Frequency of pulmonary embolism in patients with low-probability lung scanand negative lower extremity venous ultrasound

Study objectives: To define the prevalence of pulmonary embolism (PE) in pa tients who are undergoing pulmonary arteriography because of a high clinica l suspicion for PE hut who have had a low-probability lung scan and a negat ive lower extremity venous ultrasound examination. Design: A retrospective review of the medical records of 365 consecutive pa tients who underwent pulmonary arteriograms for suspected PE was undertaken . Results: Of the 365 pulmonary arteriograms, 62 were performed in patients w ith suspected PEs despite a low-probability lung scan and a negative lower extremity venous ultrasound examination. In the latter group, five patients (8%; 95% confidence interval, 2.7% to 18%) had PEs revealed on the arterio gram. Conclusions: In patients whose presentation provokes a high clinical suspic ion for PE despite having had a low-probability lung scan, a negative lower extremity venous ultrasound examination is insufficient to preclude procee ding to pulmonary angiography.