Unresolved debate on surgery for deep infiltrating endometriosis of the rectum: bowel resection or a more conservative approach?

Deep infiltrating endometriosis (DIE) of the bowel, defined by infiltration of endometriosis into the muscularis propria, or as a lesion invading the bowel wall >5 mm depth, occurs in 5.2%–12% of women with endometriosis.^{1, 2} The rectum and the distal sigmoid colon are most commonly involved.^{3, 4} Rectal involvement may cause angulation or stricture of the bowel, causing defecatory pain and constipation.⁵ Cyclical inflammation of the rectal endometriosis may lead to diarrhoea, pelvic pain and rectal bleeding.⁵

With the advancements in minimally invasive surgery, there is an increasing trend to recommend surgery for rectal DIE. This involves rectal shaving, disc excision or segmental resection.⁶ There is no clear consensus as to the optimal technique for achieving symptom control and fertility in patients with DIE.⁷ This is in part due to varying surgical techniques particularly with heterogeneity of definitions for rectal shaving, as well as results and complications.⁸

There are studies advocating for a more conservative approach. In a series of 3298 patients, only 1.1% of rectal DIE cases met criteria for bowel resection.^{9, 10} These include major symptomatic rectal stenosis, multiple nodules infiltrating the rectosigmoid junction not amenable to serial shaving or disc excision, or extensive circumferential or posterior rectal lesions where shaving or disc excision is not feasible.¹¹ While conservative surgery was traditionally appropriate for DIE <3 cm,¹² Donnez and Roman found that shaving can be safely performed up to 6 cm in size, and the Rouen disc excision technique allowed for removal of rectal nodules >5 cm in diameter with good functional outcomes.^{11, 13} Shaving alone may be performed if the nodule can be easily separated from the anterior rectum to reach the cleavage plane of the rectovaginal septum, while disc excision may be preferred for mid to low rectal nodules where shaving may be technically difficult.¹¹ They concluded that the size of the nodule should not dictate the need for rectal resection, and that the majority of DIE did not require major bowel resection. This is important, as the complication rate is significantly lower with a conservative approach: 2.2–5.7% after shaving, 9.7% after disc excision and 9.9% after segmental resection.¹⁴ However, it is advised that these techniques, particularly for larger DIE nodules be performed in centres of expertise within a multidisciplinary setting.^{7, 14}

A meta-analysis found lower bowel perforation rate, intraoperative haemorrhage, anastomotic leak and rectovaginal fistula rate after rectal shaving compared to segmental resection.¹⁴ Disc excision was associated with lower rates of anastomotic stenosis, and that segmental resection was associated with significant risk of bowel stenosis requiring additional endoscopic or surgical intervention.^{14, 15} Also, the mean duration of the procedure was longer for segmental resection (151 ± 56.3 min), than for disc excision (111.5 ± 38.2 min) and shaving (96.8 ± 48.7 min).¹⁶

Donnez and Roman reported higher complication rates after rectal resection for urinary retention (0%–17.5%), anastomotic leakage (0%–4.8%) and pelvic abscesses (0%–4.2%) compared to rectal shaving.¹¹ The rates of rectovaginal fistulas were higher after both rectal resection (0%–18.1%) and disc excision (0%–11.6%) compared to shaving (0%–2.3%).¹¹ The risk of rectovaginal fistulas was up to 18% when rectal resection was performed for DIE close to the anal verge.^{17, 18} In a series of 1135 cases requiring surgery for DIE, the total stoma rate was 19.1%.¹⁹ There was no breakdown of stoma rates between the three types of surgery, however they commented that use of stoma was more frequent in facilities with higher rates of colorectal resection, suggesting that protective stoma was not commonly performed after rectal shaving.¹⁹

Quality of life (QOL) aspects of surgery is another important consideration. A prospective study involving 82 patients studied SF-36 scores (domains: pain, physical function, physical and emotional limitations, vitality, mental health, social, general health) before and after DIE surgery.²⁰ They found that all SF-36 domains in the rectal surgery group had significantly poorer scores than patients without rectal surgery at 6–12 months after surgery except for physical function (P = 0.06) and emotional limitations (P = 0.26). Additionally, no significant differences in the SF-36 scores were found comparing rectal shave, disc excision and segmental resection 1 year after surgery.²⁰ This was also echoed in a randomized controlled trial (RCT) where there were no differences in functional outcomes and pregnancy after 5 and 7 years between shaving or disc excision versus segmental resection.^{15, 21, 22} Two case series reported significant improvement in gastrointestinal QOL after rectal shaving at 1 and 3 years postoperatively.^{23, 24} A meta-analysis found that conservative surgery presented fewer events of constipation and diarrhoea than segmental resection.⁶ In addition, temporary bladder catheterisation rate after rectal shaving was reported to be 0.19%, compared to persistent urinary retention rate of 1.4%–17.5% after rectal resection likely related to bladder atony from hypogastric plexus injury.^{9, 23, 25, 26}

There is improved sexual QOL in the rectal shaving group, compared to segmental resection.^{27, 28} On the other hand, while Low Anterior Resection Syndrome (LARS) questionnaires did not demonstrate a difference between rectal shaving, disc excision versus segmental resection, endometriosis confounds LARS symptoms, as patients had major and minor LARS symptoms preoperatively.^27-29

There are studies that support segmental resection for DIE. These include ENDORE, a RCT assessing functional outcomes in 60 patients, which did not demonstrate differences in urinary and digestive improvements from conservative versus radical surgery.³⁰ A meta-analysis with 1600 patients quoted a proven endometriosis recurrence rate of 2.5% in the bowel resection group, compared to 5.7% in the mixed surgical group that included rectal shaving and disc excision.³¹ Advocates for radical surgery argue that conservative surgery results in higher risk of recurrence in DIE. The rates of residual microscopic endometriosis was reported as high as 40% with disc excision.^32-35

On the other hand, bowel resection for DIE may be associated with positive bowel margins for endometriosis up to 15%, with a risk of recurrent endometriosis symptoms.^32-35 Furthermore, data on recurrence rates were based on short follow-up periods (2–4 years).^{31, 36} Thus, it is unclear if bowel resection provides any long-term advantage in terms of DIE recurrence. In any case, the reintervention rate was found to be <10% in three studies,^{9, 26, 37} so the risk of recurrence needs to be balanced with the risk of bowel resection. Interestingly, a recent RCT for rectal DIE did not demonstrate differences in recurrence rate or reoperation risk between segmental resection versus shave or disc excision after 7 years followup.²² Thus, this further supports less invasive surgery for DIE.

With the increasing armamentarium of combined hormonal contraceptives (CHC), levonorgesterel-releasing intra-uterine system (LNG-IUS), Dienogest or Gonadatrophin releasing hormone (GnRH) agonists (Triptorelin or Leuprorelin) that may be used postoperatively to further reduce the risk of recurrence and persistent pain,^38-41 conservative surgery may be a less risky alternative to segmental bowel resection for DIE. Bowel resection for DIE of the rectum should be reserved for major symptomatic rectal stenosis, or where it is not safe or appropriate for shaving or disc excision. Rectal resection for DIE should not be the norm, but the exception.

Author contributions

Joseph Do Woong Choi: Data curation; formal analysis; investigation; methodology; project administration; writing – original draft; writing – review and editing. Hillary Hu: Formal analysis; investigation; validation; writing – original draft; writing – review and editing. Amy Cao: Formal analysis; supervision; validation; writing – original draft; writing – review and editing. Nimalan Pathma-Nathan: Conceptualization; formal analysis; methodology; supervision; validation; writing – review and editing. James Wei Tatt Toh: Conceptualization; formal analysis; investigation; methodology; supervision; validation; writing – review and editing.