What is the Wells score for PE?

The Wells score for pulmonary embolism is a validated clinical prediction rule that combines seven weighted criteria into a single number estimating the pre-test probability of PE. It guides whether to order a D-dimer test or proceed directly to CT pulmonary angiography.

How is the Wells PE score interpreted?

In the three-tier model, 0 to 1 is low, 2 to 6 is moderate, and 7 or more is high probability. In the widely used two-tier model, a score of 4 or less is PE unlikely and over 4 is PE likely, which then drives the D-dimer versus CTPA decision.

What is a PE-unlikely result and what follows?

A two-tier score of 4 or less is PE unlikely. In these patients a negative high-sensitivity D-dimer can safely exclude PE without imaging. A positive D-dimer, or a PE-likely score, should be followed by CT pulmonary angiography or a ventilation-perfusion scan.

Why are some criteria worth three points?

Clinical signs and symptoms of DVT and the judgement that PE is the most likely diagnosis are the strongest predictors in the rule, so each carries three points. The other criteria such as tachycardia, immobilisation, and haemoptysis carry one to one and a half points.

Can I use the Wells PE score with PERC?

Yes. In very low-risk patients, the PERC (Pulmonary Embolism Rule-out Criteria) rule can be applied to avoid any testing. Otherwise the Wells score directs the D-dimer and CTPA pathway. Both tools support, rather than replace, clinical judgement.

What is the Wells Score for Pulmonary Embolism?

Apply the Wells PE criteria including clinical DVT signs, alternative diagnosis, heart rate over 100, immobilisation, prior DVT or PE, haemoptysis, and malignancy to produce a three-tier and two-tier pulmonary embolism probability for ED and respiratory teams. It runs free in your browser on Gera Tools, with nothing uploaded.

Wells Score for Pulmonary Embolism

Name: Wells Score for Pulmonary Embolism
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

What the Wells PE score does

The Wells score for pulmonary embolism translates bedside clinical features into an estimated pre-test probability of PE. By stratifying patients before any test, it lets clinicians use D-dimer and CT pulmonary angiography (CTPA) appropriately — sparing low-risk patients unnecessary radiation and contrast, while ensuring high-risk patients move quickly to definitive imaging.

How it works

Each criterion adds the weighted points shown:

Clinical signs and symptoms of DVT (leg swelling and pain on palpation) — +3
PE is the most likely diagnosis (alternative diagnosis less likely than PE) — +3
Heart rate >100 beats per minute — +1.5
Immobilisation ≥3 days or surgery in the previous 4 weeks — +1.5
Previous objectively diagnosed DVT or PE — +1.5
Haemoptysis — +1
Malignancy (treatment within 6 months or palliative) — +1

The points are summed. In the three-tier model 0–1 is low, 2–6 is moderate, and ≥7 is high probability. In the two-tier model ≤4 is “PE unlikely” and >4 is “PE likely”.

Tips and example

A patient with PE as the most likely diagnosis (+3), heart rate 110 (+1.5), and recent surgery (+1.5) scores 6 — moderate probability (three-tier) and PE likely (two-tier), warranting CTPA. For a PE-unlikely score, a negative high-sensitivity D-dimer safely excludes PE without imaging. Always combine the score with the clinical picture, the PERC rule where appropriate, and your local PE pathway.

Reading each criterion carefully

The two highest-weighted criteria each require clinical judgement, not just presence of a finding:

“Clinical signs and symptoms of DVT” (+3) means objective evidence: leg swelling and pain on palpation of the deep venous system (the calf or popliteal region). Non-specific calf pain or mild bilateral ankle oedema does not qualify. This criterion is asking whether there is a concurrent DVT, which strongly implies VTE as the diagnosis.

“PE is the most likely diagnosis” (+3) is the clinician’s overall gestalt. You score it if, after considering the presentation, PE is at least as likely as any single alternative. If the history suggests pneumonia or heart failure as a more likely explanation, do not score this criterion. The original Wells validation required that the alternative be less likely than PE, not merely possible.

PE-likely versus PE-unlikely: what each pathway means in practice

PE unlikely (score ≤4): Use a sensitive D-dimer test (ELISA-based, not latex agglutination). A negative result to the laboratory’s threshold — whether standard or age-adjusted — rules out PE and no imaging is needed. A positive result or score above 4 moves to CTPA.

PE likely (score >4): Proceed to CT pulmonary angiography or, in centres with expertise, a V/Q scan. In many units, if there will be a delay to imaging, interim anticoagulation is started pending the scan. Do not rely on D-dimer to exclude PE in this group — the prevalence is too high for a negative D-dimer to be reliably safe.

Using the PERC rule alongside Wells

In very low-risk patients, the Pulmonary Embolism Rule-out Criteria (PERC) can be applied before even calculating a Wells score. If the patient is under 50, pulse under 100, oxygen saturation 95% or above, no unilateral leg swelling, no haemoptysis, no recent surgery, no prior DVT or PE, and no exogenous oestrogen, PERC is negative and PE can be excluded without D-dimer or CTPA. PERC and Wells are complementary: PERC is the gateway; Wells directs imaging once PERC is positive or indeterminate.

Limitations

The Wells score was validated in outpatient and ED populations with suspected first-presentation PE. It performs less well in ICU patients, post-operative patients in the first days after major surgery, or patients on anticoagulation already. In those settings, clinical judgement and specialist guidance take precedence over the score alone.