Pancreatic sphincter hypertension increases the risk of post-ERCP pancreatitis

Background and Study Aims: The reason for the increased risk of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP) in patients with sphincter of Oddi dysfunction is not known. This study sought to determine whether pancreatic sphincter hypertension might explain some of the increased risk. Patients and Methods: The incidence of pancreatitis was determined from a cohort of patients who underwent pancreatic sphincter manometry. Additional data collected included: pancreatic and biliary sphincter manometry results, distal bile duct diameter, chronic pancreatitis grade by pancreatography, and endoscopic treatments. Results: Ten of 32 patients (31%) with pancreatic sphincter hypertension developed post-ERCP pancreatitis, compared to one of 33 (3%),with normal pancreatic manometry (P = 0.002). Patients with pancreatic sphincter hypertension were more likely to undergo endoscopic treatments (88%) compared to those with normal manometry (27%) (P = 0.001). The distal bile duct diameter was significantly smaller (4.5 ± 0.5 mm) in patients who developed post-ERCP pancreatitis than in those who did not (6.2 ± 0.3) (P= 0.025). Patients with small distal bile duct diameters (< 5mm) were three times more likely to develop post-ERCP pancreatitis than those with larger ducts (relative risk [RR] 3.1, 95% confidence interval [CI] 0.9, 10.7). Patients with pancreatic sphincter hypertension were ten times more likely to develop post-ERCP pancreatitis than those with normal pancreatic manometry (RR 10.3, 95% CI 1.5, 76.0). In patients with a small bile duct size, pancreatic sphincter hypertension substantially increased the risk compared to those with normal manometry (RR 18.1, 95% CI 1.1, 287.6). Conclusions: Pancreatic sphincter hypertension greatly increases the risk of post-ERCP pancreatitis in patients undergoing treatment or evaluation, or both, for sphincter of Oddi dysfunction.