Use of D-dimer and Lower Extremity Doppler Ultrasound Results to Obviate the Need for Computerised Tomographic Pulmonary Angiography

Abstract

Introduction: We hypothesise that correct interpretation of other diagnostic tests could reduce the use of computerised tomographic pulmonary angiogram (CTPA) examinations in patients with suspected pulmonary embolism (PE). Materials and Methods: We carried out a retrospective analysis of 158 patients in a 928-bed university hospital. These consecutive patients were investigated for suspected PE from May 2001 to February 2002 using CTPA. Results: There were 74 men and 84 women with a mean (±SD) age of 57 (±19) years. Overall, 56% of patients (89/158) showed clinically significant abnormalities on the CTPA examination. The overall prevalence of PE was 15% (24/158). The D-dimers were assayed in 40% (63/158) and lower limbs were scanned with Doppler ultrasound (US) in 22% (35/158) of patients. None of the 19 patients with negative D-dimer assays had PE. Of the patients who were positively tested on Doppler US, 4 were positive and 1 was negative for PE on the CTPA. None of the patients with positive Doppler US had negative D-dimer test. In retrospect, patient management based on negative D-dimer assays and positive lower extremity Doppler US studies could have reduced the need for further investigation with CTPA by 15% (24/158). Conclusion: In patients with suspected PE, correct interpretation of D-dimer and leg Doppler US tests may reduce the demand for CTPAs. Key words: CTPA, D-dimer, Doppler ultrasound, Spiral CT