Tinelli 2011.

Methods	Unit of randomisation: 546 participants Time of randomisation: at completion of surgery Blinding: single Method of randomisation: block randomisation was used to ensure balance in the numbers of participants in the 4 treatment arms. A statistician generated the entire randomisation sequence list in advance, and allocations were sequentially numbered from beginning to end Exclusion criteria for the investigation: previous uterine or pelvic surgery; previous abdominal general surgery; presurgical treatment with GnRH analogues; gynaecological malignancy; pregnancy; use of any instillation such as 32% dextran‐70, corticosteroids, anticoagulants, or non‐steroidal anti‐inflammatory drugs; haematological or coagulation disorders; presence of ongoing pelvic infection
Participants	546 participants underwent surgery Type of surgery: laparoscopic or abdominal single or multiple intracapsular myomectomy Reasons for surgery: pelvic pain, menorrhagia and growth of fibroids as verified by ultrasound; some women requested myomectomy because of infertility Mean age between groups, years: 28.9 to 30.2 Timing of second‐look surgery between groups, years: 2.3 to 2.6 Dates: January 2003 to June 2009
Interventions	Participants were subdivided into groups for laparoscopic or abdominal surgery. Participants underwent single or multiple intracapsular myomectomy. Participants were randomly assigned to placement of oxidised regenerated cellulose absorbable adhesion barrier to the uterine incision or to control without barriers
Outcomes	Primary and secondary outcomes of analysis: presence and severity of adhesions for 4 groups: laparotomy with barrier, laparotomy without barrier, laparoscopy with barrier, and laparoscopy without barrier
Notes	Funding: no external source stated Power calculation: stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation list used to reduce bias Quote: "after completion of reconstructive uterine surgery, subjects were assigned to the treatment in a 1:1 ratio using a randomization list with random permutated blocks, length of 4"
Allocation concealment (selection bias)	Unclear risk	Methods of allocation concealment not stated in the text
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not stated whether initial surgeon was blinded; however as control was no treatment, this appears unlikely. Not clearly stated whether participants were blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Surgeons who performed second‐look laparoscopy and assessment were blinded to treatment allocation
Incomplete outcome data (attrition bias) All outcomes	High risk	High attrition rate, intentionally excluding patients not requiring repeat surgery, even though these patients may have had asymptomatic adhesions Quote: "of the 694 enrolled patients, 546 (78%) were available for assessment of adhesions during a subsequent operation" Adhesions were assessed at second surgery only if the participant had undergone subsequent surgery over the 6 years. Arguably, study data may be skewed by not including the 21% of participants who did not require subsequent surgery. Reasons for subsequent surgery include "laparotomy for cesarean section, laparotomy or laparoscopy for ovarian cysts, recurrent fibroids, appendectomy, cholecystectomy, extrauterine pregnancy and infertility"
Selective reporting (reporting bias)	Unclear risk	Data reported as incidences and percentages. P values reported only for significant outcomes. No differences identified between methods and reported results. However, no pre‐publication protocol identified for reference purposes
Other bias	Low risk	No other bias identified