P024 Anorectal Manometry in Patients with Fecal Incontinence After Ileal Pouch-Anal Anastomosis for Inflammatory Bowel Disease: A Cohort Study
Authors: Young Sigrid , Smukalla Scott , Chang Shannon 
Published: December 2021

BACKGROUND:
Fecal incontinence (FI) affects up to 1 in 4 patients with inflammatory bowel disease (IBD) and is associated with inflammation, surgeries, and altered rectal sensitivity. Ileal pouch-anal anastomosis (IPAA) is a surgical intervention for select IBD patients to avoid a permanent stoma. High-resolution anorectal manometry (HRAM) studies in IBD patients with FI demonstrate lower resting pressures and rectal sensory dysfunction. However, HRAM data in IBD patients with FI post-IPAA remains limited. We hypothesized patients with FI would have lower resting and squeeze pressures and rectal hypersensitivity compared to healthy controls and that these changes would be similar after IPAA.

METHODS:
Retrospective review of prospectively collected data was conducted on patients undergoing HRAM from 2017-2021 at a single urban academic medical center. Patient characteristics (age, gender, BMI, stool frequency, diabetes, pregnancy history) and surgical history (prior perianal surgery, index vs. re-do IPAA) were obtained. HRAM variables included rectoanal inhibitory reflex (RAIR), sphincter length, resting, squeeze, cough, and push pressures, sensation thresholds (first sensation, constant sensation, desire to defecate, urgency to defecate, max tolerable volume), and balloon expulsion test (BET). HRAM outcomes in IPAA patients with FI (IPAA-FI) were compared to non-IBD patients with FI (non-IBD-FI). HRAM data for both patient cohorts were also compared to existing normative data of healthy controls. Non-IBD patients with constipation and FI were excluded from analysis. An independent samples t-test was performed (p < 0.05) for continuous variables, and chi-square test was used for categorical variables.

RESULTS:
Fifty-six patients (66% female) were in the non-IBD-FI group. Eighteen patients (67% female) were in the IPAA-FI group. Average age in the IPAA-FI cohort was 44.8 ± 13.6 vs. 66.3 ± 14.4 in the non-IBD-FI group (p< 0.01). Sphincter length in the IPAA-FI group was 2.7 ± 1.1cm vs. 3.2 ± 0.6cm in the non-IBD-FI group (p=0.03). There was no significant difference in sensation thresholds or resting, squeeze, cough, and push pressures between the two groups. Urinary incontinence was observed in 5.6% of IPAA-FI patients vs. 44.6% of non-IBD-FI patients (p < 0.01). RAIR was present in 38.5% of IPAA-FI patients vs. 100% of non-IBD-FI patients (p < 0.01). Both patient cohorts had significantly shorter sphincter length, lower squeeze and push pressures, and lower sensation thresholds compared to normative data. Resting pressures for the IPAA-FI group was not significantly different compared to healthy controls.

CONCLUSION:
Overall, anorectal pressures and sensation are similar between IPAA-FI and non-IBD-FI patients. However, the underlying FI mechanism seems to differ. Higher rates of urinary incontinence in the non-IBD-FI cohort suggests global pelvic floor dysfunction compared to IPAA-FI patients who are younger and have post-operative neuromuscular dysfunction, as evidenced by shorter sphincter length and absent RAIR. Though rectal hypersensitivity and lower squeeze/push pressures are observed in both patient groups compared to healthy controls, normal resting pressure in IPAA-FI suggests that potentially different normative ranges are needed for this cohort to accurately assess post-surgical changes and guide pre-operative counseling.