Abdellah 2011.

Methods	Randomised trial conducted in Eygpt Timing: July 2007 to February 2010
Participants	156 women assessed for eligibility in fertility clinics and 147 randomised Mean age of women in the letrozole group was 23.9 ± 3.2 years and in the LOD group was 23.6 ± 3.2 years Inclusion: Women with clomiphene‐resistant PCOS, primary or secondary infertility because of anovulation and clomiphene resistance for at least 1 year, normal sperm analysis from partner, patent tubes as seen by hysterosalpingography or diagnostic laparoscopy Exclusion: Age < 20 or > 35 years, hormonal treatment within 3 months prior to study, hyperprolactinaemia, any other endocrine, hepatic or renal disorder, presence of an organic pelvic mass, history of abdominal surgery that might have caused pelvic factor infertility
Interventions	Letrozole 5 mg/day for 5 days starting on day 3 of menses for a maximum of 6 cycles (n = 74), versus LOD ‐ each ovary was punctured 4 to 6 times depending on the size of the ovary (n = 73) Follow‐up for 6 months
Outcomes	Endometrial thickness, biochemical pregnancy, clinical pregnancy, spontaneous abortion, ovulation rate
Notes	No conflict of interest Clinical trial registration number: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "computer generated random numbers table"
Allocation concealment (selection bias)	Low risk	Quote: "achieved using serially numbered opaque envelopes that were only opened once the interventions were assigned"
Blinding of participants and personnel (performance bias) All outcomes	High risk	There are no details of blinding in the paper. Blinding was unlikely to have occurred as the interventions were oral medication versus surgery.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	There are no details of outcome assessors being blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	147 randomised; 4 in the letrozole group and 3 in the LOD dropped out of the trial, all for non‐compliance. Intention‐to‐treat analysis was not conducted
Selective reporting (reporting bias)	High risk	We could not retrieve the original protocol. Live birth rate was reported in the Results section and was not listed as an outcome in the Methods section of the paper. Adverse effects on the mother and congenital malformations were also addressed in the Discussion section of the paper but had not been reported in the results section
Other bias	Low risk	No evidence of other risk of bias