Wolff 2018.

Study characteristics
Methods	RCT, 2 arms, 19 randomised Setting: private fertility centre, USA ‐ one centre Recruitment period: unclear
Participants	Criteria related to previous IVF failure: yes, one or more previous implantation failures Inclusion criteria: women age 18‐37, one or more previous implantation failures with autologous fresh or frozen blastocyst transfer, undergoing fresh autologous IVF cycle, no other current uterine (i.e.: uterine fibroids, polyps), haematological, or genetic causes for infertility and implantation failure, one or more good quality blastocyst(s) available for transfer Exclusion criteria: those unable to comprehend the investigational nature of the proposed study, positive pregnancy test, possible causes for impaired implantation (systemic disease, endometriosis, ultrasound evidence of current hydrosalpinx, uterine polyps, uterine myomas (fibroids), uterine cavity malformations or Asherman's syndrome), poor responders defined as follicle‐stimulating hormone >12 on day 3 or less than 4 follicles on a previous IVF cycle, BMI >30 or <18
Interventions	Study group: endometrial pipelle (Endocell, Wallach, Orange, Connecticut) inserted gently through the cervix into the uterus. Two passes will be performed with the pipelle catheter. For each pass the catheter will be rotated and scraped 4 times, once in each quadrant. The procedure is performed in the month prior to the IVF cycle, and it appears in the Protocol provided that the procedure is performed twice ‐ once on cycle day 4‐7 after starting the pill and again at the Lupron evaluation visit, however it is unclear. Control group: Small cotton swab placed gently into the cervix.
Outcomes	Reported in paper: ‐ Obtained by author correspondence: live birth, clinical pregnancy, multiple pregnancy, miscarriage
Notes	Trial registration: NCT01800513 (registered Feb 2013, unclear if registered prospectively as recruitment period unclear) Additional concerns and comments: none Funding: NIH and Shady Grove (author correspondence) Author correspondence: yes, undertaken with staff from Shady Grove Publication: unpublished. Investigators provided the individual outcome data on the 19 women randomised. The majority of information was obtained from the trial registration website and verified with the investigators, and protocol and other documents provided by the authors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Authors confirmed they used a random number generator
Allocation concealment (selection bias)	High risk	It appears the authors used an open list of trial allocations, the lead investigator was contacted to open a spreadsheet and reveal the next allocation when a new participant was randomised
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Sham procedure involved placement of cotton wool bud inside cervix
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only reporting objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	No attrition
Selective reporting (reporting bias)	Unclear risk	Unclear if registered prospectively or not a recruitment period unclear
Other bias	High risk	Trial was stopped early due to difficulty recruiting (target was 254), however this is not considered a bias necessarily. However, no study results have been published, and it is possible that additional methodological flaws in the study exist which have not been detected. It is also unclear if the trial was registered prospectively or not.