Gibreel 2015.

Study characteristics
Methods	RCT, 2 arms, 387 women randomised Setting: Egypt, academic and private clinics, 3 centres Recruitment period: January 2011 ‐ June 2012 (provided by author correspondence)
Participants	Criteria relating to previous IVF failure: yes, at least one previous IVF failure Inclusion criteria: younger than 40 years of age with Exclusion criteria: women who were described as poor responders after previous IVF treatment (produced fewer than 3 oocytes or had their cycles cancelled because of poor follicular growth); women with known endocrinopathy; women undergoing tubal disconnection for hydrosalpinx; history of endometrial curettage within 3 months of the study; fibroids and other uterine factors (polyps, adhesions)
Interventions	Study group: pipelle procedure twice between days 21 and 26 of the cycle before the IVF index cycle and after initiation of the GnRHa in long agonist protocols Control group: placebo procedure using the uterine sound inserted into the cervix until the internal os on the same days of the cycle, as in women in the intervention group When the pipelle or the sound could not be introduced, a hysteroscopy was performed at the second appointment, in both groups
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage, multiple pregnancy Obtained by author correspondence: ‐
Notes	Trial registration: NCT01245309 (registered Nov 2010, registered prospectively) Additional concerns and comments: recruitment rate is approximately 22 participants per month, however across three centres this is not deemed to be particularly high. Funding: university funding Author correspondence: yes, Ahmed Gibreel is a co‐author of this Cochrane Review and the included trial Publication: full‐text.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Paper states quote:"Randomization was performed through a computer generated tables of random numbers"
Allocation concealment (selection bias)	High risk	Quote:"Women were asked to pick an opaque sealed envelope on the day of start of pituitary down‐regulation" as the envelopes were not numbered this is graded as high risk
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Paper states quote:"Women were blinded to their allocation in the trial while physicians were not blinded". Women in the control arm underwent an endometrial sound procedure.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only reporting objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	5 dropouts in total, 3 in one arm and 2 in the other arm
Selective reporting (reporting bias)	Low risk	Trial was registered prospectively and all outcomes reported
Other bias	Low risk	‐