Background

Computed tomography pulmonary angiography (CTPA) is the first-line

investigation for suspected pulmonary embolism (PE), but it carries a high

radiation dose and iodinated contrast risk. Appropriate patient selection is

therefore essential to minimise unnecessary imaging while ensuring timely

diagnosis.

This audit was designed to assess whether the Lincoln County Hospital Radiology

department is receiving appropriate CTPA referrals, based on RCR and local guidance.

Audit Standards

STD 1: 100% of referrals should include assessing pre-test probability with a PE Wells score, and use of

D-dimer if the Wells score is unlikely (<4).

STD 2:100% of referrals should follow the agreed local protocol — providing sufficient clinical detail,

including age and presenting symptoms.

Why this audit matters

CTPA delivers a substantial radiation dose. Every inappropriate scan exposes a patient

to avoidable risk without diagnostic benefit, while also consuming scanner capacity

needed for patients who genuinely require urgent imaging.

Methods

A retrospective closed-loop audit was conducted at Lincoln County Hospital

using the Royal College of Radiology (RCR) “Appropriateness of Usage of CTPA

in Suspected PE2” audit template as a framework, cross-referenced with local

CTPA vetting criteria.

Intervention

Following Cycle 1, results were presented to the Radiology and Emergency

Department teams. Educational posters summarising local CTPA referral

requirements — Wells score, D-dimer (where appropriate), and relevant

clinical information — were displayed within the Emergency Department.

Guidance was further promoted by an Emergency Medicine consultant, to increase awareness among

requesting clinicians and encourage adherence to local vetting criteria.

Results

 The greatest improvement was seen among Emergency Department referrals:

in Cycle 1, 33% of A&E referrals failed to meet vetting criteria; by Cycle 2 this

had fallen to just 20%.

Conclusions

A simple, low-cost educational intervention led to measurable improvements

in the quality and appropriateness of CTPA referrals, with the greatest

improvement observed within the Emergency Department.

Although Wells score documentation remains below the desired standard, this closed-loop

audit demonstrates that targeted education and reinforcement of NICE and RCR guidance

can improve adherence to evidence-based referral pathways and support more

appropriate use of high-radiation imaging.

Improvements in referrers’ compliance with local protocols have been made, but could be further improved —

increasing awareness in A&E has proven effective in improving clinical information included in referrals.

Recommendations & Actions

Promote local guidance for the clinical information needed for vetting, and

communicate this to other key referring departments, e.g. medical specialties

Continue to reinforce awareness in the Emergency Department to sustain the gains

already made

Undertake a further re-audit cycle to confirm improvement is maintained over time