Comparison of pregnancy outcomes in women undergoing frozen thawed embryo transfer (FET) cycles following ultrasound for endometrial morphology with and without Doppler studies- a prospective cohort study

Introduction: There is a paucity of data evaluating role of endometrial blood flow in frozen thawed embryo transfer cycles (FET cycles) in hormone replacement treatment (HRT) cycles. Objective: To compare pregnancy outcomes in women undergoing ultrasound for endometrial morphology alone to those with endometrial morphology with blood flows in frozen embryo transfer cycles. Patients: Patients aged 23 to 38 years undergoing first two frozen thawed single blastocyst embryo transfer cycles. From August 2019 to January 2020, 163 patients undergoing hormone replacement frozen embryo transfer cycles were enrolled in the study. Patients were divided in two groups. Patients in group A (n = 92) had ultrasonographic evaluation of endometrial thickness and morphology and in group B (n = 71) patients underwent ultrasound for endometrial thickness, morphology along with Doppler blood flow studies. Outcome measures: Primary outcome was clinical pregnancy rate. Secondary outcome measures were pregnancy loss rate, ongoing pregnancy rate, and ectopic pregnancy rate. Results: Clinical pregnancy rate in group A and group B was 54.34% and 47.88%. Clinical pregnancy rate was similar between both the groups (P = 0.779). Ongoing pregnancy rate in group A and B was 48.91% and 40.84%, respectively. Pregnancy loss rate (7–13 wks) was 5.4% and 7.04% in group A and group B, respectively. There was no significant difference in ongoing pregnancy rate and pregnancy loss rate between both the groups (P = 0.756). Conclusion: Additional measurement of doppler studies do not help in improving implantation and thus seems unnecessary in improving pregnancy rates and reducing pregnancy loss rates in FET cycles.