Most studies demonstrating an increased risk of venous thromboembolism in women on oral contraceptives are based on clinical manifestations of the disease. Because of the fallibility of the clinical diagnosis of suspected leg vein thrombosis, Doppler ultrasonic evaluation (with a 93% accuracy compared to venography) was performed for clinical manifestations in deep vein thrombosis in 54 women taking birth control pills and 75 women of similar age who were not on contraceptives. The clinical diagnosis was confirmed by Doppler in only 16.7% of the women taking contraceptives and 30.7% of women not taking contraceptives (P = 0.052). This study suggests that the clinical diagnosis of leg vein thrombosis is frequently erroneous, particularly in women taking oral contraceptives. Future investigations reporting venous thromboembolism associated with oral contraceptives should be based on diagnoses validated by accurate objective techniques.
PIP: Erroneous diagnosis of leg vein thrombosis among pill users could be attributed to the unreliability of clinical diagnosis. To prove this point, the result of Doppler ultrasonic evaluation of pill users with suspected leg vein thrombosis were compared with those of non-pill users suspected of deep vein thrombosis. 129 women (54 cases and 75 controls) of similar age, clinical manifestations, and absence of predisposing factors (e.g., trauma, recent surgery, malignancy) underwent a complete venous Doppler examination. The incidence of venous thrombosis among pill users was confirmed by the Doppler method in only 16.7% of pill users and 30.7% of non-pill users (P = .052). The results of this study, however, did not define the true incidence of venous thrombosis among pill users. This was attributed to the fact that only patients with suspected venous disease were objectively diagnosed; many patients with proven venous thrombosis may be asymptomatic and could not detected by conventional clinical studies. At best, this study demonstrated the necessity of using an objective screening technique, such as the Doppler ultrasonic, on patients (especially women on oral contraceptives) suspected with deep vein thrombosis; it also resulted in establishing some guidelines in managing treatment of such patients.