ClinicalUltrasound vs reference standards
A very large meta-analysis of 100 cohorts of patients showed that the sensitivity and specificity for various ultrasound techniques were 89.7% and 93.8% respectively. For the purpose of ruling out DVT, this means that about 10 out of 100 patients with the disease will be missed with ultrasound and this implies that this test can be considered for ruling out DVT in conjunction with another test. The specificity suggests that 6 out of 100 people without DVT will be identified as having the condition and this implies that this test is suitable for the purpose of confirming the presence of DVT. The meta-analysis also suggested that sensitivity decreases in asymptomatic cohorts (screening studies) (MODERATE QUALITY).
Six studies involving about 300 patients showed that the sensitivity and specificity for various proximal ultrasound techniques ranged from 60% to 89% and 71% to 100% respectively. For the purpose of ruling out DVT, this means that 11 to 40 out of 100 patients with the disease will be missed with an ultrasound and this implies that this test can be considered for ruling out DVT in conjunction with another test. The specificity suggests that 0 to 29 out of 100 people without DVT will be identified as having the condition and this suggests that ultrasound techniques were not consistently shown to be suitable for the purpose of confirming the presence of DVT (VERY LOW QUALITY).
Ultrasound scan for proximal and to distal leg veins DVT compared to reference standards
A very large meta-analysis of 100 cohorts of patients showed that the sensitivity of ultrasound techniques was 94.2% for detecting proximal vein DVTs and 63.5% in for distal vein DVTs compared to reference standards. For the purpose of ruling out DVT, this means that 6 out of 100 patients with proximal DVT will be missed with a proximal ultrasound test and this implies that this test can be considered for ruling out DVT in conjunction with another test. However, 37 out of 100 patients with distal DVT with be missed with a distal leg vein DVT. This implies that distal vein ultrasound is not adequate the purpose of detecting calf vein DVT (MODERATE QUALITY).
One study involving 160 patients who participated in a VTE prophylaxis study showed that the sensitivity and specificity for proximal ultrasonography was 60% and 90% respectively compared to venography (MODERATE QUALITY).
In contrast, the sensitivity and specificity for distal ultrasound tests was 29% and 99% respectively. For the purpose of ruling out DVT, this means that 71 out of 100 patients with the disease will be missed with a distal ultrasound test and this implies that this test is not effective in ruling out distal DVT (MODERATE QUALITY)
These studies suggest that ultrasound techniques are effective for ruling out proximal DVTs but not calf vein or distal DVTs.
Proximal vs whole leg ultrasound
Data from 283 patients in one study showed that there was a decrease which maybe of clinical importance in the incidence of DVT detected between proximal and whole leg ultrasound (LOW QUALITY).
In one study of 363 patients it is very uncertain whether there is a clinically important difference between proximal and whole leg ultrasound in 3 month VTE rate (VERY LOW QUALITY).
Proximal plus D-dimer vs whole leg ultrasound scan
Data from 1589 patients in one study showed that there was a decrease of uncertain clinical importance in the initial prevalence of DVT in the group who had proximal ultrasound plus D-dimer compared to the group who received a whole leg ultrasound (LOW QUALITY).
Data from 2098 patients in one study showed that it is uncertain if there was a clinically important difference between proximal and whole leg ultrasound in 3 month VTE rate (VERY LOW QUALITY).
EconomicAfter risk stratification with a Wells score, offering an ultrasound scan is cost-effective in the high risk group or after a positive D-dimer test. It is cost-effective to treat patients who had a positive ultrasound. Above-knee ultrasound with a repeat if negative is more cost-effective than a single above-knee or full-leg ultrasound. This evidence has potentially serious limitations and partial applicability.

From: 5, Diagnosis of deep vein thrombosis

Cover of Venous Thromboembolic Diseases
Venous Thromboembolic Diseases: The Management of Venous Thromboembolic Diseases and the Role of Thrombophilia Testing [Internet].
NICE Clinical Guidelines, No. 144.
National Clinical Guideline Centre (UK).
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