctive azithromycin safely reduces infection rates without raising the risk of neonatal adverse outcomes.

What the evidence says

We conclude that all patients, even those having a scheduled cesarean before the onset of labor or ruptured membranes, should receive prophylactic antibiotics in a single dose administered preoperatively rather than after cord clamping (Level I Evidence, Level 1A Recommendation; TABLE). In high-risk populations (eg, women in labor with ruptured membranes who are having an urgent cesarean), for whom the baseline risk of infection is high, administer the combination of cefazolin plus azithromycin in lieu of cefazolin alone (Level I Evidence, Level 1A Recommendation; TABLE).

If the patient has a history of an immediate hypersensitivity reaction to beta-lactam antibiotics, we recommend the combination of clindamycin (900 mg) plus gentamicin (1.5 mg/kg) as a single infusion prior to surgery. We base this recommendation on the need to provide reasonable coverage against a broad range of pathogens. Clindamycin covers gram-positive aerobes, such as staphylococci species and group B streptococci, and anaerobes; gentamicin covers aerobic gram-negative bacilli. A single agent, such as clindamycin or metronidazole, does not provide the broad-based coverage necessary for effective prophylaxis (Level III Evidence, Level 1C Recommendation; TABLE).

If the patient is overweight or obese, should you modify the antibiotic dose?

The prevalence of obesity in the United States continues to increase. One-third of all US reproductive-aged women are obese, and 6% of women are extremely obese.¹⁷ Obesity increases the risk of postcesarean infection 3- to 5- fold.¹⁸ Because both pregnancy and obesity increase the total volume of a drug’s distribution, achieving adequate antibiotic tissue concentrations may be hindered by a dilutional effect. Furthermore, pharmacokinetic studies consistently have shown that the tissue concentration of an antibiotic—which, ideally, should be above the minimum inhibitory concentration (MIC) for common bacteria—determines the susceptibility of those tissues to infection, regardless of whether the serum concentration of the antibiotic is in the therapeutic range.¹⁹

These concerns have led to several recent investigations evaluating different doses of cefazolin for obese patients. Pevzner and colleagues conducted a prospective cohort study of 29 women having a scheduled cesarean delivery.²⁰ The patients were divided into 3 groups: lean (BMI <30 kg m²), obese (BMI 30.0–39.9 kg m²), and extremely obese (BMI >40 kg m²). All women received a 2-g dose of cefazolin 30 to 60 minutes before surgery. Cefazolin concentrations in adipose tissue obtained at the time of skin incision were inversely proportional to maternal BMI (r, −0.67; P<.001). All specimens demonstrated a therapeutic concentration (>1 µg/g) of cefazolin for gram-positive cocci, but 20% of the obese women and 33% of the extremely obese women did not achieve the MIC (>4 µg/g) for gram-negative bacilli (P = .29 and P = .14, respectively). At the time of skin closure, 20% of obese women and 44% of extremely obese women did not have tissue concentrations that exceeded the MIC for gram-negative bacteria.

Swank and associates conducted a prospective cohort study that included 28 women.¹⁸ They demonstrated that, after a 2-g dose of cefazolin, only 20% of the obese women (BMI 30–40 kg m²) and 0% of the extremely obese women (BMI >40 kg m²) achieved an adipose tissue concentration that exceeded the MIC for gram-negative rods (8 µg/mL). However, 100% and 71.4%, respectively, achieved such a tissue concentration after a 3-g dose. When the women were stratified by actual weight, there was a statistically significant difference between those who weighed less than 120 kg and those who weighed more than 120 kg. Seventy-nine percent of the former had a tissue concentration of cefazolin greater than 8 µg/mL compared with 0% of the women who weighed more than 120 kg. Based on these observations, the authors recommended a 3-g dose of cefazolin for women who weigh more than 120 kg.

In a double-blind RCT with 26 obese women (BMI ≥30 kg m²), Young and colleagues demonstrated that, at the time of hysterotomy and fascial closure, significantly higher concentrations of cefazolin were found in the adipose tissue of obese women who received a 3-g dose of antibiotic compared with those who received a 2-g dose.²¹ However, all concentrations of cefazolin were consistently above the MIC of cefazolin for gram-positive cocci (1 µg/g) and gram-negative bacilli (4 µg/g). Further, Maggio and co-workers conducted a double-blind RCT comparing a 2-g dose of cefazolin versus a 3-g dose in 57 obese women (BMI ≥30 kg m²).²² They found no statistically significant difference in the percentage of women who had tissue concentrations of cefazolin greater than the MIC for gram-positive cocci (8 µg/g). All samples were above the MIC of cefazolin for gram-negative bacilli (2 µg/g). Based on these data, these investigators did not recommend increasing the dose of cefazolin from 2 g to 3 g in obese patients.^21,22

The studies discussed above are difficult to compare for 3 reasons. First, each study used a different MIC of cefazolin for both gram-positive and gram-negative bacteria. Second, the authors sampled different maternal tissues or serum at varying times during the cesarean delivery. Third, the studies did not specifically investigate, or were not powered sufficiently to address, the more important clinical outcome of surgical site infection. In a recent historical cohort study, Ward and Duff were unable to show that increasing the dose of cefazolin to 2 g in all women with a BMI <30 kg m² and to 3 g in all women with a BMI >30 kg m² reduced the rate of endometritis and wound infection below the level already achieved with combined prophylaxis with cefazolin (1 g) plus azithromycin (500 mg).¹⁵

Sutton and colleagues recently assessed the pharmacokinetics of azithromycin when used as prophylaxis for cesarean delivery.²³ They studied 30 women who had a scheduled cesarean delivery and who received a 500-mg intravenous dose of azithromycin that was initiated 15, 30, or 60 minutes before the surgical incision and then infused over 1 hour. They obtained maternal plasma samples multiple times during the first 8 hours after surgery. They also obtained samples of amniotic fluid, placenta, myometrium, adipose tissue, and umbilical cord blood intraoperatively. The median concentration of azithromycin in adipose tissue was 102 ng/g, which is below the MIC₅₀ for Ureaplasma species (250 ng/mL). The median concentration in myometrial tissue was 402 ng/g. The concentration in maternal plasma consistently exceeded the MIC₅₀ for Ureaplasma species.

What the evidence says

All women, regardless of weight, who will undergo cesarean delivery should receive a 2-g dose of cefazolin (Level II Evidence, Level 1B Recommendation; TABLE).If azithromycin is used in combination with cefazolin, an intravenous dose of 500 mg appears to provide adequate concentrations in serum and myometrium, but probably not in adipose tissue. More information is needed before we can make a firm recommendation about weight-based dosing of azithromycin.

CASE Resolved

For the 26-year-old obese laboring patient about to undergo cesarean delivery, reasonable steps for prevention of infection include removing the hair at the incision site with clippers or depilatory cream immediately prior to the start of surgery; cleansing the abdomen with a chlorhexidine-alcohol solution; and administering cefazolin (2 g) plus azithromycin (500 mg) preoperatively.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

Cesarean delivery is now the most commonly performed major operation in hospitals across the United States. Approximately 30% of the 4 million deliveries that occur each year are by cesarean. Endometritis and wound infection (superficial and deep surgical site infection) are the most common postoperative complications of cesarean delivery. These 2 infections usually can be treated in a straightforward manner with antibiotics or surgical drainage. In some cases, however, they can lead to serious sequelae, such as pelvic abscess, septic pelvic vein thrombophlebitis, and wound dehiscence/evisceration, thereby prolonging the patient’s hospitalization and significantly increasing medical expenses.

Accordingly, in the past 50 years many investigators have proposed various specific measures to reduce the risk of postcesarean infection. In this article, we critically evaluate 2 of these major interventions: methods of skin preparation and administration of prophylactic antibiotics. In part 2 of this series next month, we will review the evidence regarding preoperative bathing with an antiseptic, preoperative vaginal cleansing with an antiseptic solution, methods of placental extraction, closure of the deep subcutaneous layer of the abdomen, and closure of the skin.

CASE Cesarean delivery required for nonprogressing labor

A 26-year-old obese primigravid woman, body mass index (BMI) 37 kg m², at 40 weeks’ gestation has been in labor for 20 hours. Her membranes have been ruptured for 16 hours. Her cervix is completely effaced and is 7 cm dilated. The fetal head is at −1 cm station. Her cervical examination findings have not changed in 4 hours despite adequate uterine contractility documented by intrauterine pressure catheter. You are now ready to proceed with cesarean delivery, and you want to do everything possible to prevent the patient from developing a postoperative infection.

What are the best practices for postcesarean infection prevention in this patient?

Skin preparation

Adequate preoperative skin preparation is an important first step in preventing post‑ cesarean infection.

How should you prepare the patient’s skin for surgery?

Two issues to address when preparing the abdominal wall for surgery are hair removal and skin cleansing. More than 40 years ago, Cruse and Foord definitively answered the question about hair removal.¹ In a landmark cohort investigation of more than 23,000 patients having many different types of operative procedures, they demonstrated that shaving the hair on the evening before surgery resulted in a higher rate of wound infection than clipping the hair, removing the hair with a depilatory cream just before surgery, or not removing the hair at all.

Three recent investigations have thoughtfully addressed the issue of skin cleansing. Darouiche and colleagues conducted a prospective, randomized, multicenter trial comparing chlorhexidine-alcohol with povidone-iodine for skin preparation before surgery.² Their investigation included 849 patients having many different types of surgical procedures, only a minority of which were in obstetric and gynecologic patients. They demonstrated fewer superficial wound infections in patients in the chlorhexidine-alcohol group (4.2% vs 8.6%, P = .008). Of even greater importance, patients in the chlorhexidine-alcohol group had fewer deep wound infections (1% vs 3%, P = .005).

Ngai and co-workers recently reported the results of a randomized controlled trial (RCT) in which women undergoing nonurgent cesarean delivery had their skin cleansed with povidone-iodine with alcohol, chlorhexidine with alcohol, or the sequential combination of both solutions.³ The overall rate of surgical site infection was just 4.3%. The 3 groups had comparable infection rates and, accordingly, the authors were unable to conclude that one type of skin preparation was superior to the other.

The most informative recent investigation was by Tuuli and colleagues, who evaluated 1,147 patients having cesarean delivery assigned to undergo skin preparation with either chlorhexidine-alcohol or iodine-alcohol.⁴ Unlike the study by Ngai and co-workers, in this study approximately 40% of the patients in each treatment arm had unscheduled, urgent cesarean deliveries.^3,4 Overall, the rate of infection in the chlorhexidine-alcohol group was 4.0% compared with 7.3% in the iodine-alcohol group (relative risk [RR], 0.55; 95% confidence interval [CI], 0.34–0.90, P = .02).

What the evidence says

Based on the evidence cited above, we advise removing hair at the incision site with clippers or depilatory cream just before the start of surgery. The abdomen should then be cleansed with a chlorhexidine-alcohol solution (Level I Evidence, Level 1A Recommendation; TABLE).

Antibiotic prophylaxis

Questions to consider regarding antibiotic prophylaxis for cesarean delivery include appropriateness of treatment, antibiotic(s) selection, timing of administration, dose, and special circumstances.

Should you give the patient prophylactic antibiotics?

Prophylactic antibiotics are justified for surgical procedures whenever 3 major criteria are met⁵:

1. the surgical site is inevitably contaminated with bacteria
2. in the absence of prophylaxis, the frequency of infection at the operative site is unacceptably high
3. operative site infections have the potential to lead to serious, potentially life-threatening sequelae.

Without a doubt, all 3 of these criteria are fulfilled when considering either urgent or nonurgent cesarean delivery. When cesarean delivery follows a long labor complicated by ruptured membranes, multiple internal vaginal examinations, and internal fetal monitoring, the operative site is inevitably contaminated with hundreds of thousands of pathogenic bacteria. Even when cesarean delivery is scheduled to occur before the onset of labor and ruptured membranes, a high concentration of vaginal organisms is introduced into the uterine and pelvic cavities coincident with making the hysterotomy incision.⁶

In the era before prophylactic antibiotics were used routinely, postoperative infection rates in some highly indigent patient populations approached 85%.⁵ Finally, as noted previously, postcesarean endometritis may progress to pelvic abscess formation, septic pelvic vein thrombophlebitis, and septic shock; wound infections may be complicated by dehiscence and evisceration.

When should you administer antibiotics: Before the surgical incision or after cord clamping?

More than 50 years ago, Burke conducted the classic sequence of basic science experiments that forms the foundation for use of prophylactic antibiotics.⁷ Using a guinea pig model, he showed that prophylactic antibiotics exert their most pronounced effect when they are administered before the surgical incision is made and before bacterial contamination occurs. Prophylaxis that is delayed more than 4 hours after the start of surgery will likely be ineffective.

Interestingly, however, when clinicians first began using prophylactic antibiotics for cesarean delivery, some investigators expressed concern about the possible exposure of the neonate to antibiotics just before delivery—specifically, whether this exposure would increase the frequency of evaluations for suspected sepsis or would promote resistance among organisms that would make neonatal sepsis more difficult to treat.

Gordon and colleagues published an important report in 1979 that showed that preoperative administration of ampicillin did not increase the frequency of immediate or delayed neonatal infections.⁸ However, delaying the administration of ampicillin until after the umbilical cord was clamped was just as effective in preventing post‑cesarean endometritis. Subsequently, Cunningham and co-workers showed that preoperative administration of prophylactic antibiotics significantly increased the frequency of sepsis workups in exposed neonates compared with infants with no preoperative antibiotic exposure (28% vs 15%; P<.025).⁹ Based on these 2 reports, obstetricians adopted a policy of delaying antibiotic administration until after the infant’s umbilical cord was clamped.

In 2007, Sullivan and colleagues challenged this long-standing practice.¹⁰ In a carefully designed prospective, randomized, double-blind trial, they showed that patients who received preoperative cefazolin had a significant reduction in the frequency of endometritis compared with women who received the same antibiotic after cord clamping (1% vs 5%; RR, 0.2; 95% CI, 0.2–0.94). The rate of wound infection was lower in the preoperative antibiotic group (3% vs 5%), but this difference did not reach statistical significance. The total infection-related morbidity was significantly reduced in women who received antibiotics preoperatively (4.0% vs 11.5%; RR, 0.4; 95% CI, 0.18–0.87). Additionally, there was no increase in the frequency of proven or suspected neonatal infection in the infants exposed to antibiotics before delivery.

Subsequent to the publication by Sullivan and colleagues, other reports have confirmed that administration of antibiotics prior to surgery is superior to administration after clamping of the umbilical cord.^10–12 Thus, we have come full circle back to Burke’s principle established more than a half century ago.⁷

Which antibiotic(s) should you administer for prophylaxis, and how many doses?

In an earlier review, one of us (PD) examined the evidence regarding choice of antibiotics and number of doses, concluding that a single dose of a first-generation cephalosporin, such as cefazolin, was the preferred regimen.⁵ The single dose was comparable in effectiveness to 2- or 3-dose regimens and to single- or multiple-dose regimens of broader-spectrum agents. For more than 20 years now, the standard of care for antibiotic prophylaxis has been a single 1- to 2-g dose of cefazolin.

Several recent reports, however, have raised the question of whether the prophylactic effect could be enhanced if the spectrum of activity of the antibiotic regimen was broadened to include an agent effective against Ureaplasma species.

Tita and colleagues evaluated an indigent patient population with an inherently high rate of postoperative infection; they showed that adding azithromycin 500 mg to cefazolin significantly reduced the rate of postcesarean endometritis.¹³ In a follow-up report from the same institution, Tita and co-workers demonstrated that adding azithromycin also significantly reduced the frequency of wound infection.¹⁴ In both of these investigations, the antibiotics were administered after cord clamping.

In a subsequent report, Ward and Duff¹⁵ showed that the combination of azithromycin plus cefazolin administered preoperatively resulted in a very low rate of both endometritis and wound infection in a population similar to that studied by Tita et al.^13,14

Very recently, Tita and associates published the results of the Cesarean Section Optimal Antibiotic Prophylaxis (C/SOAP) trial conducted at 14 US hospitals.¹⁶ This study included 2,013 women undergoing cesarean delivery during labor or after membrane rupture who were randomly assigned to receive intravenous azithromycin 500 mg (n = 1,019) or placebo (n = 994). All women also received standard antibiotic prophylaxis with cefazolin. The primary outcome (a composite of endometritis, wound infection, or other infection within 6 weeks) was significantly lower in the azithromycin group than in the placebo group (6.1% vs 12.0%, P<.001). In addition, there were significant differences between the treatment groups in the rates of endometritis (3.8% in the azithromycin group vs 6.1% in the placebo group, P = .02) as well as in the rates of wound infection (2.4% vs 6.6%, respectively, P<.001). Of additional note, there were no differences between the 2 groups in the composite neonatal outcome of death and serious neonatal complications (14.3% vs 13.6%, P = .63).The investigators concluded that extended-spectrum prophylaxis with adjunctive azithromycin safely reduces infection rates without raising the risk of neonatal adverse outcomes.

What the evidence says

We conclude that all patients, even those having a scheduled cesarean before the onset of labor or ruptured membranes, should receive prophylactic antibiotics in a single dose administered preoperatively rather than after cord clamping (Level I Evidence, Level 1A Recommendation; TABLE). In high-risk populations (eg, women in labor with ruptured membranes who are having an urgent cesarean), for whom the baseline risk of infection is high, administer the combination of cefazolin plus azithromycin in lieu of cefazolin alone (Level I Evidence, Level 1A Recommendation; TABLE).

If the patient has a history of an immediate hypersensitivity reaction to beta-lactam antibiotics, we recommend the combination of clindamycin (900 mg) plus gentamicin (1.5 mg/kg) as a single infusion prior to surgery. We base this recommendation on the need to provide reasonable coverage against a broad range of pathogens. Clindamycin covers gram-positive aerobes, such as staphylococci species and group B streptococci, and anaerobes; gentamicin covers aerobic gram-negative bacilli. A single agent, such as clindamycin or metronidazole, does not provide the broad-based coverage necessary for effective prophylaxis (Level III Evidence, Level 1C Recommendation; TABLE).

If the patient is overweight or obese, should you modify the antibiotic dose?

The prevalence of obesity in the United States continues to increase. One-third of all US reproductive-aged women are obese, and 6% of women are extremely obese.¹⁷ Obesity increases the risk of postcesarean infection 3- to 5- fold.¹⁸ Because both pregnancy and obesity increase the total volume of a drug’s distribution, achieving adequate antibiotic tissue concentrations may be hindered by a dilutional effect. Furthermore, pharmacokinetic studies consistently have shown that the tissue concentration of an antibiotic—which, ideally, should be above the minimum inhibitory concentration (MIC) for common bacteria—determines the susceptibility of those tissues to infection, regardless of whether the serum concentration of the antibiotic is in the therapeutic range.¹⁹

These concerns have led to several recent investigations evaluating different doses of cefazolin for obese patients. Pevzner and colleagues conducted a prospective cohort study of 29 women having a scheduled cesarean delivery.²⁰ The patients were divided into 3 groups: lean (BMI <30 kg m²), obese (BMI 30.0–39.9 kg m²), and extremely obese (BMI >40 kg m²). All women received a 2-g dose of cefazolin 30 to 60 minutes before surgery. Cefazolin concentrations in adipose tissue obtained at the time of skin incision were inversely proportional to maternal BMI (r, −0.67; P<.001). All specimens demonstrated a therapeutic concentration (>1 µg/g) of cefazolin for gram-positive cocci, but 20% of the obese women and 33% of the extremely obese women did not achieve the MIC (>4 µg/g) for gram-negative bacilli (P = .29 and P = .14, respectively). At the time of skin closure, 20% of obese women and 44% of extremely obese women did not have tissue concentrations that exceeded the MIC for gram-negative bacteria.

Swank and associates conducted a prospective cohort study that included 28 women.¹⁸ They demonstrated that, after a 2-g dose of cefazolin, only 20% of the obese women (BMI 30–40 kg m²) and 0% of the extremely obese women (BMI >40 kg m²) achieved an adipose tissue concentration that exceeded the MIC for gram-negative rods (8 µg/mL). However, 100% and 71.4%, respectively, achieved such a tissue concentration after a 3-g dose. When the women were stratified by actual weight, there was a statistically significant difference between those who weighed less than 120 kg and those who weighed more than 120 kg. Seventy-nine percent of the former had a tissue concentration of cefazolin greater than 8 µg/mL compared with 0% of the women who weighed more than 120 kg. Based on these observations, the authors recommended a 3-g dose of cefazolin for women who weigh more than 120 kg.

In a double-blind RCT with 26 obese women (BMI ≥30 kg m²), Young and colleagues demonstrated that, at the time of hysterotomy and fascial closure, significantly higher concentrations of cefazolin were found in the adipose tissue of obese women who received a 3-g dose of antibiotic compared with those who received a 2-g dose.²¹ However, all concentrations of cefazolin were consistently above the MIC of cefazolin for gram-positive cocci (1 µg/g) and gram-negative bacilli (4 µg/g). Further, Maggio and co-workers conducted a double-blind RCT comparing a 2-g dose of cefazolin versus a 3-g dose in 57 obese women (BMI ≥30 kg m²).²² They found no statistically significant difference in the percentage of women who had tissue concentrations of cefazolin greater than the MIC for gram-positive cocci (8 µg/g). All samples were above the MIC of cefazolin for gram-negative bacilli (2 µg/g). Based on these data, these investigators did not recommend increasing the dose of cefazolin from 2 g to 3 g in obese patients.^21,22

The studies discussed above are difficult to compare for 3 reasons. First, each study used a different MIC of cefazolin for both gram-positive and gram-negative bacteria. Second, the authors sampled different maternal tissues or serum at varying times during the cesarean delivery. Third, the studies did not specifically investigate, or were not powered sufficiently to address, the more important clinical outcome of surgical site infection. In a recent historical cohort study, Ward and Duff were unable to show that increasing the dose of cefazolin to 2 g in all women with a BMI <30 kg m² and to 3 g in all women with a BMI >30 kg m² reduced the rate of endometritis and wound infection below the level already achieved with combined prophylaxis with cefazolin (1 g) plus azithromycin (500 mg).¹⁵

Sutton and colleagues recently assessed the pharmacokinetics of azithromycin when used as prophylaxis for cesarean delivery.²³ They studied 30 women who had a scheduled cesarean delivery and who received a 500-mg intravenous dose of azithromycin that was initiated 15, 30, or 60 minutes before the surgical incision and then infused over 1 hour. They obtained maternal plasma samples multiple times during the first 8 hours after surgery. They also obtained samples of amniotic fluid, placenta, myometrium, adipose tissue, and umbilical cord blood intraoperatively. The median concentration of azithromycin in adipose tissue was 102 ng/g, which is below the MIC₅₀ for Ureaplasma species (250 ng/mL). The median concentration in myometrial tissue was 402 ng/g. The concentration in maternal plasma consistently exceeded the MIC₅₀ for Ureaplasma species.

What the evidence says

All women, regardless of weight, who will undergo cesarean delivery should receive a 2-g dose of cefazolin (Level II Evidence, Level 1B Recommendation; TABLE).If azithromycin is used in combination with cefazolin, an intravenous dose of 500 mg appears to provide adequate concentrations in serum and myometrium, but probably not in adipose tissue. More information is needed before we can make a firm recommendation about weight-based dosing of azithromycin.

CASE Resolved

For the 26-year-old obese laboring patient about to undergo cesarean delivery, reasonable steps for prevention of infection include removing the hair at the incision site with clippers or depilatory cream immediately prior to the start of surgery; cleansing the abdomen with a chlorhexidine-alcohol solution; and administering cefazolin (2 g) plus azithromycin (500 mg) preoperatively.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

Are you in search of materials that can reinforce what you’ve told patients about how to get a good night’s sleep? Then download this handout, which includes 8 tips that cover the wake-promoting agents to avoid, the proper environment in which to go to sleep, and the dos and don’ts of before-bedtime activities. It also discusses when patients should seek professional help for a possible sleep disorder. This PDF from Neurology Reviews is available at: http://www.mdedge.com/neurologyreviews/article/115138/sleep-medicine/tips-sleep-hygiene/pdf.

Are you in search of materials that can reinforce what you’ve told patients about how to get a good night’s sleep? Then download this handout, which includes 8 tips that cover the wake-promoting agents to avoid, the proper environment in which to go to sleep, and the dos and don’ts of before-bedtime activities. It also discusses when patients should seek professional help for a possible sleep disorder. This PDF from Neurology Reviews is available at: http://www.mdedge.com/neurologyreviews/article/115138/sleep-medicine/tips-sleep-hygiene/pdf.

Are you in search of materials that can reinforce what you’ve told patients about how to get a good night’s sleep? Then download this handout, which includes 8 tips that cover the wake-promoting agents to avoid, the proper environment in which to go to sleep, and the dos and don’ts of before-bedtime activities. It also discusses when patients should seek professional help for a possible sleep disorder. This PDF from Neurology Reviews is available at: http://www.mdedge.com/neurologyreviews/article/115138/sleep-medicine/tips-sleep-hygiene/pdf.

Can the public health threat posed by the hepatitis C virus (HCV) be eliminated by 2030? Researchers in Italy say it can be done. Important elements of success will include the use of oral direct-acting antivirals and a global commitment to prevention. Earlier this year, the World Health Organization (WHO) announced plans to wipe out HCV worldwide by 2030 using the time between now and 2021 to reduce the number of annual new infections by 70%, and to slash the fatality rate by 60%. Find out what success in meeting the WHO challenge will hinge on by going to Family Practice News: http://www.mdedge.com/familypracticenews/article/114780/gastroenterology/direct-acting-antivirals-one-several-keys-hcv.

Can the public health threat posed by the hepatitis C virus (HCV) be eliminated by 2030? Researchers in Italy say it can be done. Important elements of success will include the use of oral direct-acting antivirals and a global commitment to prevention. Earlier this year, the World Health Organization (WHO) announced plans to wipe out HCV worldwide by 2030 using the time between now and 2021 to reduce the number of annual new infections by 70%, and to slash the fatality rate by 60%. Find out what success in meeting the WHO challenge will hinge on by going to Family Practice News: http://www.mdedge.com/familypracticenews/article/114780/gastroenterology/direct-acting-antivirals-one-several-keys-hcv.

Can the public health threat posed by the hepatitis C virus (HCV) be eliminated by 2030? Researchers in Italy say it can be done. Important elements of success will include the use of oral direct-acting antivirals and a global commitment to prevention. Earlier this year, the World Health Organization (WHO) announced plans to wipe out HCV worldwide by 2030 using the time between now and 2021 to reduce the number of annual new infections by 70%, and to slash the fatality rate by 60%. Find out what success in meeting the WHO challenge will hinge on by going to Family Practice News: http://www.mdedge.com/familypracticenews/article/114780/gastroenterology/direct-acting-antivirals-one-several-keys-hcv.

Systematic introduction of palliative care interventions for patients with advanced heart failure improved patients’ quality of life and spurred their development of advanced-care preferences in a pair of independently performed, controlled pilot studies. But, despite demonstrating the ability of palliative-care interventions to help heart failure patients during their final months of life, the findings raised questions about the generalizability and reproducibility of palliative-care interventions that may depend upon the skills and experience of the individual specialists who deliver the care. To learn more about these 2 studies, go to Family Practice News: http://www.mdedge.com/familypracticenews/article/115737/cardiology/palliative-care-boosts-heart-failure-patient-outcomes.

Systematic introduction of palliative care interventions for patients with advanced heart failure improved patients’ quality of life and spurred their development of advanced-care preferences in a pair of independently performed, controlled pilot studies. But, despite demonstrating the ability of palliative-care interventions to help heart failure patients during their final months of life, the findings raised questions about the generalizability and reproducibility of palliative-care interventions that may depend upon the skills and experience of the individual specialists who deliver the care. To learn more about these 2 studies, go to Family Practice News: http://www.mdedge.com/familypracticenews/article/115737/cardiology/palliative-care-boosts-heart-failure-patient-outcomes.

Systematic introduction of palliative care interventions for patients with advanced heart failure improved patients’ quality of life and spurred their development of advanced-care preferences in a pair of independently performed, controlled pilot studies. But, despite demonstrating the ability of palliative-care interventions to help heart failure patients during their final months of life, the findings raised questions about the generalizability and reproducibility of palliative-care interventions that may depend upon the skills and experience of the individual specialists who deliver the care. To learn more about these 2 studies, go to Family Practice News: http://www.mdedge.com/familypracticenews/article/115737/cardiology/palliative-care-boosts-heart-failure-patient-outcomes.

Early age at menopause was associated with the incidence of type 2 diabetes, independent of obesity and a host of other potentially confounding factors, according to a prospect cohort study. “This association is independent of potential intermediate risk factors: obesity, insulin, glucose, inflammation, but also  estradiol and other endogenous sex hormone levels,” said Taulant Muka, MD, PhD, a postdoctoral fellow at Erasmus Medical College, Rotterdam, the Netherlands. Among the 3210 participants in the study, 319 incident cases were identified over the median 10.9-year follow-up period, with a relative risk for incident diabetes of 2.29 for women undergoing menopause before age 40, and 1.49 for those experiencing menopause between the ages of 40 and 44. Read more at Family Practice News: http://www.mdedge.com/familypracticenews/article/115648/diabetes/early-menopause-risk-factor-type-2-diabetes.

Early age at menopause was associated with the incidence of type 2 diabetes, independent of obesity and a host of other potentially confounding factors, according to a prospect cohort study. “This association is independent of potential intermediate risk factors: obesity, insulin, glucose, inflammation, but also  estradiol and other endogenous sex hormone levels,” said Taulant Muka, MD, PhD, a postdoctoral fellow at Erasmus Medical College, Rotterdam, the Netherlands. Among the 3210 participants in the study, 319 incident cases were identified over the median 10.9-year follow-up period, with a relative risk for incident diabetes of 2.29 for women undergoing menopause before age 40, and 1.49 for those experiencing menopause between the ages of 40 and 44. Read more at Family Practice News: http://www.mdedge.com/familypracticenews/article/115648/diabetes/early-menopause-risk-factor-type-2-diabetes.

Early age at menopause was associated with the incidence of type 2 diabetes, independent of obesity and a host of other potentially confounding factors, according to a prospect cohort study. “This association is independent of potential intermediate risk factors: obesity, insulin, glucose, inflammation, but also  estradiol and other endogenous sex hormone levels,” said Taulant Muka, MD, PhD, a postdoctoral fellow at Erasmus Medical College, Rotterdam, the Netherlands. Among the 3210 participants in the study, 319 incident cases were identified over the median 10.9-year follow-up period, with a relative risk for incident diabetes of 2.29 for women undergoing menopause before age 40, and 1.49 for those experiencing menopause between the ages of 40 and 44. Read more at Family Practice News: http://www.mdedge.com/familypracticenews/article/115648/diabetes/early-menopause-risk-factor-type-2-diabetes.

Patients with chronic obstructive pulmonary disease (COPD) who also suffer from depression are less likely to take their COPD maintenance medications, according to a review of Medicare claims by researchers at the University of Maryland, Baltimore. Researchers found that patients with newly diagnosed depression were about 7% less likely to have good adherence to their medications. For more on this research, see the article in CHEST Physician, available at http://www.mdedge.com/chestphysician/article/115659/depression/depression-drops-copd-medication-adherence.

Patients with chronic obstructive pulmonary disease (COPD) who also suffer from depression are less likely to take their COPD maintenance medications, according to a review of Medicare claims by researchers at the University of Maryland, Baltimore. Researchers found that patients with newly diagnosed depression were about 7% less likely to have good adherence to their medications. For more on this research, see the article in CHEST Physician, available at http://www.mdedge.com/chestphysician/article/115659/depression/depression-drops-copd-medication-adherence.

Patients with chronic obstructive pulmonary disease (COPD) who also suffer from depression are less likely to take their COPD maintenance medications, according to a review of Medicare claims by researchers at the University of Maryland, Baltimore. Researchers found that patients with newly diagnosed depression were about 7% less likely to have good adherence to their medications. For more on this research, see the article in CHEST Physician, available at http://www.mdedge.com/chestphysician/article/115659/depression/depression-drops-copd-medication-adherence.

Rivaroxaban is associated with significantly more intra- and extracranial bleeding than dabigatran in patients ages 75 and older with nonvalvular atrial fibrillation (AF), according to a recent report published online in JAMA Internal Medicine. During the study period, rivaroxaban was used 2 to 3 times more often than dabigatran in AF patients in the United States. According to David J. Graham, MD, Center for Drug Evaluation and Research, FDA, that may be “partly because of prescriber misperceptions about bleeding risks with dabigatran, arising from FDA receipt of a large number of post-marketing case reports following its approval.” That’s ironic, according to Graham, since “we [now find] substantially higher bleeding risks with the use of rivaroxaban than dabigatran.” Further analysis on the data can be found in the article from Family Practice News: http://www.mdedge.com/familypracticenews/article/115021/acquired-cardiovascular-disease/rivaroxaban-linked-more-bleeding.

Rivaroxaban is associated with significantly more intra- and extracranial bleeding than dabigatran in patients ages 75 and older with nonvalvular atrial fibrillation (AF), according to a recent report published online in JAMA Internal Medicine. During the study period, rivaroxaban was used 2 to 3 times more often than dabigatran in AF patients in the United States. According to David J. Graham, MD, Center for Drug Evaluation and Research, FDA, that may be “partly because of prescriber misperceptions about bleeding risks with dabigatran, arising from FDA receipt of a large number of post-marketing case reports following its approval.” That’s ironic, according to Graham, since “we [now find] substantially higher bleeding risks with the use of rivaroxaban than dabigatran.” Further analysis on the data can be found in the article from Family Practice News: http://www.mdedge.com/familypracticenews/article/115021/acquired-cardiovascular-disease/rivaroxaban-linked-more-bleeding.

Rivaroxaban is associated with significantly more intra- and extracranial bleeding than dabigatran in patients ages 75 and older with nonvalvular atrial fibrillation (AF), according to a recent report published online in JAMA Internal Medicine. During the study period, rivaroxaban was used 2 to 3 times more often than dabigatran in AF patients in the United States. According to David J. Graham, MD, Center for Drug Evaluation and Research, FDA, that may be “partly because of prescriber misperceptions about bleeding risks with dabigatran, arising from FDA receipt of a large number of post-marketing case reports following its approval.” That’s ironic, according to Graham, since “we [now find] substantially higher bleeding risks with the use of rivaroxaban than dabigatran.” Further analysis on the data can be found in the article from Family Practice News: http://www.mdedge.com/familypracticenews/article/115021/acquired-cardiovascular-disease/rivaroxaban-linked-more-bleeding.

WASHINGTON – The bioabsorbable vascular scaffold bubble suddenly burst with the first 3-year follow-up data from a randomized trial that unexpectedly showed that the Absorb device significantly underperformed compared with Xience, a widely-used, second-generation metallic drug-eluting stent.

“As a pioneer of BVS [bioresorbable vascular scaffold] I’m disappointed,” Patrick W. Serruys, MD, said at the Transcatheter Cardiovascular Therapeutics annual meeting. “The performance of the comparator stent was spectacular.”

Mitchel L. Zoler/Frontline Medical News

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

WASHINGTON – The bioabsorbable vascular scaffold bubble suddenly burst with the first 3-year follow-up data from a randomized trial that unexpectedly showed that the Absorb device significantly underperformed compared with Xience, a widely-used, second-generation metallic drug-eluting stent.

“As a pioneer of BVS [bioresorbable vascular scaffold] I’m disappointed,” Patrick W. Serruys, MD, said at the Transcatheter Cardiovascular Therapeutics annual meeting. “The performance of the comparator stent was spectacular.”

Mitchel L. Zoler/Frontline Medical News

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

WASHINGTON – The bioabsorbable vascular scaffold bubble suddenly burst with the first 3-year follow-up data from a randomized trial that unexpectedly showed that the Absorb device significantly underperformed compared with Xience, a widely-used, second-generation metallic drug-eluting stent.

“As a pioneer of BVS [bioresorbable vascular scaffold] I’m disappointed,” Patrick W. Serruys, MD, said at the Transcatheter Cardiovascular Therapeutics annual meeting. “The performance of the comparator stent was spectacular.”

Mitchel L. Zoler/Frontline Medical News

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

EXPERT COMMENTARY

John M. Thorp Jr, MD, McAllister Distinguished Professor, Division Director, General Obstetrics and Gynecology, Vice Chair of Research, Department of Ob-Gyn, University of North Carolina Schools of Medicine and Public Health, Chapel Hill.

Five years ago one of our interns operating with the director of labor and delivery challenged him as to why we were not using evidenced-based surgical techniques for cesarean delivery. Bruised by the formidable (and at times misleading) club of “evidence-based medicine” that is held as sacrosanct by the modern obstetrician, the director responded to the charge by researching a systematic review on abdominal delivery that amalgamated studies of poor quality with precious few trials. He unilaterally decided that we needed an opening in the transparent portion of the drape overlying the incision site so that we might use “evidence” to prevent operative site infection. The end result: No change in the incidence of wound infections, and adhesive drapes that did not adhere well, thereby displacing the effluent of amniotic fluid and blood that are part of a cesarean delivery back into the first assistant’s socks, shoes, and clothing. It was as if the clock had been turned back to my early years as an attending when we had cloth drapes. So much for having an evidence-based protocol. I was thus elated at reading the results of the CORONIS trial.

Details of the study

The CORONIS trial, in which investigators randomly assigned almost 16,000 women from 7 countries (Argentina, Chile, Ghana, India, Kenya, Pakistan, and Sudan), used a sophisticated factorial design and followed up 13,153 (84%) of the women for 3 years. The investigators tested an array of technical questions about 5 intervention pairs used during abdominal delivery and reported the main outcomes of interest for each intervention, including:

• blunt versus sharp abdominal entry—no evidence of a difference in risk of abdominal hernias (adjusted risk ratio [RR], 0.66; 95% confidence interval [CI], 0.39–1.11)
• exteriorization of the uterus versus intra-abdominal repair—no evidence of a difference in risk of infertility (RR, 0.91; 95% CI, 0.71–1.18) or of ectopic pregnancy (RR, 0.50; CI, 0.15–1.66)
• single- versus double-layer closure of the uterus—no evidence of a difference in maternal death (RR, 0.78; 95% CI, 0.46–1.32) or a composite of pregnancy complications (RR, 1.20; 95% CI, 0.75–1.90)
• closure versus nonclosure of the peritoneum—no evidence of a difference in any outcomes relating to symptoms associated with pelvic adhesions, such as infertility (RR, 0.8; 95% CI, 0.61–1.06)
• chromic catgut versus polyglactin-910 sutures—no evidence of a difference in the main comparisons for adverse pregnancy outcomes in a subsequent pregnancy, such as uterine rupture (RR, 3.05; 95% CI, 0.32–29.29).

Strengths and limitations. The CORONIS trial included a large number of participants and had comprehensive follow-up, a rigorous data collection process, and the participation of many countries. The trial’s participating centers, however, were mostly large referral hospitals with high research interest; adverse outcomes might have been higher in other settings. As well, a lower incidence of subsequent pregnancy among participants limited the study’s power to detect differences in outcomes between the intervention pairs.

Conclusions. None of the alternative techniques produced any real benefits despite syntheses-suggested benefit reported in systematic reviews. Surgeon preference for cesarean delivery techniques likely will continue to guide clinical practice along with economic and institution factors.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

EXPERT COMMENTARY

John M. Thorp Jr, MD, McAllister Distinguished Professor, Division Director, General Obstetrics and Gynecology, Vice Chair of Research, Department of Ob-Gyn, University of North Carolina Schools of Medicine and Public Health, Chapel Hill.

Five years ago one of our interns operating with the director of labor and delivery challenged him as to why we were not using evidenced-based surgical techniques for cesarean delivery. Bruised by the formidable (and at times misleading) club of “evidence-based medicine” that is held as sacrosanct by the modern obstetrician, the director responded to the charge by researching a systematic review on abdominal delivery that amalgamated studies of poor quality with precious few trials. He unilaterally decided that we needed an opening in the transparent portion of the drape overlying the incision site so that we might use “evidence” to prevent operative site infection. The end result: No change in the incidence of wound infections, and adhesive drapes that did not adhere well, thereby displacing the effluent of amniotic fluid and blood that are part of a cesarean delivery back into the first assistant’s socks, shoes, and clothing. It was as if the clock had been turned back to my early years as an attending when we had cloth drapes. So much for having an evidence-based protocol. I was thus elated at reading the results of the CORONIS trial.

Details of the study

The CORONIS trial, in which investigators randomly assigned almost 16,000 women from 7 countries (Argentina, Chile, Ghana, India, Kenya, Pakistan, and Sudan), used a sophisticated factorial design and followed up 13,153 (84%) of the women for 3 years. The investigators tested an array of technical questions about 5 intervention pairs used during abdominal delivery and reported the main outcomes of interest for each intervention, including:

• blunt versus sharp abdominal entry—no evidence of a difference in risk of abdominal hernias (adjusted risk ratio [RR], 0.66; 95% confidence interval [CI], 0.39–1.11)
• exteriorization of the uterus versus intra-abdominal repair—no evidence of a difference in risk of infertility (RR, 0.91; 95% CI, 0.71–1.18) or of ectopic pregnancy (RR, 0.50; CI, 0.15–1.66)
• single- versus double-layer closure of the uterus—no evidence of a difference in maternal death (RR, 0.78; 95% CI, 0.46–1.32) or a composite of pregnancy complications (RR, 1.20; 95% CI, 0.75–1.90)
• closure versus nonclosure of the peritoneum—no evidence of a difference in any outcomes relating to symptoms associated with pelvic adhesions, such as infertility (RR, 0.8; 95% CI, 0.61–1.06)
• chromic catgut versus polyglactin-910 sutures—no evidence of a difference in the main comparisons for adverse pregnancy outcomes in a subsequent pregnancy, such as uterine rupture (RR, 3.05; 95% CI, 0.32–29.29).

Strengths and limitations. The CORONIS trial included a large number of participants and had comprehensive follow-up, a rigorous data collection process, and the participation of many countries. The trial’s participating centers, however, were mostly large referral hospitals with high research interest; adverse outcomes might have been higher in other settings. As well, a lower incidence of subsequent pregnancy among participants limited the study’s power to detect differences in outcomes between the intervention pairs.

Conclusions. None of the alternative techniques produced any real benefits despite syntheses-suggested benefit reported in systematic reviews. Surgeon preference for cesarean delivery techniques likely will continue to guide clinical practice along with economic and institution factors.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.

EXPERT COMMENTARY

John M. Thorp Jr, MD, McAllister Distinguished Professor, Division Director, General Obstetrics and Gynecology, Vice Chair of Research, Department of Ob-Gyn, University of North Carolina Schools of Medicine and Public Health, Chapel Hill.

Five years ago one of our interns operating with the director of labor and delivery challenged him as to why we were not using evidenced-based surgical techniques for cesarean delivery. Bruised by the formidable (and at times misleading) club of “evidence-based medicine” that is held as sacrosanct by the modern obstetrician, the director responded to the charge by researching a systematic review on abdominal delivery that amalgamated studies of poor quality with precious few trials. He unilaterally decided that we needed an opening in the transparent portion of the drape overlying the incision site so that we might use “evidence” to prevent operative site infection. The end result: No change in the incidence of wound infections, and adhesive drapes that did not adhere well, thereby displacing the effluent of amniotic fluid and blood that are part of a cesarean delivery back into the first assistant’s socks, shoes, and clothing. It was as if the clock had been turned back to my early years as an attending when we had cloth drapes. So much for having an evidence-based protocol. I was thus elated at reading the results of the CORONIS trial.

Details of the study

The CORONIS trial, in which investigators randomly assigned almost 16,000 women from 7 countries (Argentina, Chile, Ghana, India, Kenya, Pakistan, and Sudan), used a sophisticated factorial design and followed up 13,153 (84%) of the women for 3 years. The investigators tested an array of technical questions about 5 intervention pairs used during abdominal delivery and reported the main outcomes of interest for each intervention, including:

• blunt versus sharp abdominal entry—no evidence of a difference in risk of abdominal hernias (adjusted risk ratio [RR], 0.66; 95% confidence interval [CI], 0.39–1.11)
• exteriorization of the uterus versus intra-abdominal repair—no evidence of a difference in risk of infertility (RR, 0.91; 95% CI, 0.71–1.18) or of ectopic pregnancy (RR, 0.50; CI, 0.15–1.66)
• single- versus double-layer closure of the uterus—no evidence of a difference in maternal death (RR, 0.78; 95% CI, 0.46–1.32) or a composite of pregnancy complications (RR, 1.20; 95% CI, 0.75–1.90)
• closure versus nonclosure of the peritoneum—no evidence of a difference in any outcomes relating to symptoms associated with pelvic adhesions, such as infertility (RR, 0.8; 95% CI, 0.61–1.06)
• chromic catgut versus polyglactin-910 sutures—no evidence of a difference in the main comparisons for adverse pregnancy outcomes in a subsequent pregnancy, such as uterine rupture (RR, 3.05; 95% CI, 0.32–29.29).

Strengths and limitations. The CORONIS trial included a large number of participants and had comprehensive follow-up, a rigorous data collection process, and the participation of many countries. The trial’s participating centers, however, were mostly large referral hospitals with high research interest; adverse outcomes might have been higher in other settings. As well, a lower incidence of subsequent pregnancy among participants limited the study’s power to detect differences in outcomes between the intervention pairs.

Conclusions. None of the alternative techniques produced any real benefits despite syntheses-suggested benefit reported in systematic reviews. Surgeon preference for cesarean delivery techniques likely will continue to guide clinical practice along with economic and institution factors.

Share your thoughts! Send your Letter to the Editor to rbarbieri@frontlinemedcom.com. Please include your name and the city and state in which you practice.