A Sequential Cannulation Protocol Including Early Pancreatic Stent Placement and Needle Knife Sphincterotomy: Interim Analysis of a Randomised Trial

Abstract

Background: Competent biliary endoscopists fail selective biliary cannulation in 5-10% of cases. Needle knife sphincterotomy (NKS) can augment cannulation success, but is often used as a last resort and this may be responsible for the association with post ERCP pancreatitis (PEP). Prospective early NKS studies in difficult cannulation are few and inconclusive. Limited data exists on early pancreatic stent placement. Patients and Methods: Patients with a naïve papilla were invited to participate; exclusion criteria included pancreatic or ampullary cancer and acute pancreatitis within 2 weeks. A strict wire guided cannulation protocol was followed in all patients with allowance of a maximum of 5 minutes, 4 attempts or 2 pancreatic duct (PD) cannulations. The Fellow commenced the majority of the procedures and if any cannulation parameter was exceeded the consultant then attempted with the same protocol. If the consultant exceeded any parameter, the patient was randomized to either early NKS or continued standard cannulation (SC) for a further 10 minutes at which time cross over to NKS was allowed. PD stent insertion was performed if PD instrumentation had occurred and NKS was required. Prospective data collection included patient factors, time and comprehensive cannulation parameters. 24 hour and 30 day complication rates were assessed by phone interview and 24 hr serum lipase and amylase level. Results:1299 ERCPs were performed over 18 months. 478 patients had an intact papilla of which 319 were enrolled. 268 had early biliary cannulation success, 51 were randomized. Cannulation success was 98.4% (314/319) in the entire group - 24/26 (92%) in NKS arm and 12/25 (48%) in SC arm (p< 0.005); 13 of the SC group required salvage NKS of which 10 were successful, final success in the SC arm was 22/25 (88%). PD stent insertion was performed in 15 of NKS arm and 10 of SC arm. PEP was 5.6% overall (16 mild, 2 moderate, 0 severe), and 2.9% with early success (<10min). No difference in PEP was observed between the randomized groups (19% NKS, 20% SC). Increasing cannulation time was associated with increased risk of PEP (p=0.005). Risk of PEP increased with number of attempts on papilla, rising to greater than 10% after six or more attempts. There were no perforations or deaths. Conclusions: NKS is not associated with an increased risk of PEP and is an important intervention in salvaging cannulation success where standard attempts fail. Risk of PEP increases with greater time to cannulation and increasing cannulation attempts. Further data is required to establish whether early use of NKS (to reduce cannulation time and attempts) may reduce PEP occurrence.