Uterine vascularity during stimulation and its correlation with implantation in in-vitro fertilization

The changes in uterine artery blood flow in women undergoing in-vitro fertilization cycles were studied throughout stimulation after gonadotrophin-releasing hormone (GnRH) desensitization. The data obtained showed that the uterine vascularity was related to hormonal changes. The GnRH agonist effect was seen only after the third week of administration, and the uterine perfusion was significantly (P = 0.002) improved by the oestradiol secretion. Human chorionic gonadotrophins increased the resistance index (RI) significantly (P = 0.0001) for a period of 48 h. Then the progesterone secretion modified the curve with a significant improvement in the uterine blood flow (P = 0.03). Comparison of the RI value 2 days before human menopausal gonadotrophin (HMG) commencement, in patients with and without pregnancy, showed a higher RI in patients who did not conceive but no difference was observed on the day of embryo transfer. The pregnancy rates were similar whatever the range of the RI observed. The data available so far suggest that haemodynamic parameters alone, detected by Doppler sonography, do not provide full information on endometrial receptivity on the day of embryo transfer. A resistance index > 0.79 before HMG commencement seems to indicate poor uterine vascularity and may necessitate an increase in the HMG doses to prevent endometrial immaturity.