Pre-test probability for suspected deep vein thrombosis or pulmonary embolism, with probability bands and next-step guidance. Calculations run locally in your browser.
Disclaimer: The Wells score is a pre-test probability tool, not a diagnosis. Decisions about D-dimer, compression USG, or CT pulmonary angiography (CTPA) must integrate the full clinical picture — vitals, haemodynamic status, comorbidities, pregnancy, renal function, and bleeding risk. Always interpret high-sensitivity D-dimer against an age-adjusted cut-off (age × 10 ng/mL FEU for >50 years) where appropriate, and never rule out PE with D-dimer alone in a haemodynamically unstable patient — they need direct imaging.
Both are validated. The 3-tier system (low / moderate / high) is the original Wells stratification and is useful when you want a graded clinical impression. The 2-tier system (unlikely ≤4 / likely >4 for PE; unlikely ≤1 / likely ≥2 for DVT) is preferred by NICE NG158 and is the basis for the "PE unlikely + negative D-dimer = ruled out" pathway. This calculator shows both so you can document either, depending on your local protocol.
No. A negative D-dimer rules out PE only in patients classified as PE unlikely (Wells ≤4 in the 2-tier system, low/moderate in the 3-tier with high-sensitivity assay). Patients in the likely category need imaging — CTPA, or V/Q scan when contrast or radiation is contraindicated (pregnancy, severe renal impairment).
Yes. Wells is not validated in pregnancy; use the YEARS-adapted pregnancy pathway or LEFt rule (for DVT) instead, and start with bilateral compression USG for suspected DVT. For PE in pregnancy, chest X-ray first, then perfusion scan or low-dose CTPA depending on findings — local radiology protocols apply.
For patients >50 years with a "PE unlikely" Wells score, an age-adjusted cut-off (age × 10 ng/mL FEU, or age × 5 ng/mL DDU depending on assay units) reduces unnecessary imaging without missing clinically important PE. Confirm your lab's assay units before applying — DDU and FEU differ by a factor of 2.
No. Wells DVT is derived for first-episode lower-limb DVT in outpatients. Recurrent ipsilateral DVT and upper-limb DVT need direct imaging — compression USG of the affected limb is the next step regardless of clinical probability.
Probability bands and next-step suggestions follow NICE NG158 and ESC 2019 recommendations. Always defer to your local hospital VTE protocol where it differs.
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