Endometriosis outside the pelvis: bowel, bladder, diaphragm and other sites

Endometriosis is usually described as a condition of the pelvis, but studies have found it in the bowel wall, the bladder, the ureters, the diaphragm, the chest, abdominal wall scars and, in rare reports, muscles and nerves. How often this happens depends on who is counted. Reviews estimate bowel involvement in roughly 8 to 12 percent of women with endometriosis ^[1], two large surgical cohorts found diaphragm involvement in 1.5 and 4.7 percent ^[2][3], and thoracic disease is described mostly in case reports and small series ^[4]. Symptoms can be cyclical or constant, and many are shared with other conditions ^[5]. Assessment in the research literature draws on reported symptoms, a clinician's examination, ultrasound or MRI, findings at surgery, and pathology, and each of these answers a different question ^[6][7]. Most of the evidence comes from referral centers and case series, so the numbers describe the women those centers see more reliably than they describe women in general ^[2][4][8].

What "outside the pelvis" means in research

Researchers use several overlapping terms, and the differences affect how numbers should be read. An international terminology published in 2021 describes three broad phenotypes, superficial peritoneal, ovarian and deep disease, and lists anatomical sites for each ^[9]. Under that terminology, deep disease no longer depends on a measured depth of infiltration ^[9]. Deep disease often involves the uterosacral ligaments, the vagina, the bowel, the bladder and the ureters ^[17].

The bowel, bladder and ureters sit in or next to the pelvis. A 2026 review of extrapelvic disease points out that gastrointestinal and urinary tract involvement are the most common extragenital sites but may be considered pelvic, and it leaves them out of its scope ^[10]. This article covers them because they share assessment methods with the more distant sites.

The more distant sites include the diaphragm, pleura and lung, the abdominal wall, the groin and perineum, the umbilicus, solid organs such as the liver, and, in a small number of reports, muscle, peripheral nerves and the central nervous system ^[4][10]. A 2020 systematic review of primary extrapelvic endometriosis screened 5,465 articles and included 179, mostly case reports and case series ^[4]. The same review counted 628 articles on thoracic disease, 230 on abdominal wall and related parietal sites, 43 on abdominal organs, and only a handful on nerve, muscle or central nervous system disease ^[4]. Article counts reflect what clinicians publish, not how common each site is.

A general figure for context: about 10 percent of women of reproductive age are estimated to have endometriosis, according to the introduction of a Cochrane review of imaging tests ^[7]. The percentages in this article refer to subgroups of women who already have a diagnosis, or who were having surgery, in the studies described.

How common is each site?

A surgical series of deep disease

One often-cited description of where deep lesions occur comes from a single center's series. Chapron and colleagues reported 426 women with pelvic pain who had complete surgical removal of deep endometriosis between 1992 and 2004 ^[17]. Together they had 759 lesions that were confirmed under the microscope. By lesion, the uterosacral ligaments accounted for 52.7 percent, the intestine for 22.7 percent, the vagina for 16.2 percent, the bladder for 6.3 percent and the ureter for 2.1 percent ^[17]. Of the 759 lesions, 730 were in the pelvis and 29 in the abdomen ^[17]. Lesions were more often on the left side than on the right ^[17].

This is a count of lesions among women who were selected for a particular operation at one center. It does not give the proportion of women with endometriosis who have bowel or bladder disease, and the study was not designed to estimate that.

Bowel

A review by an international group of authors estimated that intestinal involvement by deep nodules occurs in 8 to 12 percent of women with endometriosis ^[1]. A review by a multidisciplinary surgical team states that the frequency of bowel endometriosis is unknown, and that about 90 percent of bowel disease sits in the sigmoid colon or rectum ^[11]. A meta-analysis of imaging studies gives the same figure for the rectosigmoid ^[18].

A consecutive series of 355 women who had laparoscopy for suspected endometriosis gives another angle ^[5]. Endometriosis was confirmed by pathology in 290 of them (84.5 percent), and bowel lesions were present in 7.6 percent ^[5]. In the studies included in a 2011 meta-analysis of ultrasound for bowel disease, which enrolled 1,106 women with suspected endometriosis, the prevalence of bowel endometriosis ranged from 24 percent to 73.3 percent ^[19]. A 2019 meta-analysis of eight studies reported an average prevalence of 47.3 percent ^[18]. These two numbers are not estimates for women with endometriosis in general. They come from samples drawn from imaging and surgical services, where women with more advanced disease are over-represented.

The wide span between 7.6 percent and 73 percent shows how much the population changes the answer. Each sample counts a different group.

Bladder and ureter

Estimates for urinary tract involvement vary by setting as well. A retrospective study at a university hospital included 697 patients with endometriosis, 213 of whom had deep infiltrating disease, and found urinary tract endometriosis in 52.6 percent of those 213 ^[20]. The authors concluded that the prevalence had often been underestimated ^[20]. A prospective French national series of 232 women who were having surgery for urinary tract endometriosis in 31 expert centers during one year found isolated bladder disease in 35.3 percent, isolated ureteral disease in 54.4 percent and both in 10.3 percent ^[8]. A literature review from 2012 stated that, when deep pelvic endometriosis involved the urinary system, the bladder was affected in 85 percent of cases ^[21]. The French series and the older review disagree on whether the bladder or the ureter is more often involved, which may reflect differences in the populations, the years and the definitions ^[8][21].

Deep disease in the urinary tract usually travels with disease elsewhere. In the French series, 83.1 percent of women had associated deep lesions, and ureteral disease was more often accompanied by rectosigmoid nodules than the other urinary locations ^[8].

Diaphragm

Diaphragmatic endometriosis has been described in surgical cohorts of women who already had pelvic disease. At one referral institution, 46 women out of 3,008 with pelvic endometriosis treated over seven years had it identified during surgery, about 1.5 percent ^[2]. In a tertiary referral center cohort of 1,765 women with pathology-confirmed endometriosis, diaphragmatic disease was found in 83, or 4.7 percent, and appendiceal disease in 31, or 1.8 percent ^[3]. Women with appendiceal disease were more likely to have diaphragmatic disease as well, with an odds ratio of 5.5 and a wide confidence interval of 2.1 to 14.4 ^[3].

These figures may depend on how carefully the upper abdomen was examined, since a radiology review states that standard laparoscopy may overlook posterior diaphragmatic lesions ^[22]. In a 2026 cross-sectional study, 55 women with diaphragmatic endometriosis found during pelvic surgery were followed; only one had symptoms of it, and 98.2 percent also had deep pelvic endometriosis ^[12]. A 2024 review of diaphragmatic disease states that it is one of the more common extrapelvic locations and that it may be asymptomatic ^[23].

Thoracic disease

Thoracic endometriosis syndrome describes cyclical chest events that include pneumothorax (a collapsed lung), hemothorax (blood in the chest cavity), hemoptysis (coughing blood) and lung nodules ^[13][15]. Joseph and Sahn analyzed 110 published cases in 1996 and found pneumothorax in 73 percent, hemothorax in 14 percent, hemoptysis in 7 percent and nodules in 6 percent ^[13]. More than 90 percent of the manifestations other than nodules were in the right chest ^[13]. A second compilation of 110 published cases from 2001 to 2007 found a right-sided predominance of 85 percent ^[24].

A systematic review of 18 studies and 490 women with catamenial pneumothorax reported that catamenial pneumothorax accounted for 7.3 to 36.7 percent of all pneumothorax in women of reproductive age across the included studies ^[14]. Pelvic endometriosis was reported in only 55 percent of those women, and diaphragmatic endometriosis or nodules were observed in 265 of 297 cases ^[14]. Another meta-analysis of 25 studies with 732 patients noted that up to 80 percent of women with thoracic disease had concomitant pelvic endometriosis ^[25]. The two figures, 55 percent and up to 80 percent, differ across reviews ^[14][25].

Abdominal wall, muscle, nerve and other sites

Abdominal wall endometriosis typically appears in or near a surgical scar. At one academic institution, 65 women had it removed over 12 years; 81.5 percent had a prior cesarean birth, and 9.2 percent had no prior surgery ^[26]. A 2026 systematic review of 484 cases after cesarean section reported a median of 48 months between the cesarean birth and diagnosis, and pain in 96 percent and a palpable mass in 94.1 percent ^[27]. In the same review, prior endometriosis had been reported in 9.4 percent ^[27].

Sites in muscle and nerve are reported in small numbers. A review of endometriosis of the skeletal muscular system found 78 cases in 62 published studies ^[28]. The abdominal muscles accounted for 50.7 percent of them, and 47.4 percent of the women had a normal-appearing pelvic cavity ^[28]. A 2026 meta-analysis of eight studies and 744 women evaluated surgery for sciatic nerve or sacral plexus involvement ^[29]. It described neuropathic pain as occurring in approximately 40 percent of endometriosis cases and sciatic nerve involvement in 52.3 percent of the operated women in the included studies ^[29]. These women were selected because they had sciatic pain and surgery, so the percentages do not describe endometriosis in general.

The 2020 review of extrapelvic disease found 43 articles on visceral sites, including the kidney, liver, pancreas and biliary tract ^[4].

Symptoms that research links to these sites

Symptoms in these studies share two features: they can be cyclical, and they can be unspecific.

For the bowel, the Belgian review lists constipation, diarrhea, tenesmus, dyschezia (pain with passing stool) and rarely rectal bleeding, and says that the differential diagnosis includes irritable bowel syndrome, solitary rectal ulcer syndrome and rectal tumor ^[11]. Bowel symptoms are also common in women whose bowel is not involved. In the series of 355 women who had laparoscopy, 90 percent had gastrointestinal symptoms, bloating was the most common at 82.8 percent, and 21.4 percent had previously been given a diagnosis of irritable bowel syndrome, of whom 79 percent had endometriosis confirmed ^[5]. The authors concluded that gastrointestinal symptoms did not necessarily reflect bowel involvement ^[5].

For the bladder, the Swiss university hospital study found that 68.8 percent of women with bladder endometriosis reported urinary symptoms, compared with 7.9 percent of women without urinary tract endometriosis ^[20]. Ureteral disease behaved differently. In that study, symptoms with ureteral involvement were not specific ^[20]. In the French national series, ureteral disease was more often without symptoms than the other locations, with 59.5 percent symptom-free compared with 43.3 percent ^[8]. A systematic review of 67 articles on ureteral endometriosis stated that it is often asymptomatic or causes nonspecific symptoms and that delayed diagnosis may lead to persistent hydronephrosis, which is swelling of the kidney from blocked urine flow, and eventually to loss of kidney function ^[30].

For the diaphragm, a review lists cyclical shoulder pain, right upper abdominal pain and right-sided chest pain, and notes that lesions may cause no symptoms ^[23]. A French multicenter study of 50 women who had surgery for diaphragmatic or thoracic endometriosis at five university hospitals found a median of 47 months from the first symptoms to diagnosis, with a range from 0 to 212 months ^[31]. In 38 of those 50, the diagnosis was made on clinical symptoms such as pneumothorax or chest pain ^[31].

For the chest, a systematic review of catamenial pneumothorax reported that the diagnosis was mostly made clinically, from shortness of breath and recurrent chest or shoulder pain starting from a day before to 72 hours after menses, and that the pneumothorax was on the right in 93 percent ^[14].

For scar-related abdominal wall disease, the typical features are a lump, pain, and a timing that follows the cycle, although 9.2 percent of the women in the academic center series had no prior surgery, and umbilical lesions were more frequent in women without a cesarean history ^[26]. The 2020 systematic review found that for abdominal wall and related sites, a palpable mass was present in 99 percent, cyclic pain in 71 percent and cyclic bleeding in 48 percent, and that preoperative clinical suspicion was low ^[4].

The European guideline's list of symptoms for clinicians to consider includes dysuria, dyschezia, painful rectal bleeding and hematuria, along with catamenial pneumothorax, cyclical cough or chest pain, and shoulder tip pain ^[6]. These are prompts for further assessment, not tests in themselves.

How these forms are assessed

Research separates five kinds of information: what a person reports, what a clinician finds on examination, what imaging shows, what is seen at surgery, and what pathology confirms. They are not interchangeable.

Reported symptoms and clinical examination

Symptoms are the starting point and the weakest evidence for a specific site, for the reasons given above. The European guideline says that vaginal examination may identify deep nodules or endometriomas, but with low diagnostic accuracy, and that further steps including imaging should be considered even when examination is normal ^[6]. In a systematic review of ultrasound accuracy, the authors noted that reported accuracy figures often combine imaging with symptoms and examination, so they do not isolate the imaging test itself ^[32].

Ultrasound

For bowel disease, a 2011 meta-analysis of 10 studies including 1,106 women with suspected endometriosis reported pooled sensitivity of 91 percent and specificity of 98 percent for transvaginal ultrasound in detecting rectosigmoid disease, using laparoscopy or pathology as the reference ^[19]. The authors pointed to wide confidence intervals in individual studies and to differences in whether bowel preparation was used ^[19]. A meta-analysis of the sliding sign, an ultrasound maneuver that tests whether pelvic organs move freely against one another, found it useful for predicting obliteration of the pouch of Douglas and bowel involvement, with heterogeneous bowel estimates and incompletely reported blinding ^[33].

A Cochrane review of imaging for endometriosis included 49 studies with 4,807 women and judged most to be of poor methodological quality ^[7]. For deep endometriosis overall, transvaginal ultrasound had a pooled sensitivity of 0.79 and specificity of 0.94 across nine studies with 934 women ^[7]. The review noted higher accuracy in some studies when bowel preparation or rectal water contrast was used, but too few studies for statistical comparison ^[7].

A 2023 systematic review of 30 reports on ultrasound for deep endometriosis found that specificity exceeded sensitivity at every location examined, 97 percent against 88 percent for the rectosigmoid ^[32]. The same review found that accuracy did not change over 20 years despite better equipment, and that the lowest size of lesion that can be detected is unknown ^[32].

For the bladder, a 2021 meta-analysis of eight studies with 1,052 women found a pooled ultrasound sensitivity of 55 percent and specificity of 99 percent, and judged the studies methodologically poor and heterogeneous ^[16]. A 2022 meta-analysis of 23 studies found higher pooled sensitivities, 72 percent for ultrasound and 68 percent for MRI in the bladder, and 97 percent and 87 percent in the ureter, with specificities of 99 to 100 percent ^[34]. The two bladder estimates differ, and the difference probably reflects the studies each review included and how they were graded ^[16][34].

MRI and other imaging

For rectosigmoid disease, a 2019 meta-analysis of eight studies and 1,132 women found pooled sensitivity and specificity of 88 and 90 percent for MRI and 90 and 96 percent for ultrasound, with no statistically significant difference in the area under the summary ROC curve ^[18]. A 2018 meta-analysis restricted to women who had both tests, six studies with 424 women, found broadly similar performance of the two for rectosigmoid, uterosacral and rectovaginal septum disease, with wide confidence intervals ^[35]. In the Cochrane review, MRI for deep endometriosis had a pooled sensitivity of 0.94 and specificity of 0.77 across six studies with 266 women ^[7]. That review also reported that CT with a bowel enema had the highest performance for bowel disease, but there were too few studies to give meaningful results ^[7].

An international consensus statement from eight societies supports trained-operator imaging for mapping deep disease and says that performance depends on operator expertise and anatomical site ^[36]. A European radiology consensus on MRI recommends preparation that includes fasting, antiperistaltic agents, moderate bladder filling and bowel preparation ^[37]. These are statements of expert agreement. They do not by themselves show how accurate imaging is for any one person.

For the diaphragm, a 2024 review reported MRI sensitivity of 78 to 83 percent and noted that MRI tended to underestimate extent compared with surgical findings ^[23]. For thoracic disease, a radiology review described CT as the first-line method that is poorly specific, mostly useful for excluding other lung disease, and MRI as able to show signal changes of hemorrhage within diaphragmatic or pleural lesions ^[38]. A 2026 narrative review said imaging findings in thoracic disease are often nonspecific and insufficient on their own, and that the evidence is limited by retrospective designs, small case series and inconsistent diagnostic criteria ^[39].

A prospective multicenter study of 745 women who had radical surgery for deep endometriosis at tertiary referral centers compared ultrasound with operative findings using the #Enzian classification ^[40]. Agreement was often good, but performance varied by compartment and severity, and the results come from a highly selected population ^[40]. The #Enzian system describes anatomical location, lesion size, adhesions and involvement of adjacent organs, and is meant for use with both imaging and surgery ^[41].

Surgery

At surgery, lesions are identified by visual inspection and confirmed by pathology where tissue is taken ^[6]. The literature also shows the limits of looking. In a private referral center, 25.5 percent of 51 women undergoing bowel resection had small palpable nodules near the bowel that were not seen at laparoscopy ^[42]. Reviews and cohort reports of diaphragmatic disease state that robust evidence on preoperative diagnosis is lacking and that no standardized diagnostic protocol exists ^[12][23]. The radiology review mentioned above attributes missed posterior lesions to their subhepatic location ^[22].

A review of surgery for colorectal disease covered 49 studies and 3,894 women ^[43]. Pain evaluation was patient-based in fewer than half of those studies, recurrence was reported in 5 to 25 percent over follow-up longer than two years, and the authors could not compare techniques because of varied study designs ^[43]. This article does not compare surgical approaches. Its point is that the outcome data come from heterogeneous reports.

Pathology

The European guideline says laparoscopic identification should be confirmed by histology, and that negative histology does not entirely rule out the disease ^[6]. Pathologists describe the diagnosis as usually straightforward but potentially difficult in small biopsies, in sites that are unusual, and when glands or stroma are altered or sparse ^[44]. In the intestine, the same review points to the important distinction between endometrioid carcinoma arising in endometriosis and a primary colonic adenocarcinoma ^[44]. Fine-needle aspiration of muscle lesions confirmed endometriosis in 12 of 27 attempts in one systematic review, which shows how a small sample can miss the diagnosis ^[28].

What is uncertain

How common each site is

Prevalence figures for most sites depend on which women are included and how hard the site was looked for. Bowel estimates range from 7.6 to 73 percent across samples, diaphragm figures from 1.5 to 4.7 percent in two surgical cohorts, and chest disease is mostly described in case compilations that have no denominator ^{[2][3][5][13][19][24]}.

Why it occurs

Two lines of research touch on how lesions reach distant sites. For deep pelvic lesions, Chapron and colleagues proposed that the left-sided predominance might relate to anatomical differences between the sides of the pelvis ^[17]. For the diaphragm and chest, reviews describe movement of cells through the abdomen with peritoneal fluid and, in thoracic disease, passage through diaphragmatic defects or blood vessels ^[13][23]. A compilation of 110 thoracic cases found no significant association between diaphragmatic defects and pneumothorax, which does not fit the diaphragmatic-defect explanation neatly ^[24]. For scar disease, the authors of a 2026 systematic review concluded that the infrequency of coexisting endometriosis in their sample supports the idea that implantation at the time of surgery could be sufficient to start it, which is an interpretation of case reports rather than a test of the idea ^[27].

Natural history

A 2024 meta-analysis of 19 studies in women with deep endometriosis estimated that 21.4 percent of untreated individuals had lesion progression on serial evaluation, with very wide uncertainty (95 percent confidence interval 6.8 to 40.8 percent, I² 90.5 percent) ^[45]. The authors described the natural history of deep lesions as undefined ^[45]. For asymptomatic diaphragmatic lesions, a review said that accumulating evidence suggests progression is unlikely, and in the 55-woman Iranian study none of the women who had no symptoms developed them over a mean of 34 months, although only four had a second look at surgery ^[12][23]. These are small, mostly retrospective data.

Test performance

Sensitivity and specificity depend on the examiner, the equipment, the site, whether bowel preparation was used and the reference standard, and the Cochrane review judged most included studies poor in quality ^[7][32][36]. Specificity is generally higher than sensitivity, so a positive finding on a skilled scan is more informative than a negative one ^[7][16][32]. The European guideline says a negative imaging result does not exclude endometriosis ^[6].

Treatment outcomes

Reported recurrence of thoracic disease after treatment ranges from 10.1 percent in a 592-patient review to 27 percent in a 732-patient meta-analysis and from 14.3 to 55 percent in the catamenial pneumothorax review, with differences in follow-up and treatment ^[14][15][25]. Colorectal surgery reports show similar variation ^[43]. This article describes the range of reported outcomes and does not recommend any approach.

Most of the evidence comes from specialized centers

Nearly every study cited here comes from a referral center, a university hospital, a surgical series or a pooled collection of case reports. The French national series was drawn from 31 expert centers ^[8]. The sonography accuracy study enrolled women at tertiary referral centers who were undergoing radical surgery ^[40]. The Italian diaphragm series says the surgery should be managed in a referral center ^[2]. The 2020 systematic review of extrapelvic endometriosis is built on 179 articles that were mostly case reports and series ^[4].

This pattern matters in four ways. In ultrasound studies of deep endometriosis, prevalence was 40 to 100 percent among women having surgery, depending on inclusion criteria, which shows how the sampling frame shapes the figure ^[32]. Ultrasound and MRI results come from experienced examiners and may not carry over to other settings, a point the international consensus statement makes by stressing operator expertise ^[36]. Sites such as the upper abdomen may be counted less often where they are not looked for ^[22]. Case reports describe unusual presentations, so compilations of them cannot give rates ^[4].

For thoracic, abdominal wall, muscle and nerve disease, much of what is known comes from compiled case reports ^[4][13][28].

What this does not tell you

This article summarizes published research. It does not tell any reader whether she has endometriosis in the bowel, bladder, diaphragm or elsewhere, and it does not say which symptoms point to which site. Many of the symptoms described, including bloating, bowel changes, urinary symptoms, shoulder pain and chest pain, have other causes, and the studies above show that bowel symptoms in particular occur in women whose bowel is not involved ^[5].

The percentages are not risks for an individual. They come from specific groups, such as women having surgery at a referral center, and cannot be applied to another person. A normal scan or a negative examination does not settle the question, and a positive scan does not by itself describe the whole extent of disease ^[6][7][32].

The article does not rank diagnostic tests, recommend imaging or surgery, or advise on medication. It does not cover endometriosis confined to the ovaries or peritoneum, adenomyosis, or the other causes of persistent pelvic pain, which are addressed in other places. Nothing here replaces assessment by a clinician.

References

1. Abrão MS, Petraglia F, Falcone T, Keckstein J, Osuga Y, Chapron C. Deep endometriosis infiltrating the recto-sigmoid: critical factors to consider before management. Hum Reprod Update. 2015;21(3):329-39. doi:10.1093/humupd/dmv003. PMID 25618908. https://pubmed.ncbi.nlm.nih.gov/25618908/
2. Ceccaroni M, Roviglione G, Giampaolino P, Clarizia R, Bruni F, Ruffo G, et al. Laparoscopic surgical treatment of diaphragmatic endometriosis: a 7-year single-institution retrospective review. Surg Endosc. 2013;27(2):625-32. doi:10.1007/s00464-012-2505-z. PMID 22955897. https://pubmed.ncbi.nlm.nih.gov/22955897/
3. Pagano F, Dedes I, Imboden S, Mueller MD. Connecting the dots: exploring appendiceal endometriosis in women with diaphragmatic endometriosis. Eur J Obstet Gynecol Reprod Biol. 2024;302:134-140. doi:10.1016/j.ejogrb.2024.08.045. PMID 39265199. https://pubmed.ncbi.nlm.nih.gov/39265199/
4. Andres MP, Arcoverde FVL, Souza CCC, Fernandes LFC, Abrão MS, Kho RM. Extrapelvic endometriosis: a systematic review. J Minim Invasive Gynecol. 2020;27(2):373-389. doi:10.1016/j.jmig.2019.10.004. PMID 31618674. https://pubmed.ncbi.nlm.nih.gov/31618674/
5. Maroun P, Cooper MJ, Reid GD, Keirse MJ. Relevance of gastrointestinal symptoms in endometriosis. Aust N Z J Obstet Gynaecol. 2009;49(4):411-4. doi:10.1111/j.1479-828X.2009.01030.x. PMID 19694698. https://pubmed.ncbi.nlm.nih.gov/19694698/
6. Becker CM, Bokor A, Heikinheimo O, Horne A, Jansen F, Kiesel L, et al. ESHRE guideline: endometriosis. Hum Reprod Open. 2022;2022(2):hoac009. doi:10.1093/hropen/hoac009. PMID 35350465. https://pubmed.ncbi.nlm.nih.gov/35350465/
7. Nisenblat V, Bossuyt PM, Farquhar C, Johnson N, Hull ML. Imaging modalities for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;2(2):CD009591. doi:10.1002/14651858.CD009591.pub2. PMID 26919512. https://pubmed.ncbi.nlm.nih.gov/26919512/
8. Froc E, Dubernard G, Bendifallah S, Hermouet E, Rubod-Dit-Guillet C, Canis M, et al. Clinical characteristics of urinary tract endometriosis: a one-year national series of 232 patients from 31 endometriosis expert centers (by the FRIENDS group). Eur J Obstet Gynecol Reprod Biol. 2021;264:155-161. doi:10.1016/j.ejogrb.2021.06.018. PMID 34303076. https://pubmed.ncbi.nlm.nih.gov/34303076/
9. Tomassetti C, Johnson NP, Petrozza J, Abrao MS, Einarsson JI, et al. An international terminology for endometriosis, 2021. Hum Reprod Open. 2021;2021(4):hoab029. doi:10.1093/hropen/hoab029. PMID 34693033. https://pubmed.ncbi.nlm.nih.gov/34693033/
10. Fitzgerald AC, Parker AB, Namazi G. Extrapelvic endometriosis: clinical manifestations, diagnosis, and management. Curr Opin Obstet Gynecol. 2026;38(4):277-285. doi:10.1097/GCO.0000000000001108. PMID 41968936. https://pubmed.ncbi.nlm.nih.gov/41968936/
11. Wolthuis AM, Meuleman C, Tomassetti C, D'Hooghe T, de Buck van Overstraeten A, D'Hoore A. Bowel endometriosis: colorectal surgeon's perspective in a multidisciplinary surgical team. World J Gastroenterol. 2014;20(42):15616-23. doi:10.3748/wjg.v20.i42.15616. PMID 25400445. https://pubmed.ncbi.nlm.nih.gov/25400445/
12. Haghgoo A, Faegh A, Maghsoudi R, Nasiri S, Ghahremani M, Saadat Mostafavi SR, et al. Expectant management of asymptomatic diaphragmatic endometriosis: a cross-sectional retrospective study. BMC Womens Health. 2026;26(1):557. doi:10.1186/s12905-026-04750-2. PMID 42934651. https://pubmed.ncbi.nlm.nih.gov/42934651/
13. Joseph J, Sahn SA. Thoracic endometriosis syndrome: new observations from an analysis of 110 cases. Am J Med. 1996;100(2):164-70. doi:10.1016/s0002-9343(97)89454-5. PMID 8629650. https://pubmed.ncbi.nlm.nih.gov/8629650/
14. Gil Y, Tulandi T. Diagnosis and treatment of catamenial pneumothorax: a systematic review. J Minim Invasive Gynecol. 2020;27(1):48-53. doi:10.1016/j.jmig.2019.08.005. PMID 31401265. https://pubmed.ncbi.nlm.nih.gov/31401265/
15. Nikolettos K, Patsouras A, Kotanidou S, Garmpis N, Psilopatis I, Garmpi A, et al. Pulmonary endometriosis: a systematic review. J Pers Med. 2024;14(11):1085. doi:10.3390/jpm14111085. PMID 39590577. https://pubmed.ncbi.nlm.nih.gov/39590577/
16. Gerges B, Li W, Leonardi M, Mol BW, Condous G. Meta-analysis and systematic review to determine the optimal imaging modality for the detection of bladder deep endometriosis. Eur J Obstet Gynecol Reprod Biol. 2021;261:124-133. doi:10.1016/j.ejogrb.2021.04.030. PMID 33932683. https://pubmed.ncbi.nlm.nih.gov/33932683/
17. Chapron C, Chopin N, Borghese B, Foulot H, Dousset B, Vacher-Lavenu MC, et al. Deeply infiltrating endometriosis: pathogenetic implications of the anatomical distribution. Hum Reprod. 2006;21(7):1839-45. doi:10.1093/humrep/del079. PMID 16543256. https://pubmed.ncbi.nlm.nih.gov/16543256/
18. Moura APC, Ribeiro HSAA, Bernardo WM, Simões R, Torres US, D'Ippolito G, et al. Accuracy of transvaginal sonography versus magnetic resonance imaging in the diagnosis of rectosigmoid endometriosis: systematic review and meta-analysis. PLoS One. 2019;14(4):e0214842. doi:10.1371/journal.pone.0214842. PMID 30964888. https://pubmed.ncbi.nlm.nih.gov/30964888/
19. Hudelist G, English J, Thomas AE, Tinelli A, Singer CF, Keckstein J. Diagnostic accuracy of transvaginal ultrasound for non-invasive diagnosis of bowel endometriosis: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2011;37(3):257-63. doi:10.1002/uog.8858. PMID 20954166. https://pubmed.ncbi.nlm.nih.gov/20954166/
20. Knabben L, Imboden S, Fellmann B, Nirgianakis K, Kuhn A, Mueller MD. Urinary tract endometriosis in patients with deep infiltrating endometriosis: prevalence, symptoms, management, and proposal for a new clinical classification. Fertil Steril. 2015;103(1):147-52. doi:10.1016/j.fertnstert.2014.09.028. PMID 25439849. https://pubmed.ncbi.nlm.nih.gov/25439849/
21. Maccagnano C, Pellucchi F, Rocchini L, Ghezzi M, Scattoni V, Montorsi F, et al. Diagnosis and treatment of bladder endometriosis: state of the art. Urol Int. 2012;89(3):249-58. doi:10.1159/000339519. PMID 22813980. https://pubmed.ncbi.nlm.nih.gov/22813980/
22. Jabbur Stern J, Ferreira Francisco FA, di Mango AL, Camara Belem L, Pires Franco I, Arruda de Souza C, et al. Diaphragmatic endometriosis: a practical radiologic guide to diagnosis, mapping, and multidisciplinary surgical planning. Abdom Radiol (NY). 2026. Advance online publication. doi:10.1007/s00261-026-05616-9. PMID 42360343. https://pubmed.ncbi.nlm.nih.gov/42360343/
23. Naem A, Roman H, Martin DC, Krentel H. A bird-eye view of diaphragmatic endometriosis: current practices and future perspectives. Front Med (Lausanne). 2024;11:1505399. doi:10.3389/fmed.2024.1505399. PMID 39618819. https://pubmed.ncbi.nlm.nih.gov/39618819/
24. Channabasavaiah AD, Joseph JV. Thoracic endometriosis: revisiting the association between clinical presentation and thoracic pathology based on thoracoscopic findings in 110 patients. Medicine (Baltimore). 2010;89(3):183-188. doi:10.1097/MD.0b013e3181df67d5. PMID 20453605. https://pubmed.ncbi.nlm.nih.gov/20453605/
25. Ciriaco P, Muriana P, Lembo R, Carretta A, Negri G. Treatment of thoracic endometriosis syndrome: a meta-analysis and review. Ann Thorac Surg. 2022;113(1):324-336. doi:10.1016/j.athoracsur.2020.09.064. PMID 33345783. https://pubmed.ncbi.nlm.nih.gov/33345783/
26. Ecker AM, Donnellan NM, Shepherd JP, Lee TT. Abdominal wall endometriosis: 12 years of experience at a large academic institution. Am J Obstet Gynecol. 2014;211(4):363.e1-5. doi:10.1016/j.ajog.2014.04.011. PMID 24732005. https://pubmed.ncbi.nlm.nih.gov/24732005/
27. Salmeri N, Ragusi A, Buffo C, Viganò P, Somigliana E, Vercellini P, et al. Abdominal wall endometriosis after cesarean section: a systematic review of clinical presentation, timing, and outcomes. J Minim Invasive Gynecol. 2026;33(6):694-702. doi:10.1016/j.jmig.2026.01.015. PMID 41534699. https://pubmed.ncbi.nlm.nih.gov/41534699/
28. Ye H, Shen C, Quan Q, Xi M, Li L. Endometriosis of the skeletal muscular system (ESMS): a systematic review. BMC Womens Health. 2023;23(1):37. doi:10.1186/s12905-023-02184-8. PMID 36703173. https://pubmed.ncbi.nlm.nih.gov/36703173/
29. Racca C, Franken J, Cahen M, Cicchelero A, Mormont M, Cinotti R, et al. Efficacy and safety of laparoscopic nerve decompression for neuropathic sciatic pain due to endometriosis: a systematic review and meta-analysis. Int J Gynaecol Obstet. 2026;175(2):584-594. doi:10.1002/ijgo.71087. PMID 42200541. https://pubmed.ncbi.nlm.nih.gov/42200541/
30. Barra F, Scala C, Biscaldi E, Vellone VG, Ceccaroni M, Terrone C, et al. Ureteral endometriosis: a systematic review of epidemiology, pathogenesis, diagnosis, treatment, risk of malignant transformation and fertility. Hum Reprod Update. 2018;24(6):710-730. doi:10.1093/humupd/dmy027. PMID 30165449. https://pubmed.ncbi.nlm.nih.gov/30165449/
31. Wetzel A, Philip CA, Golfier F, Bonnot PE, Cotte E, Brichon PY, et al. Surgical management of diaphragmatic and thoracic endometriosis: a French multicentric descriptive study. J Gynecol Obstet Hum Reprod. 2021;50(8):102147. doi:10.1016/j.jogoh.2021.102147. PMID 33862264. https://pubmed.ncbi.nlm.nih.gov/33862264/
32. Koninckx PR, Giovanni AD, Ussia A, Gharbi H, Al-Suwaidi S, Amro B, et al. Predictive value of ultrasound imaging for diagnosis and surgery of deep endometriosis: a systematic review. J Minim Invasive Gynecol. 2023;30(7):536-542. doi:10.1016/j.jmig.2023.03.008. PMID 36948243. https://pubmed.ncbi.nlm.nih.gov/36948243/
33. Alcázar JL, Eguez PM, Forcada P, Ternero E, Martínez C, Pascual MÁ, et al. Diagnostic accuracy of sliding sign for detecting pouch of Douglas obliteration and bowel involvement in women with suspected endometriosis: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2022;60(4):477-486. doi:10.1002/uog.24900. PMID 35289968. https://pubmed.ncbi.nlm.nih.gov/35289968/
34. Tian Z, Zhang YC, Sun XH, Wang Y, Zhao Y, Chang XH, et al. Accuracy of transvaginal ultrasound and magnetic resonance imaging for diagnosis of deep endometriosis in bladder and ureter: a meta-analysis. J Obstet Gynaecol. 2022;42(6):2272-2281. doi:10.1080/01443615.2022.2040965. PMID 35421318. https://pubmed.ncbi.nlm.nih.gov/35421318/
35. Guerriero S, Saba L, Pascual MA, Ajossa S, Rodriguez I, Mais V, et al. Transvaginal ultrasound vs magnetic resonance imaging for diagnosing deep infiltrating endometriosis: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2018;51(5):586-595. doi:10.1002/uog.18961. PMID 29154402. https://pubmed.ncbi.nlm.nih.gov/29154402/
36. Condous G, Gerges B, Thomassin-Naggara I, Becker C, Tomassetti C, Krentel H, et al. Non-invasive imaging techniques for diagnosis of pelvic deep endometriosis and endometriosis classification systems: an International Consensus Statement. Hum Reprod Open. 2024;2024(3):hoae029. doi:10.1093/hropen/hoae029. PMID 38812884. https://pubmed.ncbi.nlm.nih.gov/38812884/
37. Thomassin-Naggara I, Dolciami M, Chamie LP, Guerra A, Bharwani N, Freeman S, et al. ESUR consensus MRI for endometriosis: protocol, lexicon, and compartment-based analysis. Eur Radiol. 2025;35(11):7272-7286. doi:10.1007/s00330-025-11611-3. PMID 40425755. https://pubmed.ncbi.nlm.nih.gov/40425755/
38. Rousset P, Rousset-Jablonski C, Alifano M, Mansuet-Lupo A, Buy JN, Revel MP. Thoracic endometriosis syndrome: CT and MRI features. Clin Radiol. 2014;69(3):323-30. doi:10.1016/j.crad.2013.10.014. PMID 24331768. https://pubmed.ncbi.nlm.nih.gov/24331768/
39. Lojanica MV, Ivanovic S, Milic N, Jovic N, Rakic N, Pilic I, et al. Thoracic endometriosis and catamenial pneumothorax: imaging pitfalls and an integrated diagnostic approach. J Clin Med. 2026;15(12):4517. doi:10.3390/jcm15124517. PMID 42355685. https://pubmed.ncbi.nlm.nih.gov/42355685/
40. Montanari E, Bokor A, Szabó G, Kondo W, Trippia CH, Malzoni M, et al. Accuracy of sonography for non-invasive detection of ovarian and deep endometriosis using #Enzian classification: prospective multicenter diagnostic accuracy study. Ultrasound Obstet Gynecol. 2022;59(3):385-391. doi:10.1002/uog.24833. PMID 34919760. https://pubmed.ncbi.nlm.nih.gov/34919760/
41. Keckstein J, Saridogan E, Ulrich UA, Sillem M, Oppelt P, Schweppe KW, et al. The #Enzian classification: a comprehensive non-invasive and surgical description system for endometriosis. Acta Obstet Gynecol Scand. 2021;100(7):1165-1175. doi:10.1111/aogs.14099. PMID 33483970. https://pubmed.ncbi.nlm.nih.gov/33483970/
42. Roman H, Merlot B, Forestier D, Noailles M, Magne E, Carteret T, et al. Nonvisualized palpable bowel endometriotic satellites. Hum Reprod. 2021;36(3):656-665. doi:10.1093/humrep/deaa340. PMID 33432338. https://pubmed.ncbi.nlm.nih.gov/33432338/
43. Meuleman C, Tomassetti C, D'Hoore A, Van Cleynenbreugel B, Penninckx F, Vergote I, et al. Surgical treatment of deeply infiltrating endometriosis with colorectal involvement. Hum Reprod Update. 2011;17(3):311-26. doi:10.1093/humupd/dmq057. PMID 21233128. https://pubmed.ncbi.nlm.nih.gov/21233128/
44. Clement PB. The pathology of endometriosis: a survey of the many faces of a common disease emphasizing diagnostic pitfalls and unusual and newly appreciated aspects. Adv Anat Pathol. 2007;14(4):241-60. doi:10.1097/PAP.0b013e3180ca7d7b. PMID 17592255. https://pubmed.ncbi.nlm.nih.gov/17592255/
45. Bandini V, Giola F, Ambruoso D, Cipriani S, Chiaffarino F, Vercellini P, et al. The natural evolution of untreated deep endometriosis and the effect of hormonal suppression: a systematic literature review and meta-analysis. Acta Obstet Gynecol Scand. 2024;103(9):1722-1735. doi:10.1111/aogs.14887. PMID 38867640. https://pubmed.ncbi.nlm.nih.gov/38867640/