Congenital and acquired thrombotic risk factors in women using oral contraceptives: clinical aspects.

Abstract

We describe the thrombophilic and clinical characteristics of a group of patients who suffered venous thrombosis (VT) (n = 36) and ischemic stroke (n = 8) while taking oral contraceptives (OC). Our purpose is to ascertain whether there are differences between users of second and third generation progestogen and to investigate the influence of concurrent congenital and acquired risk factors (other than OC) on the onset of the thrombosis. The group of patients included 36 women with VT and eight with ischemic stroke. The patients' recognized predisposing factors were recorded. We also considered age, length of time on OC, types of OC, rethrombosis, family history of VT, and the presence of thrombophilic genetic defects. In the group of patients with VT, 54% were treated with second generation OC (n = 23), and 30% (n = 11) were treated with third generation OC. We found no significant statistical differences with respect to age and length of time on OC between the two types of OC. The prevalence of genetic defects in these patients--factor V (FV) Leiden, prothrombin G20210A mutation and protein S deficiency--was 19% (n = 7), 17% (n = 6), and 8% (n = 3) respectively. We observed the shortest time lapse between initiating OC and the first thrombotic event in carriers of FV Leiden and in patients with combined defects, but the differences were not significant. In patients with ischemic stroke, 50% were treated with second generation OC and 50% were treated with third generation OC. Prothrombin G20210A mutation was detected in two patients. In both patients,the stroke occurred earlier than in the rest of the patients, but these differences were not statistically significant. With respect to preventing thrombotic events in these patients, our data suggest that OC therapy should be avoided in patients with a previous history of thrombosis and in patients with an evident thrombotic tendency in the family. In patients in whom the family history of thrombosis is not very evident, it would be recommended to screen for FV Leiden, prothrombin G20210A mutation, and protein S, and to rule out OC if the patient does in fact have one of these risk factors. Moreover, if a patient develops a thrombotic complication while taking OC, an evaluation to search for a thrombophilic defect is warranted, and at the same time, alternative methods of contraception should be considered.