AB182. 153. One-year audit of CTPA requests in a tertiary referral centre in Ireland

Background: Acute pulmonary embolism is a dangerous complication of venous thromboembolism, with CT pulmonary angiography (CTPA) being the gold standard for diagnosis. The modified Wells Score can assess the probability of pulmonary embolism and categorise patients into low, moderate and high-risk groups. Patients who are in the low-risk category and where the diagnosis of pulmonary embolism is being considered should be further assessed using the pulmonary embolism rule-out criteria to determine if d-dimers are necessary. Patients in the moderate-risk category should have a d-dimer and if the result is elevated undergo CTPA. Patients within the high-risk category do not require D-dimers prior to CTPA. The purpose of this audit is to assess the rate of positive CTPA in a tertiary referral centre over a one-year period and review the request process.

Methods: A retrospective review of all CTPA results on NIMIS over a 1-year period was conducted. iLab was reviewed and D-dimer results were recorded for each patient who underwent CTPA.

Results: 1,127 CTPA scans were ordered in a one-year period. Of these scans, 172 (15.26%) reported a positive finding. D-dimers were recorded in 1,030 (91.39%) patients.

Conclusions: When requesting a CTPA from NIMIS, there is a compulsory section where D-dimers must be recorded for the request to be accepted. High-risk category patients do not require d-dimers prior to imaging, however to meet this obligation they are performed. It was found that D-dimers were ordered for the majority of patients, leading to numerous elevated readings which subsequently required imaging.

Keywords: CT pulmonary angiography (CTPA); audit; D-dimers; test