Wells Score (DVT)
DVT Pretest Probability (Wells Score)
≤0 unlikely (D-dimer rules out) · ≥2 likely (ultrasound first).
The board-friendly take on a swollen calf is that imaging is not the first step — Wells score is. Active cancer, paralysis or recent immobilization, recent bedrest 3+ days or surgery within 12 weeks, tenderness along deep veins, entire leg swelling, calf swelling 3 cm greater than asymptomatic side, pitting edema, collateral superficial veins, prior DVT — each scores 1 point; an alternative diagnosis at least as likely subtracts 2. Score 0 or less is unlikely (D-dimer rules out); 1 is moderate; 2 or higher is likely (compression ultrasound first). AANP exam vignettes test the threshold and the right next test based on probability.
- CancerActive cancer (within 6 mo or palliative)+1 point.
- ParalysisParalysis, paresis, or recent plaster immobilization of leg+1 point.
- BedriddenRecently bedridden >3 days or major surgery within 12 weeks+1 point.
- TenderLocalized tenderness along deep venous system+1 point.
- Leg swollenEntire leg swollen+1 point.
- Calf +3cmCalf swelling >3cm vs. asymptomatic leg (10cm below tibial tuberosity)+1 point.
- PittingPitting edema confined to symptomatic leg+1 point.
- CollateralCollateral superficial (non-varicose) veins+1 point.
- Prior DVTPreviously documented DVT+1 point.
- Alt dxAlternative diagnosis at least as likely as DVT−2 points. The only negative item — do not forget it.
Clinical Context
Sorts patients into low-probability ("DVT unlikely," ≤0 or ≤1 depending on 2-tier version) vs. high-probability ("DVT likely," ≥2). Low + negative D-dimer rules out DVT without imaging. High or positive D-dimer → compression ultrasound.
D-dimer alone is sensitive but not specific — use it AFTER risk stratification, not before. Common trap: using D-dimer in a high-pretest-probability patient where a positive result adds nothing and a negative result still requires imaging.
AANP primary-care stem: unilateral calf swelling with tenderness after a long flight — calculate Wells, decide on D-dimer vs. ultrasound. Recent surgery + active cancer + tenderness + unilateral swelling = easily ≥3 and needs imaging, not a D-dimer.
Practice Questions
A 46-year-old woman presents to the clinic with 3 days of mild left calf discomfort. She returned 5 days ago from a 6-hour car trip but has otherwise been ambulating normally. She has no history of cancer, no recent surgery, and no prior DVT. On exam, there is mild tenderness along the medial calf without significant swelling. Calf circumference measured 10 cm below the tibial tuberosity is 36.0 cm on the left and 35.5 cm on the right. There is no pitting edema, no entire-leg swelling, and no collateral superficial veins. The NP also notes a small posterior knee bulge consistent with a Baker's cyst on exam, which seems an equally plausible explanation for her symptoms. Vital signs are normal and she is breathing comfortably. Applying the Wells DVT criteria, what is the initial test of choice?
Related Mnemonics
- 5 T's — Cyanotic Congenital Heart Defects
- 6 P's — Acute Limb Ischemia
- CHA₂DS₂-VASc — Stroke Risk in Non-Valvular Atrial Fibrillation
- HAS-BLED — Bleeding Risk on Anticoagulation
- MR. PASS MVP — Systolic Murmurs
Sources
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