Wells Score Calculator (Pulmonary Embolism)

Wells PE score — pretest probability for pulmonary embolism. Wells 2000 Annals Intern Med (modified).

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How to use this calculator

  • Answer 7 yes/no clinical questions.
  • Read score + risk tier.
  • Low/moderate: D-dimer; high: CTPA without D-dimer.

About this calculator

Wells score for PE pretest probability. Source: Wells PS et al., "Derivation of a simple clinical model to categorize patients' probability of pulmonary embolism: increasing the model's utility with the SimpliRED D-dimer." Thromb Haemost 2000;83(3):416-20. Three-tier interpretation: ≤2 low (~3% PE), 2-6 moderate (~16%), >6 high (~40%). Dichotomized (Wells 2001): ≤4 PE unlikely, >4 PE likely — combined with D-dimer to exclude PE in the unlikely group. Also see PERC rule (Kline 2008) for very-low-risk patients. **Not medical advice — clinical judgment + imaging required.**

Frequently asked

Source of the formula?+
Wells PS et al., Thromb Haemost 2000;83:416-20 (3-tier original); refinement in Ann Intern Med 2001;135:98-107 (dichotomized).
Three-tier vs. dichotomized?+
Both validated. Dichotomized (≤4 unlikely / >4 likely) is simpler and used in PERC + D-dimer pathways. Three-tier is more granular for resource decisions.
Wells DVT vs. Wells PE?+
Different scores — Wells DVT has different items (calf swelling, pitting edema, etc.). This calc is the PE version.
PERC rule role?+
In low-risk patients (Wells <2), PERC criteria (Kline 2008) further reduces likelihood. If all 8 PERC criteria negative, PE prevalence <1.8% — D-dimer can be skipped.
Sensitivity / specificity?+
Wells + D-dimer combined: sensitivity ~99% for PE in unlikely group when D-dimer negative (van Belle 2006 Christopher study).
Is this medical advice?+
No. Educational. PE diagnosis requires labs + imaging + clinical judgment.

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