Influence of ovulation induction with human menopausal gonadotropin on uterine blood flow: Comparison of unexplained and mechanical infertility

A prospective study in patients undergoing in vitro fertilization treatment was conducted to assess whether any difference may be present in uterine blood flow between unexplained and mechanical infertility, before and during ovulation induction. The ascending branch of the uterine artery, the arcuate arteries, and the radial arteries were examined by transvaginal, color pulsed Doppler sonography on day 3 and on the day of human chorionic gonadotropin administration. Patients with mechanical factor demonstrated a decrease in resistance to blood flow in all the examined vessels during ovulation induction. Patients with unexplained infertility showed a contrasting trend in changes of uterine blood flow (e.g., as the cycle progressed, the resistance index increased). Moreover, the resistive index values on the day of human chorionic gonadotropin administration were significantly higher in patients with unexplained infertility. It is quite possible that the rise in impedance to uterine blood flow during ovulation induction and the higher impedance on the day of human chorionic gonadotropin administration in patients with unexplained infertility may be one of the factors responsible for the lower conception rate in these patients.