Low but Significant Yield of Endosonography in Patients with Suspected Sphincter of Oddi Dysfunction Type III with normal Imaging studies

Abstract

Aim: To determine the yield of endosonography (EUS) in patients with suspected Sphincter of Oddi Dysfunction (SOD) Type III in detecting abdominal abnormalities in those with normal upper endoscopy and imaging studies.

Methods: A retrospective review of patients with suspected SOD who underwent EUS prior to undergoing an ERCP was performed. The inclusion criteria were: 1. patients with right upper quadrant abdominal pain for ≥3 months; 2. no evidence of abnormalities on upper endoscopy, imaging studies and laboratory tests. Exclusion criteria were: history of acute or chronic pancreatitis, pancreas divisum, jaundice or any significant abnormality detected on prior studies. The main outcome measurements were to determine the diagnostic yield of EUS to diagnose the etiology of abdominal pain and detect clinically significant lesions.

Results: We identified 143 patients with suspected SOD type III who had undergone EUS. A diagnosis of the etiology of abdominal pain by EUS was made in 12 of 143 patients (8%) with previously normal endoscopy and imaging studies. EUS identified the following: changes consistent with chronic pancreatitis (n=5), biliary stone (n=1), side-branch intraductal papillary mucinous neoplasms of the pancreas (n=3), benign bile duct stricture (n=1). Papillary stenosis was diagnosed in two patients with common bile duct dilation detected by EUS.

Conclusions: EUS may detect significant abnormalities in a small subset of patients with suspected SOD with previous normal endoscopies and imaging studies. Although the yield of EUS is low, it should be considered in patients with persistent pain and those with a high clinical suspicion for pancreatic pathology.