RESUMEN
Many reports have indicated that oral contraceptives can increase the incidence of thromboembolic disorders. Norplant, an implant contraceptive containing levonorgestrel, has been developed recently. The aim of this study is to observe the effect of Norplant on some hemostatic parameters. The subjects in this study were divided into 5 groups. Group 1 (control) consisted of 25 female blood donors. Group 2 (N = 25), group 3 (n = 25), group 4 (n = 17) and group 5 (N = 20) consisted of subjects who had been using Norplant for 2, 3, 4, and 5 years, respectively. Prothrombin time, activated partial thromboplastin time, fibrinogen level, assay of F VII and X, antithrombin III activity, plasminogen activity, alpha 2-plasmin inhibitor activity and platelet aggregation test were done in all subjects. Our results showed that there was a significant difference (p < 0.05) on platelet aggregation induced by 10 microM of ADP between the control group and Norplant users for more than 2 years, while the other parameters did not differ significantly. It is concluded that 5 years users of Norplant did not alter blood coagulability, but increased platelet response to 10 microM of ADP.