Balen 1994.

Methods	Prospective randomised controlled trial conducted in UK (Middlesex Hospital, London) Timing: not stated
Participants	10 women randomised. Refractory PCO. Mean age (range) of the women was 29.5 (27 to 33) years and mean duration (range) of infertility was 5.6 years (4 to 8). Infertility work‐up consisted of tubal patency testing by laparoscopy, semen analysis, endocrinology. In one case the tubes were blocked, 2 had pelvic adhesions, 3 had severe oligospermia or azoospermia and underwent donor insemination. Mean BMI 23 kg/m2 Study duration and timing not stated.
Interventions	Bilateral ovarian surgery by diathermy (N=6), versus Unilateral ovarian surgery (N=4) LOD was performed with a diathermy needle creating 4 punctures/ovary, cooled with normal saline Follow‐up for 3 months
Outcomes	Pregnancy rate (by participant) Ovulation rate (by participant)
Notes	Conflict of interest: not stated Definitions: PCO: not defined. Refractory PCO: failure to ovulate on 100 mg/day (duration not specified); some had also been treated previously with tamoxifen or gonadotrophins Pregnancy: not defined Ovulation: not defined
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details in paper
Allocation concealment (selection bias)	Unclear risk	No details in paper
Blinding of participants and personnel (performance bias) All outcomes	High risk	No evidence of blinding of researchers or participants
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No details
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data reported from all 10 women
Selective reporting (reporting bias)	Unclear risk	We could not retrieve the original protocol. The outcomes mentioned in the Method section are presented in the Results section of the abstract. No live birth
Other bias	Low risk	No evidence of other risk of bias