Assessment of uterine receptivity by endometrial and sub-endometrial blood flow using SlowflowHD in hormone prepared frozen embryo transfer cycles: a pilot study.

Abstract

Utilizing SlowflowHD as a measurement of endometrial and sub-endometrial blood flow in women with infertility undergoing frozen embryo transfer (FET) cycles and correlation with pregnancy outcomes. A prospective pilot study of 99 women undergoing hormone replacement FET cycles. Ultrasounds were performed with Voluson E8 at 3-time points: day 15, day of transfer, and 11days post transfer (T + 11). SlowflowHD Doppler blood flow indices in the endometrium and sub-endometrium were compared in women who achieved pregnancy with those who did not. Using SlowflowHD, both pregnant and non-pregnant women had similar trends with decreased endometrial blood flow day of transfer compared with day 15. However, there was a borderline significantly lower mean percentage decrease of endometrial blood flow in women achieving a pregnancy (28.3% vs 42.9%). Significantly higher numbers of pregnant women had a 20% or less decrease in blood flow (21 vs 9) with increases in mean percentage blood flow on T + 11 (pregnant 39.59% vs non-pregnant 25.20%). The RI and S/D ratio in the spiral arteries was also significantly higher on transfer day in women who had a live birth RI (0.68 vs 0.65) and S/D (3.91 vs 3.17). There are blood flow changes both in pregnant and non-pregnant patients with decreases in blood flow after progesterone replacement. Pregnancy and live births were associated with a lower mean percentage drop in blood flow from day 15 to the day of transfer and elevated RI and S/D ratio on transfer day.