Antithrombin III (ATIII) deficiency is associated with a well-known thrombotic tendency. About 50% of patients heterozygous for the abnormality become symptomatic during their life time [3, 5, 6]. In old age, only 10-20% appear to remain asymptomatic [5, 10]. The homozygous state is probably incompatible with life. Several triggering factors, such as pregnancy, puer-perium, trauma and oral contraceptives have been postulated to play a role. However the exact impact of any of these factors

more »

... s to be defined [5, 11]. Recently a concomitant defect predisposing to bleeding, namely von Willebrand's disease, has been demonstrated to play a potential role in protecting patients with ATIII Trento from thrombosis [8]. Estroproges-tinics have been often associated with thrombotic phenomena both in patients with ATIII deficiency and in normal subjects [4, 9]. However the exact relationship existing between oral contraceptives and the occurrence of thrombosis in patients with ATIII deficiency remains to be clarified [1, 11]. We report here the unusual case of a young lady who developed thrombophlebitis of the legs after a short course of oral contraception. The proposita is a 26-year-old female who first came to our attention in March 1987. On that occasion she was found to have ATIII activity (chromogenic method) and antigen (Laurell method) consistent with a heterozygous true deficiency. (The levels were 60 and 50% of normal, respectively.) The mother and some family members on the maternal side were also found to have ATIII deficiency. One year earlier, at the age of 25, the patient was given an estroprogestinic preparation (Tri-gynon®, Schering AG, Berlin) to regularize menstruation. On the 10th day of therapy the patient started complaining of pain in the left inguinal area and pain and swelling in the left calf. A few days later, pain and swelling of right leg also appeared. The patient was admitted to a local hospital and a diagnosis of bilateral deep venous thrombosis was made. The suspicion was immediately confirmed by a phlebogram which showed parietal thrombi in both iliac veins and in the left popliteal vein. The contraceptive was discontinued (after 17 pills) and full dose heparin was given intravenously for 7 days. The clinical picture improved promptly. Oral anticoagulation was then started and continued for about 6 months while the clinical condition slowly reverted to normal. At the time of study the patient was in good condition and free of symptoms. The patient had never had