THE RELATIONSHIP BETWEEN OVARIAN VASCULARITY AND THE DURATION OF STIMULATION IN IN-VITRO FERTILIZATION

The role of transvaginal pulsed colour Doppler ultrasound in the asses sment of ovarian vascularity was studied in 196 in-vitro fertilization (IVF) cycles. The changes in ovarian blood flow after gonadotrophin-r eleasing hormone agonist (GnRHa) down-regulation and human menopausal gonadotrophin (HMG) stimulation were determined. The data obtained sho wed that the ovarian blood flow was significantly improved by oestradi ol secretion (P = 0.05) and human chorionic gonadotrophin (HCG) admini stration (P = 0.003). Folliculogenesis was affected by blood flow supp ly. The resistance index (RI) value was significantly different (P = 0 .05) according to the duration of ovarian stimulation. Patients with a mean RI value >0.56 had a longer stimulation with a significantly low er mean number of oocytes retrieved (P = 0.01) despite the administrat ion of a standard dose of HMG. The RI value is a good indicator of mod ifications in ovarian vascularization during stimulation. Doppler bloo d flow measurement could be used to determine the optimal timing for t he beginning of HMG administration in patients undergoing ovarian stim ulation after down-regulation for IVF treatment.