Tsui 1997.

Methods	RCT Approved by the ethics committee and written informed consent obtained from all patients Setting: China Funding: unspecified
Participants	120 ASA class 1 or 2 female patients scheduled for gynaecological lower abdominal operations through a vertical midline incision
Interventions	Treatment group: LEA (L2‐L3 or L3‐L4) with bupivacaine 0.0625% and fentanyl 3.3 mcg/mL adjusted for VAS scores < 3/10 at rest for 48 hours (n = 57) Control group: IV PCA with morphine adjusted for VAS scores < 3/10 at rest (n = 54) General anaesthesia for all participants
Outcomes	Vomiting
Notes	32% of participants in the epidural group had limb weakness Study authors contacted for additional information. Replied that original data are no longer available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomly allocated", no details
Allocation concealment (selection bias)	Unclear risk	"Before the preoperative visit, patients were randomly allocated"
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	Low risk	9 dropped out owing to blockage of the IV cannula for PCA administration (n = 5), extrusion of the epidural catheter during the study period (n = 2) or failure to receive a vertical midline incision (n = 2)
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Unclear risk	Groups well balanced Not in intention‐to‐treat