Apostolopoulos 2005

Methods	Single centre, RCT. Enrolment period: unclear. Endoscopist(s): all procedures were performed by 2 experienced endoscopists. Guidewire was handled by 2 GI interns with more than 2 years of training (information provided by authors).
Participants	Country: Greece. 123 patients with suspected choledocholithiasis.
Interventions	1. Guidewire‐assisted cannulation: a regular 0.035 inch Terumo guidewire through a 5.5F sphincterotome. Guidewire was used to access the CBD, followed by cannulation and opacification. Unclear who advanced the guidewire. 2. Contrast‐assisted cannulation: standard method of cannulation through a 5.5 F sphincterotome.
Outcomes	PEP; successful cannulation of the CBD; inadvertent PD cannulation / injection; asymptomatic hyperamylasaemia; cholangitis; mortality.
Notes	1. PEP was defined according to the consensus definition (Cotton 1991) (information provided by authors). 2. Graded severity of PEP using the Ranson's criteria and Balthazar grading (information provided by authors). Per protocol data: all episodes of PEP in the contrast‐assisted group were mild according to the Ranson's criteria, whereas using Balthazar criteria, 3 patients developed Balthazar A and 2 patients developed Balthazar B pancreatitis. ITT data: all episodes of PEP were mild in both groups. 3. No technique cross‐ove" when cannulation failed (information provided by authors). 4. Precut was not permitted (information provided by authors). According to the study protocol, 20 minutes of biliary cannulation were allowed in both groups. When access to the CBD failed, precut fistulotomy was performed, but these patients were excluded from analysis (per‐protocol analysis). We included these patients in our analysis based on the ITT principle. Successful cannulation of the CBD after precut: 3/4 patients in the guidewire‐assisted group vs. 3/3 patients in the contrast‐assisted group. 1/4 patients (Ranson: mild, Balthazar A) in the guidewire‐assisted group vs. 1/3 (Ranson: mild, Balthazar B) patients in the contrast‐assisted group developed PEP. 1/4 patient in the guidewire‐assisted group vs. 1/3 patient in the contrast‐assisted group had inadvertent PD cannulation / injection. 5. PD stents were not used for the prevention of PEP (information provided by authors).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"The patients were randomised into two groups." Conference proceeding, no further information was provided.
Allocation concealment (selection bias)	Unclear risk	Conference proceeding, no information was provided.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Conference proceeding, no information was provided. Endoscopists could not be blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Conference proceeding, no information was provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	PEP data reported in per protocol sample. Patients who failed cannulation and underwent precut were excluded from the analysis of the primary study. Additional outcome data of these patients were provided by authors of the primary study. We performed our analysis based on ITT principle, and used PP data in sensitivity analysis.
Selective reporting (reporting bias)	Low risk	Reported all important outcomes.
Other bias	Low risk	No other risk of bias.