Low-dose oral contraceptive effects on thromboelastogram criteria and relationship to hypercoagulability.

Abstract

The study was undertaken to assess hypercoagulability, by using thromboelastography, in women who use low-dose oral contraceptives (OCs). Forty-three women using low-dose OCs (<or=35 microg ethinyl estradiol) underwent thromboelastography before starting OCs and again during the third month of OC use. Prior and 3-month mean values of four thromboelastogram parameters (maximum amplitude [MA], K time, alpha angle, and R time) were compared by using paired t tests. Comparison according to progestin type was also performed with unpaired t tests. Prior versus 3-month values for MA, alpha, and K were not significantly different (P values-K: 0.8; alpha:.34; MA: 0.49); power was adequate to detect small differences. The 3-month R time was decreased compared with pre-OC values (P =.025), although the magnitude of this change was not characteristic of hypercoagulability. Comparison according to progestin type demonstrated no difference. We found no significant trend toward hypercoagulability in women who used low-dose OCs and who otherwise had no known thromboembolic risks.