Investigation of suspected pulmonary embolus - imaging frequency and diagnostic yield over 10 years in a major UK teaching hospital.

Background

Pulmonary embolism (PE) is a condition with significant morbidity and mortality. Diagnostic imaging aims to identify patients with a PE so that they can receive anticoagulation. There is evidence, predominantly from the USA, that the number of diagnostic scans for PE has increased over time and the diagnostic yield (the percentage of positive scans) has decreased. There is limited evidence on whether this is also true in the UK.

Aim

To describe the pattern of diagnostic imaging for acute PE and investigate whether there has been a change in the diagnostic yield over the last 10 years.

Methods

All adult patients who underwent either computed tomography pulmonary angiogram (CTPA) or ventilation-perfusion (V/Q) scan as an investigation for acute PE at Cambridge University Hospitals NHS Foundation Trust (CUH) between 2015 and 2024 were included. This was a retrospective study using data extracted from the hospital electronic health record (EHR) system.

Results

25,672 scans were included, comprising 23,908 CTPA and 1,764V/Q scans. The annual number of scans increased slightly over the time period, with an average increase of 1.2% per year (p < 0.05). The overall diagnostic yield was 17.0%, with no clear trend over time. There was also no clear trend in the proportion of subsegmental PE detected over time.

Conclusions

The overall number of scans performed and diagnostic yield for PE have remained relatively stable over the last decade. This is the largest study of its kind in the UK and, uniquely, also covers the entire timeline of the COVID-19 pandemic and its aftermath.