Subsequent investigation and management of patients with intermediate-category and -probability ventilation-perfusion...

The authors wished to determine the proportion of patients with intermediate-category and intermediate-probability ventilation-perfusion scintigraphy (IVQS) who proceed to further imaging for investigation of thromboembolism, to identify the defining clinical parameters and to determine the proportion of patients who have a definite imaging diagnosis of thromboembolism prior to discharge from hospital on anticoagulation therapy. One hundred and twelve VQS studies performed at the Flinders Medical Centre over a 9-month period were reported as having intermediate category and probability for pulmonary embolism. Medical case notes were available for review in 99 of these patients and from these the pretest clinical probability, subsequent patient progress and treatment were recorded. Eight cases were excluded because they were already receiving anticoagulation therapy. In the remaining 91 patients the pretest clinical probability was considered to be low in 25; intermediate in 30; and high in 36 cases. In total, 51.6% (n = 47) of these patients (8% (n = 2) with low, 66% (n = 20) with intermediate, and 69.4% (n = 25) with high pretest probability) proceeded to CT pulmonary angiography (CTPA) and/or lower limb duplex Doppler ultrasound (DUS) evaluation. Of the patients with IVQS results, 30.7% (n = 28) were evaluated with CTPA. No patient with a low, all patients with a high and 46% of patients with an intermediate pretest probability initially received anticoagulation therapy. This was discontinued in three patients with high and in 12 patients with intermediate clinical probability prior to discharge from hospital. Overall, 40% of patients discharged on anticoagulation therapy (including 39% of those with a high pretest probability) had a positive imaging diagnosis of thromboembolism The results suggest that, although the majority of patients with intermediate-to-high pretest probability and IVQS proceed to further imaging investigation, CTPA is relatively underused in this group. Most patients with a high pretest clinical probability receive anticoagulation therapy irrespective of imaging findings, and less than half of all patients discharged from hospital on anticoagulation therapy have a positive imaging diagnosis of thromboembolism.