Normal uterine arterial blood flow in postmenopausal women assessed by transvaginal color Doppler sonography: the effect of hormone replacement therapy.

We used transvaginal color Doppler sonography to study the effect of hormone replacement on the uterine arterial blood flow for 203 postmenopausal women. The regimens studied involved estrogen replacement alone, continuous combined estrogen and progestogen, and estrogen followed sequentially by combined estrogen-progestogen. The mean pulsatility index fell to 65% +/- 9% and the mean resistive index fell to 87% +/- 4% of baseline during the first month of therapy (P < 0.0001). The addition of a progestogen did not alter the effect of estrogen alone (P > 0.5). Our findings suggest that the increase in vascular flow occurs even in women who begin therapy long after menopause.