Women with endometriosis often report bowel symptoms, including constipation, abdominal bloating and dyschezia while endometriosis is known to increase the risk of irritable bowel syndrome (IBS). We hypothesized that patients with endometriosis presenting with constipation or IBS are at increased risk of functional defecatory disorders. This study aimed to characterize the clinical features and anorectal pressure profiles of patients with endometriosis presenting with constipation or IBS.

We conducted a retrospective review of patients with endometriosis referred for evaluation of bowel symptoms and underwent high-resolution anorectal manometry (HR-ARM), along with balloon expulsion testing (BET). An abnormal BET was defined as the inability to expel a rectal balloon filled with 50 ml of water within 60 seconds. Demographic, clinical, surgical, and medication histories were extracted from the medical record. Analysis of variance (ANOVA) test was used to compare anorectal pressures among groups. The study protocol was approved by institutional review board.

A total of 190 patients with endometriosis were included. The mean (SD) age was 43.1 (12.3) years, and mean BMI: 26.3 (5.8) kg/m². The cohort was predominantly White, Non-Hispanic 109 (57%), followed by Asian 23 (12%) and Hispanic/Latino 23 (12%). Pathologic confirmation of endometriosis was present in 64% of patients. Constipation 172 (91%) and IBS 123 (65%) were the most prevalent bowel symptoms. Neuropsychiatric comorbidities included anxiety 91(78%) and depression 79(68%). A history of abuse was reported by 43(25%) of patients. Chronic pain was frequently reported, including pelvic pain 103 (64%), migraine 51 (32%), chronic back pain 49 (30%), and fibromyalgia 25 (15%). Smoking history was present in 44(23%), but only 3 were active smokers. Only 76 (61%) had a history of vaginal delivery and 37 (29%) had a history of C-section. Menstruation was ongoing in 120 (64%), and 50 (28%) were postmenopausal. Hormonal therapy for endometriosis was used by 55 (29%) of patients, including OCPs, and norethindrone and 15 (8%) were on hormone replacement therapy (HRT). IUD use was reported in 40 (21%) of patients, most of whom had hormonal IUDs; followed by copper IUDs, and few with progesterone-only devices. 23 (12%) were on opioids. A total of 63 (33%) had undergone hysterectomy, 27 (16%) had prior pelvic floor surgeries, most commonly rectocele or cystocele repair. A total of 117 (62%) of patients had abnormal BET confirming the presence of functional defecatory disorders. Patients with and without defecatory disorders had comparable clinical characteristics. Patients with abnormal BET had significantly higher anal resting tone and at simulated defecation residual anal pressures were higher, intrarectal pressures were lower, reduced anal relaxation and therefore lower recto-anal pressure gradient (table 1). Rectal sensory thresholds were all at higher volumes in patients with abnormal BET and the difference was significant for urge sensation (p:0.007).

Our data reveals, for the first time, a high prevalence of functional defecatory disorders in patients with endometriosis and bowel complaints, as assessed by anorectal physiological testing. Chronic pelvic pain, painful bladder syndrome, neuropsychiatric disorders and history of abuse were common among the patients of this cohort, underscoring the coexistence of well-established risk factors for defecatory disorders in this patient population.

In conclusion, this study reveals that endometriosis profoundly affects bowel function, extending beyond chronic constipation and IBS to include functional defecatory disorders. An effective approach to gastrointestinal symptoms in endometriosis should incorporate anorectal physiological testing to ensure accurate diagnosis and guide personalized treatment. Future studies should investigate whether the pathophysiology of defecatory disorders in patients with endometriosis is directly associated with the presence of rectal lesions or primarily linked to neuroinflammatory processes induced by ectopic endometrial tissue, which may lead to hyperalgesia and increased visceral hypersensitivity and anorectal dyssynergia.