Objective: To assess the frequency of factor V Leiden in oral contraceptive users and to define possible anamnestic data that could predict the presence of factor V Leiden. Methods: Between 1997 and 1998, 583 users of oral estrogen-progestin contraceptives with no history of thrombotic disease were examined. Factor V Leiden was assessed by PCR after isola- ting DNA from a peripheral venous blood sample. Among other factors, such things as a family history of thromboembolic disease, myocardial infarction and/or stroke in a first-degree relative were monitored. In 448 users cardiovascular complications were evaluated during six months of oral contraceptive use. The data were analyzed using a MS Excel program. P-values were assessed by pair-tests and chi-square tests. Setting: 1 st Department of Obstetrics and Gynecology of Medical Faculty, Masaryk University, Brno Results: Factor V Leiden frequency was 6.5% in the study group. There were no differences bet- ween carriers and others in age, body weight, body mass index and blood pressure. Carriers had significantly more frequently positive family histories of thromboembolic disease or myocardial infarction or stroke. There were no cardiovascular complications observed in a group of 448 users. The positive family histories of any of the above-mentioned conditions have high specificity (97-99%) and a negative predictive value (0,94) with a low sensitivity (2,6-15,8%) in predicting factor V Leiden presence. Conclusion: We found a relatively high incidence of Factor V Leiden among oral contraceptive users without a history of thrombotic disease. Through a positive family history of thromboembo- lic disease or myocardial infarction or stroke, we can predict a Factor V Leiden presence with high specificity but low sensitivity.

        Key words: oral contraceptives, factor V Leiden, thromboembolic disease, family history