Deep vein thrombosis (asymptomatic): non-invasive studies could not safely exclude it.

Clinical bottom line (level 1b)

In asymptomatic orthopaedic patients, compression ultrasound could diagnose deep vein thrombosis, but could not safely exclude it.
Impedance plethysmography was unhelpful.

Ginsberg et al: Radiology 1991; 181: 651-654

Expires May 2003

The study

Setting: university hospital, Canada

130 patients (aged ?, ?% male) asymptomatic orthopaedic patients having major hip or knee surgery

Excluded if

any test inadequate

Deep vein thrombosis prophylaxis.
Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:

bilateral ascending venogram on day 10-14 post-op, or at discharge if sooner (thirteen patients had only unilateral venogram)

Diagnostic test: bilateral impedance plethysmography; bilateral ultrasound scan (common femoral, superficial femoral, popliteal to trifurcation)

The evidence

pre-test probability of deep vein thrombosis: 95%, (95% CI: 19.3% to 30.1%)

diagnostic test	deep vein thrombosis	no deep vein thrombosis	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
ultrasound scan	16	2	24.4 (5.77 to 103)	89%	0.75 (0.64 to 0.87)	20%
impedance plethysmography	7	8	2.67 (1.01 to 7.05)	47%	0.93 (0.84 to 1.02)	23%
total	61	186

Comments

Both test characteristics are worse than when used in symptomatic patients.

Citation

Ginsberg JS, Caco C, Brill-Edwards PA, et al: Venous thromboembolism in patients who have undergone major hip or knee surgery: detection with compression US and impedance plethysmography. Radiology 1991; 181: 651-654

Contributor: Chris Ball and Clare Wotton, May 2000
Reviewer:

_{Clinical Question.}

_Patient	_{asymptomatic patients having major hip or knee surgery}
_{Intervention or Exposure}	_{ultrasound scan or impedance plethysmography}
_Comparison	_venogram
_Outcome	_{diagnosis of DVT}