{"paper_id":"23b855f0-0e78-4ce6-8be5-90c7054b9ff2","body_text":"R E S E A R C H A R T I C L E Open Access\nCesarean scar endometriosis: presentation\nof 198 cases and literature review\nPing Zhang 1† , Yabing Sun 1†, Chen Zhang 1, Yeping Yang 1, Linna Zhang 1, Ningling Wang 2* and Hong Xu 1*\nAbstract\nBackground: Cesarean scar endometriosis (CSE) is the most common type of abdominal wall endometriosis (AWE). The\naim of this study was to systematically identify the clinical features of CSE and recommend precautionary measures.\nMethods: A large, retrospective study was undertaken with CSE patients treated surgically at our hospital between\nJanuary 2005 and December 2017.\nResults: A total of 198 CSE patients were enrolled, with a mean age of 32.0 ± 4.0 years. The main complaint of the\npatients was abdominal mass (98.5%), followed by cyclic pain (86.9%). The latency period of CSE was 31.6 ± 23.9 months,\nand the duration between the onset of symptoms and this surgery was 28.3 ± 25.0 months. A majority (80.8%,n = 160) of\nthe patients had undergone a Pfannenstiel incision, and a minority (19.2%,n = 38) a vertical midline incision. The latency\nperiod of CSE in the case of a Pfannenstiel incision was significantly shorter than that in thec a s eo fav e r t i c a lm i d l i n e\nincision (24.0 vs 33.0 months,P = 0.006). A total of 187 (94.4%) patients had a single endometrioma, 11 (5.6%) patients had\nmultiple endometriomas, and the 11 multiple-endometrioma patients had all undergone a Pfannenstiel incision. Lesions\nof endometrioma were common in corner sites, after either incision: 142/171 (83.0%) in Pfannenstiel incision scars and\n32/38 (84.2%) in vertical incision scars.\nConclusions:The findings of this study indicate that the Pfannenstiel incision carries a higher risk of CSE than the vertical\nmidline incision. Thorough cleaning at the conclusion of CS, particularly of both corner sites of the adipose layer and the\nfascia layer, is strongly recommended for CSE prevention. Further studies might provide additional recommendations.\nKeywords: Cesarean scar endometriosis, Abdominal wall endometriosis, Cesarean section, Pfannenstiel incision\nBackground\nEndometriosis is a sex hormone-dependent gynecological\ndisease that is characterized by the growth of endometrial\ntissue outside the uterine cavity [ 1]. It usually occurs in\nthe pelvis, at sites such as the ovaries and the pelvic peri-\ntoneum. However, ectopic endometrial tissue can also be\nfound outside the pelvis, at sites such as the lung, brain,\nbowel, and abdominal wall [ 2–4]. The presence of ectopic\nendometrial tissue embedded in the subcutaneous adipose\nlayer and the muscles of the abdominal wall is called ab-\ndominal wall endometriosis (AWE). AWE can occur\nspontaneously, but usually develops in association with a\nprevious surgical procedure, such as a cesarean section\n(CS), hysterectomy, or appendectomy [5–7].\nCesarean scar endometriosis (CSE) is the most com-\nmonly reported type of AWE [ 8]. Nominato et al. sug-\ngested that CS greatly increased the risk of developing\nAWE [9]. The pathophysiology of CSE may be due to the\ndirect implantation of endometrial tissue in the cesarean\nincision (the implantation theory) [8]. During cesarean de-\nlivery, the endometrial tissue is inoculated directly in the\ncesarean incision. With an appropriate supply of nutrients\nand hormonal stimuli, these endometrial cells survive and\nproliferate, which finally leads to CSE. Although it is an\nunusual disease, with a reported incidence of 0.03 –0.45%,\nCSE may cause long-term discomfort involving cyclic\nlower abdominal pain [ 10, 11]. Case reports of malignant\ntransformation of CSE have also been sporadically re-\nported [12–14].\n* Correspondence: nlingwang@163.com; xuhong1168@126.com\n†Ping Zhang and Yabing Sun contributed equally to this work.\n2Department of Assisted Reproduction, Shanghai Ninth People ’s Hospital,\nSchool of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China\n1The International Peace Maternity and Child Health Hospital, School of\nMedicine, Shanghai Jiao Tong University, Shanghai 200030, China\n© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0\nInternational License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and\nreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to\nthe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver\n(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.\nZhang et al. BMC Women's Health           (2019) 19:14 \nhttps://doi.org/10.1186/s12905-019-0711-8\n\nGenerally, few publications have focused on CSE, and a\nmajority of them are either case series or case reports\n[15–18]. As a large obstetric and gynecologic hospital, we\nhave treated many CSE patients and were very interested\nin identifying the characteristics associated with CSE.\nHere, we report our findings in managing CSE over ap-\nproximately the last decade, and we discuss the clinical\nfeatures and prevention strategies of this rare disease.\nMethods\nThis retrospective study was conducted in the Depart-\nment of Obstetrics and Gynecology of the International\nPeace Maternity and Child Health Hospital (IPMCH).\nThe study was approved by the ethical review committee\nof the IPMCH.\nThis study included patients diagnosed with CSE who\nreceived surgical treatment at IPMCH between January\n2005 and December 2017. The inclusion criteria were\nthe following: (1) patient had a history of at least one CS\nand the symptoms occurred after the cesarean delivery;\n(2) surgical excision with surrounding clear margins was\nperformed; and (3) pathological diagnosis for each ex-\ncised lesion was endometriosis.\nThe baseline characteristics and surgical processes of\nall of the patients were recorded in the database of our\nhospital. We conducted a computerized search of the\ndatabase according to the disease name. The preliminar-\nily selected items were further checked and screened ar-\ntificially following the inclusion criteria. The main\nsymptoms of CSE included a palpable mass, under or\naway from the scar, with cyclic pain and swelling during\nmenstruation. The latency period was defined as the time\nbetween CS and the onset of symptoms. The following in-\nformation was extracted: age, age at CS, parity, delivery\nhistory, incision type, symptoms, size of the mass, latency\nperiod, duration between symptoms and surgery, opera-\ntive findings, and histopathological evaluations.\nThe normality of continuous variables was tested using\nthe Shapiro –Wilk test. The comparisons of normally\ndistributed, continuous data were made with the Student\nt test and an analysis of variance. Two sets of nonnor-\nmally distributed, continuous data were analyzed with\nMann–Whitney U tests; otherwise, Kruskal –Wallis H\ntests were employed. The categorical data were analyzed\nwith χ2 and Fisher exact tests. The differences were con-\nsidered statistically significant when the P-value was less\nthan 0.05. Statistical analysis was performed using SPSS\nversion 17.0 (SPSS Inc., Chicago, IL, USA).\nResults\nFollowing the inclusion standards described above, a\ntotal of 198 CSE cases were ultimately enrolled and all\nthe cases were pathologically confirmed. Baseline char-\nacteristics of the patients are summarized in Table 1.\nThe mean age of the patients was 32.0 ± 4.0 years, and\nthe mean age at the time of CS was 27.1 ± 3.5 years. Par-\nity of the patients ranged from 1 to 2. All of the patients\nhad a history of CS: 186 (93.9%) patients had 1 CS, and\n12 (6.1%) had 2. The latency period of CSE ranged from\n1 to 120 months, with a mean of 31.6 ± 23.9 months.\nThe duration between the onset of symptoms and sur-\ngery was 28.3 ± 25.0 months.\nSymptoms and CSE sites of the study patients are also\nshown in Table 1. The most common symptom of the\npatients was a palpable painful abdominal mass under or\nTable 1 Baseline characteristics, symptoms, and CSE sites of the\npatientsa\nCharacteristic n (%) Mean ± SD (range)\nAge of the patients (years) 32.0 ± 4.0 (21 –43)\nAge at CS (years) 27.1 ± 3.5 (19 –37)\nParity\n1 175 (88.4)\n2 23 (11.6)\nNo. of CSs\n1 186 (93.9)\n2 12 (6.1)\nLatency period (months) 31.6 ± 23.9 (1 –120)\nDuration between symptoms\nand surgery (months)\n28.3 ± 25.0 (1–180)\nSymptoms\nAbdominal mass 195 (98.5)\nCyclic pain 172 (86.9)\nNoncyclic pain 26 (13.1)\nDysmenorrhea 64 (32.3)\nIncision type\nPfannenstiel 160 (80.8)\nVertical midline 38 (19.2)\nNo. of endometriomas\nSingle 187 (94.4)\nMultiple 11 (5.6)\nEndometrioma location\nPfannenstiel incision\nNo. of endometriomas 171 (81.8)\nLeft corner 65 (38.0)\nMiddle 29 (17.0)\nRight corner 77 (45.0)\nVertical midline incision\nNo. of endometriomas 38 (18.2)\nUpper corner 15 (39.5)\nMiddle 6 (15.8)\nLower corner 17 (44.7)\naValues are given as mean ± SD or as number (percentage)\nZhang et al. BMC Women's Health           (2019) 19:14 Page 2 of 6\n\nadjacent to the incision, accompanied with either cyclic\npain (86.9%, n = 172) or noncyclic pain (13.1%, n =2 6 ) . A\nmajority (80.8%, n = 160) of the patients had undergone a\nPfannenstiel incision, and a minority (19.2%, n =3 8 )av e r -\ntical midline incision. In the group of 198 study patients,\n187 (94.4%) patients had a single endometrioma and 11\n(5.6%) patients had multiple endometriomas. The 11\nmultiple-endometrioma patients had all undergone a\nPfannenstiel incision. In total, 209 abdominal wall endo-\nmetriomas were excised. Specifically, 171 and 38 endome-\ntriomas were excised from Pfannenstiel incision and\nvertical midline incision scars, respectively. A majority of\nthe endometriomas were located in corner sites, after\neither incision: 142/171 (83.0%) in Pfannenstiel incision\nscars and 32/38 (84.2%) in vertical incision scars.\nWe introduced an “upper bound ” and a “lower bound ”\nto describe the locations of the endometriomas for the\nfirst time. The abdominal wall was divided into the adi-\npose layer, the fascia layer, the muscular layer, and the\nperitoneal layer. The bladder was considered the deepest\nlayer involved. As shown in Tables 2, 64.6% ( n = 135) of\nthe endometriomas were located between the adipose\nlayer and the fascia layer; 14.8% ( n = 31) were located be-\ntween the adipose layer and the muscular layer. Of the\n209 endometriomas, 16 (7.7%) invaded the peritoneum;\n1 (0.5%) invaded into the abdominal cavity; and 2 (1.0%)\ninvaded the bladder.\nTo identify the risk factors for CSE, we calculated the\ndifference in latency period based on the patients ’ baseline\ncharacteristics (T able 3). Age at CS, parity, previous CS,\nand dysmenorrhea showed no significant correlation with\nthe latency period. Location of the endometriomas, such\nas under or away from the scar, or in the corner or in the\nmiddle of the scar, also showed no correlation with the la-\ntency period. However, the latency period showed signifi-\ncant correlation with the incision type, i.e., the latency\nperiod of the CSE in patients with Pfannenstiel incision\nwas significantly shorter than that in patients with vertical\nmidline incision (24.0 vs 33.0 months, P =0 . 0 0 6 ) . T h e l o -\ncation of the lower bound of the endometriomas also\nshowed a correlation with the latency period ( P =0 . 0 1 1 ) ,\ni.e., the latency period was longer when the endometrio-\nmas invaded down to the peritoneum or the bladder.\nTo confirm the difference in latency period based on inci-\nsion type, baseline character istics of the patients with\nPfannenstiel incisions or vertical midline incisions were fur-\nther compared. As shown in Table 4, no significant differ-\nence was identified in the patients’ baseline characteristics.\nDiscussion\nCSE is an uncommon iatrogenic disease caused by endo-\nmetrium implantation in the incision during cesarean\ndelivery. In the present study, we investigate 198 cases\nof CSE over a period of 13 years, providing detailed in-\nformation that helps us to better understand the clinical\ncharacteristics of this rare condition.\nSeveral theories about the pathogenesis of AWE have\nbeen proposed, such as the implantation theory, the\ncoelomic metaplasia theory, and the lymphatic or hema-\ntogenic dissemination theory [ 8, 19]. As the most com-\nmon type of AWE, CSE is best explained by the\niatrogenic direct implantation theory. During cesarean\ndelivery, endometrial tissue is seeded into the wound.\nWith an appropriate supply of nutrients and hormonal\nstimuli, these endometrial cells survive and proliferate,\nfinally leading to CSE. In the present study, most of the\nendometriomas were located in a corner of the incision\nscar: 83.0% in Pfannenstiel incision scars and 84.2% in\nvertical midline incision scars. In another large retro-\nspective study, conducted by Yan Ding et al., similar re-\nsults were obtained [ 20]. In their study, 77.1% of the\nendometriomas were located in the corners of the scars.\nThis is probably because endometrial cells are less easily\nremoved from the corners of the incisions during CS.\nThus, our data also support the iatrogenic cell implant-\nation theory. However, the implantation theory alone\ncannot completely explain the pathogenesis of CSE,\ngiven the low incidence of CSE. Residual endometrial\ncell contamination of the wound during CS occurs often\nand sometimes is inevitable, but CSE is rare. Hereditary\npredisposition may confer susceptibility to the develop-\nment of CSE [ 21].\nCS is one of the most common surgical procedures\nperformed on women worldwide. Pfannenstiel incision\nand vertical midline incision are the two most frequently\nused abdominal skin incisions. The vertical midline inci-\nsion has the advantages of speed of abdominal entry and\nless bleeding, but has a higher risk of incisional hernia\nand results in a less cosmetically pleasing scar. Con-\nversely, the Pfannenstiel incision has a lower risk of\nTable 2 Location of the endometriomas in the abdominal wall\nLower bound\nAL, n (%) FL, n (%) ML, n (%) PL, n (%) AC, n (%) B, n (%)\nUpper bound AL 12 (5.7) 135 (64.6) 31 (14.8) 11 (5.3) 1 (0.5) 1 (0.5)\nFL / 0 (0) 12 (5.7) 3 (1.4) 0 (0) 0 (0)\nML / / 0 (0) 2 (1.0) 0 (0) 1 (0.5)\nAL = adipose layer, FL = fascia layer, ML = muscular layer, P = peritoneum layer, AC = abdominal cavity, B = bladder\nZhang et al. BMC Women's Health           (2019) 19:14 Page 3 of 6\n\nincisional hernia and results in a better cosmetic appeal.\nHowever, the Pfannenstiel incision usually involves more\ndissections, and the blood loss following dissection may\nbe greater [ 22].\nCSE is a complication of cesarean surgery. Unfortu-\nnately, the relationship between the CS incision type and\nthe pathogenesis of CSE is still unknown. The Pfannenstiel\nincision is the most commonly reported type for the oc-\ncurrence of CSE; however, because of the disease rarity\nand the need for the pathological confirmation of the\ndiagnosis, it is difficult to estimate the population-wide in-\ncidence of CSE for different incision types [ 19, 20].\nDemiral et al. speculated that Pfannenstiel incisions confer\na higher risk of CSE than do midline incisions, but\nTable 3 Difference in latency period based on patients ’ baseline characteristics, symptoms, and CSE sites a\nCharacteristic n (%) Latency period (months) P-value\nMedian (quartiles)\nAge at CS (years) 0.941\n≥ 35 6 (3.0) 30.0 (10.5 –48.0)\n25–34 143 (72.2) 24.0 (12.0 –40.0)\n≤ 24 49 (24.8) 24.0 (12.0 –48.0)\nParity 0.273\nNulliparous 178 (89.2) 24.0 (12.0 –36.0)\nMultiparous 20 (10.1) 21.0 (6.0 –48.0)\nOne previous CS 0.452\nYes 21 (10.6) 24.0 (6.0 –48.0)\nNo 177 (89.4) 24.0 (12.0 –36.0)\nDysmenorrhea 0.473\nYes 64 (32.3) 19.0 (12.0 –36.0)\nNo 134 (67.7) 24.0 (12.0 –36.0)\nIncision type 0.006\nPfannenstiel 160 (80.8) 24.0 (12.0 –36.0)\nVertical midline 38 (19.2) 33.0 (24.0 –60.0)\nNo. of endometriomas 0.078\nSingle 187 (94.4) 24.0 (12.0 –48.0)\nMultiple 11 (5.6) 16.0 (12.0 –24.0)\nLocation of the endometriomas I 0.253\nUnder the scar 111 (56.1) 24.0 (12.0 –36.0)\nAway from the scar 87 (43.9) 24.0 (12.0 –48.0)\nLocation of the endometriomas II 0.153\nCorner of the scar 167 (84.3) 24.0 (12.0 –48.0)\nMiddle of the scar 31 (15.7) 30.0 (24.0 –38.0)\nUpper bound of the endometriomas 0.073\nAdipose layer 181 (91.4) 24.0 (12.0 –39.0)\nFascia layer 14 (7.1) 24.0 (18.0 –49.5)\nMuscular layer 3 (1.5) 48.0 (48.0 –56.0)\nLower bound of the endometriomas 0.011\nAdipose layer 10 (5.1) 27.0 (18.0 –39.0)\nFascia layer 130 (65.7) 24.0 (12.0 –36.0)\nMuscular layer 41 (20.7) 24.0 (16.0 –48.0)\nPeritoneum 12 (6.1) 48.0 (27.0 –60.0)\nAbdominal cavity 3 (1.5) 30.0 (9.0–30.0)\nBladder 2 (1.0) 40.0 (24.0–40.0)\naMann–Whitney U test for comparing two sets; Kruskal –Wallis H test for comparing multiple sets\nZhang et al. BMC Women's Health           (2019) 19:14 Page 4 of 6\n\nwithout sufficient evidence [ 23]. In this study, the latency\nperiod of CSE was 31.6 ± 23.9 months, which was compar-\nable with that reported in other studies [ 19, 24]. However,\nwhen comparing the latency period of CSE in patients\nwith Pfannenstiel incisions to those with vertical midline\nincisions, we observed a significantly shorter latency in\nPfannenstiel incisions (24.0 vs 33.0 months, P =0 . 0 0 6 )\n(T able3). In other words, CSE in patients with Pfannen-\nstiel incisions occurred earlier than in patients with verti-\ncal incisions. This indicates that, compared to the vertical\nincision, the Pfannenstiel incision might be more favorable\nto the implantation and proliferation of the residual\nendometrial cells. We suggest two possible causes for the\nfavorable role of the Pfannenstiel incision. First, the Pfan-\nnenstiel incision involves wider dissection planes and\nmore gaps, rendering tissue irrigation difficult and indu-\ncing much more endometrial cell contamination [ 22]. The\nsecond cause is a larger nutrient supply. Due to the longi-\ntudinal pattern of the abdominal vessels and the large dis-\nsection, more capillaries are cut off during a Pfannenstiel\nincision than in a vertical incision, causing more blood\nloss. Endometrial cells require an adequate blood supply\nto survive in their ectopic sites, and angiogenesis plays an\nimportant role in the pathogenesis of endometriosis [ 25].\nTherefore, more blood loss in the Pfannenstiel incision\nwould provide a relatively rich nutritional environment\nfor the implantation and growth of residual endometrial\ncells, favoring the occurrence of CSE. Consistent with this\nexplanation, all 11 patients in this study who had multiple\nendometriomas had Pfannenstiel incisions. These research\nfindings demonstrate that the Pfannenstiel incision prob-\nably carries a higher risk of CSE than the vertical midline\nincision. Another interesting result from this study is that\ndeeper endometrioma locations are correlated with longer\nlatency periods. This is probably due to the fact that the\ndeeper endometriomas could not be easily noticed.\nAlthough CSE is a rare event, it manifests as a painful\nsubcutaneous mass and usually bothers the patient for\nseveral years. Additionally, CSE can undergo malignant\nchange, which is rapidly fatal and has a survival rate of\nonly 57% [ 14]. Hence, it is necessary to take precautions\nto prevent or reduce the occurrence of CSE. On the\nbasis of the implantation theory, we propose a variety of\nmeasures: careful flushing and irrigating before closure;\nusing separate needles for uterine and abdominal clos-\nure; and not using a sponge to clean the endometrial\ncavity following complete delivery. Extending the breast-\nfeeding period to delay menstruation has also been pro-\nposed for preventing CSE, but without scientific\ncorroboration [ 21]. In our study, 83.3% (174/209) of the\nscar endometriomas were located in corner sites of the\nwound. Therefore, the abdominal wound should be\ncleaned thoroughly with saline solution before closure,\nespecially the corner sites. Additionally, endometriomas\nwere more common in superficial parts of the abdominal\nwall, i.e., 12/209 (5.7%) were present in the adipose layer\nand 135/209 (64.6%) between the adipose layer and the\nfascia layer, accounting for 70.3% of the total endome-\ntriomas. Therefore, careful flushing and irrigation of the\nadipose layer and fascia layer during closure is critical.\nAll of the patients in our study underwent surgical ex-\ncision for the treatment of CSE. Generally, surgical treat-\nment offers the best chance for both making a definitive\ndiagnosis and treating CSE. Medical therapy has a low\nsuccess rate is associated with adverse effects.\nAs a retrospective study, some limitations in this study\ncould not be avoided. For example, the data about the\nCS procedures lacked details such as the layers of clos-\nure, type of suture materials, and operation duration.\nThese factors might also affect the occurrence of CSE.\nTo address these questions, further studies will be re-\nquired in the future.\nConclusions\nConcerning the rising CS rate, CSE may occur more fre-\nquently than generally assumed. Early diagnosis, treat-\nment, and prevention of CSE are worthy of our\nattention. In our large, retrospective study, we systemat-\nically reviewed the clinical features of CSE and we pro-\nvide the first evidence that the Pfannenstiel incision\ncarries a higher risk of CSE than the vertical midline in-\ncision. The findings in this study will help us to better\nunderstand CSE and devise precautionary measures to\nreduce the occurrence of the disease.\nAbbreviations\nAWE: Abdominal wall endometriosis; CS: Cesarean section; CSE: Cesarean scar\nendometriosis\nTable 4 Comparison of the baseline characteristics between\npatients with Pfannenstiel incision or vertical midline incision a\nCharacteristic Pfannenstiel Vertical midline P-value\nn (%) n (%)\nAge at CS (years) 0.334\n≥ 35 4 (2.5) 2 (5.2)\n25–34 119 (74.4) 24 (63.2)\n≤ 24 37 (23.1) 12 (31.6)\nParity 0.195\nNulliparous 146 (73.7) 32 (16.2)\nMultiparous 14 (7.1) 6 (3.0)\nOne previous CS 0.248\nYes 15 (7.6) 6 (3.0)\nNo 145 (73.2) 32 (16.2)\nDysmenorrhea 0.782\nYes 51 (25.8) 13 (6.6)\nNo 109 (55.1) 25 (12.6)\naFisher exact test\nZhang et al. BMC Women's Health           (2019) 19:14 Page 5 of 6\n\nFunding\nThis study was supported by the Natural Science Foundation of Shanghai\nCity, China (No. 15ZR1444100; No. 16ZR1419500; and No. 17411972800). The\nfunding agency had no influence on the design of the study; the collection,\nanalysis, and interpretation of data; and the writing of the manuscript.\nAvailability of data and materials\nThe datasets used and/or analyzed during the current study are available\nfrom the corresponding author on reasonable request.\nAuthors’ contributions\nPZ proposed the study concept and design, assisted by HX. YBS, YPY, and LNZ\nacquired and checked the data. CZ and NLW carried out the data analyses. PZ\ndrafted the manuscript. All of the authors approved the final version of the\nmanuscript.\nEthics approval and consent to participate\nThe study was approved by the ethical review committee of the International\nPeace Maternity and Child Health Hospital (IPMCH).\nConsent for publication\nConsent was obtained from the patients for the publication of this report.\nCompeting interests\nThe author declares that they have no competing interests.\nPublisher’sN o t e\nSpringer Nature remains neutral with regard to jurisdictional claims in\npublished maps and institutional affiliations.\nReceived: 27 June 2018 Accepted: 3 January 2019\nReferences\n1. Williams HE, Barsky S, Storino W. Umbilical endometrioma (silent type). Arch\nDermatol. 1976;112(10):1435–6.\n2. Steck WD, Helwig EB. Cutaneous endometriosis. Clin Obstet Gynecol. 1966;\n9(2):373–83.\n3. Markham SM, Carpenter SE, Rock JA. Extrapelvic endometriosis. Obstet\nGynecol Clin N Am. 1989;16(1):193 –219.\n4. Ideyi SC, Schein M, Niazi M, Gerst PH. Spontaneous endometriosis of the\nabdominal wall. Dig Surg. 2003;20(3):246 –8.\n5. Blanco RG, Parithivel VS, Shah AK, Gumbs MA, Schein M, Gerst PH.\nAbdominal wall endometriomas. Am J Surg. 2003;185(6):596 –8.\n6. Dwivedi AJ, Agrawal SN, Silva YJ. Abdominal wall endometriomas. Dig Dis\nSci. 2002;47(2):456–61.\n7. Koger KE, Shatney CH, Hodge K, McClenathan JH. Surgical scar\nendometrioma. Surg Gynecol Obstet. 1993;177(3):243 –6.\n8. Horton JD, Dezee KJ, Ahnfeldt EP, Wagner M. Abdominal wall\nendometriosis: a surgeon's perspective and review of 445 cases. Am J Surg.\n2008;196(2):207–12.\n9. Nominato NS, Prates LF, Lauar I, Morais J, Maia L, Geber S. Caesarean section\ngreatly increases risk of scar endometriosis. Eur J Obstet Gynecol Reprod\nBiol. 2010;152(1):83–5.\n10. Rani PR, Soundararaghavan S, Rajaram P. Endometriosis in abdominal scars--\nreview of 27 cases. Int J Gynaecol Obstet. 1991;36(3):215 –8.\n11. Chang Y, Tsai EM, Long CY, Chen YH, Kay N. Abdominal wall\nendometriomas. J Reprod Med. 2009;54(3):155 –9.\n12. Matter M, Schneider N, McKee T. Cystadenocarcinoma of the abdominal\nwall following caesarean section: case report and review of the literature.\nGynecol Oncol. 2003;91(2):438 –43.\n13. Leng J, Lang J, Guo L, Li H, Liu Z. Car cinosarcoma arising from atypical\nendometriosis in a cesarean section scar. Int J Gynecol Cancer. 2006;16(1):432–5.\n14. Alberto VO, Lynch M, Labbei FN, Jeffers M. Primary abdominal wall clear cell\ncarcinoma arising in a caesarean section scar endometriosis. Ir J Med Sci.\n2006;175(1):69–71.\n15. Gaunt A, Heard G, McKain ES, Stephenson BM. Caesarean scar\nendometrioma. Lancet. 2004;364(9431):368.\n16. Demir B, Senerbahce Z, Guzel AI, Demir S, Kilinc N. Abdominal wall\nendometriosis following cesarean section: report of five cases. Clin Exp\nObstet Gynecol. 2011;38(3):288 –90.\n17. Ozel L, Sagiroglu J, Unal A, Unal E, Gunes P, Baskent E, et al. Abdominal wall\nendometriosis in the cesarean section surgical scar: a potential diagnostic\npitfall. J Obstet Gynaecol Res. 2012;38(3):526 –30.\n18. Wicherek L, Klimek M, Skret-Magierlo J, Czekierdowski A, Banas T, Popiela TJ,\net al. The obstetrical history in patients with Pfannenstiel scar\nendometriomas--an analysis of 81 patients. Gynecol Obstet Investig. 2007;\n63(2):107–13.\n19. Bektas H, Bilsel Y, Sari YS, Ersoz F, Koc O, Deniz M, et al. Abdominal wall\nendometrioma: a 10-year experience and brief review of the literature. J\nSurg Res. 2010;164(1):e77 –81.\n20. Ding Y, Zhu J. A retrospective review of abdominal wall endometriosis in\nShanghai, China. Int J Gynaecol Obstet. 2013;121(1):41 –4.\n21. Zhao X, Lang J, Leng J, Liu Z, Sun D, Zhu L. Abdominal wall\nendometriomas. Int J Gynaecol Obstet. 2005;90(3):218 –22.\n22. Mathai M, Hofmeyr GJ. Abdominal surgical incisions for caesarean section.\nCochrane Database Syst Rev. 2007;1:CD004453.\n23. Demiral G, Aksoy F, Ozcelik A, Saban B, Kusak M, Ekinci O, et al. Cesarean\nscar endometriosis: presentation of eleven clinical cases and review of the\nliterature. J Turk Soc Obstet Gynecol. 2011;8(3):209 –13.\n24. Kang J, Baek JH, Lee WS, Cho TH, Lee JN, Lee WK, et al. Clinical\nmanifestations of abdominal wall endometriosis: a single center experience.\nArch Gynecol Obstet. 2013;287(2):301 –5.\n25. McLaren J. Vascular endothelial growth factor and endometriotic\nangiogenesis. Hum Reprod Update. 2000;6(1):45 –55.\nZhang et al. BMC Women's Health           (2019) 19:14 Page 6 of 6","source_license":"CC0","license_restricted":false}