Background: Gonadotrophins are used in many assisted reproduction units to achieve a better success rate by increasing the number of replaced embryos. However, high oestradiol concentrations are associated with altered physiological functions and its complications. We investigated whether high oestradiol concentrations (> or =20 000 pmol/l) after ovarian stimulation in infertile women would affect the uterine haemodynamics at the time of embryo transfer.
Methods: Colour Doppler indices of utero-ovarian arteries and endometrial colour signals were measured. Fifty-eight women undergoing ovarian stimulation for IVF were classified according to serum oestradiol concentrations on the day of human chorionic gonadotrophin injection into moderate responders (oestradiol <20 000 pmol/l; n = 39) and high responders (oestradiol > or =20 000 pmol/l; n = 19).
Results: Haemodynamic parameters were significantly lower in high responders; the uterine arterial pulsatility index (PI) and resistance index (RI) were (median; range) 1.87 (0.84-2.82) and 0.79 (0.57-0.90) respectively; ovarian artery PI was 0.57 (0.40-1.12) and RI was 0.43 (0.33-0.64). In moderate responders the uterine PI and RI were 2.63 (1.46-5.92) and 0.88 (0.77-1.10) respectively. Ovarian PI was 0.81 (0.32-3.72) and RI was 0.55 (0.23-0.97). The number of women showing endometrial colour signals was significantly lower in high responders (63%) than in moderate responders (92%) (P < 0.05). A further increase in oestradiol (> or =25 000 pmol/l; n = 8) showed significantly (P = 0.03) fewer endometrial colour signals [1.5 (0-8)] compared with moderate responders [4 (0-14)].
Conclusion: Despite low uterine PI and RI, the endometrial blood flow in high responders appears to be impaired. This may contribute to the decline in implantation efficiency noted in high responders.