Scores & indices
Wells score calculator (PE)
Seven criteria that decide the D-dimer question: can a blood test rule PE out, or does this patient need imaging first?
How to read the result
Wells (PE) falls into these published bands.
A patient with clinical signs of DVT and a heart rate over 100 — no other criteria.
Wells 4.5 — PE likely
Above the two-tier threshold: proceed to CTPA; a D-dimer cannot exclude PE at this probability.
Who this is for
For clinicians working up suspected pulmonary embolism. The two-tier Wells strategy anchors testing: at 4 or below, PE is unlikely and a negative D-dimer safely ends the work-up; above 4, PE is likely and the pathway goes straight to CT pulmonary angiography — a D-dimer cannot rule it out at that probability. Paired in-app with PERC and a guided PE work-up.
How it works
What it calculates
Pre-test probability of pulmonary embolism from seven clinical criteria, anchoring the D-dimer strategy.
The two-tier pathway
Score ≤ 4: PE unlikely — a negative D-dimer safely rules it out without imaging (consider PERC first in genuinely low-risk patients). Score > 4: PE likely — go straight to CT pulmonary angiography; a D-dimer cannot rule out PE at this probability.
Worth remembering
"PE is the most likely diagnosis" carries 3 points and is deliberately subjective — the score formalises gestalt rather than replacing it.
Built on published evidence
- Wells et al. 2000
Codification last reviewed 2026-08-28, and checked against published reference values in automated tests on every release — see the full evidence ledger.
Questions clinicians ask
Is 'PE is the most likely diagnosis' too subjective to score?
It is deliberately subjective — three points of formalised clinical gestalt. The score was derived and validated with that judgement inside it, so second-guessing it away changes the tool's performance.
When should PERC come before the D-dimer?
When your overall suspicion is already low (below ~15%): a fully negative PERC in that patient rules PE out with no blood test at all, avoiding the false-positive D-dimer cascade.
Two-tier or three-tier Wells?
This tool leads with the two-tier cut (≤4 unlikely, >4 likely) used by the validated D-dimer strategies; the classic three-tier bands are shown alongside for continuity with older literature.
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