Summary
The aim of this study was to prospectively evaluate the accuracy of real-time B-mode
ultrasonography in the diagnosis of asymptomatic proximal deep vein thrombosis (DVT)
in hip surgery patients. Venography was adopted as the gold standard. We studied 100
consecutive patients undergoing hip surgery: 60 patients for hip fracture and 40 patients
for elective hip replacement. Bilateral real-time B-mode ultrasonography was performed
prior to bilateral venography. The two diagnostic procedures were performed on the
same day by different investigators unaware of the assigned prophylatic regimen for
DVT Compressibility of the vein segment was adopted as the single criterion for DVT.
Venography was performed and judged by radiologists unaware of the ultrasonography
results. In 13 limbs venography was either impossible to perform or not adequate for
judgement. Ultrasonography and an adequate venography was obtained in 187 limbs. A
venography proven DVT was observed in 49 limbs (26.2%) and a proximal DVT in 21 limbs
(11.2%). All the patients were asymptomatic for DVT. The sensitivity and specificity
of real time B-mode ultrasonography for proximal DVT were 57% (95% confidence interval:
C. I. 36–80) and 99% (C. I. 99–100), respectively and the positive and negative predictive
values were 93% (C.I. 73–100) and 95% (C.I. 91–97), respectively. The sensitivity
and specificity for overall DVT were 25% (C.I. 11–38) and 99% (C.I. 97–100), respectively
and the positive and negative predictive values were 92% (C. I. 73–100) and 79% (C.I.
76–85), respectively. Our data indicate that realtime B-mode ultrasonography for its
high specificity could make venography unnecessary in patients with positive results.
However, because of its low sensitivity it cannot be used for the screening of DVT
in asymptomatic patients, nor can it replace venography for outcome measurements in
clinical trials on DVT prophylaxis.
