Diamond 1996.

Methods	Unit of randomisation: women Method of randomisation: computer‐generated Timing of randomisation: end of surgery Blinding: surgeon unaware of randomisation at second‐look laparoscopy Multi‐centre trial
Participants	Women undergoing uterine myomectomy at laparotomy with at least 1 posterior uterine incision ≥ 1 cm. Similar baseline characteristics, including age, size and number of myomas, and number of uterine incisions N = 127 Microsurgery: no Dropouts: 6 (withdrew or excluded because of new medications) Age, years: 34 Location: USA (19 centres) Timing: 1993 to 1995 Pre‐existing adhesions Cause of adhesions: not stated
Interventions	Sodium hyaluronate and carboxymethylcellulose vs no treatment
Outcomes	Adhesion formation at the time of second‐look laparoscopy (mean days 23, range 7 to 70) Outcomes included number of adhesion sites, severity score, and surface area of uterine adhesions No pregnancy outcomes reported
Notes	Power calculations: not stated Documented by video Multi‐centre trial Sponsored by Genzyme No intention‐to‐treat analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Clear method of randomisation derived from computer‐generated randomisation list No clear source of bias Quote: "at each centre each enrolled patient was assigned consecutively a study number that corresponded to an identically numbered sealed study envelope, which determined the patient's treatment assignment via a computer derived randomisation list. After completion of myomectomy, patients were randomised at each centre into two groups"
Allocation concealment (selection bias)	Low risk	Numbered, sealed envelopes created before patient enrolment used to provide allocation, decreasing risk of bias Quote: "at each centre each enrolled patient was assigned consecutively a study number that corresponded to an identically numbered sealed study envelope, which determined the patient's treatment assignment via a computer derived randomisation list. After completion of myomectomy, patients were randomised at each centre into two groups"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Study authors do not explicitly state that patients were blinded, but all patients had the initial myomectomy and the SLL: "after completion of the myomectomy and associated procedures, but before closure of the abdominal cavity, patients were randomized at each center into two groups: no treatment controls and patients to receive the Seprafilm study device" Surgeons were not blinded, but randomisation took place intraoperatively to minimise performance bias: "after myomectomy, just before closure of the abdominal cavity, women randomized for no treatment (n = 68) received neither Seprafilm nor a placebo"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Videotapes of the SLL were reviewed by an independent blinded observer: "videotapes recorded during laparoscopy subsequently were reviewed at a central site by a single independent observer blinded to the patient's treatment assignment, to serve as the basis for the efficacy data on Seprafilm"
Incomplete outcome data (attrition bias) All outcomes	Low risk	6 (out of 127) participants were withdrawn
Selective reporting (reporting bias)	Unclear risk	Data presented graphically and as percentages. P values stated for outcomes. No omission of outcomes and no subsets of data. Although this was an infertility study, no pregnancy outcomes stated
Other bias	Low risk	No other bias identified