Sphincter of Oddi Dysfunction Under Fire

Home of Fred the Snake (and Dr. Peter)

The idea that dysfunction of the sphincter of Oddi (SOD) can result in increased pressure in the bile duct and pancreas, and thereby cause pain, has become popular in recent years, especially in USA.

This has led to thousands of patients undergoing sphincter ablation by ERCP, sphincterotomy, a procedure not without significant risk.

Indeed these cases comprised at least a quarter of my ERCP practice. About 10 years ago my colleagues and I started to worry whether the benefits were really worth the potential short- and long-term complications. We chose to initiate a major study of patients in whom there has been the least proof of benefit, those with bad pains after gall bladder removal without any objective evidence for biliary obstruction (a dilated bile duct or elevated liver labs) so-called type III SOD.

It took the best part of a decade, and $7m from the National Institute of Health, to plan and complete the EPISOD study and come up with the answer, which was unequivocal and iconoclastic, published in the Journal of the American Medical Association (JAMA 2014; 311 (20):2101-2109). Patients getting the sphincterotomy treatment did no better than those having a sham/placebo treatment. This is having, hopefully, the effect of steering these troubled patients away from ERCP and towards other treatment modalities. It is also raising questions about the SOD concept in other clinical contexts.

The value of ERCP treatment of patients with “SOD type II”, with a dilated bile duct or elevated liver labs, is based on a number of cohort studies, mainly of poor quality, and 3 small and old randomized trials. We are planning to study this group in a similar stringent manner, and indeed the related concept of “gall bladder dyskinesia”, a common reason for gall bladder removal in USA, but rarely elsewhere.

I will be in Italy next week to participate in the 4th Rome convention on Functional Digestive Disorders to help update the Rome Foundation guidance in this foggy clinical minefield. More soon(ish).