Wells score (pulmonary embolism)
Clinical probability for PE
- ESC 2019 PE guideline
- Christopher Study validation
Sources last checked: 2026-10-13
Wells score (pulmonary embolism)
Clinical probability for PE
Two-tier rule: ESC 2019 places D-dimer testing as the next diagnostic step in this group; a negative D-dimer rules out PE.
The banding here follows the two-tier (unlikely/likely) rule. A three-tier version also exists (< 2 low, 2–6 moderate, > 6 high) — don't mix them up.
Interpretation
| 0–4 — PE unlikely | Two-tier rule: ESC 2019 places D-dimer testing as the next diagnostic step in this group; a negative D-dimer rules out PE. |
|---|---|
| > 4 — PE likely | Two-tier rule: ESC 2019 places CT pulmonary angiography as the next diagnostic step in this group. |
What is the Wells score (pulmonary embolism)?
The Wells score estimates the clinical (pre-test) probability of pulmonary embolism from seven bedside items. Wells and colleagues in Ottawa derived it in 2000 and validated the dichotomised version (PE unlikely ≤ 4, PE likely > 4) with D-dimer in 930 emergency patients in 2001. The 2019 ESC pulmonary embolism guideline bases the diagnostic strategy on clinical probability from a validated rule such as Wells or the revised Geneva score.
When to use it
- Haemodynamically stable outpatients or emergency patients with suspected acute pulmonary embolism.
- To decide between D-dimer testing first (PE unlikely) and direct CT pulmonary angiography (PE likely).
- To document pre-test probability before imaging, as recommended by ESC 2019.
When not to use it
- Suspected high-risk PE with shock or hypotension — ESC 2019 uses a separate pathway based on bedside echocardiography or CTPA.
- Pregnancy, where adapted algorithms (pregnancy-adapted YEARS, revised Geneva with D-dimer) are better studied.
- Hospitalised patients, in whom D-dimer is frequently raised and the rule performs less well.
How it is calculated
| Criterion | Points |
|---|---|
| Clinical signs of DVT | +3 |
| PE is the most likely diagnosis, or equally likely | +3 |
| Heart rate > 100/min | +1.5 |
| Immobilisation ≥ 3 days or surgery in the last 4 weeks | +1.5 |
| Previous DVT or PE | +1.5 |
| Haemoptysis | +1 |
| Active malignancy | +1 |
Clinical pearls and limitations
- The banding here follows the two-tier (unlikely/likely) rule. A three-tier version also exists (< 2 low, 2–6 moderate, > 6 high) — don't mix them up.
- The 'PE most likely diagnosis' item carries 3 points and is subjective — it drives most of the variation between clinicians.
- ESC 2019 endorses age-adjusted D-dimer cut-offs (age × 10 µg/L above 50 years) in the PE-unlikely group, which reduces imaging.
- In the Dutch Christopher Study, a PE-unlikely score with a normal D-dimer had a 3-month VTE rate of 0.5 %.
- Do not mix the two-tier (≤ 4 / > 4) and three-tier (< 2 / 2–6 / > 6) versions within one pathway.
Frequently asked questions
Wells score for PE: what is the cut-off?
In the two-level version, ≤ 4 points means PE unlikely (ESC 2019: D-dimer as the next step) and > 4 means PE likely (ESC 2019: CTPA as the next step). The three-level version uses < 2 low, 2–6 moderate and > 6 high probability.
Wells or revised Geneva — which does ESC recommend?
ESC 2019 recommends basing the diagnostic strategy on clinical probability assessed by clinical judgement or a validated prediction rule and lists both. The revised Geneva score is fully objective, which some departments prefer.
Wells, PERC or YEARS?
PERC is only for patients already judged low probability, to avoid D-dimer testing. YEARS uses three Wells items with a D-dimer threshold that depends on them. Wells remains the classic rule for stratifying all comers.
Evidence and guidelines
- Primary source: Wells PS et al. Excluding pulmonary embolism at the bedside without diagnostic imaging. Ann Intern Med 2001;135(2):98-107.
- Konstantinides SV et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J 2020;41(4):543-603 (diagnostic strategy based on clinical probability from a validated rule; two-level or three-level scheme).
- van Belle A et al. (Christopher Study). Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA 2006;295(2):172-179.
Have a follow-up question?
Medelix answers clinical questions from current guidelines and studies — every statement with its source.
Ask Medelix about the Wells score (pulmonary embolism)Related calculators
Embed this calculatorFree to use on your website, intranet or teaching page. Copy the code below.
<iframe src="https://medelix.ai/en/embed/wells-pe" title="Wells score (pulmonary embolism) – Medelix" width="100%" height="620" style="border:0;max-width:720px" loading="lazy"></iframe>
<p><a href="https://medelix.ai/en/calculators/wells-score-pulmonary-embolism">Wells score (pulmonary embolism) calculator by Medelix</a></p>For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.