Prospective study on the usefulness of lung scan in patients with deep vein thrombosis of the lower limbs

Background: Asymptomatic pulmonary embolism (PE) is a common finding in pat ients with deep venous thrombosis (DVT) of the lower limbs, but the usefuln ess of seeking for silent PE in patients with acute DVT has not been evalua ted. Patients and methods. This was a prospective study involving consecuti ve patients with acute symptomatic proximal DVT (confirmed by objective met hods) and no clinical suspicion of PE. All patients underwent chest X-ray, ventilation-perfusion lung scan and arterial blood gases on admission, and received anticoagulant therapy. Those with scintigraphic evidence of PE und erwent repeated lung scan and blood gases 7 days later. The aim of the stud y was to assess how many patients with silent PE develop symptoms while on heparin therapy, and in how many of them such symptoms are due to recurrent PE. Results: 946 consecutive patients with acute, proximal DVT had no cont raindications to full-dose anticoagulant therapy. Baseline Lung scan reveal ed high-probability defects (silent PE) in 200 (21%). Seven of these 200 pa tients had symptomatic recurrences during the 7-day study period, and an in ferior vena cava filter was inserted. Besides, 6 patients developed PE symp toms, but no new perfusion defects were found on repeated scan. They switch ed to coumarin therapy, and they did not develop any further complications. Conclusions: Lung scan in patients with symptomatic DVT and no clinical su spicion of PE may be useful, since some patients with silent PE may develop symptoms while on heparin therapy. Without a baseline scintigraphy all the se patients would have been considered to have recurrent PE, and vena cava interruption could have been performed.