Screening for acute DVT: optimal utilization of the vascular diagnostic laboratory

Since the introduction of venous duplex ultrasound scanning in the early 1980s, many articles have been published describing its use for the diagnosis of deep vein thrombosis (DVT) in symptomatic and asymptomatic high-risk patients. Although technological advances have improved B-mode imaging and Doppler signal processing in the last 2 decades, duplex ultrasonography still has limitations in the diagnosis of acute DVT. Besides those that are technological in nature, there also are limitations because of a lack of standards from one vascular laboratory to another. Studies vary according to the ultrasound techniques used, diagnostic criteria, number and types of patients studied, reimbursement guidelines, and compliance with established standards. Duplex examinations vary from unilateral to bilateral, limited to complete, proximal to distal, and imaging only to imaging combined with Doppler techniques. The sensitivity and specificity of duplex ultrasound for identifying symptomatic proximal DVT are in excess of 95%; however, these drop considerably for asymptomatic DVT in high-risk patients and in patients with isolated calf vein thrombosis. Nevertheless, the utilization of the vascular laboratory to screen for acute DVT in all patients, regardless of the limitations in specific populations, is increasing steadily, whereas reimbursement and the number of technologists available to perform these examinations is decreasing. To achieve optimal utilization of the vascular laboratory, national standards in the form of clinical pathways using evidence from the literature need to be developed and utilized. In addition, referring physicians need to be educated on the accuracy and limitations of duplex ultrasound scanning to avoid both overtreatment and undertreatment of acute DVT.