Diagnostic approach to pulmonary embolism and lessons from a busy acute assessment unit in the UK

The diagnosis of pulmonary embolism (PE) can be very elusive and, if missed, may have fatal consequences. Conversely, PE can be over-diagnosed, with the concomitant risks associated with unnecessary anticoagulation. Although there are many tests that used in the diagnosis of PE, no test can exclude this condition with 100% certainty, and PE has been reported even after a negative pulmonary angiography. The diagnosis of PE depends on the interpretation of the available tests in the context of pre-test clinical probabilities. Ventilation/perfusion (V′/Q′) scan and computerised tomographic pulmonary angiography (CTPA) are the main screening tests used for patients with suspected PE. However, both V′/Q′ scan and CTPA have to be supplemented by other diagnostic modalities because of their diagnostic limitations. This article reviews the literature concerning the diagnosis of PE, with particular reference to the approach in our acute assessment unit. We conclude by describing two learning points from real cases presenting with suspected PE, in order to highlight how the diagnosis can be missed or made inaccurately.