Cholecystectomy With Intraoperative Management of Bile Duct Stones in Norway - the BILNOR Study

The BILNOR study (Cholecystectomy with intraoperative management of bile duct stones in Norway) is a prospective, multicenter observational study evaluating how common bile duct stones (CBDS) are best managed when patients also need a cholecystectomy. Although ERCP followed by later cholecystectomy is still the most frequently used strategy, it often requires two separate procedures, with additional discomfort, risk, admissions, and costs. Single-stage alternatives-either intraoperative ERCP (including rendezvous techniques) or laparoscopic common bile duct exploration (LCBDE)-may reduce resource use and improve the patient pathway, but are unevenly available across Norwegian hospitals and have differing complication profiles.

The primary focus of BILNOR is transcystic LCBDE, a technique implemented at Oslo University Hospital in 2019 using a structured "step-up" approach (e.g., saline flushing, pharmacologic relaxation, guidewire passage, papillary balloon dilatation up to 8 mm, and transcystic choledochoscopy with stone extraction; intraoperative ERCP if needed/available). The study will estimate real-world stone clearance (defined as no repeat biliary intervention within 90 days), technical success (intraoperative clearance on cholangiography), and 30-day complications including a study-specific definition of post-procedure pancreatitis, as well as bile leak and other Clavien-Dindo graded events. Health economic outcomes (length of stay and costs per patient) and which procedural steps are most often required to achieve clearance are also assessed.

A secondary aim is to compare LCBDE with intraoperative ERCP regarding efficacy, complication rates, and costs, including a non-inferiority assessment for stone clearance. The planned total sample size is approximately 340 patients (155 per group plus allowae for dropouts). Learning-curve effects will be addressed with center-level sensitivity analyses excluding early cases. Inclusion is planned to start March 1, 2026, with expansion to additional centers as the technique spreads in Norway.

Inclusion criteria

• Age over 18 years
• Preoperatively image proven choledocholithiasis or bile duct sludge (US / CT / MRI)

• ≤ 8 mm size
• ≤ 5 stones
• Not proximal bile duct stones
• Planned cholecystectomy with intraoperative bile duct clearance (LCBDE or intraoperative ERCP)

Exclusion criteria

• Previous cholecystectomy
• Medically unfit for surgery (frailty, comorbidity)
• Technically inoperable (hostile abdomen, inflammatory processes, bleeding conditions, cirrhosis)
• Pregnancy