[Occult pulmonary embolism in patients with proximal deep venous thrombosis]

It is known that proximal deep-vein thrombosis (DVT) of the lower limbs is associated with a high risk of pulmonary embolism (PE). However, only a few patients presenting with clinically symptomatic DVT exhibit symptoms or signs suggestive of this complication. The prevalence of silent PE in these patients is unknown. In order to assess the true prevalence of PE in a patient population presenting with venographically proven proximal DVT but without symptoms of PE, a perfusion lung scan was performed in 100 consecutive patients at presentation. Fifty-nine patients (59%) had a high probability lung scan (segmental or larger perfusion defects in lung areas free from abnormalities as shown by conventional chest x-ray) at the initiation of heparin treatment. At repeated lung scanning, performed after 10 days of anticoagulant treatment, complete to partial improvement was observed in 41 of these patients (71%), whereas in 13 (23%) the picture was unchanged and in 3 (5.2%) it worsened. In 6 patients who developed symptoms suggestive of PE during the study period, a lung scan was immediately repeated and correct interpretation of the clinical manifestation was permitted by comparison with the initial scan. It is concluded that lung-scan--detected asymptomatic PE occurs frequently in patients with proximal DVT, and that the majority of these emboli resolve within 10 days of anticoagulant treatment. In order to manage correctly patients who develop clinical manifestations suggestive of PE while undergoing therapy for venous thrombosis, a baseline lung scan is strongly recommended in all patients with proven proximal DVT.