New test spots more lung clots but seems to result in over-diagnosis

The introduction of CT pulmonary angiography has been associated with an 80% rise in the detection of pulmonary emboli in the US, but with little change in death rates.

Professor Renda Soylemez Wiener and colleagues argue this is evidence of over-diagnosis. They say some patients are helped, but many are harmed by the adverse effects of unnecessary treatment.

This article is the first of a series looking at the risks and harms of over-diagnosis in a range of common conditions. The series, together with the Preventing Overdiagnosis conference in September, are part of the BMJ's Too Much Medicine campaign to help tackle the threat to health and the waste of money caused by unnecessary care.

Pulmonary embolism has been described as one of the most commonly missed deadly diagnoses. Until recently, ventilation-perfusion (VQ) scanning was the first line test, but a new technology introduced in 1998