The diagnostic yield of CTPA: pulmonary embolism, alternative diagnoses and incidental findings

In this retrospective study we assess the diagnostic yield of computed tomography pulmonary angiogram (CTPA) and the incidence of alterative and incidental diagnoses.

The results of all CTPA scans performed in our trust over a period of 18 months were reviewed and all diagnoses noted. Data collected was descriptively analysed.

A total of 1138 scans were performed (56.5% men, mean age 59 years). A diagnosis of pulmonary embolism (PE) was made in 20.2%, an alternative aetiology for presenting symptoms in 26.4% and incidental findings in 19.5%. The commonest alternative diagnosis was pneumonia (9.5%).

Significant numbers of CTPA yield unexpected findings, which may provide an explanation for the clinical presentation. Furthermore substantial numbers of incidental pathologies are also diagnosed which may lead to inappropriate resource utilization and increased patient anxiety.