Assessment of Uterine Receptivity by the Subendometrial- Endometrial Blood Flow Distribution Pattern in Frozen- thawed Embryo Transfer Cycles

Objective: To investigate the correlation of blood flow detected by 2-Dimensional Power Doppler (2D-PD) sonography in the subendometrial-endometrial unit with the pregnancy outcome in frozen-thawed embryo transfer (FET) cycles. Study design: Prospective non-randomized observational study. Materials and methods: A total of 127 patients undergoing their first FET cycle were recruited and prepared using hormone replacement therapy. All patients were evaluated for subendometrial-endometrial blood flow by 2D-PD once the endometrium was ≥ 7 mm thick. Progesterone supplement was added and transfer of 2 to 3 cleavage stage good quality embryos was done after 3 days. Results: The difference in the BMI, FSH, LH and endometrial thickness of women in the three zones was not statistically significant (p > 0.05). However, women with blood flow in zone 1 were of older age as compared to women in zone 3 with a statistically significant difference (p = 0.0001). In the present study, the overall pregnancy rate was 35.43% (45/127). Women having blood flow in zone 3 or 4 showed a rising trend of pregnancy rate as compared to those in zone 1 and 2 although it was not statistically significant (p = 0.15). But, clinical pregnancy and implantation rates were significantly higher in women with zone 3 or 4 penetration compared with zone 1 or 2 penetration (p = 0.03 and 0.01, respectively). Conclusion: The subendometrial-endometrial vascularity has a useful predictive value for pregnancy outcome in FET cycles. However, larger studies are needed to reach definite conclusion.