Complete venous ultrasound in outpatients with suspected pulmonary embolism

Background: Compression ultrasonography (US) confined to the proximal veins is usually performed to detect deep vein thrombosis (DVT) in patients with suspected pulmonary embolism (PE). Recent studies suggested a limited yield of proximal US when multislice computed tomography (MSCT) was used. Objectives: To assess whether performing an additional distal vein US would increase the diagnostic yield of the test. Patients and methods: Data of 855 consecutive outpatients included in a multicenter randomized controlled trial were analyzed. Patients were investigated by a sequential diagnostic strategy including clinical probability assessment, D-dimer measurement, proximal US and MSCT. Proximal US was completed by an examination of the distal veins, the result of which was not disclosed to the physician in charge of the patient. Results: US was positive in 21% of patients, of whom 10% (53/541) had proximal DVT and 11% (59/541) isolated distal DVT. Of the 59 patients with distal DVT, 21 (36%) had no PE on MSCT. Twenty of those 21 patients were not given anticoagulant therapy and had an uneventful follow-up. The diagnostic performance of distal US for the diagnosis of PE was as follows: sensitivity 22% [95% confidence interval (CI) 17-29]; specificity 94% (95% CI 91-96); positive likelihood ratio 3.9 (95% CI 2.4-6.4). Conclusions: In patients with suspected PE, distal US has limited diagnostic performance, and its additional use only modestly increases the yield of US. Moreover, it carries a high false-positive rate, impeding the use of distal US as a confirmatory test for PE.