Farr Nezhat, MD

Endometriosis is a benign disease characterized by endometrial glands and stroma outside of the uterine cavity. It is commonly associated with pelvic pain and infertility. Ectopic endometrial tissue is predominantly located in the pelvis, but it can appear anywhere in the body, where it is referred to as extragenital endometriosis. The bowel and urinary tract are the most common sites of extragenital endometriosis.¹

Laparoscopic management of extragenital endometriosis has been described since the 1980s.² However, laparoscopic management of genitourinary endometriosis is still not widespread.^3,4 Physicians are often unfamiliar with the signs and symptoms of genitourinary endometriosis and fail to consider it when a patient presents with bladder pain or hematuria, which may or may not be cyclic. Furthermore, many gynecologists do not have the experience to correctly identify the various forms of endometriosis that may appear on the pelvic organ, including the serosa and peritoneum, as variable colored spots, blebs, lesions, or adhesions. Many surgeons are also not adequately trained in the advanced laparoscopic techniques required to treat genitourinary endometriosis.⁴

In this article, we describe the clinical presentation and diagnosis of genitourinary endometriosis and discuss laparoscopic management strategies with and without robotic assistance.

Clinical presentation and diagnosis of genitourinary endometriosis

While ureteral and bladder endometriosis are both diseases of the urinary tract, they are not always found together in the same patient. The bladder is the most commonly affected organ, followed by the ureter and kidney.^3,5,6 Endometriosis of the bladder usually presents with significant lower urinary tract symptoms. In contrast, ureteral endometriosis is usually silent with no apparent urinary symptoms.

Ureteral endometriosis. Cyclic hematuria is present in less than 15% of patients with ureteral endometriosis. Some patients experience cyclic, nonspecific colicky flank pain.^7-9 Otherwise, most patients present with the usual symptoms of endometriosis, such as pelvic pain and dysmenorrhea. In a systematic review, Cavaco-Gomes and colleagues described 700 patients with ureteral endometriosis; 81% reported dysmenorrhea, 70% had pelvic pain, and 66% had dyspareunia.¹⁰ Rarely, ureteral endometriosis can result in silent kidney loss if the ureter becomes severely obstructed without treatment.^11,12

Continue to: The lack of symptoms makes...

The lack of symptoms makes the early diagnosis of ureteral endometriosis difficult. As with all types of endometriosis, histologic evaluation of a biopsy sample is diagnostic. Multiple imaging modalities have been used to preoperatively diagnose ureteral involvement, including computed tomography,¹³ magnetic resonance imaging (MRI),¹⁴ intravenous pyelogram (IVP), and pelvic ultrasonography. However, each of these imaging modalities is limited in both sensitivity and the ability to characterize depth of tissue invasion.

In a study of 245 women undergoing pelvic ultrasonography, Pateman and colleagues reported that an experienced sonographer was able to visualize the bilateral ureters in 93% of cases.¹⁵ Renal ultrasonography is indicated in any woman suspected of having genitourinary tract involvement with the degree of hydroureter and level of obstruction noted during the exam.¹⁶

In our group, we perform renography to assess kidney function when hydroureter is noted preoperatively. Studies suggest that if greater than 10% of normal glomerular filtration rate remains, the kidney is considered salvageable, and near-normal function often returns following resection of disease. If preoperative kidney function is noted to be less than 10%, consultation with a nephrologist for possible nephrectomy is warranted.

We find that IVP is often helpful for preoperatively identifying the level and degree of ureteral involvement, and it also can be used postoperatively to evaluate for ureteral continuity (FIGURE 1). Sillou and colleagues showed MRI to be adequately sensitive for the detection of intrinsic ureteral endometriosis, but they reported that MRI often overestimates the frequency of disease.¹⁷ Authors of a 2016 Cochrane review of imaging modalities for endometriosis, including 4,807 women in 49 studies, reported that no imaging test was superior to surgery for diagnosing endometriosis.¹⁸ However, the review notably excluded genitourinary tract endometriosis, as surgery is not an acceptable reference standard, given that many surgeons cannot reliably identify such lesions.¹⁸

Bladder endometriosis. Unlike patients with ureteral endometriosis, those with bladder endometriosis are typically symptomatic and experience dysuria, hematuria, urinary frequency, and suprapubic tenderness.^7,19 Urinary tract infection, interstitial cystitis, and cancer must be considered in the differential diagnosis. Urinalysis and urine culture should be performed, and other diagnostic procedures such as ultrasonography, MRI, and cystoscopy should be considered to evaluate for endometriosis of the bladder.

Ultrasound and MRI of the bladder both demonstrate a high specificity for detecting bladder endometriosis, but they lack sensitivity for lesions less than 3 cm.²⁰ Deep infiltrating endometriosis of the bladder can be identified at the time of cystoscopy, which can assist in determining the need for ureteroneocystostomy if lesions are within 2 cm of the urethral opening.²⁰ Cystoscopy also allows for biopsy to be performed if underlying malignancy is of concern.¹⁹

In our group, when bladder endometriosis is suspected, we routinely perform preoperative bladder ultrasonography to identify the lesion and plan to perform intraoperative cystoscopy at the time of laparoscopic resection.^19,21

Continue to: Treatment...

Treatment

Medical management

Empiric medical therapies for endometriosis are centered around the idea that ectopic endometrial tissue responds to treatment in a similar manner as normal eutopic endometrium. The goals of treatment are to reduce or eliminate cyclic menstruation, thereby decreasing peritoneal seeding and suppressing the growth and activity of established ectopic implants. Medical therapy commonly involves the use of gonadotropin-releasing hormone agonists or antagonists, danazol, combined oral contraceptives, progestins, and aromatase inhibitors.

Medical therapy is commonly employed for patients with mild or early-stage disease and in those who are poor surgical candidates or decline surgery. Medical management alone clearly is contraindicated in the setting of ureteral obstruction and—in our opinion—may not be a good option for those with endometriosis of the ureter, given the potential for recurrence and potential serious sequelae of reduced renal function.²² Therefore, surgery has become the standard approach to therapy for mild to moderate cases of ureteral endometriosis.³

Medical therapy for patients with endometriosis of the bladder is generally considered a temporary solution as hormonal suppression, with its associated adverse effects, must be maintained throughout menopause. However, if endometriosis lesions lie within close proximity to the trigone, medical management is preferred, as surgical excision in the area of the trigone may predispose patients to neurogenic bladder and retrograde bladder reflux.^23,24

Surgical management

The objectives of surgical treatment for genitourinary tract endometriosis are to excise all visible disease, to prevent or delay recurrence of the disease to the extent possible, and to avoid any further morbidity—in particular, to preserve renal function in cases of ureteral endometriosis—and to avoid iatrogenic injury to surrounding pelvic nervous structures^25-27 (FIGURE 2). The surgical approach depends on the technical expertise of the surgeon and the availability of necessary instrumentation. In our experience, laparoscopy with or without robotic assistance is the preferred surgical approach.^{3,4,6,11,28-32}

Others have reported on the benefits of laparoscopy over laparotomy for the surgical management of genitourinary endometriosis. In a review of 61 patients who underwent either robot-assisted laparoscopic (n = 25) or open (n = 41) ureteroneocystostomy (n = 41), Isac and colleagues reported the procedure was longer in the laparoscopic group (279 min vs 200 min, P<.001), but the laparoscopic group had a shorter hospital stay (3 days vs 5 days, P<.001), used fewer narcotics postoperatively (P<.001), and had lower intraoperative blood loss (100 mL vs 150 mL, P<.001).³² No differences in long-term outcomes were observed in either cohort.

In a systematic review of 700 patients undergoing laparoscopic surgery for ureteral endometriosis, Cavaco-Gomes and colleagues reported that conversion to laparotomy occurred in only 3% to 7% of cases.¹⁰ In instances of ureteral endometriosis, laparoscopy provides greater visualization of the intraperitoneal contents over laparotomy, enabling better evaluation and treatment of lesions.^3,29,33,34 Robot-assisted laparoscopy provides the additional advantages of 3D visualization, potential for an accelerated learning curve over traditional laparoscopy, improvement in dissection technique, and ease of suturing technique.^6,35,36

Continue to: Extrinsic disease...

Extrinsic disease. In our group, we perform ureterolysis for extrinsic disease.²⁵ The peritoneal incision is made in an area unaffected by endometriosis. Using the suction irrigator, a potential space is developed under the serosa of the ureter by injecting normal saline or lactated Ringer’s solution. By creating a fluid barrier between the serosa and underlying tissues, the depth of surgical incision and lateral thermal spread are minimized. Grasping forceps are used to peel the peritoneum away.^25,37,38

Intrinsic disease. Unlike extrinsic disease, intrinsic disease can infiltrate the muscularis, lamina propria, and ureteral lumen, resulting in proximal dilation of the ureter with strictures.⁸ In this situation, ureteral compromise is likely and resection of the ureter is indicated^3,28 (FIGURE 3). Intrinsic disease can be suggested by preoperative imaging or when there is evidence of deep infiltrating disease on physical exam, such as rectovaginal nodularity.^30,39 When intrinsic ureteral disease is known, consultation with a urologist to plan a joint procedure is advisable. The procedure chosen to re-establish a functional ureter following resection depends on the location and extent of the involved ureter. Resection in close proximity to the bladder may be repaired by ureteroneocystostomy with or without psoas hitch,^30,39,40 whereas resection of more proximal ureter may be repaired using Boari flap, ileal interposition, or autotransplantation. Lesions in the upper third or middle ureter may be repaired using ureterouretral anastomosis.^6,7,30,41-43

Continue to: Bladder endometriosis...

Bladder endometriosis. Surgical treatment for bladder endometriosis depends on the depth of invasion and the location of the lesion (FIGURE 4). Lesions of the superficial aspect of the bladder identified at the time of laparoscopy can be treated with either excision or fulguration^28,35,44 In our group, we perform excision over fulguration to remove the entire lesion and obtain a pathologic diagnosis. Deeper lesions involving the detrusor muscle are likely to be an endometrioma of the bladder. In these cases, laparoscopic excision is recommended.⁷ Rarely, lesions close to the interureteric ridge may require ureteroneocystostomy.^19,45

In our experience, laparoscopic resection of bladder endometriomas is associated with better results in terms of symptom relief, progression of disease, and recurrence risk compared with other approaches. When performing laparoscopic excision of bladder lesions, we concomitantly evaluate the bladder lesion via cystoscopy to ensure adequate margins are obtained. Double-J stent placement is advised when lesions are within 2 cm of the urethral meatus to ensure ureteral patency during the postoperative period.⁴⁵ A postoperative cystogram routinely is performed 7 to 14 days after surgery to ensure adequate repair prior to removing the urinary catheter.^9,25,46,47

Postsurgical follow-up

Follow-up after treatment of genitourinary tract endometriosis should include monitoring the patient for symptoms of recurrence. Regular history and physical examination, renal function testing, and, in some instances, pelvic ultrasonography, all have a role in surveillance for recurrent ureteric disease. IVP or MRI may be warranted if a recurrence is suspected. A high index of suspicion should be maintained on the part of the clinician to avoid the devastating consequences of silent kidney loss. Patients should be counseled about the risk of disease recurrence, especially in those not undergoing postoperative hormonal suppression.

In conclusion

While endometriosis of the genitourinary tract is rare, patients can experience significant morbidity. Medical management of the disease is often limited by substantial adverse effects that limit treatment duration and is best used postoperatively after excision. An adequate physical exam and preoperative diagnostic imaging can be employed to characterize the extent of disease. When extensive disease involving the ureter is suspected, preoperative consultation with a urologist is encouraged to plan a multidisciplinary approach to surgical resection.

The ideal approach to surgery is laparoscopic resection with or without robotic assistance. Treatment of ureteral disease most commonly involves ureterolysis for cases of extrinsic disease but may require total resection of the ureter with concurrent ureteral reconstruction when disease is intrinsic to the ureter. Surgery for bladder endometriosis depends on the depth of invasion and location of the lesion. Superficial bladder lesions can be treated with fulguration or excision, while deeper lesions involving the detrusor muscle require excision. Lesions in close proximity to the interureteric ridge may require ureteroneocystostomy. Follow-up after excisional procedures involves monitoring the patient for signs and symptoms of disease recurrence, especially in cases of ureteral involvement, to avoid the devastating consequences of silent kidney loss.

Endometriosis is a benign disease characterized by endometrial glands and stroma outside of the uterine cavity. It is commonly associated with pelvic pain and infertility. Ectopic endometrial tissue is predominantly located in the pelvis, but it can appear anywhere in the body, where it is referred to as extragenital endometriosis. The bowel and urinary tract are the most common sites of extragenital endometriosis.¹

Laparoscopic management of extragenital endometriosis has been described since the 1980s.² However, laparoscopic management of genitourinary endometriosis is still not widespread.^3,4 Physicians are often unfamiliar with the signs and symptoms of genitourinary endometriosis and fail to consider it when a patient presents with bladder pain or hematuria, which may or may not be cyclic. Furthermore, many gynecologists do not have the experience to correctly identify the various forms of endometriosis that may appear on the pelvic organ, including the serosa and peritoneum, as variable colored spots, blebs, lesions, or adhesions. Many surgeons are also not adequately trained in the advanced laparoscopic techniques required to treat genitourinary endometriosis.⁴

In this article, we describe the clinical presentation and diagnosis of genitourinary endometriosis and discuss laparoscopic management strategies with and without robotic assistance.

Clinical presentation and diagnosis of genitourinary endometriosis

While ureteral and bladder endometriosis are both diseases of the urinary tract, they are not always found together in the same patient. The bladder is the most commonly affected organ, followed by the ureter and kidney.^3,5,6 Endometriosis of the bladder usually presents with significant lower urinary tract symptoms. In contrast, ureteral endometriosis is usually silent with no apparent urinary symptoms.

Ureteral endometriosis. Cyclic hematuria is present in less than 15% of patients with ureteral endometriosis. Some patients experience cyclic, nonspecific colicky flank pain.^7-9 Otherwise, most patients present with the usual symptoms of endometriosis, such as pelvic pain and dysmenorrhea. In a systematic review, Cavaco-Gomes and colleagues described 700 patients with ureteral endometriosis; 81% reported dysmenorrhea, 70% had pelvic pain, and 66% had dyspareunia.¹⁰ Rarely, ureteral endometriosis can result in silent kidney loss if the ureter becomes severely obstructed without treatment.^11,12

Continue to: The lack of symptoms makes...

The lack of symptoms makes the early diagnosis of ureteral endometriosis difficult. As with all types of endometriosis, histologic evaluation of a biopsy sample is diagnostic. Multiple imaging modalities have been used to preoperatively diagnose ureteral involvement, including computed tomography,¹³ magnetic resonance imaging (MRI),¹⁴ intravenous pyelogram (IVP), and pelvic ultrasonography. However, each of these imaging modalities is limited in both sensitivity and the ability to characterize depth of tissue invasion.

In a study of 245 women undergoing pelvic ultrasonography, Pateman and colleagues reported that an experienced sonographer was able to visualize the bilateral ureters in 93% of cases.¹⁵ Renal ultrasonography is indicated in any woman suspected of having genitourinary tract involvement with the degree of hydroureter and level of obstruction noted during the exam.¹⁶

In our group, we perform renography to assess kidney function when hydroureter is noted preoperatively. Studies suggest that if greater than 10% of normal glomerular filtration rate remains, the kidney is considered salvageable, and near-normal function often returns following resection of disease. If preoperative kidney function is noted to be less than 10%, consultation with a nephrologist for possible nephrectomy is warranted.

We find that IVP is often helpful for preoperatively identifying the level and degree of ureteral involvement, and it also can be used postoperatively to evaluate for ureteral continuity (FIGURE 1). Sillou and colleagues showed MRI to be adequately sensitive for the detection of intrinsic ureteral endometriosis, but they reported that MRI often overestimates the frequency of disease.¹⁷ Authors of a 2016 Cochrane review of imaging modalities for endometriosis, including 4,807 women in 49 studies, reported that no imaging test was superior to surgery for diagnosing endometriosis.¹⁸ However, the review notably excluded genitourinary tract endometriosis, as surgery is not an acceptable reference standard, given that many surgeons cannot reliably identify such lesions.¹⁸

Bladder endometriosis. Unlike patients with ureteral endometriosis, those with bladder endometriosis are typically symptomatic and experience dysuria, hematuria, urinary frequency, and suprapubic tenderness.^7,19 Urinary tract infection, interstitial cystitis, and cancer must be considered in the differential diagnosis. Urinalysis and urine culture should be performed, and other diagnostic procedures such as ultrasonography, MRI, and cystoscopy should be considered to evaluate for endometriosis of the bladder.

Ultrasound and MRI of the bladder both demonstrate a high specificity for detecting bladder endometriosis, but they lack sensitivity for lesions less than 3 cm.²⁰ Deep infiltrating endometriosis of the bladder can be identified at the time of cystoscopy, which can assist in determining the need for ureteroneocystostomy if lesions are within 2 cm of the urethral opening.²⁰ Cystoscopy also allows for biopsy to be performed if underlying malignancy is of concern.¹⁹

In our group, when bladder endometriosis is suspected, we routinely perform preoperative bladder ultrasonography to identify the lesion and plan to perform intraoperative cystoscopy at the time of laparoscopic resection.^19,21

Continue to: Treatment...

Treatment

Medical management

Empiric medical therapies for endometriosis are centered around the idea that ectopic endometrial tissue responds to treatment in a similar manner as normal eutopic endometrium. The goals of treatment are to reduce or eliminate cyclic menstruation, thereby decreasing peritoneal seeding and suppressing the growth and activity of established ectopic implants. Medical therapy commonly involves the use of gonadotropin-releasing hormone agonists or antagonists, danazol, combined oral contraceptives, progestins, and aromatase inhibitors.

Medical therapy is commonly employed for patients with mild or early-stage disease and in those who are poor surgical candidates or decline surgery. Medical management alone clearly is contraindicated in the setting of ureteral obstruction and—in our opinion—may not be a good option for those with endometriosis of the ureter, given the potential for recurrence and potential serious sequelae of reduced renal function.²² Therefore, surgery has become the standard approach to therapy for mild to moderate cases of ureteral endometriosis.³

Medical therapy for patients with endometriosis of the bladder is generally considered a temporary solution as hormonal suppression, with its associated adverse effects, must be maintained throughout menopause. However, if endometriosis lesions lie within close proximity to the trigone, medical management is preferred, as surgical excision in the area of the trigone may predispose patients to neurogenic bladder and retrograde bladder reflux.^23,24

Surgical management

The objectives of surgical treatment for genitourinary tract endometriosis are to excise all visible disease, to prevent or delay recurrence of the disease to the extent possible, and to avoid any further morbidity—in particular, to preserve renal function in cases of ureteral endometriosis—and to avoid iatrogenic injury to surrounding pelvic nervous structures^25-27 (FIGURE 2). The surgical approach depends on the technical expertise of the surgeon and the availability of necessary instrumentation. In our experience, laparoscopy with or without robotic assistance is the preferred surgical approach.^{3,4,6,11,28-32}

Others have reported on the benefits of laparoscopy over laparotomy for the surgical management of genitourinary endometriosis. In a review of 61 patients who underwent either robot-assisted laparoscopic (n = 25) or open (n = 41) ureteroneocystostomy (n = 41), Isac and colleagues reported the procedure was longer in the laparoscopic group (279 min vs 200 min, P<.001), but the laparoscopic group had a shorter hospital stay (3 days vs 5 days, P<.001), used fewer narcotics postoperatively (P<.001), and had lower intraoperative blood loss (100 mL vs 150 mL, P<.001).³² No differences in long-term outcomes were observed in either cohort.

In a systematic review of 700 patients undergoing laparoscopic surgery for ureteral endometriosis, Cavaco-Gomes and colleagues reported that conversion to laparotomy occurred in only 3% to 7% of cases.¹⁰ In instances of ureteral endometriosis, laparoscopy provides greater visualization of the intraperitoneal contents over laparotomy, enabling better evaluation and treatment of lesions.^3,29,33,34 Robot-assisted laparoscopy provides the additional advantages of 3D visualization, potential for an accelerated learning curve over traditional laparoscopy, improvement in dissection technique, and ease of suturing technique.^6,35,36

Continue to: Extrinsic disease...

Extrinsic disease. In our group, we perform ureterolysis for extrinsic disease.²⁵ The peritoneal incision is made in an area unaffected by endometriosis. Using the suction irrigator, a potential space is developed under the serosa of the ureter by injecting normal saline or lactated Ringer’s solution. By creating a fluid barrier between the serosa and underlying tissues, the depth of surgical incision and lateral thermal spread are minimized. Grasping forceps are used to peel the peritoneum away.^25,37,38

Intrinsic disease. Unlike extrinsic disease, intrinsic disease can infiltrate the muscularis, lamina propria, and ureteral lumen, resulting in proximal dilation of the ureter with strictures.⁸ In this situation, ureteral compromise is likely and resection of the ureter is indicated^3,28 (FIGURE 3). Intrinsic disease can be suggested by preoperative imaging or when there is evidence of deep infiltrating disease on physical exam, such as rectovaginal nodularity.^30,39 When intrinsic ureteral disease is known, consultation with a urologist to plan a joint procedure is advisable. The procedure chosen to re-establish a functional ureter following resection depends on the location and extent of the involved ureter. Resection in close proximity to the bladder may be repaired by ureteroneocystostomy with or without psoas hitch,^30,39,40 whereas resection of more proximal ureter may be repaired using Boari flap, ileal interposition, or autotransplantation. Lesions in the upper third or middle ureter may be repaired using ureterouretral anastomosis.^6,7,30,41-43

Continue to: Bladder endometriosis...

Bladder endometriosis. Surgical treatment for bladder endometriosis depends on the depth of invasion and the location of the lesion (FIGURE 4). Lesions of the superficial aspect of the bladder identified at the time of laparoscopy can be treated with either excision or fulguration^28,35,44 In our group, we perform excision over fulguration to remove the entire lesion and obtain a pathologic diagnosis. Deeper lesions involving the detrusor muscle are likely to be an endometrioma of the bladder. In these cases, laparoscopic excision is recommended.⁷ Rarely, lesions close to the interureteric ridge may require ureteroneocystostomy.^19,45

In our experience, laparoscopic resection of bladder endometriomas is associated with better results in terms of symptom relief, progression of disease, and recurrence risk compared with other approaches. When performing laparoscopic excision of bladder lesions, we concomitantly evaluate the bladder lesion via cystoscopy to ensure adequate margins are obtained. Double-J stent placement is advised when lesions are within 2 cm of the urethral meatus to ensure ureteral patency during the postoperative period.⁴⁵ A postoperative cystogram routinely is performed 7 to 14 days after surgery to ensure adequate repair prior to removing the urinary catheter.^9,25,46,47

Postsurgical follow-up

Follow-up after treatment of genitourinary tract endometriosis should include monitoring the patient for symptoms of recurrence. Regular history and physical examination, renal function testing, and, in some instances, pelvic ultrasonography, all have a role in surveillance for recurrent ureteric disease. IVP or MRI may be warranted if a recurrence is suspected. A high index of suspicion should be maintained on the part of the clinician to avoid the devastating consequences of silent kidney loss. Patients should be counseled about the risk of disease recurrence, especially in those not undergoing postoperative hormonal suppression.

In conclusion

While endometriosis of the genitourinary tract is rare, patients can experience significant morbidity. Medical management of the disease is often limited by substantial adverse effects that limit treatment duration and is best used postoperatively after excision. An adequate physical exam and preoperative diagnostic imaging can be employed to characterize the extent of disease. When extensive disease involving the ureter is suspected, preoperative consultation with a urologist is encouraged to plan a multidisciplinary approach to surgical resection.

The ideal approach to surgery is laparoscopic resection with or without robotic assistance. Treatment of ureteral disease most commonly involves ureterolysis for cases of extrinsic disease but may require total resection of the ureter with concurrent ureteral reconstruction when disease is intrinsic to the ureter. Surgery for bladder endometriosis depends on the depth of invasion and location of the lesion. Superficial bladder lesions can be treated with fulguration or excision, while deeper lesions involving the detrusor muscle require excision. Lesions in close proximity to the interureteric ridge may require ureteroneocystostomy. Follow-up after excisional procedures involves monitoring the patient for signs and symptoms of disease recurrence, especially in cases of ureteral involvement, to avoid the devastating consequences of silent kidney loss.

Endometriosis is a benign disease characterized by endometrial glands and stroma outside of the uterine cavity. It is commonly associated with pelvic pain and infertility. Ectopic endometrial tissue is predominantly located in the pelvis, but it can appear anywhere in the body, where it is referred to as extragenital endometriosis. The bowel and urinary tract are the most common sites of extragenital endometriosis.¹

Laparoscopic management of extragenital endometriosis has been described since the 1980s.² However, laparoscopic management of genitourinary endometriosis is still not widespread.^3,4 Physicians are often unfamiliar with the signs and symptoms of genitourinary endometriosis and fail to consider it when a patient presents with bladder pain or hematuria, which may or may not be cyclic. Furthermore, many gynecologists do not have the experience to correctly identify the various forms of endometriosis that may appear on the pelvic organ, including the serosa and peritoneum, as variable colored spots, blebs, lesions, or adhesions. Many surgeons are also not adequately trained in the advanced laparoscopic techniques required to treat genitourinary endometriosis.⁴

In this article, we describe the clinical presentation and diagnosis of genitourinary endometriosis and discuss laparoscopic management strategies with and without robotic assistance.

Clinical presentation and diagnosis of genitourinary endometriosis

While ureteral and bladder endometriosis are both diseases of the urinary tract, they are not always found together in the same patient. The bladder is the most commonly affected organ, followed by the ureter and kidney.^3,5,6 Endometriosis of the bladder usually presents with significant lower urinary tract symptoms. In contrast, ureteral endometriosis is usually silent with no apparent urinary symptoms.

Ureteral endometriosis. Cyclic hematuria is present in less than 15% of patients with ureteral endometriosis. Some patients experience cyclic, nonspecific colicky flank pain.^7-9 Otherwise, most patients present with the usual symptoms of endometriosis, such as pelvic pain and dysmenorrhea. In a systematic review, Cavaco-Gomes and colleagues described 700 patients with ureteral endometriosis; 81% reported dysmenorrhea, 70% had pelvic pain, and 66% had dyspareunia.¹⁰ Rarely, ureteral endometriosis can result in silent kidney loss if the ureter becomes severely obstructed without treatment.^11,12

Continue to: The lack of symptoms makes...

The lack of symptoms makes the early diagnosis of ureteral endometriosis difficult. As with all types of endometriosis, histologic evaluation of a biopsy sample is diagnostic. Multiple imaging modalities have been used to preoperatively diagnose ureteral involvement, including computed tomography,¹³ magnetic resonance imaging (MRI),¹⁴ intravenous pyelogram (IVP), and pelvic ultrasonography. However, each of these imaging modalities is limited in both sensitivity and the ability to characterize depth of tissue invasion.

In a study of 245 women undergoing pelvic ultrasonography, Pateman and colleagues reported that an experienced sonographer was able to visualize the bilateral ureters in 93% of cases.¹⁵ Renal ultrasonography is indicated in any woman suspected of having genitourinary tract involvement with the degree of hydroureter and level of obstruction noted during the exam.¹⁶

In our group, we perform renography to assess kidney function when hydroureter is noted preoperatively. Studies suggest that if greater than 10% of normal glomerular filtration rate remains, the kidney is considered salvageable, and near-normal function often returns following resection of disease. If preoperative kidney function is noted to be less than 10%, consultation with a nephrologist for possible nephrectomy is warranted.

We find that IVP is often helpful for preoperatively identifying the level and degree of ureteral involvement, and it also can be used postoperatively to evaluate for ureteral continuity (FIGURE 1). Sillou and colleagues showed MRI to be adequately sensitive for the detection of intrinsic ureteral endometriosis, but they reported that MRI often overestimates the frequency of disease.¹⁷ Authors of a 2016 Cochrane review of imaging modalities for endometriosis, including 4,807 women in 49 studies, reported that no imaging test was superior to surgery for diagnosing endometriosis.¹⁸ However, the review notably excluded genitourinary tract endometriosis, as surgery is not an acceptable reference standard, given that many surgeons cannot reliably identify such lesions.¹⁸

Bladder endometriosis. Unlike patients with ureteral endometriosis, those with bladder endometriosis are typically symptomatic and experience dysuria, hematuria, urinary frequency, and suprapubic tenderness.^7,19 Urinary tract infection, interstitial cystitis, and cancer must be considered in the differential diagnosis. Urinalysis and urine culture should be performed, and other diagnostic procedures such as ultrasonography, MRI, and cystoscopy should be considered to evaluate for endometriosis of the bladder.

Ultrasound and MRI of the bladder both demonstrate a high specificity for detecting bladder endometriosis, but they lack sensitivity for lesions less than 3 cm.²⁰ Deep infiltrating endometriosis of the bladder can be identified at the time of cystoscopy, which can assist in determining the need for ureteroneocystostomy if lesions are within 2 cm of the urethral opening.²⁰ Cystoscopy also allows for biopsy to be performed if underlying malignancy is of concern.¹⁹

In our group, when bladder endometriosis is suspected, we routinely perform preoperative bladder ultrasonography to identify the lesion and plan to perform intraoperative cystoscopy at the time of laparoscopic resection.^19,21

Continue to: Treatment...

Treatment

Medical management

Empiric medical therapies for endometriosis are centered around the idea that ectopic endometrial tissue responds to treatment in a similar manner as normal eutopic endometrium. The goals of treatment are to reduce or eliminate cyclic menstruation, thereby decreasing peritoneal seeding and suppressing the growth and activity of established ectopic implants. Medical therapy commonly involves the use of gonadotropin-releasing hormone agonists or antagonists, danazol, combined oral contraceptives, progestins, and aromatase inhibitors.

Medical therapy is commonly employed for patients with mild or early-stage disease and in those who are poor surgical candidates or decline surgery. Medical management alone clearly is contraindicated in the setting of ureteral obstruction and—in our opinion—may not be a good option for those with endometriosis of the ureter, given the potential for recurrence and potential serious sequelae of reduced renal function.²² Therefore, surgery has become the standard approach to therapy for mild to moderate cases of ureteral endometriosis.³

Medical therapy for patients with endometriosis of the bladder is generally considered a temporary solution as hormonal suppression, with its associated adverse effects, must be maintained throughout menopause. However, if endometriosis lesions lie within close proximity to the trigone, medical management is preferred, as surgical excision in the area of the trigone may predispose patients to neurogenic bladder and retrograde bladder reflux.^23,24

Surgical management

The objectives of surgical treatment for genitourinary tract endometriosis are to excise all visible disease, to prevent or delay recurrence of the disease to the extent possible, and to avoid any further morbidity—in particular, to preserve renal function in cases of ureteral endometriosis—and to avoid iatrogenic injury to surrounding pelvic nervous structures^25-27 (FIGURE 2). The surgical approach depends on the technical expertise of the surgeon and the availability of necessary instrumentation. In our experience, laparoscopy with or without robotic assistance is the preferred surgical approach.^{3,4,6,11,28-32}

Others have reported on the benefits of laparoscopy over laparotomy for the surgical management of genitourinary endometriosis. In a review of 61 patients who underwent either robot-assisted laparoscopic (n = 25) or open (n = 41) ureteroneocystostomy (n = 41), Isac and colleagues reported the procedure was longer in the laparoscopic group (279 min vs 200 min, P<.001), but the laparoscopic group had a shorter hospital stay (3 days vs 5 days, P<.001), used fewer narcotics postoperatively (P<.001), and had lower intraoperative blood loss (100 mL vs 150 mL, P<.001).³² No differences in long-term outcomes were observed in either cohort.

In a systematic review of 700 patients undergoing laparoscopic surgery for ureteral endometriosis, Cavaco-Gomes and colleagues reported that conversion to laparotomy occurred in only 3% to 7% of cases.¹⁰ In instances of ureteral endometriosis, laparoscopy provides greater visualization of the intraperitoneal contents over laparotomy, enabling better evaluation and treatment of lesions.^3,29,33,34 Robot-assisted laparoscopy provides the additional advantages of 3D visualization, potential for an accelerated learning curve over traditional laparoscopy, improvement in dissection technique, and ease of suturing technique.^6,35,36

Continue to: Extrinsic disease...

Extrinsic disease. In our group, we perform ureterolysis for extrinsic disease.²⁵ The peritoneal incision is made in an area unaffected by endometriosis. Using the suction irrigator, a potential space is developed under the serosa of the ureter by injecting normal saline or lactated Ringer’s solution. By creating a fluid barrier between the serosa and underlying tissues, the depth of surgical incision and lateral thermal spread are minimized. Grasping forceps are used to peel the peritoneum away.^25,37,38

Intrinsic disease. Unlike extrinsic disease, intrinsic disease can infiltrate the muscularis, lamina propria, and ureteral lumen, resulting in proximal dilation of the ureter with strictures.⁸ In this situation, ureteral compromise is likely and resection of the ureter is indicated^3,28 (FIGURE 3). Intrinsic disease can be suggested by preoperative imaging or when there is evidence of deep infiltrating disease on physical exam, such as rectovaginal nodularity.^30,39 When intrinsic ureteral disease is known, consultation with a urologist to plan a joint procedure is advisable. The procedure chosen to re-establish a functional ureter following resection depends on the location and extent of the involved ureter. Resection in close proximity to the bladder may be repaired by ureteroneocystostomy with or without psoas hitch,^30,39,40 whereas resection of more proximal ureter may be repaired using Boari flap, ileal interposition, or autotransplantation. Lesions in the upper third or middle ureter may be repaired using ureterouretral anastomosis.^6,7,30,41-43

Continue to: Bladder endometriosis...

Bladder endometriosis. Surgical treatment for bladder endometriosis depends on the depth of invasion and the location of the lesion (FIGURE 4). Lesions of the superficial aspect of the bladder identified at the time of laparoscopy can be treated with either excision or fulguration^28,35,44 In our group, we perform excision over fulguration to remove the entire lesion and obtain a pathologic diagnosis. Deeper lesions involving the detrusor muscle are likely to be an endometrioma of the bladder. In these cases, laparoscopic excision is recommended.⁷ Rarely, lesions close to the interureteric ridge may require ureteroneocystostomy.^19,45

In our experience, laparoscopic resection of bladder endometriomas is associated with better results in terms of symptom relief, progression of disease, and recurrence risk compared with other approaches. When performing laparoscopic excision of bladder lesions, we concomitantly evaluate the bladder lesion via cystoscopy to ensure adequate margins are obtained. Double-J stent placement is advised when lesions are within 2 cm of the urethral meatus to ensure ureteral patency during the postoperative period.⁴⁵ A postoperative cystogram routinely is performed 7 to 14 days after surgery to ensure adequate repair prior to removing the urinary catheter.^9,25,46,47

Postsurgical follow-up

Follow-up after treatment of genitourinary tract endometriosis should include monitoring the patient for symptoms of recurrence. Regular history and physical examination, renal function testing, and, in some instances, pelvic ultrasonography, all have a role in surveillance for recurrent ureteric disease. IVP or MRI may be warranted if a recurrence is suspected. A high index of suspicion should be maintained on the part of the clinician to avoid the devastating consequences of silent kidney loss. Patients should be counseled about the risk of disease recurrence, especially in those not undergoing postoperative hormonal suppression.

In conclusion

While endometriosis of the genitourinary tract is rare, patients can experience significant morbidity. Medical management of the disease is often limited by substantial adverse effects that limit treatment duration and is best used postoperatively after excision. An adequate physical exam and preoperative diagnostic imaging can be employed to characterize the extent of disease. When extensive disease involving the ureter is suspected, preoperative consultation with a urologist is encouraged to plan a multidisciplinary approach to surgical resection.

The ideal approach to surgery is laparoscopic resection with or without robotic assistance. Treatment of ureteral disease most commonly involves ureterolysis for cases of extrinsic disease but may require total resection of the ureter with concurrent ureteral reconstruction when disease is intrinsic to the ureter. Surgery for bladder endometriosis depends on the depth of invasion and location of the lesion. Superficial bladder lesions can be treated with fulguration or excision, while deeper lesions involving the detrusor muscle require excision. Lesions in close proximity to the interureteric ridge may require ureteroneocystostomy. Follow-up after excisional procedures involves monitoring the patient for signs and symptoms of disease recurrence, especially in cases of ureteral involvement, to avoid the devastating consequences of silent kidney loss.

Illustration: Kimberly Martens for OBG Management

Related article:
Endometriosis: Expert answers to 7 crucial questions on diagnosis

Etiology

Endometriomas are extensively described in the literature, and their origin is the subject of several theories. In 1921, Sampson noted luteal membrane and ovarian epithelial tissues within endometriomas and was the first to indicate that endometriomas may result from the invasion of functional cysts by endometrial tissue.^2,4,5 In 1979, Czernobilsky and Morris⁶ found endometrial and oviduct-like epithelium in ovarian endometriosis and concluded that ovarian tissue may be a common histologic precursor. Several other authors subsequently have reported finding different types of tissue within ovarian endometriomas, and not all of these chocolate cysts showed histologic evidence of endometriosis.^4,7,8

Read about the classification of endometriomas

Disease classification

Our classification system identifies 2 types of endometriomas on the basis of their etiologies and characteristics. Type I, which arise from endometrial tissue implanted on the ovarian surface, are also called true endometriomas. Invagination of cortex and subsequent hemorrhage from endometrial tissue result in cyst formation. Endometrial tissue (endometrial stroma and glands) is histologically present in all type I endometriomas.^1,4,9 These endometriomas usually are small (<5 cm in diameter) and have a densely adherent fibrous capsule.⁴ Often, there is no clear plane between cyst wall and ovarian stroma.³

Type II endometriomas arise from functional cysts involved in or invaded by cortical or pelvic side-wall endometrial implants or by type I endometriomas. Type II endometriomas are subclassified by the extent of endometrial implant involvement in the cyst wall. Type IIA endometriomas are hemorrhagic cysts with less than 10% of endometrial tissue within the cyst wall. Similar to the functional cysts from which they originate, type IIA endometriomas have a cyst wall that is separated easily from ovarian tissue during surgery.^4,7,9 Although type II endometriomas tend to be larger than their type I counterparts, in some cases they are identified at an early stage of 2 to 5 cm. Endometriomas larger than 5 cm are almost always type II.⁴

Type IIB and IIC endometriomas have endometrial implants and fibrosis within their cyst walls, with progressively more endometrial invasion in type IIC endometriomas (>50%) than in type IIB (10% to 50%). Consequently, type IIB cysts are relatively easy to dissect from ovarian tissue, except adjacent to an endometriotic area where the cyst densely adheres to the ovarian stroma. In type IIC, endometrial tissue more extensively penetrates the capsule, making dissection of diseased tissue from the ovarian stroma more difficult; in fact, separating type IIC cyst wall from ovarian stroma can be as challenging as excising a type I endometrioma.⁷ In most cases, a type IIC cyst is attached by adhesions and fibrosis to the pelvic side wall or uterus and ruptures during mobilization (TABLE).

Related article:
Imaging the endometrioma and mature cystic teratoma

Presentation and diagnosis

Almost all patients with an endometrioma concurrently have peritoneal endometriosis, which is characterized by dysmenorrhea, dyspareunia, chronic pelvic pain, infertility, and, in some cases, gastrointestinal or genitourinary dysfunction.¹ Pelvic examination may reveal an adnexal mass that is an endometrioma, or an endometrioma may appear on imaging obtained in a pelvic pain or infertility work-up. Given its 73% sensitivity, 94% specificity, safety, and low cost, transvaginal ultrasonography is the preferred imaging modality for endometrioma.³ The characteristic ultrasonographic appearance is that of a round, homogeneous, fluid-filled mass with low-level echoes.¹ Magnetic resonance imaging is appropriate when a more sensitive imaging modality is indicated, as for a patient with risk factors for malignancy.^3,10–12

Read about the surgical management of endometriomas

Surgical management

Indications for surgical excision of endometriomas include pelvic pain, infertility, and prevention and diagnosis of malignancy. Endometriomas may be excised prior to use of assisted reproductive technology.^13–15 Medical therapy, such as oral contraceptives, can be used to reduce the size of endometriomas but does not improve fertility.³ Certain ovarian cancers are more common in women with endometriosis, and ovarian tumors are thought to develop in about 1% of ovarian endometriosis cases.^1,12 Therefore, endometrioma excision may reduce the risk of malignancy. As with other ovarian cysts, large endometriomas may be excised to reduce the risks of rupture and torsion.

Don't miss the video that accompanies this article!

---

To watch the authors perform laparoscopic excision of type I and type II endometriomas, click here

 

Approach

Laparoscopy is the preferred approach for endometrioma excision. Controversy exists regarding the ideal procedure: complete excision (with stripping of the cyst capsule) or drainage and ablation of the cyst wall. Compared with drainage and ablation, excision reduces recurrence of endometriomas; relieves dysmenorrhea, dyspareunia, pelvic pain, and other symptoms; and improves fertility.^13,16 The recurrence rate may be as low as 5.8% with complete excision but is 90% with simple transvaginal aspiration.^17,18 If not performed properly, however, cyst capsule stripping may damage nearby ovarian stroma and decrease the ovarian reserve.¹⁴ Some authors have advocated combining excision and ablation—performing cystectomy until there is no longer a clear plane between capsule and ovarian stroma and then ablating any remaining endometrial tissue.⁸

With type I and IIC endometriomas, we have seen the endometrial cyst wall infiltrating the ovarian stroma so deeply there is not always a definable plane. By contrast, type IIA and IIB endometriomas typically have a plane between the cyst wall and the ovarian cortex. In type II endometriomas, endometrial implants on the ovarian cortex infiltrate the plane of the cyst wall such that the juxtaposing lipomatous follicular cyst detaches with minimal intraoperative traction. Portions of type II endometriomas containing fibrosis and adhesions may become more difficult to peel off the cyst wall. For most endometriomas, at least 1 spot is difficult to peel off the ovary, and extra care must be taken at the hilum of ovary to avoid excising healthy ovarian cortex.^4,5,7,8

Our surgical approach accounts for the described variations in type I and II endometriomas. Endometrial contents often spill as the endometrioma is dissected off neighboring structures. When possible, endometriomas should be aspirated and irrigated prior to cystectomy to avoid seeding the pelvis and abdomen with spilled endometriotic contents. We use hydrodissection, the injection of dilute vasopressin with a laparoscopic needle, to create a plane between cyst wall and ovarian stroma and strip the cyst capsule with laparoscopic graspers. Type I endometriomas adhere densely to the ovary. Given the presence of fibrosis and adhesions, the cyst is excised in a piecemeal fashion. Care is taken to remove any endometrial implants from the ovary while preserving as much of the ovarian tissue as possible.¹

Type II endometriomas are larger cysts originating from the invasion of endometrial implants or type I endometrioma into functional cysts. The difficulty of capsule excision varies according to the extent of endometrial invasion. Type IIA endometriomas contain less than 10% endometrial tissue within the cyst capsule. Thus, the standard ovarian cystectomy stripping technique is successful in removing more than 90% of the cyst capsule. Special care is taken in stripping the residual small portion that involves the endometrial glands and stroma and adheres densely to the ovary.

The larger proportion of endometrial tissue present in type IIB and IIC endometriomas degrades the plane between the cyst capsule and the ovarian stroma, making excision more difficult. Similar to the type I excision, a piecemeal approach is often necessary. If complete stripping of the cyst capsule would result in extensive loss of healthy ovarian tissue, then electrocautery, plasma energy, or laser ablation can be selectively used to destroy focal areas of endometrial invasion. Complete ablation may be difficult, as the endometrioma wall can be up to 5 mm thick.¹⁹ For these thick-walled endometriomas, we recommend excision (vs ablation), which lowers the risk of endometrioma recurrence.

Related article:
Endometriosis and pain: Expert answers to 6 questions targeting your management options
 

Conclusion

Endometriomas, common adnexal masses in women affected by endometriosis, may exacerbate pelvic pain and impair fertility. Gynecologists should be prepared to excise endometriomas completely and exercise care in preserving as much of the ovarian stroma as possible. We classify endometriomas into 2 types: type I, which develop from invagination of endometrial implants in the ovarian cortex, and type II, which stem from invasion of functional cysts by endometrial implants or type I endometrioma. This distinction guides surgical management. We hope this article and its accompanying video will be helpful in guiding laparoscopic excision of type I and II endometriomas.

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.

Illustration: Kimberly Martens for OBG Management

Related article:
Endometriosis: Expert answers to 7 crucial questions on diagnosis

Etiology

Endometriomas are extensively described in the literature, and their origin is the subject of several theories. In 1921, Sampson noted luteal membrane and ovarian epithelial tissues within endometriomas and was the first to indicate that endometriomas may result from the invasion of functional cysts by endometrial tissue.^2,4,5 In 1979, Czernobilsky and Morris⁶ found endometrial and oviduct-like epithelium in ovarian endometriosis and concluded that ovarian tissue may be a common histologic precursor. Several other authors subsequently have reported finding different types of tissue within ovarian endometriomas, and not all of these chocolate cysts showed histologic evidence of endometriosis.^4,7,8

Read about the classification of endometriomas

Disease classification

Our classification system identifies 2 types of endometriomas on the basis of their etiologies and characteristics. Type I, which arise from endometrial tissue implanted on the ovarian surface, are also called true endometriomas. Invagination of cortex and subsequent hemorrhage from endometrial tissue result in cyst formation. Endometrial tissue (endometrial stroma and glands) is histologically present in all type I endometriomas.^1,4,9 These endometriomas usually are small (<5 cm in diameter) and have a densely adherent fibrous capsule.⁴ Often, there is no clear plane between cyst wall and ovarian stroma.³

Type II endometriomas arise from functional cysts involved in or invaded by cortical or pelvic side-wall endometrial implants or by type I endometriomas. Type II endometriomas are subclassified by the extent of endometrial implant involvement in the cyst wall. Type IIA endometriomas are hemorrhagic cysts with less than 10% of endometrial tissue within the cyst wall. Similar to the functional cysts from which they originate, type IIA endometriomas have a cyst wall that is separated easily from ovarian tissue during surgery.^4,7,9 Although type II endometriomas tend to be larger than their type I counterparts, in some cases they are identified at an early stage of 2 to 5 cm. Endometriomas larger than 5 cm are almost always type II.⁴

Type IIB and IIC endometriomas have endometrial implants and fibrosis within their cyst walls, with progressively more endometrial invasion in type IIC endometriomas (>50%) than in type IIB (10% to 50%). Consequently, type IIB cysts are relatively easy to dissect from ovarian tissue, except adjacent to an endometriotic area where the cyst densely adheres to the ovarian stroma. In type IIC, endometrial tissue more extensively penetrates the capsule, making dissection of diseased tissue from the ovarian stroma more difficult; in fact, separating type IIC cyst wall from ovarian stroma can be as challenging as excising a type I endometrioma.⁷ In most cases, a type IIC cyst is attached by adhesions and fibrosis to the pelvic side wall or uterus and ruptures during mobilization (TABLE).

Related article:
Imaging the endometrioma and mature cystic teratoma

Presentation and diagnosis

Almost all patients with an endometrioma concurrently have peritoneal endometriosis, which is characterized by dysmenorrhea, dyspareunia, chronic pelvic pain, infertility, and, in some cases, gastrointestinal or genitourinary dysfunction.¹ Pelvic examination may reveal an adnexal mass that is an endometrioma, or an endometrioma may appear on imaging obtained in a pelvic pain or infertility work-up. Given its 73% sensitivity, 94% specificity, safety, and low cost, transvaginal ultrasonography is the preferred imaging modality for endometrioma.³ The characteristic ultrasonographic appearance is that of a round, homogeneous, fluid-filled mass with low-level echoes.¹ Magnetic resonance imaging is appropriate when a more sensitive imaging modality is indicated, as for a patient with risk factors for malignancy.^3,10–12

Read about the surgical management of endometriomas

Surgical management

Indications for surgical excision of endometriomas include pelvic pain, infertility, and prevention and diagnosis of malignancy. Endometriomas may be excised prior to use of assisted reproductive technology.^13–15 Medical therapy, such as oral contraceptives, can be used to reduce the size of endometriomas but does not improve fertility.³ Certain ovarian cancers are more common in women with endometriosis, and ovarian tumors are thought to develop in about 1% of ovarian endometriosis cases.^1,12 Therefore, endometrioma excision may reduce the risk of malignancy. As with other ovarian cysts, large endometriomas may be excised to reduce the risks of rupture and torsion.

Don't miss the video that accompanies this article!

---

To watch the authors perform laparoscopic excision of type I and type II endometriomas, click here

 

Approach

Laparoscopy is the preferred approach for endometrioma excision. Controversy exists regarding the ideal procedure: complete excision (with stripping of the cyst capsule) or drainage and ablation of the cyst wall. Compared with drainage and ablation, excision reduces recurrence of endometriomas; relieves dysmenorrhea, dyspareunia, pelvic pain, and other symptoms; and improves fertility.^13,16 The recurrence rate may be as low as 5.8% with complete excision but is 90% with simple transvaginal aspiration.^17,18 If not performed properly, however, cyst capsule stripping may damage nearby ovarian stroma and decrease the ovarian reserve.¹⁴ Some authors have advocated combining excision and ablation—performing cystectomy until there is no longer a clear plane between capsule and ovarian stroma and then ablating any remaining endometrial tissue.⁸

With type I and IIC endometriomas, we have seen the endometrial cyst wall infiltrating the ovarian stroma so deeply there is not always a definable plane. By contrast, type IIA and IIB endometriomas typically have a plane between the cyst wall and the ovarian cortex. In type II endometriomas, endometrial implants on the ovarian cortex infiltrate the plane of the cyst wall such that the juxtaposing lipomatous follicular cyst detaches with minimal intraoperative traction. Portions of type II endometriomas containing fibrosis and adhesions may become more difficult to peel off the cyst wall. For most endometriomas, at least 1 spot is difficult to peel off the ovary, and extra care must be taken at the hilum of ovary to avoid excising healthy ovarian cortex.^4,5,7,8

Our surgical approach accounts for the described variations in type I and II endometriomas. Endometrial contents often spill as the endometrioma is dissected off neighboring structures. When possible, endometriomas should be aspirated and irrigated prior to cystectomy to avoid seeding the pelvis and abdomen with spilled endometriotic contents. We use hydrodissection, the injection of dilute vasopressin with a laparoscopic needle, to create a plane between cyst wall and ovarian stroma and strip the cyst capsule with laparoscopic graspers. Type I endometriomas adhere densely to the ovary. Given the presence of fibrosis and adhesions, the cyst is excised in a piecemeal fashion. Care is taken to remove any endometrial implants from the ovary while preserving as much of the ovarian tissue as possible.¹

Type II endometriomas are larger cysts originating from the invasion of endometrial implants or type I endometrioma into functional cysts. The difficulty of capsule excision varies according to the extent of endometrial invasion. Type IIA endometriomas contain less than 10% endometrial tissue within the cyst capsule. Thus, the standard ovarian cystectomy stripping technique is successful in removing more than 90% of the cyst capsule. Special care is taken in stripping the residual small portion that involves the endometrial glands and stroma and adheres densely to the ovary.

The larger proportion of endometrial tissue present in type IIB and IIC endometriomas degrades the plane between the cyst capsule and the ovarian stroma, making excision more difficult. Similar to the type I excision, a piecemeal approach is often necessary. If complete stripping of the cyst capsule would result in extensive loss of healthy ovarian tissue, then electrocautery, plasma energy, or laser ablation can be selectively used to destroy focal areas of endometrial invasion. Complete ablation may be difficult, as the endometrioma wall can be up to 5 mm thick.¹⁹ For these thick-walled endometriomas, we recommend excision (vs ablation), which lowers the risk of endometrioma recurrence.

Related article:
Endometriosis and pain: Expert answers to 6 questions targeting your management options
 

Conclusion

Endometriomas, common adnexal masses in women affected by endometriosis, may exacerbate pelvic pain and impair fertility. Gynecologists should be prepared to excise endometriomas completely and exercise care in preserving as much of the ovarian stroma as possible. We classify endometriomas into 2 types: type I, which develop from invagination of endometrial implants in the ovarian cortex, and type II, which stem from invasion of functional cysts by endometrial implants or type I endometrioma. This distinction guides surgical management. We hope this article and its accompanying video will be helpful in guiding laparoscopic excision of type I and II endometriomas.

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.

Illustration: Kimberly Martens for OBG Management

Related article:
Endometriosis: Expert answers to 7 crucial questions on diagnosis

Etiology

Endometriomas are extensively described in the literature, and their origin is the subject of several theories. In 1921, Sampson noted luteal membrane and ovarian epithelial tissues within endometriomas and was the first to indicate that endometriomas may result from the invasion of functional cysts by endometrial tissue.^2,4,5 In 1979, Czernobilsky and Morris⁶ found endometrial and oviduct-like epithelium in ovarian endometriosis and concluded that ovarian tissue may be a common histologic precursor. Several other authors subsequently have reported finding different types of tissue within ovarian endometriomas, and not all of these chocolate cysts showed histologic evidence of endometriosis.^4,7,8

Read about the classification of endometriomas

Disease classification

Our classification system identifies 2 types of endometriomas on the basis of their etiologies and characteristics. Type I, which arise from endometrial tissue implanted on the ovarian surface, are also called true endometriomas. Invagination of cortex and subsequent hemorrhage from endometrial tissue result in cyst formation. Endometrial tissue (endometrial stroma and glands) is histologically present in all type I endometriomas.^1,4,9 These endometriomas usually are small (<5 cm in diameter) and have a densely adherent fibrous capsule.⁴ Often, there is no clear plane between cyst wall and ovarian stroma.³

Type II endometriomas arise from functional cysts involved in or invaded by cortical or pelvic side-wall endometrial implants or by type I endometriomas. Type II endometriomas are subclassified by the extent of endometrial implant involvement in the cyst wall. Type IIA endometriomas are hemorrhagic cysts with less than 10% of endometrial tissue within the cyst wall. Similar to the functional cysts from which they originate, type IIA endometriomas have a cyst wall that is separated easily from ovarian tissue during surgery.^4,7,9 Although type II endometriomas tend to be larger than their type I counterparts, in some cases they are identified at an early stage of 2 to 5 cm. Endometriomas larger than 5 cm are almost always type II.⁴

Type IIB and IIC endometriomas have endometrial implants and fibrosis within their cyst walls, with progressively more endometrial invasion in type IIC endometriomas (>50%) than in type IIB (10% to 50%). Consequently, type IIB cysts are relatively easy to dissect from ovarian tissue, except adjacent to an endometriotic area where the cyst densely adheres to the ovarian stroma. In type IIC, endometrial tissue more extensively penetrates the capsule, making dissection of diseased tissue from the ovarian stroma more difficult; in fact, separating type IIC cyst wall from ovarian stroma can be as challenging as excising a type I endometrioma.⁷ In most cases, a type IIC cyst is attached by adhesions and fibrosis to the pelvic side wall or uterus and ruptures during mobilization (TABLE).

Related article:
Imaging the endometrioma and mature cystic teratoma

Presentation and diagnosis

Almost all patients with an endometrioma concurrently have peritoneal endometriosis, which is characterized by dysmenorrhea, dyspareunia, chronic pelvic pain, infertility, and, in some cases, gastrointestinal or genitourinary dysfunction.¹ Pelvic examination may reveal an adnexal mass that is an endometrioma, or an endometrioma may appear on imaging obtained in a pelvic pain or infertility work-up. Given its 73% sensitivity, 94% specificity, safety, and low cost, transvaginal ultrasonography is the preferred imaging modality for endometrioma.³ The characteristic ultrasonographic appearance is that of a round, homogeneous, fluid-filled mass with low-level echoes.¹ Magnetic resonance imaging is appropriate when a more sensitive imaging modality is indicated, as for a patient with risk factors for malignancy.^3,10–12

Read about the surgical management of endometriomas

Surgical management

Indications for surgical excision of endometriomas include pelvic pain, infertility, and prevention and diagnosis of malignancy. Endometriomas may be excised prior to use of assisted reproductive technology.^13–15 Medical therapy, such as oral contraceptives, can be used to reduce the size of endometriomas but does not improve fertility.³ Certain ovarian cancers are more common in women with endometriosis, and ovarian tumors are thought to develop in about 1% of ovarian endometriosis cases.^1,12 Therefore, endometrioma excision may reduce the risk of malignancy. As with other ovarian cysts, large endometriomas may be excised to reduce the risks of rupture and torsion.

Don't miss the video that accompanies this article!

---

To watch the authors perform laparoscopic excision of type I and type II endometriomas, click here

 

Approach

Laparoscopy is the preferred approach for endometrioma excision. Controversy exists regarding the ideal procedure: complete excision (with stripping of the cyst capsule) or drainage and ablation of the cyst wall. Compared with drainage and ablation, excision reduces recurrence of endometriomas; relieves dysmenorrhea, dyspareunia, pelvic pain, and other symptoms; and improves fertility.^13,16 The recurrence rate may be as low as 5.8% with complete excision but is 90% with simple transvaginal aspiration.^17,18 If not performed properly, however, cyst capsule stripping may damage nearby ovarian stroma and decrease the ovarian reserve.¹⁴ Some authors have advocated combining excision and ablation—performing cystectomy until there is no longer a clear plane between capsule and ovarian stroma and then ablating any remaining endometrial tissue.⁸

With type I and IIC endometriomas, we have seen the endometrial cyst wall infiltrating the ovarian stroma so deeply there is not always a definable plane. By contrast, type IIA and IIB endometriomas typically have a plane between the cyst wall and the ovarian cortex. In type II endometriomas, endometrial implants on the ovarian cortex infiltrate the plane of the cyst wall such that the juxtaposing lipomatous follicular cyst detaches with minimal intraoperative traction. Portions of type II endometriomas containing fibrosis and adhesions may become more difficult to peel off the cyst wall. For most endometriomas, at least 1 spot is difficult to peel off the ovary, and extra care must be taken at the hilum of ovary to avoid excising healthy ovarian cortex.^4,5,7,8

Our surgical approach accounts for the described variations in type I and II endometriomas. Endometrial contents often spill as the endometrioma is dissected off neighboring structures. When possible, endometriomas should be aspirated and irrigated prior to cystectomy to avoid seeding the pelvis and abdomen with spilled endometriotic contents. We use hydrodissection, the injection of dilute vasopressin with a laparoscopic needle, to create a plane between cyst wall and ovarian stroma and strip the cyst capsule with laparoscopic graspers. Type I endometriomas adhere densely to the ovary. Given the presence of fibrosis and adhesions, the cyst is excised in a piecemeal fashion. Care is taken to remove any endometrial implants from the ovary while preserving as much of the ovarian tissue as possible.¹

Type II endometriomas are larger cysts originating from the invasion of endometrial implants or type I endometrioma into functional cysts. The difficulty of capsule excision varies according to the extent of endometrial invasion. Type IIA endometriomas contain less than 10% endometrial tissue within the cyst capsule. Thus, the standard ovarian cystectomy stripping technique is successful in removing more than 90% of the cyst capsule. Special care is taken in stripping the residual small portion that involves the endometrial glands and stroma and adheres densely to the ovary.

The larger proportion of endometrial tissue present in type IIB and IIC endometriomas degrades the plane between the cyst capsule and the ovarian stroma, making excision more difficult. Similar to the type I excision, a piecemeal approach is often necessary. If complete stripping of the cyst capsule would result in extensive loss of healthy ovarian tissue, then electrocautery, plasma energy, or laser ablation can be selectively used to destroy focal areas of endometrial invasion. Complete ablation may be difficult, as the endometrioma wall can be up to 5 mm thick.¹⁹ For these thick-walled endometriomas, we recommend excision (vs ablation), which lowers the risk of endometrioma recurrence.

Related article:
Endometriosis and pain: Expert answers to 6 questions targeting your management options
 

Conclusion

Endometriomas, common adnexal masses in women affected by endometriosis, may exacerbate pelvic pain and impair fertility. Gynecologists should be prepared to excise endometriomas completely and exercise care in preserving as much of the ovarian stroma as possible. We classify endometriomas into 2 types: type I, which develop from invagination of endometrial implants in the ovarian cortex, and type II, which stem from invasion of functional cysts by endometrial implants or type I endometrioma. This distinction guides surgical management. We hope this article and its accompanying video will be helpful in guiding laparoscopic excision of type I and II endometriomas.

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.

Endometriosis is a common condition, occurring in this country in 1 of 10 women of reproductive age. An association between endometriosis and subsequent ovarian carcinoma has been reported for decades, yet it is only recently that our knowledge has deepened enough to support more rational methods for preventing the malignancy.

Each year, approximately 22,000 new cases of ovarian cancer are diagnosed. The lifetime risk of developing this malignancy is low, but it is the deadliest of the gynecologic malignancies, with diagnosis usually made in advanced stages when prognosis is poor.

Endometriosis shows some characteristics of malignancy, such as the development of local and distant foci, and attachment to and invasion of other tissues with subsequent damage to these tissues. Endometriosis also is characterized by recurrent, unregulated cell proliferation and estrogen-dependent growth.

Our attempts during the past 2 decades to detect ovarian carcinoma at the early stages through a combined screening modality involving transvaginal ultrasound and a test for the serum level of cancer antigen 125 have failed to provide any survival benefit or even any measurable reduction in morbidity. Today, early-stage ovarian carcinoma, which has a 5-year survival rate of more than 90%, is diagnosed in only a minority of women.

There is good news, however. In recent years our insight into the pathophysiology of ovarian cancer has deepened, providing us with a new paradigm for ovarian cancer pathogenesis that divides ovarian epithelial carcinoma into two distinct types with distinct molecular profiles – one which originates largely in the distal portion of the fallopian tube and the other which traces back to endometriosis.

This new paradigm strengthens and helps to explain the reported association between endometriosis and ovarian cancer. It also has important clinical implications for current practice. While we have much more to learn about the etiology of endometriosis and the causes of malignant transformation, our current knowledge provides a strong rationale for identification and close monitoring of some patients with endometriosis deemed at risk for ovarian cancer, risk-reducing medical management, earlier and more meticulous surgical treatment, and close monitoring.

By combining this new approach to endometriosis with consideration of salpingectomy after completion of childbearing, we have an unprecedented opportunity to reduce the incidence of epithelial ovarian cancer.

Dual pathogenesis

The majority of ovarian cancers are of epithelial origin and fall into four histologic categories: serous, endometrioid, clear cell, and mucinous. In recent years, we have gained a deeper understanding of the pathogenesis of ovarian carcinoma, with an array of epidemiologic, histologic, and molecular data showing us that epithelial ovarian cancers are also of two distinct types (Am J Obstet Gynecol. 2015 Sep;213[3]:262-7).

One of these types, a high-grade serous carcinoma, appears to arise in many cases in the epithelium of the fallopian tube. The other type of tumor is a low-grade carcinoma – particularly of the endometrioid and clear cell histologic subtypes – that originates largely from ovarian endometriotic lesions or from borderline serous tumors in the case of serous histology.

The majority of diagnosed stage 1 ovarian cancers are carcinomas of this low-grade type and not high-grade serous carcinomas. In a study of 76 consecutive stage 1 carcinomas, investigators found that ovarian endometriosis was present in 40 of the 76 cases. More than two-thirds of the 76 cases (71%) were nonserous cancers, and almost all of these cases were associated with endometriosis based on histologic examination (Fertil Steril. 2007 Oct;88[4]:906-10).

This study was among the first to show that the majority of stage 1 ovarian carcinomas are not high-grade serous carcinomas, but rather nonserous, primarily endometrioid and clear cell, cancers. The research demonstrated that endometriosis should be viewed as a potential precursor lesion to specific subtypes of ovarian cancer.

The malignant transformation of endometriosis was first suggested by Dr. J. A. Sampson in 1925, and a number of studies – in addition to the 2007 landmark study – have since described ovarian cancer arising from endometriosis, based on the frequent co-occurrence in surgical specimens.

Most recently, a study from the Ovarian Cancer Association Consortium (OCAC) found that women who reported a history of endometriosis had a significantly higher risk of developing ovarian cancer than the general population (odds ratio, 1.46).

Investigators of this critical study pooled data from 13 ovarian cancer case-control studies involving more than 13,226 controls and 7,911 women with invasive epithelial ovarian cancer – 818 (6.2%) and 738 (9.3%) of whom, respectively, reported a history of endometriosis. Specifically, they determined that self-reported endometriosis was associated with a 3.05-fold increased risk for clear cell invasive ovarian cancer and a 2.04-fold increased risk of endometrioid ovarian cancer.

Moreover, a significant association between preexisting endometriosis and low-grade serous invasive ovarian cancer (OR, 2.11) was demonstrated, while no association was found between endometriosis and the risk of high-grade serous invasive ovarian cancer (Lancet Oncol. 2012 Apr;13[4]:385-94).

A second recently published report – a meta-analysis of 20 case-control and 15 cohort studies published between 1990 and 2012 and involving more than 444,000 patients – found that endometriosis increased cancer risk in case-control or two-arm cohort studies by 27% (relative risk, 1.265) and by approximately 80% in single-arm cohort studies (standard incidence ratio, 1.797). Endometrioid and clear cell carcinomas were more common in endometriosis-associated ovarian cancer, while serous carcinoma was less frequent (Br J Cancer. 2014 Apr 2;110[7]:1878-90).

Findings of both of these large studies have served to clarify the association between endometriosis and specific histologic subtypes and suggested that there are important differences in the pathogenesis of low-grade and high-grade serous ovarian carcinomas.

Clinical implications

It is not clear what causes malignant transformation or what predisposes some patients with endometriosis to develop ovarian cancer, but the risk likely involves genetic and epigenetic influences as well as immunologic, inflammatory, and hormonal factors.

The molecular profiles of the main two types of ovarian cancer are different: While the majority of high-grade serous ovarian tumors are characterized by TP53 mutations, the low-grade carcinomas are characterized by a variety of mutations, including KRAS, BRAF, ERBB2, CTNNB1, and BCL2 mutations.

There currently are not enough data to recommend genetic screening tests in patients with endometriosis, but our hope is that we eventually will be able to screen for “high-risk” endometriotic lesions by testing for genes specific to various histologic subtypes of low-grade ovarian cancer, or by finding and utilizing other biomarkers.

Courtesy of Dr. Farr Nezhat

In the meantime, we believe it is important to more thoroughly treat endometriosis and to identify and follow women with a history of the condition, especially those with a long-standing history, those with a history of endometriosis associated with infertility, and those with ovarian endometrioma. Each of these factors predisposes patients to a higher risk of malignant transformation.

Complete surgical resection of all visible endometriosis is the most effective treatment and will afford the best cancer prevention, even in women who are asymptomatic. In a recent Swedish national registry case-control study, women who underwent radical surgical excision of all visible endometriosis were significantly less likely (OR, 0.30) to develop ovarian cancer (Acta Obstet Gynecol Scand. 2013 May;92[5]:546-54).

Suppressive hormonal therapy is another treatment option for patients with no interest in conceiving. Most large endometriomas are functional ovarian cysts that have been invaded by cortical ovarian endometriosis or by small primary endometriomas (J Reprod Med. 1992 Sep;37[9]:771-6).

While hormonal therapy will not always result in complete regression of endometriotic lesions, it will decrease the recurrence rate of endometriomas and can be considered for long-term prevention of potentially premalignant lesions. It is most effective when it follows surgical excision of endometriomas and associated endometriosis.

A patient who has completed childbearing at the time of surgical resection may be offered bilateral salpingectomy, regardless of menopausal status. Salpingectomy in both average and high-risk populations (e.g., BRCA 1/2 carriers) not only prevents high-grade serous carcinoma by eliminating the site of origin, but also may decrease the risk of endometrioid and clear cell carcinoma by blocking the passageway that enables the flow of endometrium and factors that induce inflammation. It is estimated that the procedure reduces the risk of ovarian cancer by 40%.

Interestingly, tubal ligation has historically been shown to decrease the risk of ovarian cancer, and recent data have shown that the risk of endometrioid and clear cell carcinoma is cut even more than the risk of high-grade serous carcinoma (Int J Epidemiol. 2013 Apr;42[2]:579-89).

Courtesy Dr. Farr Nezhat

The Society of Gynecologic Oncology recommends that risk-reducing salpingectomy be considered at the time of hysterectomy or other abdominal or pelvic surgery, and in lieu of tubal ligation. The American College of Obstetricians and Gynecologists similarly has stated that prophylactic salpingectomy may offer clinicians the opportunity to prevent ovarian cancer in their patients. Salpingectomy is an important option for all patients, but is especially important when the fallopian tubes are found to be damaged by endometriosis and/or pelvic inflammatory disease. When imaging studies show that endometriomas are present and resection is not performed, pelvic ultrasound should become part of the patient’s routine examination.

Most endometriomas have a homogeneous appearance; any significant increase in size or a change in the homogeneous cystic characteristics to a more heterogeneous appearance with mural components should raise suspicion about malignant change.

It can be difficult to detect relatively small endocystic components with ultrasound, so if there is any doubt about whether there is some heterogeneous consistency, an MRI should be performed. MRI is showing more promise in detecting malignant change. Hyperdense mural nodules within the ovary and rapid growth of an endometrioma have both been associated with malignant transformation and can be seen on these images.

In a cohort study comparing MRI findings of 10 patients with ovarian adenocarcinoma to 10 patients with benign endometriomas, investigators found mural nodules in all 10 malignancies but in only three of the benign cases (AJR Am J Roentgenol. 2000 Nov;175[5]:1423-30).

Long-term follow-up is necessary to understand the timeline of transformation in patients with mural nodules. This together with increasing knowledge of molecular events underpinning evolution of endometriosis will lead to better screening and preventive strategies.

Dr. Nezhat is the director of minimally invasive gynecologic surgery and robotics at Winthrop University Hospital in Mineola, N.Y., and an adjunct professor of obstetrics, gynecology, and reproductive medicine at the State University of New York at Stony Brook. He reported having no financial disclosures.

Endometriosis is a common condition, occurring in this country in 1 of 10 women of reproductive age. An association between endometriosis and subsequent ovarian carcinoma has been reported for decades, yet it is only recently that our knowledge has deepened enough to support more rational methods for preventing the malignancy.

Each year, approximately 22,000 new cases of ovarian cancer are diagnosed. The lifetime risk of developing this malignancy is low, but it is the deadliest of the gynecologic malignancies, with diagnosis usually made in advanced stages when prognosis is poor.

Endometriosis shows some characteristics of malignancy, such as the development of local and distant foci, and attachment to and invasion of other tissues with subsequent damage to these tissues. Endometriosis also is characterized by recurrent, unregulated cell proliferation and estrogen-dependent growth.

Our attempts during the past 2 decades to detect ovarian carcinoma at the early stages through a combined screening modality involving transvaginal ultrasound and a test for the serum level of cancer antigen 125 have failed to provide any survival benefit or even any measurable reduction in morbidity. Today, early-stage ovarian carcinoma, which has a 5-year survival rate of more than 90%, is diagnosed in only a minority of women.

There is good news, however. In recent years our insight into the pathophysiology of ovarian cancer has deepened, providing us with a new paradigm for ovarian cancer pathogenesis that divides ovarian epithelial carcinoma into two distinct types with distinct molecular profiles – one which originates largely in the distal portion of the fallopian tube and the other which traces back to endometriosis.

This new paradigm strengthens and helps to explain the reported association between endometriosis and ovarian cancer. It also has important clinical implications for current practice. While we have much more to learn about the etiology of endometriosis and the causes of malignant transformation, our current knowledge provides a strong rationale for identification and close monitoring of some patients with endometriosis deemed at risk for ovarian cancer, risk-reducing medical management, earlier and more meticulous surgical treatment, and close monitoring.

By combining this new approach to endometriosis with consideration of salpingectomy after completion of childbearing, we have an unprecedented opportunity to reduce the incidence of epithelial ovarian cancer.

Dual pathogenesis

The majority of ovarian cancers are of epithelial origin and fall into four histologic categories: serous, endometrioid, clear cell, and mucinous. In recent years, we have gained a deeper understanding of the pathogenesis of ovarian carcinoma, with an array of epidemiologic, histologic, and molecular data showing us that epithelial ovarian cancers are also of two distinct types (Am J Obstet Gynecol. 2015 Sep;213[3]:262-7).

One of these types, a high-grade serous carcinoma, appears to arise in many cases in the epithelium of the fallopian tube. The other type of tumor is a low-grade carcinoma – particularly of the endometrioid and clear cell histologic subtypes – that originates largely from ovarian endometriotic lesions or from borderline serous tumors in the case of serous histology.

The majority of diagnosed stage 1 ovarian cancers are carcinomas of this low-grade type and not high-grade serous carcinomas. In a study of 76 consecutive stage 1 carcinomas, investigators found that ovarian endometriosis was present in 40 of the 76 cases. More than two-thirds of the 76 cases (71%) were nonserous cancers, and almost all of these cases were associated with endometriosis based on histologic examination (Fertil Steril. 2007 Oct;88[4]:906-10).

This study was among the first to show that the majority of stage 1 ovarian carcinomas are not high-grade serous carcinomas, but rather nonserous, primarily endometrioid and clear cell, cancers. The research demonstrated that endometriosis should be viewed as a potential precursor lesion to specific subtypes of ovarian cancer.

The malignant transformation of endometriosis was first suggested by Dr. J. A. Sampson in 1925, and a number of studies – in addition to the 2007 landmark study – have since described ovarian cancer arising from endometriosis, based on the frequent co-occurrence in surgical specimens.

Most recently, a study from the Ovarian Cancer Association Consortium (OCAC) found that women who reported a history of endometriosis had a significantly higher risk of developing ovarian cancer than the general population (odds ratio, 1.46).

Investigators of this critical study pooled data from 13 ovarian cancer case-control studies involving more than 13,226 controls and 7,911 women with invasive epithelial ovarian cancer – 818 (6.2%) and 738 (9.3%) of whom, respectively, reported a history of endometriosis. Specifically, they determined that self-reported endometriosis was associated with a 3.05-fold increased risk for clear cell invasive ovarian cancer and a 2.04-fold increased risk of endometrioid ovarian cancer.

Moreover, a significant association between preexisting endometriosis and low-grade serous invasive ovarian cancer (OR, 2.11) was demonstrated, while no association was found between endometriosis and the risk of high-grade serous invasive ovarian cancer (Lancet Oncol. 2012 Apr;13[4]:385-94).

A second recently published report – a meta-analysis of 20 case-control and 15 cohort studies published between 1990 and 2012 and involving more than 444,000 patients – found that endometriosis increased cancer risk in case-control or two-arm cohort studies by 27% (relative risk, 1.265) and by approximately 80% in single-arm cohort studies (standard incidence ratio, 1.797). Endometrioid and clear cell carcinomas were more common in endometriosis-associated ovarian cancer, while serous carcinoma was less frequent (Br J Cancer. 2014 Apr 2;110[7]:1878-90).

Findings of both of these large studies have served to clarify the association between endometriosis and specific histologic subtypes and suggested that there are important differences in the pathogenesis of low-grade and high-grade serous ovarian carcinomas.

Clinical implications

It is not clear what causes malignant transformation or what predisposes some patients with endometriosis to develop ovarian cancer, but the risk likely involves genetic and epigenetic influences as well as immunologic, inflammatory, and hormonal factors.

The molecular profiles of the main two types of ovarian cancer are different: While the majority of high-grade serous ovarian tumors are characterized by TP53 mutations, the low-grade carcinomas are characterized by a variety of mutations, including KRAS, BRAF, ERBB2, CTNNB1, and BCL2 mutations.

There currently are not enough data to recommend genetic screening tests in patients with endometriosis, but our hope is that we eventually will be able to screen for “high-risk” endometriotic lesions by testing for genes specific to various histologic subtypes of low-grade ovarian cancer, or by finding and utilizing other biomarkers.

Courtesy of Dr. Farr Nezhat

In the meantime, we believe it is important to more thoroughly treat endometriosis and to identify and follow women with a history of the condition, especially those with a long-standing history, those with a history of endometriosis associated with infertility, and those with ovarian endometrioma. Each of these factors predisposes patients to a higher risk of malignant transformation.

Complete surgical resection of all visible endometriosis is the most effective treatment and will afford the best cancer prevention, even in women who are asymptomatic. In a recent Swedish national registry case-control study, women who underwent radical surgical excision of all visible endometriosis were significantly less likely (OR, 0.30) to develop ovarian cancer (Acta Obstet Gynecol Scand. 2013 May;92[5]:546-54).

Suppressive hormonal therapy is another treatment option for patients with no interest in conceiving. Most large endometriomas are functional ovarian cysts that have been invaded by cortical ovarian endometriosis or by small primary endometriomas (J Reprod Med. 1992 Sep;37[9]:771-6).

While hormonal therapy will not always result in complete regression of endometriotic lesions, it will decrease the recurrence rate of endometriomas and can be considered for long-term prevention of potentially premalignant lesions. It is most effective when it follows surgical excision of endometriomas and associated endometriosis.

A patient who has completed childbearing at the time of surgical resection may be offered bilateral salpingectomy, regardless of menopausal status. Salpingectomy in both average and high-risk populations (e.g., BRCA 1/2 carriers) not only prevents high-grade serous carcinoma by eliminating the site of origin, but also may decrease the risk of endometrioid and clear cell carcinoma by blocking the passageway that enables the flow of endometrium and factors that induce inflammation. It is estimated that the procedure reduces the risk of ovarian cancer by 40%.

Interestingly, tubal ligation has historically been shown to decrease the risk of ovarian cancer, and recent data have shown that the risk of endometrioid and clear cell carcinoma is cut even more than the risk of high-grade serous carcinoma (Int J Epidemiol. 2013 Apr;42[2]:579-89).

Courtesy Dr. Farr Nezhat

The Society of Gynecologic Oncology recommends that risk-reducing salpingectomy be considered at the time of hysterectomy or other abdominal or pelvic surgery, and in lieu of tubal ligation. The American College of Obstetricians and Gynecologists similarly has stated that prophylactic salpingectomy may offer clinicians the opportunity to prevent ovarian cancer in their patients. Salpingectomy is an important option for all patients, but is especially important when the fallopian tubes are found to be damaged by endometriosis and/or pelvic inflammatory disease. When imaging studies show that endometriomas are present and resection is not performed, pelvic ultrasound should become part of the patient’s routine examination.

Most endometriomas have a homogeneous appearance; any significant increase in size or a change in the homogeneous cystic characteristics to a more heterogeneous appearance with mural components should raise suspicion about malignant change.

It can be difficult to detect relatively small endocystic components with ultrasound, so if there is any doubt about whether there is some heterogeneous consistency, an MRI should be performed. MRI is showing more promise in detecting malignant change. Hyperdense mural nodules within the ovary and rapid growth of an endometrioma have both been associated with malignant transformation and can be seen on these images.

In a cohort study comparing MRI findings of 10 patients with ovarian adenocarcinoma to 10 patients with benign endometriomas, investigators found mural nodules in all 10 malignancies but in only three of the benign cases (AJR Am J Roentgenol. 2000 Nov;175[5]:1423-30).

Long-term follow-up is necessary to understand the timeline of transformation in patients with mural nodules. This together with increasing knowledge of molecular events underpinning evolution of endometriosis will lead to better screening and preventive strategies.

Dr. Nezhat is the director of minimally invasive gynecologic surgery and robotics at Winthrop University Hospital in Mineola, N.Y., and an adjunct professor of obstetrics, gynecology, and reproductive medicine at the State University of New York at Stony Brook. He reported having no financial disclosures.

Endometriosis is a common condition, occurring in this country in 1 of 10 women of reproductive age. An association between endometriosis and subsequent ovarian carcinoma has been reported for decades, yet it is only recently that our knowledge has deepened enough to support more rational methods for preventing the malignancy.

Each year, approximately 22,000 new cases of ovarian cancer are diagnosed. The lifetime risk of developing this malignancy is low, but it is the deadliest of the gynecologic malignancies, with diagnosis usually made in advanced stages when prognosis is poor.

Endometriosis shows some characteristics of malignancy, such as the development of local and distant foci, and attachment to and invasion of other tissues with subsequent damage to these tissues. Endometriosis also is characterized by recurrent, unregulated cell proliferation and estrogen-dependent growth.

Our attempts during the past 2 decades to detect ovarian carcinoma at the early stages through a combined screening modality involving transvaginal ultrasound and a test for the serum level of cancer antigen 125 have failed to provide any survival benefit or even any measurable reduction in morbidity. Today, early-stage ovarian carcinoma, which has a 5-year survival rate of more than 90%, is diagnosed in only a minority of women.

There is good news, however. In recent years our insight into the pathophysiology of ovarian cancer has deepened, providing us with a new paradigm for ovarian cancer pathogenesis that divides ovarian epithelial carcinoma into two distinct types with distinct molecular profiles – one which originates largely in the distal portion of the fallopian tube and the other which traces back to endometriosis.

This new paradigm strengthens and helps to explain the reported association between endometriosis and ovarian cancer. It also has important clinical implications for current practice. While we have much more to learn about the etiology of endometriosis and the causes of malignant transformation, our current knowledge provides a strong rationale for identification and close monitoring of some patients with endometriosis deemed at risk for ovarian cancer, risk-reducing medical management, earlier and more meticulous surgical treatment, and close monitoring.

By combining this new approach to endometriosis with consideration of salpingectomy after completion of childbearing, we have an unprecedented opportunity to reduce the incidence of epithelial ovarian cancer.

Dual pathogenesis

The majority of ovarian cancers are of epithelial origin and fall into four histologic categories: serous, endometrioid, clear cell, and mucinous. In recent years, we have gained a deeper understanding of the pathogenesis of ovarian carcinoma, with an array of epidemiologic, histologic, and molecular data showing us that epithelial ovarian cancers are also of two distinct types (Am J Obstet Gynecol. 2015 Sep;213[3]:262-7).

One of these types, a high-grade serous carcinoma, appears to arise in many cases in the epithelium of the fallopian tube. The other type of tumor is a low-grade carcinoma – particularly of the endometrioid and clear cell histologic subtypes – that originates largely from ovarian endometriotic lesions or from borderline serous tumors in the case of serous histology.

The majority of diagnosed stage 1 ovarian cancers are carcinomas of this low-grade type and not high-grade serous carcinomas. In a study of 76 consecutive stage 1 carcinomas, investigators found that ovarian endometriosis was present in 40 of the 76 cases. More than two-thirds of the 76 cases (71%) were nonserous cancers, and almost all of these cases were associated with endometriosis based on histologic examination (Fertil Steril. 2007 Oct;88[4]:906-10).

This study was among the first to show that the majority of stage 1 ovarian carcinomas are not high-grade serous carcinomas, but rather nonserous, primarily endometrioid and clear cell, cancers. The research demonstrated that endometriosis should be viewed as a potential precursor lesion to specific subtypes of ovarian cancer.

The malignant transformation of endometriosis was first suggested by Dr. J. A. Sampson in 1925, and a number of studies – in addition to the 2007 landmark study – have since described ovarian cancer arising from endometriosis, based on the frequent co-occurrence in surgical specimens.

Most recently, a study from the Ovarian Cancer Association Consortium (OCAC) found that women who reported a history of endometriosis had a significantly higher risk of developing ovarian cancer than the general population (odds ratio, 1.46).

Investigators of this critical study pooled data from 13 ovarian cancer case-control studies involving more than 13,226 controls and 7,911 women with invasive epithelial ovarian cancer – 818 (6.2%) and 738 (9.3%) of whom, respectively, reported a history of endometriosis. Specifically, they determined that self-reported endometriosis was associated with a 3.05-fold increased risk for clear cell invasive ovarian cancer and a 2.04-fold increased risk of endometrioid ovarian cancer.

Moreover, a significant association between preexisting endometriosis and low-grade serous invasive ovarian cancer (OR, 2.11) was demonstrated, while no association was found between endometriosis and the risk of high-grade serous invasive ovarian cancer (Lancet Oncol. 2012 Apr;13[4]:385-94).

A second recently published report – a meta-analysis of 20 case-control and 15 cohort studies published between 1990 and 2012 and involving more than 444,000 patients – found that endometriosis increased cancer risk in case-control or two-arm cohort studies by 27% (relative risk, 1.265) and by approximately 80% in single-arm cohort studies (standard incidence ratio, 1.797). Endometrioid and clear cell carcinomas were more common in endometriosis-associated ovarian cancer, while serous carcinoma was less frequent (Br J Cancer. 2014 Apr 2;110[7]:1878-90).

Findings of both of these large studies have served to clarify the association between endometriosis and specific histologic subtypes and suggested that there are important differences in the pathogenesis of low-grade and high-grade serous ovarian carcinomas.

Clinical implications

It is not clear what causes malignant transformation or what predisposes some patients with endometriosis to develop ovarian cancer, but the risk likely involves genetic and epigenetic influences as well as immunologic, inflammatory, and hormonal factors.

The molecular profiles of the main two types of ovarian cancer are different: While the majority of high-grade serous ovarian tumors are characterized by TP53 mutations, the low-grade carcinomas are characterized by a variety of mutations, including KRAS, BRAF, ERBB2, CTNNB1, and BCL2 mutations.

There currently are not enough data to recommend genetic screening tests in patients with endometriosis, but our hope is that we eventually will be able to screen for “high-risk” endometriotic lesions by testing for genes specific to various histologic subtypes of low-grade ovarian cancer, or by finding and utilizing other biomarkers.

Courtesy of Dr. Farr Nezhat

In the meantime, we believe it is important to more thoroughly treat endometriosis and to identify and follow women with a history of the condition, especially those with a long-standing history, those with a history of endometriosis associated with infertility, and those with ovarian endometrioma. Each of these factors predisposes patients to a higher risk of malignant transformation.

Complete surgical resection of all visible endometriosis is the most effective treatment and will afford the best cancer prevention, even in women who are asymptomatic. In a recent Swedish national registry case-control study, women who underwent radical surgical excision of all visible endometriosis were significantly less likely (OR, 0.30) to develop ovarian cancer (Acta Obstet Gynecol Scand. 2013 May;92[5]:546-54).

Suppressive hormonal therapy is another treatment option for patients with no interest in conceiving. Most large endometriomas are functional ovarian cysts that have been invaded by cortical ovarian endometriosis or by small primary endometriomas (J Reprod Med. 1992 Sep;37[9]:771-6).

While hormonal therapy will not always result in complete regression of endometriotic lesions, it will decrease the recurrence rate of endometriomas and can be considered for long-term prevention of potentially premalignant lesions. It is most effective when it follows surgical excision of endometriomas and associated endometriosis.

A patient who has completed childbearing at the time of surgical resection may be offered bilateral salpingectomy, regardless of menopausal status. Salpingectomy in both average and high-risk populations (e.g., BRCA 1/2 carriers) not only prevents high-grade serous carcinoma by eliminating the site of origin, but also may decrease the risk of endometrioid and clear cell carcinoma by blocking the passageway that enables the flow of endometrium and factors that induce inflammation. It is estimated that the procedure reduces the risk of ovarian cancer by 40%.

Interestingly, tubal ligation has historically been shown to decrease the risk of ovarian cancer, and recent data have shown that the risk of endometrioid and clear cell carcinoma is cut even more than the risk of high-grade serous carcinoma (Int J Epidemiol. 2013 Apr;42[2]:579-89).

Courtesy Dr. Farr Nezhat

The Society of Gynecologic Oncology recommends that risk-reducing salpingectomy be considered at the time of hysterectomy or other abdominal or pelvic surgery, and in lieu of tubal ligation. The American College of Obstetricians and Gynecologists similarly has stated that prophylactic salpingectomy may offer clinicians the opportunity to prevent ovarian cancer in their patients. Salpingectomy is an important option for all patients, but is especially important when the fallopian tubes are found to be damaged by endometriosis and/or pelvic inflammatory disease. When imaging studies show that endometriomas are present and resection is not performed, pelvic ultrasound should become part of the patient’s routine examination.

Most endometriomas have a homogeneous appearance; any significant increase in size or a change in the homogeneous cystic characteristics to a more heterogeneous appearance with mural components should raise suspicion about malignant change.

It can be difficult to detect relatively small endocystic components with ultrasound, so if there is any doubt about whether there is some heterogeneous consistency, an MRI should be performed. MRI is showing more promise in detecting malignant change. Hyperdense mural nodules within the ovary and rapid growth of an endometrioma have both been associated with malignant transformation and can be seen on these images.

In a cohort study comparing MRI findings of 10 patients with ovarian adenocarcinoma to 10 patients with benign endometriomas, investigators found mural nodules in all 10 malignancies but in only three of the benign cases (AJR Am J Roentgenol. 2000 Nov;175[5]:1423-30).

Long-term follow-up is necessary to understand the timeline of transformation in patients with mural nodules. This together with increasing knowledge of molecular events underpinning evolution of endometriosis will lead to better screening and preventive strategies.

Dr. Nezhat is the director of minimally invasive gynecologic surgery and robotics at Winthrop University Hospital in Mineola, N.Y., and an adjunct professor of obstetrics, gynecology, and reproductive medicine at the State University of New York at Stony Brook. He reported having no financial disclosures.