The effect of endometrial injury on ongoing pregnancy rate in unselected subfertile women undergoing in vitro fertilization: a randomized controlled trial

STUDY QUESTION Does endometrial injury in the cycle preceding ovarian stimulation for in vitro fertilization (IVF) improve the ongoing pregnancy rate in unselected subfertile women? SUMMARY ANSWER Endometrial injury induced by endometrial aspiration in the preceding cycle does not improve the ongoing pregnancy rate in unselected subfertile women undergoing IVF. WHAT IS KNOWN ALREADY Implantation failure remains one of the major limiting factors for IVF success. Mechanical endometrial injury in the cycle preceding ovarian stimulation of IVF treatment has been shown to improve implantation and pregnancy rates in women with repeated implantation failures. There is limited data on unselected subfertile women, especially those undergoing their first IVF treatment. STUDY DESIGN, SIZE, DURATION This randomized controlled trial recruited 300 unselected subfertile women scheduled for IVF/ICSI treatment between March 2011 and August 2013. Subjects were randomized into endometrial aspiration (EA) (n = 150) and non-EA (n = 150) groups according to a computer-generated randomization list. PARTICIPANTS/MATERIALS, SETTING, METHODS Subjects were recruited and randomized in the assisted reproductive unit at the University of Hong Kong. In the preceding cycle, women in the EA group underwent endometrial aspiration using a Pipelle catheter in mid-luteal phase. All women were treated with a cycle of IVF/ICSI. Pregnancy outcomes were compared. MAIN RESULTS AND THE ROLE OF CHANCE There were no significant differences in baseline or cycle characteristics between the groups. There were 209 subjects (69.7%) who were undergoing their first IVF cycle and 91 (30.3%) subjects who had repeated cycles. There was no significant difference in ongoing pregnancy rates [26.7% (40/150) versus 32.0% (48/150); RR 0.833 (95% CI 0.585–1.187), P = 0.375] in the EA and non-EA groups. The implantation rates [32.8% (67/204) versus 29.7% (68/229); RR 1.080 (95% CI 0.804–1.450), P = 0.120], clinical pregnancy rates [34.0% (51/150) versus 38.0 (57/150); RR 0.895 (95% CI 0.661–1.211), P = 0.548], miscarriage rates [30.3% (17/56) versus 18.6% (11/59), RR 1.628 (95% CI 0.838–3.164), P = 0.150] and multiple pregnancy rates [31.3% (16/51) versus 19.3% (11/57), RR 1.626 (95% CI 0.833–3.172), P = 0.154] were all comparable between the EA and non-EA groups. Subgroup analysis in women having first embryo transfer (n = 209) also demonstrated no significant difference in ongoing pregnancy rates, but for women unde