Venous duplex imaging: Should it replace hemodynamic tests for deep venous thrombosis?

Abstract

Noninvasive diagnosis of deep venous thrombosis has traditionally relied on detection of alterations in venous hemodynamics. Although phleborheography is among the most sensitive tests, it is inadequate for diagnosing infrapopliteal and nonocclusive proximal thrombi and for surveillance of patients at high risk for deep venous thrombosis. Venous duplex imaging is a new technique being rapidly accepted, however, without the same critical analysis given to previous diagnostic modalities. The purpose of this study is to evaluate the diagnostic acumen of venous duplex imaging compared to phleborheography and ascending phlebography in two distinct patient groups, and to determine whether patient selection, and thus the location or magnitude of thrombi have significant influence on these diagnostic tests. One hundred ten extremities in 103 patients were prospectively evaluated with venous duplex imaging, phleborheography, and ascending phlebography within the same 24-hour period. Patients were categorized into one of two groups: Diagnostic—patients evaluated because of clinical suspicion of acute deep venous thrombosis; and Surveillance—patients at high risk of postoperative deep venous thrombosis after total joint replacement, but not symptomatic. Patients in the diagnostic group had a greater frequency of deep venous thrombosis (p < 0.001) and significantly more occluding above-knee thrombi (p = 0.054) compared to those in the surveillance group. Phleborheography detected 73% (2737) of above-knee thrombi in the diagnostic group compared to 29% (27) in the surveillance group (p = 0.036). This difference was not noted with venous duplex imaging, which detected 100% of above-knee thrombi in both diagnostic and surveillance groups and 78% (79) of all below-knee thrombi. Venous duplex imaging was significantly more sensitive than phleborheography for detecting both above-knee and below-knee thrombi (p < 0.001) and importantly, the negative predictive value of venous duplex imaging was significantly higher than phleborheography (p < 0.001). Based on these observations it appears that venous duplex imaging offers superior noninvasive, diagnostic acumen without the limitations of traditional hemodynamic techniques. Venous duplex imaging reliably diagnosed nonocclusive and infrapopliteal thrombi, thereby offering superior epidemiologic and natural history capability in patients with acute deep venous thrombosis. In experienced vascular laboratories venous duplex imaging may be more sensitive than ascending phlebography and may become the new diagnostic standard for deep venous thrombosis.