Newer imaging approaches in suspected pulmonary embolism (PE) such as the PISA-PED perfusion lung scanning criteria,¹ spiral computed tomography,² and leg vein ultrasound³ are attracting widespread interest. Attempts are being made to clarify and rationalise clinical diagnosis,⁴ and the use of low molecular weight heparin in PE⁵ is increasing. However, it is often forgotten that clinical suspicion of PE turns out to be incorrect in five out of every six patients properly investigated.^6 7 Since in most district general hospitals imaging tests for suspected PE cannot usually be arranged immediately, such patients have to be admitted and heparin started while awaiting an isotope lung scan which often fails to give an unequivocal answer. All this is costly in time and resources and engenders considerable anxiety in the patient.

A simple cheap and accurate test to exclude PE that is also available out of hours would be of great interest to general . . . [Full text of this article]