Wallweiner 1998.

Methods	Unit of randomisation: participant Method of randomisation: not stated Time of randomisation: at completion of surgery Blinding: yes
Participants	Women (N = 40) undergoing initial treatment for endometriosis by laparoscopy‐vaporisation of peritoneal deposits, excision of endometrioma, reconstructive surgery, and adhesiolysis No dropouts Mean age, years: 27 Pre‐existing adhesions: yes Cause of adhesions: endometriosis Microsurgery: no Location: Germany Timing: not stated 7 dropouts: 4 were pregnant, 2 withdrew, and 1 had such dense adhesions at laparoscopy of both ovaries that no assessment could be made Pre‐existing adhesions: nil Mean age, years: 28 No other cause of infertility found Timing: 1994 to 1995 Country: UK (1 centre)
Interventions	Oxidised regenerated cellulose applied to all injured visceral peritoneal surfaces of ovary,tubes and uterus vs no treatment Other adjuvants used: none Second‐look laparoscopy Timing: 3 to 6 months after initial surgery Surgeon unaware: yes Adhesiolysis: nil
Outcomes	Adhesions at second‐look laparoscopy: 3 to 6 months later Incidence (per participant) Severity according to scoring system Surface area Extent: area, area differential, % improvement Incidence in participants with endometriomas Severity in participants with endometriomas Adverse outcomes: unknown Pregnancy: not stated
Notes	Power calculations: nil Sponsorship: not stated Documentation: video
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation not clearly stated
Allocation concealment (selection bias)	Unclear risk	Not clearly stated in 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	Unclear risk	States that evaluator performing second‐look laparoscopy was not familiar with the initial operative site, but does not clearly state that evaluator was blinded to treatment allocation
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No mention of whether withdrawals or dropouts occurred during the study
Selective reporting (reporting bias)	Unclear risk	Data reported as numbers in a dichotomous score. P values stated. No conversion or subsets of data. No pre‐publication protocol for reference purposes
Other bias	Low risk	No other bias identified

AFS: American Fertility Society.

BBT: basal body temperature.

CI: confidence interval.

GnRH: gonadotrophin‐releasing hormone.

HSG: hysterosalpingogram.

mAFS: modified American Fertility Society.

PID: pelvic inflammatory disease.

PTFE: polytetrafluoroethylene.

SD: standard deviation.

SEM: standard error of the mean.

SLL: second‐look laparoscopy.