Diagnostic methods for deep vein thrombosis: venous Doppler examination, phleborheography, iodine-125 fibrinogen uptake, and phlebography

Abstract

Since clinical diagnosis of DVT is often inaccurate, it has become accepted that an objective means of diagnosing clot in the deep venous system becomes critically important in the management of these patients. Important to understanding the diagnostic capabilities of any test are the anatomic and physiologic characteristics of the deep venous system. The venous Doppler examination monitors the velocity of blood flowing through a particular vein. Doppler probes in the 5 to 10 mHz range are routinely used. Respiratory variation is a normal finding due to a diminished flow signal during inspiration, followed by a progressive increase in flow signal during expiration. Characteristics of the spontaneous flow signals are the most important part of interpreting the venous Doppler examination. In addition, the response to distal or proximal compression (augmentation) adds important information to the interpretation; however, the response during any augmentation maneuver depends on the rapidity of compression, the force of compression, the quantity of blood in the veins at the time of compression, and the distance between the Doppler probe and the compression point. The literature reports a wide range of sensitivity and specificity for the Doppler examination, but there is uniform agreement and an observable trend that physicians with a large experience and a dedicated interest will obtain much better results than physicians with less experience and less interest. Phleborheography is a six-channel volumetric plethysmographic technique that monitors volume changes in the lower extremities associated with respiration and foot and calf compression. The volumetric tracings obtained are similar to the velocity profiles obtained on the venous Doppler examination. The criteria used in interpreting phleborheographic tracings are respiratory waves and baseline elevation (major criteria), and prominent arterial pulse waves and foot emptying (minor criteria). Previously reported overall sensitivities for detecting DVT are 83 to 93 percent, with sensitivities of detecting proximal vein thrombosis of 92 to 96 percent. Specificities have been reported to be 87 to 97 percent. In a prospective analysis of 126 extremities with phleborheography and phlebography carried out within the same 24 hour period at Temple University Hospital, we found an overall sensitivity of 79 percent (51 of 65 patients); however, the sensitivity for proximal vein thrombosis was 91 percent (49 of 54 patients).(ABSTRACT TRUNCATED AT 400 WORDS)