Izquierdo Rodriguez 2020.

Study characteristics
Methods	RCT, 2 arms, 352 randomised Setting: Spain, one private IVF centre (ProcreaTec Fertility Clinic) Recruitment period: January 2017 to October 2018
Participants	Criteria relating to previous IVF failure: no Inclusion criteria: women undergoing egg donation, Included patients’ age ranged between 18 and 50 years, and all had normal uterine cavity, assessed by 2D transvaginal ultrasound. Patients with endometrial polyps were only included if polypectomy was performed at least 2 months before the treatment cycle. Exclusion criteria: severe male factor (less than 2 million sperm per mL) or if they presented any factor interfering with embryo implantation, such as uterine abnormalities (uterine fibroids classified as 0–2 FIGO stage, Müllerian malformations, or severe adenomyosis) or unilateral or bilateral hydrosalpinx; BMI over 35 kg/m2, previous endometrial scratch or hysteroscopy (less than a month before the randomisation)
Interventions	Study group: Scratch performed 5 to 10 days before their period started and the endometrial preparation began. The scratch was carried out in an out‐patient setting under abdominal ultrasound guidance. A speculum was inserted into the vagina and after cervix disinfection with an iodine solution, an endometrial biopsy catheter (Pipelle de Cornier,Laboratoire CCD, France) was inserted through the cervix into the uterine cavity. Once in the cavity, the catheter piston was partially removed to create a suction effect and the catheter was then moved back and forth and rotated 360° in order to scratch the four walls. Control group: no procedure
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage, multiple pregnancy Obtained via author correspondence: the authors provided data subgrouped by women with/without recurrent implantation failure, which we have used in the subgroup analyses. The authors stated that quote:"3 patients were scratch was difficult, 6 patients who referred some mild pain and 9 patients that suffered from some spotting some days after the technique and before their period started" however that "there was not a specific questionnaire or scale to report pain or bleedings and not all patients were specifically asked just after the scratch. Since some data were obtained after the treatment, it was possible that this information was not 100% accurate, so that is why it was not included in our paper" and also we have not included it in this review for the same reasons.The authors also provided the results subgrouped by RIF nonRIF.
Notes	Trial registration: NCT03108157 (registered Apr 2017, registered 3 months retrospectively) Additional concerns and comments: recruitment rate is approximately 16 participants per month, which may be considered high for a trial recruiting over a period of only 22 months, however cannot on its own be considered a serious risk of bias. The authors suggested the recruitment rate may be higher than other studies owing to the wider inclusion criteria used in the study. The authors provided the live birth data among women with recurrent implantation failure, and the overall live birth rate in this group was 57% (81/143) which is relatively high for a recurrent implantation failure population, and was also higher than the women in the study without implantation failure, however the women in this study were receiving donated eggs. Funding: this work was fully supported by ProcreaTec Fertility Center. This research received no specific grant from any funding agency in the public, commercial, or not‐for‐profit sectors Author correspondence: yes, with Alexandra Izquierdo, izquierdo.alexandra@yahoo.es Publication: full‐text.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The paper states that quote:“The randomization chart was obtained by a web‐based randomization program (randomization.com) using simple randomization. Patients were allocated to a treatment arm (group A—intervention arm, group B—control arm) and then received the instructions for their treatment protocol.”
Allocation concealment (selection bias)	High risk	There is no description of the randomisation process, however the authors confirmed that they quote:"used the software to obtain a long list of allocations and patients were included in consecutive order. If patients accepted the study, they were assigned to each group at the moment they accepted the treatment and dates, according to the list" and specifically that "we could see the next allocation" therefore allocations were not concealed
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was used as the paper states quote:Blinding was not possible since patients in the study group received an intervention and those in control group did not (no placebo intervention was performed).”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	No subjective outcomes reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Although in the paper it was not clear, we confirmed with the authors that there were no women lost to follow‐up or withdrawn from the trial. The 5 women that appear to have been lost in Figure 1 had missing data for pregnancy complications and newborn information only.
Selective reporting (reporting bias)	Low risk	Trial was registered late, but only by 3 months, and all outcomes were collected. therefore rated as low‐risk
Other bias	Low risk	‐