Selective use of the duplex scan in diagnosis of deep venous thrombosis

BACKGROUND: The introduction of managed care, with its emphasis on cost containment, makes it of paramount importance that all tests ordered be specific, selective, and appropriate. METHOD: The data concerning patients who underwent a duplex scan to determine the presence of deep venous thrombosis (DVT) over a 68-month period, were reviewed in order to determine if the test was ordered appropriately. The symptoms that prompted the test, type of physician ordering the test, and demographic data for both the patients who tested positive and negative were tabulated. RESULTS: A total of 2,841 duplex scans were ordered over a 68-month period for presumptive diagnosis of DVT of an extremity. A total of 524 (18%) scans were positive for thrombosis; however, 27% (144) of these were superficial or a small isolated thrombus in the calf or forearm. Thus, only 380 studies, or 13% of the total scans ordered, were positive for a major DVT requiring treatment. The only symptoms consistently found in the positive group were pain, edema, dyspnea, and a history of DVT. Of the types of physicians ordering the test, emergency department physicians were least specific, with only 12% of the scans ordered being positive for DVT; surgeons were more selective and had a 19% positive rate, while internal medicine physicians had a 20% positive rate. CONCLUSION: The duplex scan allows the physician the ability to easily diagnose venous thrombosis, but its indications need to be more carefully guided by history, physical examination, risk factors, and logic to enhance its use and effectiveness. This study analyzes the risk factors and symptoms involved in order to assist the clinician in determining when the duplex scan is indicated. Am J Surg. 1995;170:201-205.