Hamza 2016.

Study characteristics
Methods	Randomised controlled trial, 2 groups, setting not described, authors are from Egypt (affiliation: Menoufia University) Study duration: not described Number of participants randomised: unknown Number of participants analysed: 146
Participants	Inclusion and exclusion criteria: not described Cause of infertility: unexplained infertility (described in trial registry)
Interventions	Intervention group: endometrial scratching by pipelle for 1 minute in the luteal phase (described in trial registry); it is unknown whether scratching was performed in the same cycle as intrauterine insemination (IUI) or in the cycle preceding IUI Control group: "sham procedure by pressure on the cervix by piece of gauze" (described in the trial registry) Degree of endometrial injury: pipelle Timing of endometrial injury: in the luteal phase of a spontaneous menstrual cycle (not described on which day) Study length: not described Type of conception: IUI
Outcomes	Reported in the abstract: Clinical pregnancy (not defined) Multiple pregnancy
Notes	Only a conference abstract was available Funding source: not described Conflicts of interest: not described Trial registration: PACTR201509001264171 (registration date September 2015, start date September 2015). Based on information in the trial registry, the trial was registered prospectively. However, start date is not confirmed by study authors, and actual study duration is not described in the abstract Author correspondence was undertaken, but we did not receive a response
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomisation in 1:1 ratio was carried out using computer‐generated simple random tables"
Allocation concealment (selection bias)	Unclear risk	Not reported in the abstract. Use of "sealed opaque envelopes" was described on the trial registration page. However it remains unclear whether this was the actual method of allocation concealment, and whether these envelopes were sequentially numbered
Blinding of participants (performance bias)	Unclear risk	Abstract did not report blinding of participants. A sham procedure was performed, but it is unclear whether participants were effectively blinded
Blinding of personnel (performance bias)	Unclear risk	Abstract did not report any blinding of personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstract did not report blinding of outcome assessors, and it was unlikely; however outcomes were unlikely to be influenced by lack of blinding, as there were no patient‐reported outcomes
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Abstract did not report any information about missing data
Selective reporting (reporting bias)	Unclear risk	All outcomes reported in the abstract were pre‐specified in the trial registry. However, it is unclear whether the trial was truly registered prospectively, as the actual start date of the trial is not confirmed by study authors. Therefore risk of reporting bias is rated as unclear
Other bias	High risk	Enrolment and follow‐up were completed within 8 months (September 2015 to April 2016) (data from trial registration page). The follow‐up duration was not described, but clinical pregnancy was one of the outcomes of the trial. The last participant probably would have been enrolled in the sixth month. It seems unlikely to us that a study with 146 participants can be completed in such a short period; however it is not impossible