Maged 2016.

Study characteristics
Methods	Randomised controlled trial, 2 groups, set in Department of Obstetrics and Gynaecology, Faculty of Medicine, at Benha University Hospital, and at private centres for infertility, Egypt January 2010 to January 2015 Number of participants randomised: 154 Number of participants analysed: 154
Participants	Inclusion criteria: women with unexplained infertility assigned for intrauterine insemination (IUI) (requiring normal semen analysis); must have ≥ 1 patent (functioning) tube and no significant intrauterine or pelvic abnormalities (demonstrated on ultrasound, hysteroscopy, or laparoscopy); normal serum follicular stimulating hormone levels ≤ 12 mIU/mL Exclusion criteria: female partner > 40 years of age; ovarian cyst; uterine lesions; previous diagnosis of moderate to severe endometriosis; body mass index ≥ 35 kg/m²; polycystic ovary syndrome or anovulatory; signs of hyperandrogaenemia Cause of infertility: unexplained infertility
Interventions	Intervention group: endometrial scratching on the day of trigger of the first IUI cycle Control group: no endometrial scratching Both groups: participants given 100 mg clomiphene citrate on Day 3 to 7 of spontaneous menstrual cycle, followed by daily 150 IU of human menopausal gonadotropin. When 2 dominant follicles of 17 mm diameter or a luteinising hormone surge occurs, participants are given 5000 IU of human chorionic gonadotropin. 24 to 36 hours later, IUI is performed Degree of endometrial injury: No. 8 neonatal feeding tube Timing of endometrial injury: on the day of trigger Study length: 3 cycles (scratching performed only in the first cycle) Type of conception: IUI
Outcomes	Reported in the paper: Clinical pregnancy rate: confirmed by presence of visible intrauterine gestational sac(s) on ultrasonography Miscarriage rate (first‐trimester abortion) Multiple pregnancy rate Ectopic pregnancy rate
Notes	Funding source: study authors received no financial support Conflicts of interest: study author(s) declared no potential conflicts of interest Trial registration: NCT02349750 (retrospectively registered) Author correspondence undertaken
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Described as "randomly" in the text. Author correspondence confirmed the sequence was computer generated Quote: "allocation list was generated by a computer"
Allocation concealment (selection bias)	High risk	Quote: "using sealed envelope" Quote from author correspondence: "codes were inserted into envelopes by a third party (secretary). The participants and the physicians were blinded to the identity of each envelope until it is opened and paper unfolded by a nurse" However, the envelopes were not numbered
Blinding of participants (performance bias)	High risk	Study did not report blinding of participants, and it was unlikely; lack of participant blinding is anticipated to introduce performance bias
Blinding of personnel (performance bias)	High risk	Study did not report any blinding of personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Study did not report blinding of outcome assessors, and it was unlikely; however outcomes were unlikely to be influenced by lack of blinding
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were no losses to follow‐up/dropouts/discontinuation of treatment
Selective reporting (reporting bias)	Unclear risk	Study was retrospectively registered. Study authors confirmed that they did not record live birth and pain
Other bias	Low risk	We did not identify any other sources of bias