DUPLEX SCANNING IN THE POSTOPERATIVE SURVEILLANCE OF PATIENTS UNDERGOING TOTAL HIP-ARTHROPLASTY

Color flow duplex imaging is a well-established method for the diagnos is of deep vein thrombosis in symptomatic patients; however, the sensi tivity and specificity of duplex scanning compared with venography in high-risk asymptomatic patients are not known. Consecutive patients un dergoing total hip arthroplasty who consented to have bilateral venogr aphy on days 8 to 12 were included in this prospective study. One hund red and fifty-one venograms were finally obtained in 78 patients. All duplex scanning was performed with the Ultramark 9 ATL (Advanced Techn ology Laboratories) by one investigator. In the beginning of the study , the first 44 legs, only the femoropopliteal segment was tested and t he result was based on B-mode compression; the sensitivity for the dup lex was 56% (5/9), and the specificity, 94% (33/35). In the next 107 l egs, the addition of color to our criteria improved the sensitivity of the duplex scan from 55% to 93% (13/14) for the femoropopliteal segme nt and the specificity from 94% to 99% (92/93). For the calf segment, in the same 107 legs, using the color facility of the duplex, the sens itivity and specificity were 79% (15/19) and 97% (85/88), respectively . The color facility of new-generation machines makes duplex scanning reliable for the detection of proximal deep vein thrombosis, even in a symptomatic high-risk patients. For the detection of calf deep vein th rombosis, however, more experience is needed. A larger study is necess ary to confirm these preliminary data.