Pick the clinical question — DVT or PE — then check every criterion that applies. The score, risk category, and recommended next step update automatically.
Wells DVT — score interpretation:
- ≥2: DVT likely → compression ultrasound
- <2: DVT unlikely → D-dimer (image only if positive)
- Three-tier: ≤0 low · 1–2 moderate · ≥3 high
Wells PE — score interpretation:
- >4: PE likely → CT pulmonary angiography (CTPA)
- ≤4: PE unlikely → D-dimer (consider PERC); CTPA only if positive
- Three-tier: <2 low · 2–6 moderate · >6 high
All computation runs in your browser; no values are stored or transmitted.
When to Use
Appropriate population
- Outpatient or ED patients with suspected lower-extremity DVT (unilateral leg pain, swelling, tenderness)
- Patients with suspected PE (dyspnea, pleuritic chest pain, tachycardia, hemoptysis, syncope)
- CKD/ESRD patients — VTE risk is elevated in CKD; the Wells category is especially useful here because it lets you avoid contrast CTPA when probability is low (D-dimer first)
- Triage before deciding D-dimer vs definitive imaging
Do not apply Wells to confirm or exclude VTE in pregnancy or in patients already on therapeutic anticoagulation without specialist input.
Pearls & Pitfalls
Key pearls & pitfalls
- Wells is a pretest probability tool, not a rule-out. A low/unlikely score must be paired with a negative D-dimer to safely defer imaging.
- The "alternative diagnosis at least as likely as DVT" (−2) and "PE is the #1 diagnosis" (+3) items are subjective — they carry the most weight and the most inter-rater variability.
- CKD & CTPA: iodinated contrast carries contrast-associated AKI risk. In advanced CKD (and especially dialysis-dependent patients with residual function), consider V/Q scanning as the imaging alternative for PE.
- D-dimer in CKD/older patients: D-dimer rises with age and with reduced eGFR, lowering specificity. Use an age-adjusted cutoff (age × 10 µg/L FEU for age >50) to limit false positives and unnecessary imaging.
- The two-tier PE model (likely/unlikely at a cut of 4) is the most widely validated for D-dimer pairing.
Why Use It
VTE is common, frequently atypical, and dangerous to miss — yet imaging everyone is costly and, with CTPA, carries radiation and contrast-associated AKI risk. A structured pretest probability lets you stratify rationally: low/unlikely patients can often be cleared with a (age-adjusted) D-dimer, while high/likely patients move directly to definitive imaging. In CKD this triage is especially valuable because it minimizes avoidable contrast exposure.
Wells Criteria Calculator
Choose the clinical question, then check every criterion that applies. The score, risk category, and recommended next step update automatically.
Wells DVT criteria
Wells PE criteria
⚕ The Wells criteria estimate pretest probability only — they do not confirm or exclude VTE. Final decisions require correlation with D-dimer and/or imaging and individualized clinical judgment. For educational reference only. References: Wells PS et al., Lancet 1997 & Thromb Haemost 2000.
Next Steps
DVT pathway
- DVT likely (≥2): Proceed to compression ultrasound of the affected leg.
- DVT unlikely (<2): Order a (age-adjusted) D-dimer. Negative → DVT excluded; positive → ultrasound.
PE pathway
- PE likely (>4): Go directly to CT pulmonary angiography (CTPA). In advanced CKD, weigh V/Q scanning to avoid contrast.
- PE unlikely (≤4): Apply the (age-adjusted) D-dimer — consider PERC if very low risk. Negative → PE excluded; positive → CTPA (or V/Q in CKD).
In CKD specifically
- Prefer the D-dimer-first route whenever the category permits, to spare iodinated contrast.
- Use an age-adjusted D-dimer cutoff; a low eGFR raises D-dimer and reduces specificity.
- If imaging for PE is required and eGFR is markedly reduced, discuss V/Q scintigraphy with radiology.
Evidence & References
References
- Wells PS, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350(9094):1795–1798.
- Wells PS, et al. Derivation of a simple clinical model to categorize patients' probability of pulmonary embolism. Thromb Haemost. 2000;83(3):416–420.
- Konstantinides SV, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2020;41(4):543–603.
