Functional outcomes of bowel resection versus shaving or disc excision of colorectal endometriosis: a systematic review protocol

Endometriosis is a prevalent gynaecological condition affecting approximately 6%–10% of women of reproductive age worldwide. 1 It is characterised by the abnormal presence of endometrial tissue outside the uterus which induces a chronic inflammatory state that is most commonly associated with pelvic pain and infertility. 1 2 Endometriosis encompasses three clinical presentations: peritoneal endometriosis, ovarian endometriosis (endometriomas) and deeply infiltrative endometriosis (DIE). 3 DIE has been defined as endometriosis that invades more than 5 mm beneath the peritoneum. 4 While DIE primarily involves the pelvic peritoneum, ovaries and rectovaginal septum, it can also infiltrate extrapelvic sites, such as the bowel. 1 This causes a subset of patients to experience symptoms such as altered bowel habits, dyschezia and tenesmus. 2 In rarer cases, intestinal endometriosis may also cause rectal bleeding, bowel obstruction and bowel perforation. 2 5 The exact prevalence of endometriosis involving the intestine is estimated to occur between 3.8% and 37% of all cases of endometriosis. 6 While endometriosis of the intestine has been observed from the small bowel to the anal canal, approximately 90% of cases involve the sigmoid colon or rectum. 7 Patients with colorectal endometriosis can have severe symptoms that are refractory to medical therapy. In these cases, surgical intervention is indicated. The surgical management of colorectal endometriosis presents a clinical challenge due to its proximity to vital anatomical structures and the potential for complications. Depending on the lesion’s location, size and depth of infiltration, two main surgical approaches are used. These include segmental bowel resection or the more conservative approaches of shaving or full-thickness disc excision. Segmental colorectal resection involves the removal of the affected segment of the bowel followed by anastomosis. The shaving technique is reserved for superficial lesions which do not invade beyond the serosa and require surgical dissection of the lesion from the affected bowel wall with an aim of not entering the bowel lumen. There are multiple surgical methods for disc excision, all of which ultimately result in a full-thickness excision of the endometriotic lesion along with the surrounding bowel wall, followed by closure either with sutures or staples. The goal of surgical treatment is to completely eradicate symptomatic endometriotic lesions while achieving a high standard of long-term results with regard to symptomatic relief, recurrence rates and functional outcomes. 2 8 There are limited data available to guide the choice of resection technique based on the functional bowel outcomes of bowel resection, shaving and disc excision in treating colorectal endometriosis. Three published systematic reviews have investigated the clinical outcomes of surgical management of endometriosis with bowel involvement. The first systematic review incorporated literature up until February 2010 and was not outcome or surgical-technique specific. 9 The data were reported in such a way that a comparison of clinical outcomes between different surgical techniques was not possible in this review. The second review focused on the influence of surgery on postoperative fertility only and did not include patients who underwent shaving excision. 10 The third systematic review was specifically focused on segmental bowel resections for endometriosis and their indications, outcomes and complications according to the level of resection and the volume of the nodule. 11 A literature review published in 2017 compared the surgical techniques of shaving, discoid resection and bowel resection in terms of surgical outcomes, complications and recurrence rates, however, did not specifically outline their functional outcomes from a bowel function or pain perspective. 8 There is a noticeable gap in high-quality evidence which compares the effectiveness of the various surgical approaches in terms of their functional bowel outcomes. This protocol, therefore, aims to outline the methods that will be used in a systematic review of the available literature, which to our knowledge is the first of its kind, comparing the functional bowel outcomes as well as postoperative pain and Low Anterior Resection Syndrome (LARS) scores following bowel resection, shaving and disc excision when treating colorectal endometriosis in females.

This study does not require ethics approval as it is a systematic review. There are no safety concerns. The results of the review described within this protocol will be disseminated through presentations at relevant conferences and publication in a peer-reviewed journal. The methods employed within this review may be used to inform future reviews, particularly those exploring the outcomes of surgery on treating bowel endometriosis.

This systematic review focuses on comparing the functional bowel outcomes of bowel resection, shaving and disc excision when treating colorectal endometriosis. Colorectal endometriosis will be defined as DIE involving the colon or rectum. We have described our methods as per Preferred Reporting Items for Systematic Review and Meta-Analysis for Protocol (PRISMA) recommendations, and this checklist is included as online supplemental additional file 1 . The final reporting of this study will be compliant with the main PRISMA statement. This study is registered on PROSPERO, an international register of systematic reviews. Patients and public were not involved in writing this protocol. Definitions as per PICO-D have been adapted for the purpose of this review: Participants: females undergoing surgical intervention for colorectal endometriosis. As defined above, colorectal endometriosis is DIE involving the colon or rectum. Surgical interventions include bowel resection, shaving or full-thickness disc excision. Interventions: use of bowel resection. Bowel resection is defined as surgical removal of the affected segment of bowel followed by primary anastomosis. Comparator: use of more conservative approaches such as shaving or full-thickness disc excision. Shaving is defined as surgical separation of the endometriotic lesion from the colon or rectum to reach the uninvolved plane of the bowel wall without disruption of luminal integrity. Full-thickness disc excision is defined as full-thickness excision of the endometriotic lesion along with the surrounding bowel wall, followed by closure either with sutures or staples. Outcomes: Primary outcome is comparing functional bowel outcomes which include faecal incontinence, faecal urgency, frequent bowel movements, clustered stools, dyschezia, constipation and diarrhoea between the different methods of surgical treatment. Secondary outcome will be quality of life based on the LARS score and incidence of postoperative pain. 12 Timing: Databases including MEDLINE, EMBASE and Cochrane will be searched from the beginning of each database until February 2024. Design: Given the lack of randomised controlled trials, all quantitative papers will be considered eligible for this review. Exclusion criteria: Articles will be excluded if they are not a journal article, not a report based on empirical research (eg, protocol, editorial), reviews, not human research and not in the English language. We will use the PRISMA guideline to search MEDLINE, EMBASE and Cochrane databases from the beginning of each database to February 2024. An update of the search will be conducted prior to submission to a journal. Further studies will be obtained from scanning reference lists of relevant studies and citation searching of key papers identified for inclusion. A search strategy was developed with the initial support of a medical research librarian. Keywords included bowel, function, colon, rectum, endometriosis, bowel resection, shaving and disc excision. The full search strategy for all databases is included as online supplemental additional file 2 . After searching, the shortlisted articles will be exported to Endnote V.X9 (Thomson Reuters, New York, USA) for storage of study records, abstracts and full-text articles. Data will be stored on a password-protected server-based platform, that is, accessible by both reviewers. At each stage of the data selection process, back up files of the database will be made to retrace any steps as needed in the review process. The process of study selection will be conducted by two researchers. In the initial screening stage, the authors will conduct a title search and identify abstracts, which potentially meet the criteria for study selection. Abstracts for which it is unclear whether to include in the study will be further assessed against the criteria after acquiring full-text articles. This will be done independently to reduce the risk of bias. Discrepancies between two reviews will be resolved by consultation with the senior author. Detailed notations of decisions made to include or exclude studies and the rationale for these decisions will be documented. The flow of studies throughout the selection process will be reported using a PRISMA diagram. Once the studies for inclusion have been identified, information outlined in a standardised data extraction form ( online supplemental additional file 3 ) will be collected. Data from all included studies will be extracted. The form will be piloted and optimised by the two reviewers using a subset of three randomly selected studies that satisfy the eligibility criteria. The two reviewers will independently extract data from the rest of the included list of articles. This study will compare the functional outcomes between the different methods of surgical treatment. Primary outcome is comparing the functional bowel outcomes which include faecal incontinence, faecal urgency, frequent bowel movements, clustered stools, dyschezia, constipation and diarrhoea between the different methods of surgical treatment. Secondary outcome will be quality of life based on the LARS score and incidence of postoperative pain. 12 The following data will be extracted from the included studies: General study information including study title, citation, authors, year of publication, country of publication and journal. Characteristics of the study including aim, study design and method of recruitment. Participant characteristics including baseline demographics. Outcomes result of primary outcome, risk of bias assessment and overall conclusion. The risk of bias will be ascertained by two reviewers independently using published, structured and validated risk of bias assessment tools appropriate for the study type. We will use the I 2 statistic to quantify whether there are any inconsistencies among the included studies. Significant statistic heterogeneity exists if the I 2 value exceeds 50% and subgroup analyses will be conducted to explore possible causes. Funnel plots will be used to detect the potential reporting biases if more than 10 studies are included into the meta-analysis. The Egger’s test will be used to determine funnel plot asymmetry. Studies will be included in data synthesis if they fulfil the eligibility criteria. Data will be presented in a descriptive narrative and supplemented with tables and figures where appropriate. Meta-analyses will be undertaken where meaningful; if the participants, intervention and study design are homogeneous enough to warrant pooling. If the I 2 value is between 50% and 75%, a random-effects model will be used. If the I 2 value is higher than 75%, we will provide a descriptive analysis. A fixed-effects model will be used if the I 2 value is lower than 50%.