Non-Invasive Diagnosis of Deep Venous Thrombosis

A systematic review 1 including 43 studies on accuracy of diagnosis compared with contrast venography and safety of withholding anticoagulants when results were normal was abstracted in DARE. The accuracy of ultrasonography or impedance plethysmography was higher for proximal than for distal deep venous thrombosis (DVT), and was higher for symptomatic than for asymptomatic DVT. The accuracy estimates appeared to be higher for ultrasonography than for plethysmography, but the studies did not compare these two methods directly. Withholding anticoagulation in symptomatic patients with normal results produced a mean frequency of subsequent confirmed DVT of 2.0% (95% CI 0.0% to 4.9%) at 6 months following normal serial venous ultrasonography and of 1.5% (95% CI 0.8 to 2.2%) for normal serial impedance plethysmography. Neither test was found to be a safe management approach for asymptomatic patients with a high risk for DVT (based on three studies). The combination of clinical assessment with either of the evaluated tests appears to improve diagnostic accuracy. No clinically useful evidence was found for the combination of fibrinogen leg scanning and impedence plethysmography, and no firm conclusions could be reached regarding the combination of D-dimer blood testing with either of the other two tests. For the diagnosis of recurrent DVT by ultrasonography, a new non-compressible common femoral or popliteal vein or a 4 mm or greater increase in venous diameter during compression compared with a previous result strongly suggests recurrent DVT.

A systematic review 1 including 5 studies (212 extremities) for diagnostic accuracy analysis and one additional study (249 extremities) for analysis of indeterminate results was abstracted in DARE. The pooled sensitivity, specificity and accuracy of calf sonography were 92.5% (95% confidence interval, CI: 81.8 to 97.9), 98.7% (95% CI: 95.5 to 99.9) and 97.2% (95% CI: 93.9 to 99.0), respectively. The frequency of indeterminate examinations (4 studies) ranged from 9.3 to 82.7%. The combined frequency was 54.6%.

Comment: The quality of evidence is downgraded by potential reporting bias (limited literature search).

The following decision support rules contain links to this evidence summary:

• Ultrasonograpy as the first imaging examination in suspected deep venous thrombosis http://www.ebmeds.org/ebmeds/ebmeds_home.asp?mode=scripts&submode=view&id=scr00507&country=UK

References

• Kearon C, Julian JA, Newman TE, Ginsberg JS. Noninvasive diagnosis of deep venous thrombosis. McMaster Diagnostic Imaging Practice Guidelines Initiative. Ann Intern Med 1998 Apr 15;128(8):663-77. [PubMed] [DARE]
• Gottlieb RH, Widjaja J, Tian L, Rubens DJ, Voci SL. Calf sonography for detecting deep venous thrombosis in symptomatic patients: experience and review of the literature. J Clin Ultrasound 1999 Oct;27(8):415-20. [PubMed] [DARE]