{"paper_id":"d6432d89-bc1a-4008-bfe3-e0ef36d75728","body_text":"R E S E A R C H Open Access\nRole of preoperative ultrasound mapping in\nthe surgical management of deep\ninfiltrating endometriosis: a prospective\nobservational study\nSamar M. El-Maadawy 1,2* , Nesreen Alaaeldin 2 and Charles B. Nagy 3\nAbstract\nBackground: Endometriosis is a challenging gynecological condition that has a profound influence on the quality\nof life of affected women. Transvaginal ultrasound is considered the first-line imaging method in preoperative\nassessment of the extent and severity of endometriosis. Accurate preoperative mapping can aid the surgeon in\npatient counselling, selection of the most appropriate surgical method that minimizes the operative and post-\noperative complications. The aim of our study is to evaluate the accuracy of transvaginal sonography (TVS) in\nprecisely assessing the size, location and extent of deep infiltrating endometriosis (DIE) using a new modified\nendometriosis mapping proforma with histopathological confirmation. Our prospective observational study\nincluded 101 women with clinically suspected DIE who underwent TVS followed by laparoscopy from October 2018\nto December 2020 with a maximum of 4 weeks interval. Precise mapping of DIE was done during TVS and\nlaparoscopy. Results were correlated with histopathology findings.\nResults: DIE was confirmed by histopathology in 88 patients. Sensitivity and specificity for individual DIE locations\nwere rectovaginal septum 67.9% and 98.6%; vagina 52.2% and 98.7%; uterosacral ligaments 82.5% and 96.2%; torus\n96.4% and 97.3%; parametrium 68.8% and 96.9%; rectum 100% and 98.8%; bladder 100% and 100%, ureters 63.4%\nand 99.0%; scar endometriosis 100% and 100%; pouch of Douglas obliteration 97.7% and 100%. No statistically\nsignificant difference was detected between ultrasound and histopathology size. Ultrasound tended to\nunderestimate the lesion size; the underestimation was more pronounced for lesions > 3 cm. “Butterfly” and “tram-\ntrack” signs are two new sonographic signs related to posterior compartment DIE. No post-operative complications\nwere recorded. There were no cases of DIE recurrence. Eleven out of 22 cases of infertility achieved pregnancy\nduring 18 months follow-up.\nConclusion: TVS provides a thorough and accurate evaluation of the extent of endometriosis. An experienced\nradiologist can use E-PEP to provide an accurate demonstration of the location and extent of DIE which helps the\nsurgeon select the most appropriate surgical approach ensuring radical treatment of the disease and minimizing\nshort- and long-term complications.\nKeywords: Endometriosis, Ultrasound imaging, Laparoscopic surgery\n© The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,\nwhich permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give\nappropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if\nchanges were made. The images or other third party material in this article are included in the article's Creative Commons\nlicence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons\nlicence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain\npermission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.\n* Correspondence: samarmaadawy@gmail.com\n1Department of Radiology, National Cancer Institute, Cairo University, Cairo,\nEgypt\n2Department of Radiology, Medcare Women and Children Hospital, Sheikh\nZayed Road, P.O Box 215565, Dubai, UAE\nFull list of author information is available at the end of the article\nEgyptian Journal of Radiology\nand Nuclear Medicine\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine\n         (2021) 52:159 \nhttps://doi.org/10.1186/s43055-021-00526-w\n\nBackground\nEndometriosis is a challenging gynecological condition\nthat has a profound influence on the quality of life of af-\nfected women. It is described as ectopic endometrial tis-\nsue present outside the uterus affecting women of the\nreproductive age group with a prevalence of about 10%\n[1]. Deep infiltrating endometriosis (DIE) is defined as\nthe presence of endometriotic tissue, smooth muscle\nhyperplasia and fibrosis below the peritoneum 5 mm in\ndepth accounting for about 15 to 30% of all endometri-\nosis cases [ 2, 3].\nThe most prevalent manifestations include infertility, dys-\nmenorrhea, dyspareunia, pelvic pain, dyschezia and urinary\nsymptoms [ 4]. DIE-induced symptoms are non-specific,\noften leading to missed or delayed diagnosis [5, 6].\nPhysical examination is known to have limitations in\nthe diagnosis and quantification of DIE [ 7, 8]. Having a\nreliable imaging modality to specify the extent and loca-\ntion of DIE preoperatively plays a key role in surgical\nplanning [ 9]. The exact surgical approach and participat-\ning multispecialty surgical team are largely dependent\non preoperative diagnostic evaluation.\nDiagnostic laparoscopy is widely recognized as the\ngold standard for the diagnosis of endometriosis. How-\never, it has its own limitations when it comes to the\nassessment of pelvic, deep infiltrating or extra-pelvic\nendometriosis [ 10]. Transvaginal sonography (TVS) and\nmagnetic resonance imaging (MRI) have been well docu-\nmented to diagnose and specify DIE locations and are\nwidely used imaging techniques in clinical practice [ 11–\n13]. In addition to being cost effective, TVS has been\nshown to be comparable to MRI in the diagnosis of\nendometriosis and is considered the first-line imaging\nmethod [ 14–16].\nPrevious studies have attempted to map DIE preopera-\ntively [ 9, 17]. The purpose of our study is to evaluate the\naccuracy of TVS in diagnosing DIE by comparing im-\naging findings with laparoscopy and histopathology\nusing a new modified endometriosis mapping proforma\nthat can be interpreted easily by the radiologists and sur-\ngeons in which the precise location, size and extent of\nlesions are defined to assist in surgical planning minim-\nizing operative and post-operative complications.\nMethods\nThis prospective observational single-institution study in-\ncluded all consecutive patients with clinically suspected\nendometriosis who underwent ultrasound followed by\nlaparoscopy from October 2018 to December 2020. The\nstudy was approved by the Institutional Ethics Committee.\nWritten informed consent was obtained from all patients\nwho agreed to take part in this study. The study was re-\nported in accordance with the Standards for Reporting for\nDiagnostic accuracy studies (STARD guidelines) [18].\nInclusion criteria included premenopausal women\nwith suspected DIE who are willing to undergo TVS or,\nin the case of virgin females, transrectal sonography\n(TRS) followed by laparoscopy. Exclusion criteria in-\ncluded patients who refused TVS or TRS, patients who\nperformed ultrasound at an outside facility or did only\nMRI, patients who were not eligible or refused surgery\nand patients who lacked informed consent.\nDIE was clinically suspected based on detailed clinical\nhistory and physical examination. A case history pro-\nforma was obtained for all cases by the surgeon which\nincluded symptoms, parity, previous medical and surgi-\ncal treatments and infertility with pregnancy outcome\nwhen applicable. A visual analogue scale (VAS) was re-\ncorded for all patients from 0 –10 where 0 corresponds\nto no pain and 10 is the maximum pain [ 19, 20].\nEndometriosis mapping proforma\nWe developed an Endometriosis Preoperative Evaluation\nProforma (E-PEP) which is a new modified preoperative\nmapping tool used to assess the severity and extent of\nendometriosis in a standardized staged manner used\nduring our TVS protocol for cases with suspected DIE\nin four basic steps: uterus, adnexal endometriosis,\nDouglas pouch obliteration and finally DIE mapping.\nThe E-PEP is filled by marking the site and size of endo-\nmetriosis with schematic diagrams to sketch the DIE lo-\ncations. The E-PEP was marked by the radiologist after\nTVS then by the surgeon after laparoscopy who was\nblinded to the radiologists ’ mapping findings. (Fig. 1).\nUltrasound examination\nAll ultrasound examinations were conducted transvaginally\nexcept for four virgin females in which TRS was performed\nusing a Voluson E8 (GE Healthcare) ultrasound machine\nwith a 5 –9-MHz transvaginal transducer. The examination\nwas done at any time irrespective of the menstrual phase\nwith a partially filled urinary bladder. No bowel preparation\nwas needed. Conventional 2D and 3D volume acquisition\nusing tomographic ultrasound imaging (TUI) and volume\ncontrast imaging (VCI) was used. The ultrasound studies\nwere performed by two radiologists who are highly experi-\nenced in the field of women imaging particularly TVS\nassessment of DIE. Between ultrasound and surgery,\npatients had a maximum interval of 4 weeks.\nOur ultrasound protocol follows the consensus statement\nfrom the International Deep Endometriosis Analysis\n(IDEA) group [21]. The uterine position is assessed whether\nanteverted, retroverted or wi th isolated retraction of the\nuterine fundus which gives an indication about the pres-\nence of adhesions and POD obliteration [22]. The uterus is\nthen examined for signs of adenomyosis which is com-\nmonly associated with endometriosis [23]. Next, ovaries are\nevaluated for cysts particularly endometriomas with the\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 2 of 11\n\ntypical low-grade echoes of “ground glass ” appearance\n[24]. The adnexa are then evaluated for signs of hydrosal-\npinx and peritoneal inclusion cysts. Evaluation of ovarian\nmobility is done by vaginal probe pressure and/or abdom-\ninal pressure using the free hand of the examiner. Free\nmobility of the ovaries in relation to surrounding struc-\ntures indicates the absence of adhesions [ 25]. The “sliding\nsign” is utilized to reveal partial or complete Pouch of\nDouglas obliteration [22].\nThe final step is mapping of DIE. Tenderness-guided\nsonography is a key approach in pathological site detec-\ntion when searching for DIE [ 26]. We divided DIE into\nthe following five groups inspired from the Enzian classi-\nfication [ 27]:\nFig. 1 Endometriosis Preoperative Evaluation Proforma (E-PEP). The proforma is filled out and marked according to ultrasound and laparoscopy\nfindings. The site of deep infiltrating endometriosis can be also sketched in the schematic diagrams on the left corresponding to each group\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 3 of 11\n\nGroup 1 :\n– Rectovaginal septum (RVS)\n– Vagina\nGroup 2 :\n– Right uterosacral ligament (USL)\n– Left USL\n– Torus uterinum\n– Right parametrium\n– Left parametrium\nGroup 3 :\n– Cranial rectum\n– Caudal rectum\nGroup 4:\n– Bladder\n– Right ureter\n– Left ureter\nGroup 5 :\n– Other locations including scar endometriosis\nDIE nodules have different characteristics depending\non the anatomical location and diagnosis when irregular\nhypoechoic nodular lesions adherent to the surrounding\nstructures are identified with tenderness on probe pres-\nsure [ 28]. Caudal rectal lesions were defined as plaques\nfound below the level of USL, while those above this\nlevel considered rectosigmoid junction or cranial rectal\nlesions [ 9]. Involvement of the rectal wall appears as ir-\nregular hypoechoic thickening of the bowel wall that\nmay lead to luminal compromise [ 29]. The largest diam-\neter of the lesions was recorded.\nSurgery\nA laparoscopic approach was adopted for all 101 cases.\nAll cases were performed by the same surgeon who had\nspecific training in managing difficult deep endometri-\nosis cases by laparoscopy; some cases were carried out in\ncollaboration with a colorectal surgeon and urologist.\nInitial assessment of the extent of the disease was car-\nried out guided by the ultrasound report findings plus\nvisual and tactile assessment for superficial and deep\nendometriotic nodules. For lesions involving the uterosa-\ncral ligaments, uterine torus, rectosigmoid colon or\nparametrium, ureterolysis was carried out first and then\nopening of the medial para-rectal space and sparing of\nthe hypogastric nerves then proceeding to dissection of\nthe rectovaginal space before excision of the\nendometriotic nodules. Rectosigmoid nodules were ex-\ncised mostly using the shaving technique with only few\ncases needing rectal disc excision or segmental bowel re-\nsection in cases of sub-occlusive lesions. Bowel lesions\ngreater than 3 cm in length and more than 0.5 cm in\ndepth were not suitable for adequate shaving and needed\ndisc excision. Lesions causing luminal compromise or\ninvolving 50% or more of the bowel circumference\nneeded segmental bowel resection. Ovarian endometrio-\nmas were excised using the stripping technique. Lesions\ninvolving the vagina were removed using full-thickness\nexcision of the vaginal wall. Surgical findings were docu-\nmented using the British Society for Gynecological En-\ndoscopy (BSGE) surgical data sheet [ 30].\nFollowing surgery, all specimens were sent to the same\nlaboratory for histopathological confirmation.\nStatistical analysis\nData were statistically described in terms of mean ±\nstandard deviation (± SD). Numerical data were tested\nfor the normal assumption using the Kolmogorov-\nSmirnov test. A comparison between TP lesions and\nmissed lesions was done using the Mann-Whitney U test\nfor independent samples. Comparison between US size\nand pathological size within TP lesions was done using a\npaired t test. Agreement between the size measured by\nUS and pathology was done using interclass correlation\n(ICC) coefficient. p values less than 0.05 were considered\nstatistically significant. All statistical calculations were\ndone using the computer program IBM SPSS (Statistical\nPackage for the Social Science; IBM Corp, Armonk, NY,\nUSA) release 22 for Microsoft Windows.\nResults\nPatient flow, demographics and clinical characteristics\nOne hundred and thirty-five women were initially en-\nrolled. Twenty-nine patients who refused TVS or TRS,\nperformed ultrasound at an outside facility or did only\nMRI were initially excluded. One hundred and six pa-\ntients eventually performed standardized TVS/TRS and\nwere eligible for surgery. Fifteen patients who had no\nevidence of DIE on ultrasound were still qualified for\nsurgery due to the presence of endometriomas in 10 pa-\ntients and adenomyosis with severe pelvic pain in five\npatients. Five patients refused surgery. Following exclu-\nsion criteria, 101 patients were ultimately included in\nour study (Fig. 2).\nStudy population characteristics are summarized in\nTable 1.\nAccuracy of TVS in individual DIE locations\nEighty-eight women were found to have DIE as con-\nfirmed on laparoscopy and histopathology. Ultrasound\ndetected DIE in 86 cases (85.1%) and laparoscopy\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 4 of 11\n\ndetected DIE in two additional cases; each had a solitary\nplaque of DIE at the left USL.\nThe performance of TVS for each individual DIE loca-\ntion is shown in Table 2. Vaginal DIE was found to have\nthe lowest sensitivity and accuracy with a sensitivity of\n52.2% and accuracy of 88.1%, while bladder DIE and scar\nendometriosis were shown to have the highest sensitivity\nand accuracy with a value of 100% (Fig. 3).\nAdenomyosis was observed by ultrasound in 36 cases\n(35.6%) all of which were associated with DIE, except for\nsix cases (16.7%). Ovarian endometriomas were seen in\n79 cases (78.2%). The right ovary was involved in 59\ncases (58.4%), the left ovary in 47 cases (46.5%) and bi-\nlateral endometriomas in 27 cases (26.7%). DIE was as-\nsociated with ovarian endometriomas in 72 out of 79\ncases (91.1%) and without ovarian endometriomas in 13\nout of 22 cases (59.1%).\nPouch of Douglas obliteration was seen by ultrasound\nin 84 cases (83.2%). Complete obliteration was seen in\n34 cases (33.7%) with 33 out of 34 cases (97.1%) showing\nevidence of DIE by TVS. The sensitivity and accuracy of\nTVS in detecting pouch of Douglas obliteration was high\nat 97.7% and 98.0% respectively.\nUSL involvement by DIE was seen by ultrasound in 60\ncases (59.4%). Bilateral USL involvement was seen in 23\ncases (22.8%). TVS was accurate in detecting USL DIE\nwith an accuracy of 92.1% and 88.1% on the right and\nleft sides, respectively. The torus was almost always af-\nfected with bilateral USL involvement with 22 out of 23\ncases (95.7%) of bilateral USL DIE showing torus plaques\nresulting in a “butterfly” configuration. In the sagittal\nview, we observed that USL and rectal bowel loop in-\nvolvement gave a “tram-track” configuration caused by\nthickening of the affected USL and bowel loop with\nintervening increased tissue echogenicity caused by asso-\nciated perilesional fibrotic and chronic inflammatory\nchanges (Fig. 4).\nUltrasound revealed DIE of the rectum in 42 cases\n(41.6%). The cranial rectum was affected in 24 cases\n(23.8%) and the caudal rectum in 18 cases (17.8%). The\nFig. 2 Flow diagram of the study population based on STARD recommendation\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 5 of 11\n\naccuracy and sensitivity of TVS was very high for the\ncranial and caudal rectum at 100 % and 99% respectively\nwith no missed lesions and only one false positive lesion\nat each site. Thirty-six cases were treated with rectal\nshaving and five cases with disc excision. One case per-\nformed segmental bowel resection due to involvement of\nthe bowel wall more than 60% of the circumference as-\nsociated with luminal compromise; therefore, shaving or\ndisc excision was not appropriate. Histopathological as-\nsessment of cases with disc excision and segmental\nbowel resection revealed mucosal involvement. In cases\nwhere shaving was done, histopathology confirmed mus-\ncular layer involvement. Ultrasound showed a 100%\naccuracy in detecting muscular layer involvement and\n50% for mucosal involvement (Fig. 5).\nUreteric involvement was seen in six patients (5.9%),\nthree of which (3%) were bilateral. TVS detected a total\nof eight extrinsic and one intrinsic ureteric lesion with a\nsensitivity of 63.4% and accuracy of 97%. Ureteric reim-\nplantation was performed for the intrinsic and stenting\nfor the extrinsic lesions.\nCorrelation between ultrasound and histopathology size\nA comparison of US size and pathology size of true posi-\ntive (TP) lesions for each group is shown in Table 3.\nThere was no statistically significant difference between\nthe ultrasound size and pathology size except in groups\n4 and 5 which is mostly due to the small number of le-\nsions in these groups. Except for group 3, ultrasound ap-\npeared to underestimate lesions size with a mean\ndifference ranging from 0.43 cm in group 2 to 0.75 cm\nin group 5. For larger lesions > 3 cm, the underestima-\ntion was more pronounced, with a mean difference ran-\nging from 0.86 cm in group 2 to 1.7 cm in group 1.\nCorrelation between TP lesions and missed lesions\nWe compared the size of TP lesions and missed lesions\nin groups 1, 2 and 4. No missed lesions were recorded in\ngroups 3 and 5. There was no statistically significant dif-\nference between the size of TP cases and missed lesions\nwith p values of 0.168, 0.812 and 0.637, respectively. The\nmean diameter of missed lesions was 1.2 cm for groups\n1 and 4 and 1.6 cm for group 2.\nOperative complications and fertility outcome\nNo operative or post-operative complications were re-\ncorded in our study population which reflects the multi-\ndisciplinary approach. Over a period of up to 2 years of\nfollow-up, we had no cases of recurrent DIE. Eleven out\nof 22 cases (50%) of infertility achieved pregnancy over a\nperiod of 18 months, all of which were spontaneous ex-\ncept for two cases requiring in vitro fertilization (IVF).\nDiscussion\nIn our study, we showed that TVS allows for thorough\nand accurate evaluation of the extent of endometriosis.\nExperienced radiologists can use E-PEP to provide ac-\ncurate demonstration of the location and extent of DIE\nwhich aids the surgeon in preoperative assessment and\nintra-operative management.\nAs reported by Exacoustos et al., our study showed\nhigh sensitivity and accuracy of TVS in detecting pouch\nof Douglas obliteration [ 9]. This was contrasted with\nFratelli et al. which could be explained by their retro-\nspective study design [ 31]. We also found strong correl-\nation with complete pouch of Douglas obliteration and\npresence of DIE with 97.1% with complete obliteration\nTable 1 Study population characteristics\nPatient characteristics signs and\nsymptoms (No. 101)\nMean +/− SD;\nNo. (%)\nAge(y) 37.1 ± 6.2\nParity\n0 63 (62.4)\n1–2 28 (27.7)\n≥ 3 10 (9.0)\nPrevious medical treatment 82 (81.2)\nDuration of medical treatment (mo) 5.9 ± 6.8\nPrevious surgery of endometriosis 30(29.7)\nNumber of previous surgical intervention\n0 70 (69.3)\n1–2 25 (24.8)\n≥3 6 (5.9)\nDysmenorrhea 101 (100)\nVAS scorea 8.8 ± 1.4\nPelvic pain 97 (96.0)\nVAS scorea 7.5 ± 1.5\nDeep dyspareunia 68 (67.3)\nVAS scorea 6.6 ± 1.3\nDyschezia 39 (38.6)\nVAS scorea 6.8 ± 1.68\nDysuria/frequency 12 (11.9)\nInfertilityb 22 (21.8)\nInfertility duration (y)\n2 4 (4.0)\n3 8 (7.9)\n≥ 4 10 (9.9)\nIncomplete rectal emptying 19 (18.8)\nConstipation 69 (68.3)\nDiarrhoea 9 (8.9)\nNo number, SD standard deviation, mo month, y year\naVisual analogue scale (VAS) (ranges from 0 to 10, with 0 corresponding to no\npain and 10 corresponding to maximum pain). bInfertility is defined as failure\nof sexually active non-contraceptive couple to conceive after 1 year\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 6 of 11\n\nTable 2 Accuracy of TVS in diagnosing DIE with laparoscopy and histopathology as the gold standard\nDIE Localization Prevalence % (n) Sensitivity (%) Specificity (%) PVP (%) PVN (%) LR+ LR- Accuracy (%)\nGroup 1\nRectovaginal septum 19.8 (20) 67.9 98.6 95.0 88.9 48.5 0.33 90.1\nVagina 12.9 (13) 52.2 98.7 92.3 87.5 40.2 0.48 88.1\nGroup 2\nRight USL 42.6 (43) 84.0 98.0 97.7 86.2 42.0 0.16 91.1\nLeft USL 40.6 (41) 80.9 94.4 92.7 85.0 14.5 0.20 88.1\nTorus uterinum 28.7 (29) 96.4 97.3 93.1 98.6 35.2 0.04 97.0\nRight parametrium 19.8 (20) 73.9 96.2 85.0 92.6 19.5 0.27 91.1\nLeft parametrium 15.8 (16) 63.6 97.5 87.5 90.6 25.4 0.37 90.1\nGroup 3\nCranial rectum 23.8 (24) 100.0 98.7 95.8 100.0 76.9 0.00 99.0\nCaudal rectum 17.8 (18) 100.0 98.8 94.4 100.0 83.3 0.00 99.0\nGroup 4\nBladder 3.0 (3) 100.0 100.0 100.0 100.0 – 0.0 100.0\nRight ureter 5.0 (5) 66.7 98.9 80.0 97.9 60.6 0.34 97.0\nLeft ureter 4 (4) 60.0 99.0 75.0 97.9 60.0 0.40 97.0\nGroup 5\nScar/anterior abdominal\nwall endometriosis\n4 (4) 100.0 100.0 100.0 100.0 – 0.00 100.0\nDIE deep infiltrating endometriosis, PVP positive predictive value, PVN negative predictive value, LR+ positive likelihood ratio, LR− negative likelihood ratio, USL\nuterosacral ligament\nFig. 3 a Axial and b sagittal ultrasound images in a 36-year-old woman with pathologically proven scar endometriosis related to previous a\ncaesarean section scar. An irregularly shaped hypoechoic lesion inseparable from the anterior abdominal wall muscle was noted. c and d\nIntraoperative photographs showing the dissected lesion. Part of the abdominal wall muscle had to be dissected with the insertion of a mesh\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 7 of 11\n\nshowing signs of DIE by TVS as observed by Reid et al.\n[22]. Therefore, complete pouch of Douglas obliteration\nshould warrant meticulous search for DIE.\nThe lowest sensitivity and accuracy in our study was\nreported in vaginal DIE with a sensitivity of 52.2% and\naccuracy of 88.1%, similarly observed in previous studies\n[9, 28]. This may be due to vaginal probe characteristics\nwe used which provides suboptimal structure detection\nnear the tip of the probe. Two studies reported higher\nsensitivity values of 67% and 62% respectively [ 32, 33].\nFig. 4 a and b Transverse TVS image at the level of USL in a 35-year-old woman showing right and left USL (red and green arrows) as well as\ntorus uterinum DIE (blue star) giving a “butterfly” configuration. c Intraoperative photograph showing the butterfly lesion. d and e Sagittal TVS\nimage showing left USL (white arrow) and caudal rectal bowel DIE (black arrow) giving a “tram-track” configuration. f 3D volume acquisition of\nthe “tram-track” lesion using tomographic ultrasound imaging (TUI)\nFig. 5 a Sagittal TVS image in a 37-year-old woman showing a full-thickness plaque of DIE at the caudal rectum with subsequent luminal\ncompromise. b 3D volume acquisition of the rectal DIE using tomographic ultrasound imaging (TUI) in a sagittal plane and c volume contrast\nimaging (VCI) in sagittal, axial and coronal planes. d Intraoperative photograph showing the rectal plaque (black arrow) before shaving\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 8 of 11\n\nHowever, they included a fewer number of patients\nwith 48 and 65 patients meeting their inclusion re-\nquirements. A study by Guerriero and colleagues\nwhich included 88 patients reported a high sensitivity\nof 91% [ 34]. Their results could be explained by using\na generous amount of gel inside the transvaginal\nprobe cover establishing a “stand-off”. Koninckx et al.\nproposed using a clinical approach in diagnosing vagi-\nnal DIE rather than imaging with TVS which they\nconsidered to be operator dependant [ 4]. We believe\nthat clinical examination should complement ultra-\nsonography when assessing vaginal DIE.\nThe most frequently encountered location of DIE in\nour series was USL with 59.4% prevalence similarly\nstated by previous studies [ 28, 31]. Our sensitivity and\nspecificity were high at 82.5% and 98.4% respectively\nsimilar to previously published results [ 9, 16, 33, 35].\nOther investigators reported lower sensitivity and speci-\nficity [ 28, 31, 32, 36, 37]. In our series, the torus was al-\nmost always affected with bilateral USL involvement\nwith 95.7% of bilateral uterosacral DIE showing torus\nplaques. In our experience, torus involvement should be\ncarefully looked for with bilateral USL disease. We de-\nscribed two new sonographic signs: the “butterfly” and\n“tram-track” signs. To the best of our knowledge, these\ntwo signs were not described in the literature before.\nThe reproducibility of these two new signs needs further\nevaluation.\nWe found very high sensitivity and accuracy of TVS in\ncranial and caudal rectal DIE at 100% and 99% respect-\nively. Several authors reported high sensitivities of more\nthan 90% [ 9, 28, 33, 38]. Other investigators reported\nlower sensitivities of less than 50% [ 35, 36]. However,\nboth studies had a low incidence of bowel involvement\nin their sample population. Our study showed low ac-\ncuracy in detecting the involvement of the mucosal layer\nas published by previous investigators [ 9, 28, 39]. How-\never, we cannot draw firm conclusions from our figures\nsince only six patients who performed segmental bowel\nresection and disc excisions could be analysed. We be-\nlieve that the decision for surgery should be based on\nclinical history, pelvic examination and imaging findings.\nWe adopted a conservative surgical approach for recto-\nsigmoid DIE favouring bowel shaving and disc excision\nover segmental bowel resection. A conservative surgical\ntechnique has been shown to compare favourably to seg-\nmental bowel resection with regard to surgical, func-\ntional outcomes and recurrence rate [ 40, 41].\nIn our study, 100% sensitivity and accuracy were ob-\nserved in DIE of the bladder close to published results\nby other investigators [ 9, 16, 28, 33, 35, 36]. However,\nwe only had three lesions in our series therefore, no suf-\nficient data is available to draw firm conclusions. TVS\ndetected a total of eight extrinsic and one intrinsic ur-\neteric lesions with a sensitivity of 63.4% and accuracy of\n97% similar to the results published by Exacoustos et al.\nwho concluded that the incidence of intrinsic ureteric\nDIE is low as well as its associated hydroureter with low\nsensitivity of TVS [ 9]. We also agree with their interpret-\nation that extrinsic involvement should be suspected\nwith DIE involving the USL and parametrium.\nThere was no statistically significant difference be-\ntween the size DIE nodules detected by TVS and size re-\nported by histopathology which was consistent with a\nprevious study [ 32]. The only statistical difference was\nobserved in groups 4 and 5 which could be due to the\nsmall number of lesions in these groups. The ultrasound\ntended to underestimate the lesion size which was more\npronounced in lesions > 3 cm in line with Leone et al. ’s\nstudy [ 42]. We suggest that the underestimation in lar-\nger lesions may be attributable to extensive surrounding\nfibrosis as well as the location that is difficult to be eval-\nuated by TVS. This was especially obvious in lesions lo-\ncated in group 1.\nWe found no statistically significant difference be-\ntween the size of TP lesions and missed lesions in con-\ntrast to results published by Fratelli et al. [ 31].\nTherefore, we can conclude that the site rather than the\nsize of the lesion is more significant in lesion detection.\nThe limitation of our study is the high occurrence of\nendometriosis because of the way the patients were\nselected and the setting of the study at a centre of excel-\nlence for endometriosis. Also, the surgeon was com-\npletely blinded to the mapping proforma but not to the\nradiology report which could not be completely avoided\nfor proper surgical management.\nConclusion\nTVS allows a systematic comprehensive and accurate as-\nsessment of the size and location of pelvic and deep in-\nfiltrating endometriosis. The use of E-PEP can be\nutilized by the radiologist and surgeon to ensure that\nmapping information is correctly passed on. Precise\nmapping of endometriosis is pivotal for patient counsel-\nling to tailor the most appropriate surgical approach en-\nhancing the patient quality of life and fertility, ensuring\nTable 3 Correlation between ultrasound size and\nhistopathology size\nGroup US size (cm) Pathology size (cm) ICC P\nMean ± SD Mean ± SD\n1 1.35 ± 0.32 1.89 ± 0.75 0.68 0.002\n2 1.63 ± 0.41 2.05 ± 0.50 0.69 0.000\n3 2.69 ± 1.0 2.65 ± 0.91 0.92 0.000\n4 1.27 ± 0.51 1.65 ± 0.35 0.84 0.365\n5 2.63 ± 0.92 3.38 ± 1.11 0.97 0.030\nICC interclass correlation\nEl-Maadawy et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:159 Page 9 of 11\n\nradical excision of the disease and minimizing operative\nand post-operative complications.\nAbbreviations\nBSGE: British Society for Gynaecological Endoscopy; DIE: Deep infiltrating\nendometriosis; E-PEP: Endometriosis Preoperative Evaluation Proforma;\nIDEA: International Deep Endometriosis Analysis; IVF: In vitro fertilization;\nMRI: Magnetic resonance imaging; RVS: Rectovaginal septum; SD: Standard\ndeviation; SPSS: Statistical Package for the Social Science; STARD: Statement\nfor Reporting Diagnostic Accuracy Studies; TP: True positive; TRS: Transrectal\nsonography; TUI: Tomographic ultrasound imaging; TVS: Transvaginal\nsonography; USL: Uterosacral ligament; VAS: Visual analogue scale;\nVCI: Volume contrast imaging\nAcknowledgements\nThe authors would like to acknowledge Dr. Szabolcs Papp for his expertise as\na colorectal surgeon and Dr. Magdy Ibrahim for providing the statistical\nadvice for this manuscript.\nAuthors’ contributions\nThe scientific guarantor of this study is C.N. S.M.E.: Review of literature,\nsuggesting the idea, data collection and analysis, performing ultrasound and\nreporting ultrasound findings, writing the original draft, reviewing and\nediting the manuscript. N.A.: Data collection and analysis, performing\nultrasound and reporting ultrasound findings, reviewing and editing the\nmanuscript. C.N.: Data collection and analysis, perform the surgery and\nreporting surgical findings, reviewing and editing the manuscript. All authors\nhave read and approved the manuscript.\nFunding\nThe authors declare that they did not receive funding for this research.\nAvailability of data and materials\nThe data sets used and analysed during the current study are available from\nthe corresponding author on reasonable request.\nDeclarations\nEthics approval and consent to participate\nMedcare Hospitals & Clinics Ethics Committee approval was obtained.\nReference number is not applicable. Written informed consent was obtained\nfrom all patients who agreed to take part in this study.\nConsent for publication\nAll patients included in this research gave written informed consent to\npublish the data contained within the study.\nCompeting interests\nThe authors declare that they have no competing interests.\nAuthor details\n1Department of Radiology, National Cancer Institute, Cairo University, Cairo,\nEgypt. 2Department of Radiology, Medcare Women and Children Hospital,\nSheikh Zayed Road, P.O Box 215565, Dubai, UAE. 3Department of Obstetrics\nand Gynaecology, Medcare Women and Children Hospital, Sheikh Zayed\nRoad, P. O Box 215565, Dubai, UAE.\nReceived: 16 April 2021 Accepted: 3 June 2021\nReferences\n1. Bulun SE (2009) Endometriosis. N Engl J Med 360(3):268 –279. https://doi.\norg/10.1056/NEJMra0804690\n2. 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