Wells Score for Pulmonary Embolism Calculator

How it works

DVT signs 3 + PE most likely 3 + HR > 100 1.5 + immobilisation/surgery 1.5 + prior VTE 1.5 + haemoptysis 1 + cancer 1 (maximum 12.5) · three-tier: < 2 low, 2–6 moderate, > 6 high · two-tier: ≤ 4 unlikely, > 4 likely · age-adjusted D-dimer cut-off = age × 10 µg/L FEU over 50 · YEARS threshold 1,000 µg/L with no YEARS item, 500 with any

The Wells criteria (Wells 2000, validated in emergency patients in 2001) turn the clinical picture of a suspected pulmonary embolism into a pre-test probability. Two items carry most of the weight: signs of a deep vein thrombosis and the clinician’s judgement that PE is the leading diagnosis. In the original three-tier model, PE was found in 1.3% of low-, 16.2% of moderate- and 37.5% of high-probability patients. Guidelines now favour the two-tier version: with a score of 4 or less (“PE unlikely”), a negative high-sensitivity D-dimer rules PE out without imaging; with a score above 4, patients go to CT pulmonary angiography. Over age 50, the ADJUST-PE study showed that a cut-off of age × 10 µg/L (FEU) safely rules out more patients than the fixed 500. Enter the D-dimer in the unit your lab reports — DDU values are about half of FEU values. The calculator also shows the simplified Wells score (one point per item), the three YEARS items with their D-dimer threshold, and, for low-probability patients, the eight-item PERC rule, which can avoid even the D-dimer. Wells applies to haemodynamically stable patients; it was not validated in pregnancy and is less reliable in inpatients.

Worked example

A post-operative patient with a heart rate of 110 and a swollen leg, where PE seems the most likely diagnosis: 3 + 3 + 1.5 + 1.5 = 9 — high probability and PE likely, so CT pulmonary angiography comes next whatever the D-dimer. A 72-year-old with only a heart rate of 105 scores 1.5: low probability, PE unlikely; her D-dimer cut-off is 72 × 10 = 720 µg/L FEU, so a result of 600 rules PE out without imaging, although the fixed 500 cut-off would have sent her to CT.

Sources: Wells PS et al. Derivation of a simple clinical model to categorize patients’ probability of pulmonary embolism. Thromb Haemost 2000;83:416–420 · Wells PS et al. Excluding pulmonary embolism at the bedside without diagnostic imaging. Ann Intern Med 2001;135:98–107 · van Belle A et al (Christopher Study). Effectiveness of managing suspected PE using an algorithm combining clinical probability, D-dimer testing and CT. JAMA 2006;295:172–179 · Gibson NS et al. Further validation and simplification of the Wells clinical decision rule in pulmonary embolism. Thromb Haemost 2008;99:229–234 · Righini M et al (ADJUST-PE). Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism. JAMA 2014;311:1117–1124 · van der Hulle T et al. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study). Lancet 2017;390:289–297 · Kline JA et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected PE (PERC). J Thromb Haemost 2004;2:1247–1255 · Konstantinides SV et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J 2020;41:543–603 · MDCalc — Wells’ Criteria for Pulmonary Embolism

Frequently asked questions