Wells Score Calculator for DVT
Ten items, one subtraction, and a testing strategy: who gets a d-dimer, who goes straight to ultrasound, and why the hemiplegic leg deserves a lower threshold for both.
Reviewed by Zaka Ahmed, MD Clinical reference · 4 min read
Wells Score — DVT
Score each item for a patient with a suspected first DVT. Note the final item subtracts two points when an alternative diagnosis is at least as likely.
Score every item to see the probability tier and testing strategy.
Suggested next step
Educational tool only. The Wells DVT score applies to suspected first DVT in outpatients; performance degrades in inpatients, prior DVT, and pregnancy. It estimates probability — it does not diagnose or exclude — and does not replace clinical judgment or in-person evaluation.
Clinical notes & interpretation Scoring guidance, pitfalls, FAQs, and references
How the score earns its keep
The Wells DVT model splits patients into an "unlikely" tier, where a negative high-sensitivity d-dimer ends the workup, and a "likely" tier, where ultrasound is the first move. The subtraction item is the one clinicians forget: cellulitis, a ruptured Baker cyst, a gastrocnemius tear, and chronic venous insufficiency each mimic DVT, and crediting a genuinely more-likely alternative with −2 is what keeps the score honest. In hospitalized patients d-dimer specificity is poor and the exclusion arm weakens; the score still organizes the reasoning, but imaging thresholds drop.
The stroke unit is a DVT factory — act like it
Half the classic Virchow triad arrives with the stroke: stasis in the paretic limb and an acute-phase prothrombotic state. Without prophylaxis, DVT rates in hemiplegic patients historically ran high, most of it silent and most of it in the paralyzed leg. The working rules: intermittent pneumatic compression from admission in immobile patients (CLOTS 3 showed a real reduction in proximal DVT and a mortality signal), pharmacologic prophylaxis when hemorrhagic risk allows, and a hard rule that new asymmetric swelling, calf tenderness, or unexplained low-grade fever in the paretic leg gets an ultrasound the same day. In ICH, where prophylactic heparin is delayed, the diagnostic threshold should be lower still — and a proximal DVT there forces the IVC-filter-versus-anticoagulation conversation that is far better had with an ultrasound in hand.
Frequently asked questions.
What Wells DVT score means "likely"?
Two or more under the two-tier model (≈28% prevalence); below 2 is "unlikely" (≈6%). The older three-tier version (≤0 low, 1–2 moderate, ≥3 high) appears in earlier literature.
Can it be used for a suspected recurrent DVT?
Cautiously at best — "previously documented DVT" adds a point, but the model was designed for first episodes and post-thrombotic change makes both exam and ultrasound harder to interpret. Comparison with prior imaging matters more than the score.
Proximal or whole-leg ultrasound?
Either is acceptable in a validated pathway. A negative proximal study in a "likely" patient needs a repeat at 5–7 days (to catch propagating calf DVT) or a whole-leg study up front.
References.
- Wells PS, Anderson DR, Rodger M, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227–1235. PubMed
- Dennis M, Sandercock P, et al. Effectiveness of intermittent pneumatic compression in reduction of risk of deep vein thrombosis in patients who have had a stroke (CLOTS 3). Lancet. 2013;382(9891):516–524. PubMed
- Kearon C, de Wit K, Parpia S, et al. Diagnosis of pulmonary embolism with d-dimer adjusted to clinical probability (PEGeD). N Engl J Med. 2019;381(22):2125–2134. PubMed