What are the Wells criteria?

The Wells criteria are two clinical prediction rules used to estimate the pre-test probability of venous thromboembolism: one for pulmonary embolism (PE) and one for deep vein thrombosis (DVT). Each rule assigns points to specific clinical features; the total score stratifies patients into low, intermediate, or high probability groups and guides further testing such as D-dimer or imaging.

How is the Wells score for pulmonary embolism interpreted?

For the commonly used 3-level Wells score for PE: a score of 0–1 points indicates low probability, 2–6 points indicates intermediate probability, and 7 or more points indicates high probability of pulmonary embolism. Some practices also use a 2-level model (PE unlikely if ≤ 4, PE likely if > 4).

How is the Wells score for DVT interpreted?

For the Wells score for DVT: a score of 0 or less indicates low probability, 1–2 points indicates moderate probability, and 3 or more points indicates high probability of deep vein thrombosis. A 2-level model is also used in some guidelines (DVT unlikely if ≤1, DVT likely if ≥2).

Can the Wells criteria rule out PE or DVT on their own?

No. The Wells criteria are not diagnostic tests. They estimate pre-test probability and must be combined with D-dimer testing and/or imaging according to guideline-based diagnostic algorithms. A low Wells score plus a negative high-sensitivity D-dimer can safely exclude PE or DVT in many patients, but clinical judgment is always required.

Should I use the PE or DVT Wells score?

Use the PE Wells score if pulmonary embolism is your primary concern (e.g., pleuritic chest pain, dyspnea, hemoptysis). Use the DVT Wells score if the main concern is lower limb deep vein thrombosis (e.g., unilateral leg swelling, pain, erythema). The two scores share some items but are validated for different clinical presentations.

Wells Criteria Calculator for DVT & Pulmonary Embolism (PE)

How the Wells Criteria Calculator Works

The Wells criteria are validated clinical prediction rules that estimate the pre‑test probability of venous thromboembolism (VTE). This calculator includes both:

Wells score for pulmonary embolism (PE)
Wells score for deep vein thrombosis (DVT)

Select the appropriate tab (PE or DVT), tick the clinical features that apply to your patient, and the tool will automatically compute the total score and provide a probability category with suggested next steps.

Wells Score for Pulmonary Embolism

The original Wells PE score assigns weighted points to seven clinical variables. The total score can be interpreted using a 3‑level or 2‑level model.

PE Wells score items and points

Clinical signs of DVT → +3.0
PE more likely than alternative diagnosis → +3.0
Heart rate > 100 bpm → +1.5
Immobilization ≥ 3 days or surgery in previous 4 weeks → +1.5
Previous DVT or PE → +1.0
Hemoptysis → +1.0
Malignancy (on treatment, treated in last 6 months, or palliative) → +1.0

PE score interpretation

3‑level model
- Low probability: ≤ 1.0
- Intermediate probability: 2.0–6.0
- High probability: ≥ 7.0
2‑level model
- PE unlikely: ≤ 4.0
- PE likely: > 4.0

Wells Score for Deep Vein Thrombosis (DVT)

The Wells DVT score uses nine variables, including one negative item that subtracts points when an alternative diagnosis is at least as likely as DVT.

DVT Wells score items and points

Active cancer → +1.0
Paralysis, paresis, or recent immobilization of leg → +1.0
Recently bedridden ≥ 3 days or major surgery within 12 weeks → +1.0
Localized tenderness along deep venous system → +1.0
Entire leg swollen → +1.0
Calf swelling > 3 cm compared with asymptomatic leg → +1.0
Pitting edema confined to symptomatic leg → +1.0
Collateral superficial veins (non‑varicose) → +1.0
Alternative diagnosis at least as likely as DVT → −2.0

DVT score interpretation

3‑level model
- Low probability: ≤ 0
- Moderate probability: 1–2
- High probability: ≥ 3
2‑level model
- DVT unlikely: ≤ 1
- DVT likely: ≥ 2

Suggested Diagnostic Pathways (Simplified)

Exact workup depends on local protocols, patient stability, and availability of tests. The following is a simplified overview commonly used in practice:

Low probability (PE or DVT)
- Order a high‑sensitivity D‑dimer.
- If D‑dimer is negative: VTE can usually be excluded without imaging.
- If D‑dimer is positive: proceed to imaging (CTPA for PE, compression ultrasound for DVT).
Intermediate probability
- Either obtain D‑dimer or proceed directly to imaging depending on clinical context.
High probability / “VTE likely”
- Proceed directly to imaging.
- Consider empiric anticoagulation if imaging is delayed and bleeding risk is acceptable.

Limitations and Clinical Caveats

The Wells criteria are not diagnostic; they estimate pre‑test probability.
They were derived and validated mainly in adults with suspected VTE in emergency or outpatient settings.
Performance may be reduced in special populations (pregnancy, cancer, postoperative patients, elderly, inpatients).
Always integrate the score with clinical judgment, vital signs, ECG, chest imaging, and local guidelines.

References

Wells PS et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997.
Wells PS et al. Excluding pulmonary embolism at the bedside without diagnostic imaging. Ann Intern Med. 2001.
Current major society guidelines on VTE diagnosis (e.g., ESC, ACCP, ACEP).