Wallin 1986.

Methods	RCT Approved by the ethics committee and informed consent obtained Setting: Sweden Funding: governmental (plus a contribution from industry)
Participants	30 patients scheduled for elective cholecystectomy; 3 loss to follow‐up (27 analysed: 17 female and 10 male)
Interventions	Treatment group: TEA (T12‐L1; catheter inserted 3 to 4 cm passed the needle tip) with bupivacaine 0.5% started before the incision, and 0.25% intermittent injection of 10 to 14 mL every 3 hours for 24 hours after surgery (n = 12) Control group: postoperative IM pentazocine 30 to 60 mg on request (n = 15) General anaesthesia for all participants
Outcomes	Time of first flatus (hours) Time of first stool (hours)
Notes	Study authors contacted for additional information on 23 July 2014, but did not reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"the Mudy was randomized", no details
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	3 in the epidural group lost to follow‐up (failed epidural)
Selective reporting (reporting bias)	Low risk	All results provided
Other bias	Unclear risk	Groups well balanced Not in intention‐to‐treat (n = 12 for epidural in the results)