Sphincter of Oddi Dysfunction Is Associated with Pancreatic Duct Anomalies

Abstract

Purpose: Sphincter of Oddi dysfunction is known to be associated with pancreas divisum but other types of pancreatic ductal anomalies (PDA) have not been well studied. Duct toruosity and tight angulation can make deep guidewire cannulation difficult or impossible. Recognition of ductal anomalies is important in patients with suspected SOD because of the need for deep pancreatic cannulation and stent placement for prophylaxis of post-ERCP pancreatitis. Methods: Data form 1428 consecutive ERCP procedures performed on 1032 patients between 1999 and 2005 were collected prospectively. Two subsets of patients were then extracted from the database: those diagnosed with sphincter of Oddi dysfunction (SOD) and patients with PDA. Each PDA was independently reviewed and classified by a radiologist trained in reading ERCP studies. PDAs were classified as looping above main duct (upper ansa), looping below main duct (lower ansa), tightly angulated (switchback), dorsal dominant, or mixed PDA. Results: Of the 1032 patients included in our study, 270 (26%) were identified as having SOD of which 27 (10%) had PDAs. There were 762 without SOD of which 7 (0.9%) had PDAs. Thus PDAs occurred more frequently in patients with SOD than without SOD (p<0.0001). Of the 34 total patients with PDAs, there were 9 (26%) upper ansa loops, 10 (29%) lower ansa loops, 10 (29%) switchback loops, 1 (3%) dorsal dominant, and 4 (12%) mixed PDAs. Conclusions: PDAs occur much more frequently in patients with SOD compared to patients without SOD. Recognition of PDAs is important in patients with suspected SOD because the potential difficulty to achieve deep guidewire cannulation and subsequent pancreatic stent placement. An association between SOD and PDA may imply a congenital etiology for SOD.Table: Correlation of PDAs with SOD