Patent Accessory Pancreatic Duct Prevent Post-ERCP pancreatitis

Abstract

Background/Aims: Pancreatitis is the most important complication of ERCP. Moreover, efforts to understand its pathogenesis and to identify ways to reduce the frequency and severity of this complication have shown no convincing benefit to date. Although very complex factors are involved in the development of post-ERCP pancreatitis, mechanical injury to the papilla causing papillary edema and restriction of pancreatic juice flow, and hydrostatic injury from over-injection are the most common causes. We have prospectively examined patency of the accessory pancreatic duct (APD) by dye-injection ERP. We examined the role of the APD in vivo, and proposed a new way to prevent post-ERCP pancreatitis. Methods: During ERP, 2 or 3 ml of contrast medium containing indigo carmine was injected through a catheter in the main pancreatic duct (MPD) with usual pressure in 443 cases. Dye excretion from the minor papilla was then observed endoscopically. Results: Of 312 controls, patency of the APD was observed in 43%, whereas in 51 patients with acute pancreatitis, only 8 (16%) had a patent APD (p<0.01). In particular, patency of the APD was seen in only one of 17 patients with acute biliary pancreatitis. Patency of the APD showed a close relationship to the course and terminal shape of the APD. The long-type APD, which joined the MPD at its neck portion and ran straight from the upper dorsal pancreatic duct, was more frequently patent than the short-type APD which joined the MPD near its first inferior branch and followed a descending course (75.5% patency vs. 36.0%, p<0.01). Regarding terminal shape of the APD, patency of the cudgel (89.2%) and spindle type (92.0%) was more frequent than of the branch type (5.9%) or saccular type (16.7%) (p<0.01). According to the above findings, we retrospectively examined patency of the APD in 25 patients with acute pancreatitis after diagnostic ERP (6500 cases). Patency of the APD was estimated at only 8% (2/25). Furthermore, 3 cases showing acute pancreatitis after stone extraction with endoscopic balloon dilatation, exhibited nonpatent APD. Conclusions: A patent APD may prevent acute pancreatitis by lowering the pressure in the MPD. During ERCP, in cases with short type APD or APD with branch or saccular terminal shape, endoscopists should be more cautious and never persist when selective cannulation is difficult, or alternatively consider prophylactic pancreatic stenting.