Karimzadeh 2009.

Study characteristics
Methods	RCT, 2 arms, 115 randomised Setting: Iran in an academic setting Recruitment period: Unclear
Participants	Criteria related to previous IVF failure: yes, recurrent implantation failure (defined as 2 to 6 unsuccessful cycles of IVF‐embryo transfer with previous transfer of at least 10 high‐grade embryos without achievement of clinical pregnancy) Inclusion criteria: age between 20 and 40 years; no history of blood disease; Exclusion criteria: age > 40 years; poor response in previous cycles (defined as day 3 follicle‐stimulating hormone > 10 IU mL or < 4 follicles on the day of trigger in previous cycle); uterine malformation; presence of endometrioma; ultrasound evidence of hydrosalpinx
Interventions	Study group: 1 endometrial injury procedure using Pipelle de Cornier on days 21‐26 of spontaneous cycle Control group: no intervention
Outcomes	Reported in paper: clinical pregnancy Obtained by author correspondence: ‐
Notes	Trial registration: does not appear to be registered Additional concerns and comments: one of the authors is an author on a paper which has been retracted for duplication, as it was very similar to another paper by the same author group in a different journal (Mohsenzadeh 2018). Funding: Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences. 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	Quote: "Random selection to either group was performed by drawing a piece of paper from the bag containing equal number of printed paper for each method"
Allocation concealment (selection bias)	High risk	No description of any safeguards in place to ensure allocation concealment and prevent someone from replacing the paper and selecting another
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was employed
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only objective outcomes reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Nine women lost to follow‐up in each arm (4 and 5)
Selective reporting (reporting bias)	High risk	Trial does not appear to have been registered and important outcomes such as live birth and adverse events not reported
Other bias	High risk	Trial not registered. Authors are also co‐authors of a retracted paper.