Wells Score, PERC & Geneva Calculator

About the Wells Score, PERC & Geneva Calculator

Four bedside rules for suspected venous thromboembolism, each as a checklist with its published points and risk groups:

• the Wells score for pulmonary embolism (PE), in its two-level form (PE likely or unlikely, as NICE uses it) and its three-level form;
• the PERC rule, which rules out PE without a D-dimer test when clinical suspicion is already low;
• the revised Geneva score, built from objective findings only, with its simplified one-point-per-item version;
• the Wells score for deep vein thrombosis (DVT).

Tick what applies and the result updates at once, with what the source studies found in each group and the next step in NICE guideline NG158. It is written for clinicians; nothing you tick leaves your browser.

Common uses

• Scoring a breathless or chest-pain patient in the emergency department before deciding between a D-dimer test and imaging.
• Checking whether the PERC rule allows a low-risk patient to skip the D-dimer.
• Documenting the score and the criteria behind it in the clinical notes.
• Teaching or revising the criteria with the points beside each item.

The criteria and their points

• Wells PE (NICE two-level table): clinical signs and symptoms of DVT 3 · an alternative diagnosis less likely than PE 3 · heart rate over 100 1.5 · immobilisation for more than 3 days or surgery in the previous 4 weeks 1.5 · previous DVT or PE 1.5 · haemoptysis 1 · malignancy (on treatment, treated in the last 6 months, or palliative) 1. Maximum 12.5.
• PERC: age 50 or over · heart rate 100 or more · SaO₂ below 95% · haemoptysis · oestrogen use · surgery or trauma requiring hospitalisation within 4 weeks · previous venous thromboembolism · unilateral leg swelling. PERC is negative only when none is present.
• Revised Geneva: age over 65 1 · previous DVT or PE 3 · surgery or lower-limb fracture within a month 2 · active malignancy (or cured less than a year) 2 · unilateral lower-limb pain 3 · haemoptysis 2 · heart rate 75–94 3, or 95 or more 5 · pain on deep venous palpation of the leg with unilateral oedema 4. Maximum 22. The simplified score gives each item 1 point (heart rate 95 or more: 2), maximum 9.
• Wells DVT (NICE two-level table): active cancer · paralysis, paresis or recent plaster of the leg · bedridden 3 days or more or major surgery within 12 weeks · localised tenderness along the deep veins · entire leg swollen · calf swelling 3 cm or more · pitting oedema of the symptomatic leg · collateral superficial veins · previously documented DVT — 1 point each; an alternative diagnosis at least as likely as DVT −2.

Risk groups and what the studies found

• Wells PE, two levels: 4 or less “PE unlikely”, more than 4 “PE likely”. In the derivation study 7.8% of “unlikely” patients had PE, and 2.2% with a negative D-dimer (1.7% on validation). In a later management study of 3,306 patients, “unlikely” with a normal D-dimer was followed by venous thromboembolism in 0.5% over 3 months.
• Wells PE, three levels: below 2 low, 2–6 moderate, above 6 high — PE in 1.3%, 16.2% and 37.5% of 930 emergency department patients.
• PERC: with a low gestalt suspicion (below 15%), PERC negative was followed by venous thromboembolism or death in 16 of 1,666 patients (1.0%) within 45 days — below the 2% the study set as its safety target.
• Revised Geneva: 0–3 low, 4–10 intermediate, 11 or more high — PE in 8%, 28% and 74% of the validation set. Two levels: 5 or less unlikely, 6 or more likely.
• Simplified Geneva: 0–1 low, 2–4 intermediate, 5 or more high — PE in 9.7%, 22.4% and 45.5% in its prospective validation of 1,621 patients. Two levels: 2 or less unlikely, 3 or more likely.
• Wells DVT: 1 point or less “DVT unlikely”, 2 or more “DVT likely” (NICE). Three levels (0 or less, 1–2, 3 or more): DVT in 5.0%, 17% and 53% in a review of 14 studies with more than 8,000 outpatients.

Next steps in NICE NG158

• PE likely: a CT pulmonary angiogram (CTPA) immediately if possible — a V/Q SPECT or planar V/Q scan for people with contrast allergy, severe renal impairment (creatinine clearance below 30 ml/min) or a high risk from irradiation — and interim therapeutic anticoagulation if imaging is delayed.
• PE unlikely: a D-dimer test with the result within 4 hours if possible (interim anticoagulation if not); a positive result leads to imaging, a negative one makes PE unlikely. An age-adjusted D-dimer threshold can be considered over 50.
• DVT likely: a proximal leg vein ultrasound within 4 hours if possible, and a D-dimer if it is negative; a negative scan with a positive D-dimer is repeated 6 to 8 days later.
• DVT unlikely: a D-dimer test within 4 hours; if positive, an ultrasound scan.
• PERC: NICE suggests considering it when suspicion is low on the overall clinical impression and other diagnoses are feasible, and notes it has not been validated in people with COVID-19.

Sources

• NICE guideline NG158, Venous thromboembolic diseases: diagnosis, management and thrombophilia testing — two-level Wells tables and recommendations 1.1.2–1.1.21
• Wells PS et al. Derivation of a simple clinical model to categorize patients’ probability of pulmonary embolism · Excluding pulmonary embolism at the bedside without diagnostic imaging
• 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
• Kline JA et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism · Prospective multicenter evaluation of the pulmonary embolism rule-out criteria
• Le Gal G et al. Prediction of pulmonary embolism in the emergency department: the revised Geneva score · Klok FA et al. Simplification of the revised Geneva score · Robert-Ebadi H et al. Prospective validation of the simplified Geneva score
• Wells PS et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management · Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis · Does this patient have deep vein thrombosis?

Limitations

• Pre-test probability only: none of these rules diagnoses or excludes PE or DVT on its own — they decide which test comes next.
• Each rule was derived and validated in a particular setting (Wells PE, PERC and Geneva in emergency departments, Wells DVT in outpatients). Elsewhere — hospital inpatients, for example — they are less certain.
• Wells PE and Wells DVT include the clinician’s judgement of an alternative diagnosis, which carries 3 or −2 points.
• PERC applies only when clinical suspicion is already low; it is not a substitute for the Wells or Geneva score in other patients.
• It does not interpret D-dimer values: cut-offs depend on the assay and, for an age-adjusted threshold, on local practice.

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