Baum 2012.

Study characteristics
Methods	RCT, 2 arms, 36 randomised Setting: Israel, academic research clinic, one centre Recruitment period: July 2006‐June 2009
Participants	Criteria relating to previous IVF failure: yes, diagnosis of RIF (3 or more unsuccessful cycles of IVF‐ET with good ovarian response in previous cycles) Inclusion criteria: age 18‐41; scheduled for IVF with fresh embryo transfer on the next cycle Exclusion criteria: uterine malformation; presence of endometrioma; ultrasound evidence of hydrosalpinx
Interventions	Study group: pipelle procedure undertaken twice, on days 9–12 and 21–24 of the spontaneous menstrual cycle preceding the IVF treatment cycle Control group: cervical pipelle was done by introducing the biopsy catheter into the cervix without scraping or taking a biopsy specimen, on the same days as above
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage Obtained by author correspondence: ‐
Notes	Trial registration: NCT00411021 (registered Dec 2006, retrospective registration however was initiated post 2010) Additional concerns and comments: none Funding: none stated Author correspondence: attempted but no response received Publication: full‐text
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed quote:"using a table of random numbers"
Allocation concealment (selection bias)	Unclear risk	No description
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants were blinded by use of a cervical pipelle procedure.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only reporting objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	Appears to be no attrition
Selective reporting (reporting bias)	High risk	Trial was registered 6 months into recruitment, however no outcomes listed. Live birth reported, however adverse events such as pain not reported.
Other bias	High risk	On the trial registration page the study authors planned to include 70 women in a cross‐over trial; however in the published study, only 36 women were included and only 1 phase of the study was described. Reasons for the early stop are not stated. Additionally, the trial was registered late.