Comparison of Doppler ultrasound indices of uterine artery and sub endometrial blood supply in frozen embryo transfer with and without repeated implantation failure: A cross-sectional study

 Uterine blood supply has been identified as a potential factor in implantation failure.

 This study aimed to investigate Doppler indices in the uterine artery, including vascular flow and resistance, as well as the amount of sub-endometrial blood supply in women with a history of repeated implantation failure (RIF) compared to the non-RIF group.

 This cross-sectional study was conducted with 139 women candidates for frozen embryo transfer in Yazd Reproductive Sciences Institute, Yazd, Iran from February to July 2023. Group A (n = 68) included women with a history of more than 2 RIF, and group B (n = 71) included women candidates for implantation for the first time without RIF. Doppler ultrasound indices of uterine artery and sub-endometrium, including sub-endometrial flow, uterine artery flow, uterine artery resistance, and peak systolic velocity, were recorded.

 No significant differences were observed in uterine artery Doppler pulsatility index and peak systolic velocity between groups, but the uterine artery resistance index was significantly higher in the A group (p < 0.001). A significant difference was observed in the perfusion area between groups. 60/68 women in the group A had endometrial perfusion in areas 2 and 3 (p < 0.001).

 Our study revealed that women with RIF exhibited higher resistance index in sub-endometrial arteries compared to the non-RIF group.