P381 Defining the phenotype of bowel dysfunction in patients with endometriosis

Introduction Bowel symptoms often accompany pelvic pain in patients with endometriosis and adenomyosis, however the pathophysiology of these symptoms is unclear. The aim of this study is to determine the nature of gut physiological dysfunction in patients with endometriosis and compare this to patients with no abnormality and presumed functional causes for their symptoms. Methods Patients were recruited at the point of referral to our tertiary endometriosis centre for pelvic pain. Inclusion criteria: aged 18–50 years, the presence of bowel symptoms, and no known bowel disease. Participants completed symptom questionnaires (0–10 numeric rating scale, IBS-SSS, PACSYM, HADS, VSI) and underwent a bowel transit (Sitz marker) test, high resolution anorectal manometry (HRAM) with electrosensation, and MRI proctogram. They also underwent an abdomino-pelvic MRI scan to detect endometriosis lesions and other pathology. Patients with and without pathology on MRI were compared using Fischer’s and Mann-Whitney-U tests. Results A total of 101 patients were recruited, of whom 95 underwent a bowel transit study, 74 underwent HRAM, and 82 underwent MRI. Mean age was 32.5 years (SD:7.2) and BMI was 26.8 (SD:7.9). Their distribution of endometriosis is shown in figure 1. Patients with endometriosis or adenomyosis on MRI had a particular symptom phenotype: Worse chronic dyschaezia (mean 3.8 vs 2.3, p=0.026) Less fluctuation in nausea with the menstrual cycle (1.0/10 vs 2.9/10, p=0.016). In terms of physiology, patients with endometriosis or adenomyosis on MRI: were more likely to have slow bowel transit than those without (38.3% vs 15.6%, p=0.043) constipation scores correlated with bowel transit time (rho=0.316, p=0.031) had lower rates of defaecatory dyssynergia (22.5% vs 54.5%, p=0.023) often had rectal hypersensitivity to distension, but at a similar prevalence to those without disease on MRI (36.6% vs 26.9%, p=0.439) In particular, patients with deep rectovaginal endometriosis had significantly lower threshold to electrical stimulation compared to those with no disease (12.9 vs 20.2 milliAmps, p=0.017). Conclusions Different pathophysiological mechanisms underlie bowel symptoms in patients with adenomyosis or endometriosis on MRI disease compared to those with presumed functional origins of their symptoms – in particular the former seem to have slow gut transit with a hypersensate rectum and non-dyssynergic evacuation. This suggests that abdomino-pelvic MRI should be used to quantify endometriosis burden in female patients with pain and bowel symptoms, as this has implications for the management of patients with proven endometriosis.