Wells Score for PE Calculator

Estimate the Pretest Probability of Pulmonary Embolism

Wells Score for PE Formula

Formula

\[ \text{Wells PE score} = 3(a_{\text{DVT}}) + 3(a_{\text{PE likely}}) + 1.5(a_{\text{HR}>100}) + 1.5(a_{\text{immob}}) + 1.5(a_{\text{prev VTE}}) + 1(a_{\text{hemo}}) + 1(a_{\text{cancer}}) \]

Where:

\(a_{\text{DVT}}\) — 1 if there are clinical signs and symptoms of DVT, otherwise 0
\(a_{\text{PE likely}}\) — 1 if PE is the most likely diagnosis, otherwise 0
\(a_{\text{HR}>100}\) — 1 if the heart rate exceeds 100 bpm, otherwise 0
\(a_{\text{immob}}\) — 1 if the patient was immobilized for at least 3 days or had surgery within 4 weeks, otherwise 0
\(a_{\text{prev VTE}}\) — 1 if there is a previous objectively diagnosed DVT or PE, otherwise 0
\(a_{\text{hemo}}\) — 1 if there is hemoptysis, otherwise 0
\(a_{\text{cancer}}\) — 1 if there is malignancy treated within 6 months or currently palliative, otherwise 0

The score is the sum of weighted clinical criteria and ranges from 0 to 12.5 points. It estimates the probability that a patient's symptoms are caused by pulmonary embolism before any laboratory or imaging test is performed.

The total is classified either by the three-tier model (low < 2, moderate 2–6, high > 6 points) or by the two-tier model used in the Christopher study (PE unlikely ≤ 4, PE likely > 4 points).

Wells Score for PE – Calculation Example

Example: a patient presents with a swollen, tender calf suggestive of DVT, a heart rate of 110 bpm, no hemoptysis, no recent surgery or immobilization, no previous DVT or PE, no active malignancy, and an alternative diagnosis is considered more likely than PE.

\[ \text{Score} = 3 + 1.5 = 4.5 \text{ points} \]

Result: 4.5 points — moderate probability (three-tier model); PE likely (two-tier model, since the score is above 4). This corresponds to a PE prevalence of roughly 15–25%; the patient should typically proceed to CT pulmonary angiography rather than relying on D-dimer alone.

How to Use the Wells PE Calculator

Check the box Clinical signs and symptoms of DVT if the symptomatic leg shows minimum swelling and tenderness along the deep venous system (+3 points).
Check Pulmonary embolism is the most likely diagnosis if, in your clinical judgement, PE explains the presentation better than alternatives such as pneumonia, pneumothorax, musculoskeletal pain, or heart failure (+3 points).
Enter the patient's Heart rate (HR) in bpm — 1.5 points are added automatically when it exceeds 100 bpm.
Check Immobilization for at least 3 days or surgery within 4 weeks if applicable (+1.5 points).
Check Previous objectively diagnosed DVT or pulmonary embolism if the patient has a confirmed history (+1.5 points).
Check Hemoptysis and Malignancy treated within 6 months or currently palliative if applicable (+1 point each).
Read the total Wells PE score, the probability category in the three-tier model, the two-tier classification, and the interpretation of what the result means for further testing.

What Is the Wells Score for Pulmonary Embolism?

The Wells score is the most widely used clinical prediction rule for estimating the pretest probability of pulmonary embolism — that is, how likely PE is before you order D-dimer or imaging. It was originally developed by Wells and colleagues (Lancet, 1997) and has since been validated in large prospective studies, including the Christopher study (JAMA, 2006) that established the simplified two-tier version now recommended in many guidelines.

The score matters because pulmonary embolism can be difficult to suspect on symptoms alone: shortness of breath, chest pain, and tachycardia are common to many conditions. By combining the strongest clinical predictors — signs of DVT, subjective judgement that PE is the most likely diagnosis, tachycardia above 100 bpm, immobilization or recent surgery, previous venous thromboembolism, hemoptysis, and active malignancy — the Wells score stratifies patients into groups with very different PE prevalences. In validation studies, PE was found in roughly 1–4% of low-risk patients, 15–25% of moderate-risk patients, and 40–65% of high-risk patients.

The purpose of the score is not to diagnose PE, but to guide the diagnostic pathway. A low or "PE unlikely" result means a D-dimer test is an appropriate first step: if the D-dimer is normal, PE can be excluded without exposing the patient to contrast CT radiation. A high or "PE likely" result usually warrants going straight to CT pulmonary angiography, because even a normal D-dimer may not lower the probability enough to rule out the disease safely in this group.

The two classification models can give different answers for the same patient — a score of 4.5 is "moderate" in the three-tier model but "PE likely" in the two-tier model. Both are shown so you can follow whichever pathway your local protocol uses. Note that some guidelines adjust D-dimer thresholds by age or use the simplified Wells criteria where every item scores 1 point and HR > 100 counts twice; check which variant your institution applies.

Assumptions and Limitations

The item "PE is the most likely diagnosis" is a subjective judgement, which is why inter-observer agreement for the Wells score is only moderate. Two clinicians can score the same patient differently.
The score estimates probability, not certainty. PE still occurs in low-scoring patients, and a high score does not confirm the diagnosis — imaging is always required to establish it.
The original score performs best in the population it was derived from (mostly emergency department and inpatients with suspected PE). It has not been as thoroughly validated in pregnant patients, children, or patients already on anticoagulation.
Conditions not captured by the score — recent long-distance travel, estrogen therapy, thrombophilia, or strong family history — may raise the probability beyond what the number suggests.
The calculator uses the traditional point weights (+3, +1.5, +1). If your protocol uses the dichotomized variant, mentally convert: any criterion present counts as 1 point, with HR > 100 bpm counted twice.
This tool is for educational and clinical decision-support use; it does not replace clinical judgement, institutional protocols, or the assessment of a qualified physician.

Related Calculators

For suspected deep vein thrombosis in the leg rather than PE, use the Wells Score for DVT calculator. Other clinical decision rules you may find useful include the HEART Score for chest pain, the CURB-65 Score for pneumonia severity, and the qSOFA Score for suspected sepsis.

Frequently Asked Questions

How do I calculate the Wells PE score by hand?

Add the points for each criterion present: clinical signs of DVT (+3), clinical judgement that PE is the most likely diagnosis (+3), heart rate over 100 bpm (+1.5), immobilization for at least 3 days or surgery within 4 weeks (+1.5), previously confirmed DVT or PE (+1.5), hemoptysis (+1), and active or recently treated cancer (+1). The maximum possible total is 12.5 points. For example, tachycardia of 110 bpm plus a history of PE gives \(1.5 + 1.5 = 3\) points.

What is a normal or dangerous Wells score?

There is no "normal" value — the score estimates how likely PE is before testing. Under 2 points is low probability (PE found in roughly 1–4% of patients), 2–6 is moderate (about 15–25%), and above 6 is high (about 40–65%). In the two-tier model, 4 points or fewer means "PE unlikely" and more than 4 means "PE likely." Any score is only a probability estimate; a low score never fully excludes PE on its own.

Why do the three-tier and two-tier models give different answers for the same score?

The models use different cutoffs, so borderline scores land in different groups. A score of 3 to 4 is "moderate" in the three-tier model but "PE unlikely" in the two-tier model, while 4.5 to 6 is "moderate" yet "PE likely." The two-tier version was introduced by the Christopher study to simplify decisions: "PE unlikely" goes to D-dimer first, "PE likely" goes straight to CT pulmonary angiography. Follow whichever pathway your local protocol uses.

How does the Wells score work together with a D-dimer test?

The score determines whether D-dimer testing is useful. In the "PE unlikely" or low-probability group, a normal D-dimer can safely rule out PE without imaging. In the "PE likely" or high-probability group, D-dimer is skipped because even a normal result cannot lower the probability enough — CT pulmonary angiography is performed directly. Some guidelines use age-adjusted D-dimer cutoffs (age × 10 µg/L for patients over 50), which increase the usefulness of D-dimer in older patients.

Is the Wells PE score accurate, and who should not use it?

It is well validated in emergency department and hospitalized adults with suspected PE, but it performs less reliably in pregnant women, children, and patients already on anticoagulation. Because the item "PE is the most likely diagnosis" is a subjective judgement, two clinicians can score the same patient differently. Risk factors the score ignores — long flights, estrogen therapy, thrombophilia, or strong family history — can raise the true probability. Always combine the score with clinical judgement.

Does a heart rate of exactly 100 bpm count in the Wells score?

No. The criterion is a heart rate strictly greater than 100 bpm, so 100 bpm itself adds no points while 101 bpm adds 1.5. Heart rate is entered in beats per minute (bpm); if you have a value in beats per second or from an ECG strip, convert it first (multiply beats per second by 60). Use a measured resting rate, since pain or anxiety at the time of measurement can inflate it.

Can the Wells score diagnose pulmonary embolism?

No — it only estimates the pretest probability and guides which test to order next. Even patients in the high-probability group sometimes have normal CT angiography, and PE occasionally occurs in low-scoring patients. The diagnosis must be confirmed or excluded with objective testing such as D-dimer, CT pulmonary angiography, or ventilation-perfusion scanning. If a patient is hemodynamically unstable with suspected massive PE, follow your institutional massive PE protocol rather than waiting for scoring.

Wells Score for Pulmonary Embolism Calculator