Cycle-to-cycle variation in utero-ovarian hemodynamic indices in ovarian stimulation and natural cycles of the same women and its effect on the outcome of assisted reproduction treatment

Objective: To investigate the blood flow parameters between cycles of the same women to assess whether parameters predicting a successful pregnancy in a stimulation cycle could be used to determine the outcome of subsequent natural cycles. Design: A prospective study. Setting: Assisted reproduction unit, the University of Hong Kong. Patient(s): Fifty-eight IVF cycles and 40 natural cycles were evaluated. Intervention(s): Assessments of the utero-ovarian pulsatility indices (PIS), resistance indices (RIs), and endometrial color signals. Result(s): In IVF cycles, the pregnancy rate (27%) was similar to that in frozen-thawed embryo transfer (FET) (28%) cycles. The utero-ovarian Pis and Rls in IVF cycles were significantly lower than those in the natural cycles. There was a significant correlation between the uterine PI in stimulation cycles and that in natural cycles. In IVF cycles, the pregnancy rate declined significantly when the uterine PI was >2.70 and the RI was >0.9. In FET cycles, no decline in pregnancy rate was seen. Conceptional FET cycles showed significantly higher uterine PI, uterine RI, and endometrial color signals compared with conceptional IVF cycles. Conclusion(s): Hemodynamic parameters in stimulation cycles are different from those in natural cycles, and the values of various parameters in predicting pregnancy are also different.