The Use of Computed Tomography of Pulmonary Angiogram in a District Hospital

Background. Computed tomography of pulmonary angiogram (CTPA) is a widely used investigation in patients with suspected pulmonary embolism (PE). It is not without adverse effects either through contrast injection or radiation exposure. International guidelines suggest that patients with a low/intermediate clinical probability and negative D-dimer do not require CTPA to exclude PE. Method. A retrospective audit of 100 consecutive CTPA scans was performed at a district general hospital from January to May 2012 to assess adherence to the current guidelines for diagnosis of acute PE and utilisation of CTPA. Result. Of the total 88 CTPA scans that were included in the study, 14% were positive for PE. At least 6%, potentially up to 30% of all the scans, could have been avoided by adherence to current guidelines, thereby improving the positive yield to as high as 19%. Clinical probability scores were documented in only 3%. Orthopaedics requested 3% of all scans and the Assessment Treatment and Rehabilitation (ATR) unit had the highest number of CTPA requests per 100 departmental inpatient admissions. Conclusion. Adherence to the current guidelines can reduce the number of CTPA scans required and may reduce cost, contrast exposure, and radiation burden. 1. Introduction Computed Tomography Pulmonary Angiography (CTPA) is the most commonly employed investigation in patients with suspected acute pulmonary embolism (PE). Most evidence is derived from the large University Hospitals in North America. Most scans are performed in smaller centres around the world. CTPA scanning is convenient as it is accessible after hours and it can often offer alternative diagnoses; however, its disadvantages includes cost, contrast use, and radiation exposure [1, 2]. In a theoretical analysis, it was estimated that current typical testing practices for PE in the Emergency Department would prevent six deaths and 24 major nonfatal PE events, but also cause 36 deaths and 37 nonfatal major harms per 10,000 from contrast-induced renal failure, radiation-induced cancer, and major haemorrhage from anticoagulation [1]. Current guidelines based on studies in tertiary centres suggest using a clinical probability score (Wells criteria or Geneva score) and D-dimer testing prior to requesting CTPA. The pivotal aspects of these guidelines in CTPA-experienced institutions with quantitative D-dimer assay are [2, 3] as follows.(1)Low/intermediate clinical probability and negative D-dimer excludes PE without CTPA. (2)Low/intermediate clinical probability and positive D-dimer needs CTPA to