Functional constipation refractory to medical management: The anal sphincters are the problem

Most patients with functional constipation (FC) improve with medical treatment. For those with refractory symptoms, we propose a comprehensive and multidisciplinary work-up and decision-making approach to therapy. We retrospectively reviewed patients referred to our center between 2019-2022 with suspected FC who had failed medical management. All patients underwent a contrast enema, anorectal manometry, examination under anesthesia, rectal biopsy (if needed), and botulinum toxin injection (as indicated). 54 patients were evaluated using our algorithm. One was found to have anal stenosis on exam. The rectoanal inhibitory reflex (RAIR) was normal in 41(76%) patients and unable to be elicited in 12(22%). Two (17%) patients without a RAIR had Hirschsprung Disease (HD) and underwent a pull-through. 10(83%) with no RAIR had normal biopsies and were managed successfully with laxatives. Of the 41 patients with a normal RAIR, 14(34%) had high resting pressures (external sphincters) or non-relaxing (internal) sphincters and received botulinum toxin. 8(57%) of them were emptying well after one month. 24 patients failed laxatives (with or without botulinum toxin injections) and then underwent a Malone procedure. 23(96%) of these patients improved with antegrade flushes. One patient (1/21, 4.1%) did not undergo Malone and instead underwent colonic manometry and a sigmoid resection, after which he emptied well. We propose a systematic multidisciplinary approach for constipated patients who failed medical management starting with assessment of anal sphincters. This allows for targeted adjustment of laxative regimen, use of botulinum toxin to the internal and/or external anal sphincter and antegrade flushes via a Malone. IV