Clinical outcome of patients with a 'low probability' of pulmonary embolism on ventilation-perfusion lung scan.

Lung ventilation and perfusion (V/Q) scintigraphy is usually indicated when pulmonary embolism (PE) is a suspected diagnosis. Typically, V/Q scintigraphic interpretation is reported as a "normal," "low," "intermediate," or "high probability" of PE. Although a "low probability" interpretation does not exclude the diagnosis of PE, it significantly reduces the likelihood. We retrospectively analyzed up to one year of follow-up in 90 patients who were clinically suspected of having PE, but in whom V/Q scintigraphy implied a low probability of PE. None of the 90 patients demonstrated clinical evidence of PE subsequent to the V/Q scan. Our findings suggest that significant pulmonary embolism is uncommon and that the clinical course appears to be predictable in patients with a low probability V/Q scan.