Diagnosis of deep vein thrombosis after operation for fracture of the proximal femur: comparative study of ultrasonography and venography.

Abstract

We compared investigative methods to study the diagnostic capability of ultrasonography. Subjects were 75 patients with proximal femur fractures who underwent surgery from March 2002 to December 2003. Biochemical assays were carried out on days 3 and 7, and D-dimer levels were investigated as a time series. Ascending lower limb venography and ultrasonography were carried out nearly simultaneously in all cases on day 7. The incidence of deep vein thrombosis (DVT)-positive findings on venography was 61.3% (46/75). Venography results demonstrated a diagnostic sensitivity of 95.5% and specificity of 91.4% using a D-dimer cutoff of 1microg/ml on postoperative day 7. By ultrasonography, diagnostic sensitivity for DVT was 78.3%, and specificity was 96.5%. Among all proximal area cases, there were 18 limbs with DVT seen on venography among which were 17 limbs in cases demonstrating DVT at the same site on ultrasonography, a correct diagnosis rate of 94.4%. For the diagnosis of a thrombus more proximal than the popliteal area, a location at high risk for occurrence of pulmonary embolism, ultrasonography provided results nearly on par with those obtained by venography. Thus, we believe that ultrasonography allowed a more noninvasive, accurate diagnosis and more rapid treatment in cases where D-dimer values were 1 microg/ml or more on postoperative day 7.