Stain 1991.

Methods	Randomised clinical trial of pts found to have CBDS on ERCP and fit to undergo surgery, randomised to either ERCP/ES + surgery or surgery "alone" . Single centre. All pts suspected of having CBDS (bilirubin > 2 mg/dl, raised amylase, USS evidence of CBDS) underwent ERCP. Follow‐up: exclusions not listed. Drop‐outs not listed. Sample size calculations: no. No power analysis stated.
Participants	Los Angeles. USA 52 pts completed the study. Commencement and completion dates not stated. Inclusion criteria: Intact gallbladder, gallstones on USS, CBDS proven on ERC. Exclusion criteria: None stated. Essential investigations: USS, serum biochemistry, ERC, IOC, T‐tube cholangiogram in all having CBDE.
Interventions	Group 1: ERCP followed by ES and stone extraction by basket or spontaneous passage. Subsequent OC +/‐ CBDE in all cases. Surgery scheduled electively. CBDE performed on basis of ERCP findings and IOC. Group 2: ERCP followed by OC scheduled electively. CBDE performed as necessary.
Outcomes	Mortality, morbidity, stone clearance rate, retained stones after surgery, operation time, hospital stay.
Notes	Pts in both groups had ERC, therefore surgery arm had complications of ERC. Low ERCP/ES stone clearance rate (65%).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation sequence.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible.
Selective reporting (reporting bias)	Low risk	None.
Incomplete outcome data	Low risk	No missing data.
For‐profit bias	Low risk	Appears free of for‐profit support.
Other bias	Low risk	None.