Answer to question of the day: Suspected DVT
And here is is…. the answer to our suspected DVT question:
d. It can be used to discharge patients based on their underlying estimated clinical risk score
D-dimer test can be used to exclude DVT in patients who are assessed to be in the category of “low clinical risk” of DVT.
An individuals pre-test risk can be estimated using a “Wells score”. A patient who is clinically “low risk” with a negative D dimmer can be reassured.
The Wells score is shown below.
| Active Cancer | +1 |
| Paralysis Paresis or plaster to extremity | +1 |
| Bedridden for 3 days/ surgery within last 12 weeks | +1 |
| Localised tenderness along distribution of deep venous system | +1 |
| Entire leg swollen | +1 |
| Calf swelling >3cm compared to the other leg | +1 |
| Pitting oedema confined to the symptomatic leg | +1 |
| Previous DVT | +1 |
| Collateral superficial veins (non-varicose) | +1 |
| Alternative diagnosis at least as likely as DVT | -2 |
| <0=Low Pre-test Probability
1-2=Moderate Pre-test Probability >3=High pre-test probability |
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The Wells score and an example of its clinical application in terms of planning investigations into a DVT
Although you clearly can’t memorise a wells score its clear from the score itself that patients with numerous risk factors (e.g a man with lung cancer with a swollen right leg with pitting oedema) that a negative D-dimer is not sensitive enough to rule the diagnosis out.
D-dimer is still of some use in patients with a low pre-test probability score.
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answer is d