Diagnosis of thromboembolic disease: Combined ventilation perfusion lung scan and compression ultrasonography

The clinical management of pulmonary embolism and deep venous thrombosis of the legs are similar and requires prolonged anticoagulation therapy. The standard diagnostic approach in patients suspected of pulmonary embolism is ventilation-perfusion (V/Q) lung scan and compression ultrasonography to detect deep venous thrombosis. This retrospective study analyzed the role of V/Q lung scan and compression ultrasonography in detection of thromboembolic disease. One hundred-twenty consecutive patients (65 female, 55 male) age range 18-95 (Mean age 60.7) suspected for pulmonary embolism underwent concomitant V/Q lung scan and compression ultrasonography of the lower extremities. The clinical and radiographic correlation was performed. Of patients with non-diagnostic (Low or intermediate probability) lung scans, 15.4% (14/91) received anticoagulation therapy for pulmonary embolism. These patients had either high pre-clinical suspicion for PE or underwent pulmonary arteriogram. However, there was an additional 7% (7/91) increase in the number of patients who received anticoagulation therapy based on the results of ultrasound with confidence interval (3%-16%). We conclude that V/Q lung scan is a more sensitive examination for thromboembolic disease, and has a high negative predictive value. Ultrasonography of lower extremities demonstrated higher specificity and positive predictive value. Among patients with non-diagnostic lung scan, the detection rate of thromboembolic disease is improved with addition of ultrasound.