Introduction/Aim: Computerized tomography pulmonary angiography (CTPA) is widely regarded as the gold standard test for diagnosing pulmonary embolism (PE). Globally, in recent years, CTPAs are increasingly available, however the proportion of PE-positive scans has paradoxically plummeted. Unnecessary CTPAs expose patients to potentially harmful radiation and impose additional economic costs on our health system. In accordance with the choosing wisely campaign, this study aims to evaluate CTPAs performed to determine the associated indications for and outcomes including diagnostic yield and impact.

Methods: We conducted a retrospective audit assessing CTPAs performed at the Gold Coast Health Service from 1–31 July 2020. We perused electronic medical records and imaging, and utilized data analysis to obtain outcomes of interest.

Results: Two hundred fifty-one CTPAs were performed within the study period, with 28 (11%) positive for PE. Dyspnoea and/or chest pain were present in 75% of patients. Haemoptysis (5.5%) and syncope (5%) were uncommon. One hundred thirty-nine CTPAs (55%) were requested by ED, compared to 15 (6%) by respiratory, 71 (28%) by other medical specialties, and 26 (10%) by surgery, ICU, after hours and O&G combined. Only 81 patients (32%) had a D-dimer prior to CTPA. Of these, 15 patients had a negative age-adjusted result (age × ng/ml), and all proceeded to negative CTPAs. Only 19 patients had a modified Well's score. Alternative diagnoses were detected in 99 patients (39%). Eight patients had concomitant PE and other pathology. In total, 92 CTPAs (36.7%) directly resulted in change in management (e.g., anticoagulation, antibiotics).

Conclusion: This study suggests scope for improving the clinical decision-making behind CTPA requests. Meticulous pretest risk assessment with D-Dimer may reduce avoidable CTPAs. The versatility of CTPAs is evident given significant proportion of alternative diagnoses. We are planning a prospective ED-centric study to assess the impact of the new suspected PE diagnostic pathway on CTPA requests and outcomes.