Does ovarian stimulation affect uterine artery impedance?

Purpose: We evaluated the effect of induction of ovulation on uterine perfusion. Methods: In 42 infertile women transvaginal color Doppler was performed at days 16-21 of a spontaneous ovulatory cycle and prior to embryo transfer in an in vitro fertilization (IVF) cycle. Indication for treatment was mainly tubal or unexplained infertility. Results: Uterine artery pulsatility index was significantly (P < 0.001) lower in IVF than in natural cycles, 3.24 +/- 0.72 2.64 +/- 0.53 (mean +/- SD), with a mean reduction of 18%. The reduction was higher, although not significantly, in the women who conceived (20%) than in those who did not (15%), and in those with a basal PI > 3.0 (20%) as opposed to those with normal values (16%). The percentage reduction correlated with patient age and with estradiol concentration, number of follicles, and oocytes recruited. Conclusions: Induction of superovulation reduces impedance to flow in the uterine circulation. The amplitude of this effect appears to be regulated partially by patient age and by effectiveness of ovarian stimulation.