Does Negative Computed Tomography Pulmonary Angiography Always Exclude PE?

The 2008 PIOPED II study demonstrated that computed tomographic pulmonary angiography (CTPA) had high specificity (96%) but only moderate sensitivity (83%) for identifying patients with pulmonary embolism (PE; NEJM JW Gen Med Jul 15 2006 and N Engl J Med 2006; 354:2317). With technology improvements, false-negative CTPA findings now occur in 1% or fewer patients with low-to-moderate pretest probability of PE (J Intern Med 2011; 269:433). However, whether CTPA can rule out PE effectively in patients with high pretest probability is unclear.

In this meta-analysis of 22 studies (nearly 12,000 patients with suspected PE), CTPA was negative in two thirds of patients. Among those with negative CTPA findings, the frequency of objectively confirmed …