Endometrial scratching before euploid embryo transfer: a case-control study

To evaluate the effect of endometrial scratching on in vitro fertilization (IVF) success rates in women undergoing frozen embryo transfer with preimplantation genetic testing for aneuploidy (PGT-A).

Biopsy was performed at oocyte retrieval in cases and compared to those who did not undergo scratching (controls). Endpoints included pregnancy loss, total pregnancy, clinical pregnancy rate (CPR), ongoing pregnancy rate/live birth rate (OPR), and the incidence of chronic endometritis (CE).

Women in case and control groups had similar characteristics, such as age, body mass index, and parity. Overall total pregnancy rate was 82.43% following single euploid embryo transfer in cases compared to 85.7% in controls (p = 0.57; OR = 1.27; 95% CI = 0.565 to 2.78). CPR was 73.3% and 76.2% (p = 0.62; OR = 1.18; 95% CI = 0.594 to 2.29), and OPR between groups was 64.8% and 72.3% (p = 0.28; OR = 1.42; 95% CI = 0.74 to 2.7). First trimester loss rate was similar at 16.9%% and 15.5%%, respectively (p = 0.82). Subjects who underwent scratching closer to their frozen embryo transfer (≤ 3 months) had a similar overall pregnancy rate to those with a longer delay between retrieval and frozen embryo transfer (> 3 months 81.4% vs.87.5%; p = 0.56). CE incidence was 10.8% (8 out of 74; 95% CI = 5.5% to 19.9%). The odds of having a second trimester loss were significantly higher in the scratch group compared to controls (p = 0.03; OR = infinity; 95% CI = 1.3 to infinity).

Endometrial scratching before frozen euploid embryo transfer did not influence pregnancy outcome but increased the chances of second trimester loss. CE was a frequent finding in those undergoing endometrial scratching at the time of retrieval.