Excessive deposition of fibrin, platelets and platelet thrombi on vascular subendothelium during contraceptive drug treatment.

We investigated the effect of oral contraceptives on thrombogenesis induced by subendothelium of rabbit aorta (SE), exposed to flowing non-anticoagulated blood in an annular flow chamber. Six healthy women on sequential contraceptive drugs (0.05 mg aethinylestradiol/day, 0.125 mg desogestrel/day) were compared with 6 women without hormonal contraception and 6 men. On contraceptive drug treatment, blood values were significantly increased for fibrinogen (2.6 +/- 0.2 vs 1.9 +/- 0.1 g/l) and fibrinopeptide A (3.9 +/- 0.9 vs 0.9 +/- 0.1 ng/ml), whereas antithrombin III was decreased (81 +/- 4 vs 97 +/- 6%). Fibrin deposition on vascular subendothelium was more than four-fold increased when measured morphologically (63.4 +/- 2.5 vs 14.6 +/- 6.8% coverage of SE surface with fibrin) as well as immunologically (29.3 +/- 2.2 vs 4.5 +/- 1.9 micrograms fibrin/cm2 of SE). Thrombus volumes were more than two-fold increased in women with contraceptives (9.0 +/- 1.4 vs 3.7 +/- 1.0 micron 3/micron 2). Our study shows that during contraceptive drug treatment the exposure of flowing blood to vascular subendothelium leads to excessive deposition of fibrin and platelet thrombi. Measurement of blood interactions with subendothelium might be of predictive value in hypercoagulable states such as contraceptive treatment.