Effect of conjugated estrogens on vaginal blood flow in surgically menopausal women

The effect of an intravenous bolus of 25 mg of conjugated estrogen (Premarin) on vaginal blood flow in seven surgically menopausal women was measured by a thermal conductance probe. Electrical power (0.8 W) was supplied to a resistance wire incorporated in the surface of the probe, and its surface temperature was monitored continuously for 30 minutes six times daily for 3 days. The mean temperature difference (ΔT) between the heated probe surface and the vagina remained unchanged during a preinjection control day. While there were individual differences in response, analysis of mean ΔT during the first day following the injection of the estrogen revealed a significant linear downward trend at ΔT, indicating a rise in vaginal blood flow. ΔT plateaued on day 2 and showed a slight rise in the morning of day 3. It may be concluded that estrogen administered in this dose and form markedly increases vaginal blood flow.