Background: CT pulmonary angiography (CTPA), D-dimer testing, and pre-test probability scoring have greatly improved the ability to manage patients with suspected pulmonary embolism. International guidelines suggest combining these investigations for the best yield. We have been investigating the use of CTPA in patients with suspected pulmonary embolism (PE) admitted to the Department of General Medicine at Christchurch Hospital, New Zealand.
Methods: A retrospective audit of 100 patients with suspected pulmonary embolism who had a CTPA performed between October 2003 and April 2004.
Results: CTPA was positive for PE in 31% of admissions. The pre-test probability was documented in only 4% of admissions. All patients with PE had a significantly elevated D-dimer (> 499 ng/mL). Wells score calculated by the investigators showed 59 (59%) to have a low, 33 (33%) a moderate, and 8 (8%) a high risk for PE. Of these, PE was diagnosed in 9 (15%), 15 (45%), and 7 (88%) respectively; 93% of patients had a blood gas performed, yet only 77% had the D-dimer measured. No patient with a measured and negative D-dimer had a diagnosis of a PE; 32 CTPAs were performed on 32 patients out of hours.
Conclusion: There was a very low uptake of the formal use of pre-test probability scores by medical registrars. This audit confirms that, in patients with low or moderate risk of PE and a negative D-dimer, an alternative diagnosis should be considered. The management of suspected venous thromboembolism (VTE) could be improved; it is likely that after hours CTPA could be reduced.