Wells DVT Score Calculator — Deep Vein Thrombosis Pre-test Probability

How to Use This Calculator

1. Select Yes or No for each of the 9 Wells DVT criteria.
2. Wells DVT score, pre-test probability, and recommended diagnostic pathway display instantly.
3. Use the 2-Tier tab (DVT Likely/Unlikely) if your institution uses that classification.
4. Use the D-Dimer Integration tab to determine next steps based on D-dimer result.

Formula

Example

Frequently Asked Questions

• What is the Wells DVT score? ▼
  The Wells DVT score is a validated clinical decision rule that estimates the pre-test probability of deep vein thrombosis (DVT) in patients with leg symptoms. Developed by Philip Wells and colleagues and published in The Lancet in 1997, the score uses nine clinical criteria: active cancer, paralysis or recent plaster cast, bedridden more than three days or surgery within 12 weeks, localised deep venous tenderness, entire leg swelling, calf swelling more than 3 cm compared to the asymptomatic side, pitting oedema greater in the symptomatic leg, non-varicose collateral superficial veins, and whether an alternative diagnosis is at least as likely as DVT (which subtracts 2 points). The total score stratifies patients into low (0 or less), moderate (1–2), or high (3 or more) DVT probability, or into the simpler two-tier DVT Unlikely (1 or less) / DVT Likely (2 or more) classification.
• How does the Wells DVT score guide clinical management? ▼
  The Wells DVT score is used alongside D-dimer testing and compression ultrasonography to create an efficient diagnostic pathway. In low-probability patients (score 0 or below), a negative D-dimer test effectively excludes DVT without imaging, reducing unnecessary ultrasound use. In moderate-probability patients (score 1–2), guidelines vary — some recommend D-dimer first, others proceed directly to ultrasound. In high-probability patients (score 3 or more), proximal compression ultrasound should be performed directly, as D-dimer adds little diagnostic value when pre-test probability is high. If ultrasound is negative in high-probability patients, a repeat scan in 6–8 days is recommended to detect calf vein thrombosis that may propagate proximally. The two-tier version (DVT Likely or Unlikely) is used in some guidelines for simplicity.
• What is the sensitivity and specificity of the Wells DVT score? ▼
  The original Wells DVT validation study showed that the high-probability score identified DVT in approximately 53% of patients, moderate probability in 17%, and low probability in only 5%. The score has been validated in multiple subsequent studies. A 2006 meta-analysis by Oudega et al. in the British Journal of General Practice found that using Wells score plus D-dimer to rule out DVT in primary care had a sensitivity of 95–100% and a negative predictive value of approximately 99%. Specificity of the Wells score alone is lower — many patients with high scores do not have DVT — which is why imaging confirmation is always required for positive results. The score performs less well in elderly patients, patients with prior DVT, and those with concurrent medical illness.
• Can the Wells DVT score be used in pregnancy? ▼
  The Wells DVT score has limited validation in pregnancy and requires caution. D-dimer is physiologically elevated throughout pregnancy and is unreliable as a rule-out test in pregnant patients. This means the D-dimer-guided pathway (D-dimer negative = DVT excluded) cannot be applied in pregnant women. Compression ultrasonography is the primary diagnostic modality in pregnancy and should be used without relying on D-dimer for exclusion. Some studies suggest the Wells score criteria still predict DVT presence in pregnancy, but the cut-off thresholds may differ. The RCOG Green-top Guideline 37a recommends that any pregnant woman with suspected DVT should have compression ultrasound regardless of pre-test probability scoring, given the consequences of missing DVT in pregnancy.
• What is the difference between the Wells DVT score and the Wells PE score? ▼
  Both scores were developed by Philip Wells but for different VTE presentations. The Wells DVT score assesses the probability of DVT in a symptomatic limb and uses nine criteria including limb-specific findings. The Wells PE score estimates the probability of pulmonary embolism and uses different criteria including heart rate above 100, haemoptysis, malignancy, prior VTE, clinical signs of DVT, PE being the most likely diagnosis, and recent surgery or immobilisation. The two scores are independent tools and are not interchangeable. A patient can have a high Wells DVT score and a low Wells PE score, or vice versa. Both are used as pre-test probability assessments to guide D-dimer and imaging decisions in their respective suspected diagnoses.

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