Long-term use of oral contraceptive therapy in women with the prothrombin 20210 G-A polymorphism without thrombotic complications: a study of 13 women (12 heterozygotes and 1 homozygote)

Thirteen female patients with the prothrombin 20210 G-A abnormality (twelve heterozygotes and one homozygote) were selected out of 551 patients admitted to our Department of Medicine or to our Outpatient Hemostasis Units between January 1999 and October 2000. The selection was based on the fact that all patients had taken or were still taking oral contraceptives (OC) for a period of 3 years or longer than 3 years. None of these patents as gathered from history, physical examination, private physician records and our records has shown any DVT during or immediately after OC intake. Physical and compression ultrasonography examinations at the time of study were all negative. The average length of oral contraceptives therapy (OCT) was 10 years (range 3-23). The average age of patients at the time of oral contraception was 30 years. The 13 women had also 17 pregnancies without any venous thrombosis. The observations casts several doubt about the prothrombotic effect of this polymorphism. Since DVT has been shown to occur occasionally even in normal women, it is likely that the same may occur in women with this polymorphism regardless of the existence or not of any pathogenetic relationship between the two phenomena. Occasional reports suggesting a link between this polymorphism and oral contraception-related venous thrombosis should be carefully evaluated in order to avoid premature and incorrect conclusions.