The relationship between ovarian vascularity and the duration of stimulation in in-vitro fertilization.

The role of transvaginal pulsed colour Doppler ultrasound in the assessment of ovarian vascularity was studied in 196 in-vitro fertilization (IVF) cycles. The changes in ovarian blood flow after gonadotrophin-releasing hormone agonist (GnRHa) down-regulation and human menopausal gonadotrophin (HMG) stimulation were determined. The data obtained showed that the ovarian blood flow was significantly improved by oestradiol secretion (P = 0.05) and human chorionic gonadotrophin (HCG) administration (P = 0.003). Folliculogenesis was affected by blood flow supply. 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 lower mean number of oocytes retrieved (P = 0.01) despite the administration of a standard dose of HMG. The RI value is a good indicator of modifications in ovarian vascularization during stimulation. Doppler blood flow measurement could be used to determine the optimal timing for the beginning of HMG administration in patients undergoing ovarian stimulation after down-regulation for IVF treatment.