Uterine artery Doppler and endometrial blood flow in frozen embryo transfer: A cohort study

Background: The implantation rate after assisted reproductive technology depends on ۲ important factors, good quality embryo and endometrial receptivity. Endometrial receptivity is mainly assessed by ultrasound measurement of endometrial thickness and morphology. Objective: This study aimed to investigate the relationship between uterine artery Doppler indices/endometrial perfusion and pregnancy rate. Materials and Methods: This cohort study was done on ۲۵۰ women who were candidates for frozen embryo transfer from January to July ۲۰۲۲. For assessing endometrial receptivity, we performed a Doppler ultrasound of the uterus before embryo transfer with apparently desirable endometrium (endometrial thickness ≥ ۷ mm and ۳ line endometrial pattern). In addition, the women were divided into ۲ groups according to assisted reproductive technology outcome (clinical pregnancy), group I positive clinical pregnancy, and group II negative clinical pregnancy, and uterine artery indices and endometrial perfusion were compared between these groups. Results: Uterine artery Doppler showed that the pulsatility index was significantly different between positive and negative clinical pregnancy groups, but resistance index and peak systolic velocity (PSV) did not have statistically significant differences. Also, endometrial perfusion was significantly different between the ۲ groups of clinical pregnancy. Endometrial perfusion was significantly better in positive clinical pregnancy groups. Conclusion: Doppler ultrasound can help to assess endometrial receptivity.