Wells Score for PE Calculator

The Wells score is not an equal-weight checklist. Clinical signs of DVT and "PE is the most likely diagnosis" each carry 3 points because they were the strongest predictors in the original derivation study; tachycardia, recent immobilization or surgery, and a prior DVT/PE each carry 1.5 points; and hemoptysis and active malignancy each carry 1 point as the weakest predictors. The point values reflect how strongly each finding predicted a confirmed PE in that derivation cohort, not how easy each finding is to check for.

The original 3-tier model sorts patients into low (score 0-1), moderate (2-6), or high (>6) probability bands, each with its own PE prevalence. The simplified 2-tier model, introduced by the later Christopher study, collapses those into just "PE unlikely" (score 4 or below) versus "PE likely" (above 4). The 2-tier version is more common in emergency protocols today because it maps directly onto a single decision: order a D-dimer for "unlikely," or proceed straight to CT pulmonary angiography for "likely."

Not by itself. Low risk (score 0-1) carried roughly a 1.3% PE prevalence in the original derivation cohort -- reassuring, but not zero. The standard next step for a low or "PE unlikely" score is a D-dimer test; a negative D-dimer in that setting has a high negative predictive value and can reasonably exclude PE without imaging, but the Wells score alone, without a following D-dimer or imaging, does not rule PE out.

High probability (score above 6 in the 3-tier model) carried roughly a 37.5% PE prevalence in the original derivation cohort -- meaning more than a third of patients scoring in that range actually had a confirmed PE. At that pre-test probability, D-dimer testing is generally skipped because even a negative result wouldn't lower the probability enough to be reassuring, and patients typically proceed directly to CT pulmonary angiography or another definitive imaging study.