π« Wells Score for Pulmonary Embolism
Is PE likely or unlikely, by the numbers?
Wells score (0-12.5)
For informational purposes only, not medical advice.
The Wells score for pulmonary embolism sums seven clinical items to a 0-12.5 score: over 4 means PE likely, 4 or under means PE unlikely. A patient with heart rate over 100 (1.5), prior VTE (1.5), and active malignancy (1) scores 4: PE unlikely by the two-tier rule, moderate probability by the three-tier rule, and the usual next step is a D-dimer before any scan.
Published by Phil Wells in 1998 and refined since, the score's real job is deciding who needs a D-dimer versus who goes straight to CT. Used properly, it cuts unnecessary scans without missing clots.
How to Use This Calculator
Answer the seven items from the bedside assessment. The two heaviest items, DVT signs and clinical judgment that PE is the top diagnosis, carry 3 points each and usually decide the outcome.
Answer the examination items: clinical signs of DVT (leg swelling, tenderness) and whether PE is the number one diagnosis or equally likely.
Answer the history items: heart rate over 100, immobilization or recent surgery, previous VTE, hemoptysis, and active malignancy.
Read the score with both the two-tier (likely/unlikely) and three-tier (low/moderate/high) interpretations, plus the typical next test.
The Seven Criteria
The subjective item, PE is the number one diagnosis, is the score's most debated feature and also one of its most predictive. It captures the clinician's synthesis of the whole picture, which turns out to carry real signal. The simplified Wells drops the 1.5s to 1s for mental math; this calculator uses the original weights.
| Score | Two-tier | Three-tier |
|---|---|---|
| 4 or less | PE unlikely | Low (under 2) or moderate (2-6) |
| Over 4 | PE likely | Moderate or high (over 6) |
Worked Example
A 62-year-old with treated colon cancer, a prior DVT five years ago, heart rate 108, no leg symptoms, and pleuritic chest pain where the clinician ranks PE as the top diagnosis: PE top diagnosis 3, heart rate 1.5, prior VTE 1.5, malignancy 1, totaling 7. That is PE likely, high probability, and the patient goes to CT pulmonary angiography without waiting on a D-dimer.
Contrast the calculator's default example: heart rate over 100, prior VTE, and malignancy but PE not the top diagnosis scores 4, PE unlikely. The 3 points for clinical judgment are the entire difference between scanning now and testing with D-dimer first, which shows how much weight the score gives the clinician's read.
Reading Your Result
PE unlikely with a negative D-dimer effectively rules out PE in most settings; that combination is the score's highest-value output, sparing the scan. PE likely skips the D-dimer because a negative one would not be trusted at high pretest probability. The three-tier version refines the middle: low-probability patients get D-dimer, moderate and high go to imaging.
My take: the Wells score fails most often when the subjective item is gamed. Scoring PE as top diagnosis to justify a scan you already wanted corrupts the tool. Answer it before deciding you want the scan, not after.
Limits
Wells was derived in emergency departments with suspected PE; it performs worse in inpatients, the elderly, and pregnancy, where gestalt and gestalt-plus-D-dimer need adjustment. It also does not apply to patients already on anticoagulation or with a confirmed DVT, where the question answers itself.
Related Tools
Two Wells inputs have their own pages: the blood pressure checker for vitals context and the BMI calculator, since obesity nudges VTE risk. For heart-focused risk, the diabetes risk calculator covers a shared risk factor.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the Wells score for PE?
A 7-item clinical prediction rule for suspected pulmonary embolism, scoring 0 to 12.5 points. Over 4 means PE likely; 4 or under means PE unlikely. It guides whether to order a D-dimer or go straight to CT pulmonary angiography.
How do you calculate the Wells score?
Add 3 points each for DVT signs and PE as top diagnosis, 1.5 each for heart rate over 100, immobilization or recent surgery, and prior VTE, and 1 each for hemoptysis and active malignancy. Maximum 12.5.
What does PE likely mean?
A Wells score over 4, indicating high enough pretest probability that a negative D-dimer cannot be trusted. These patients proceed directly to CT pulmonary angiography.
What does PE unlikely mean?
A score of 4 or less. Combined with a negative D-dimer, PE is effectively ruled out and no scan is needed. With a positive D-dimer, imaging follows.
What is the difference between two-tier and three-tier Wells?
Two-tier splits at 4 into PE likely versus unlikely, which maps directly to scan versus D-dimer decisions. Three-tier splits into low (under 2), moderate (2-6), and high (over 6) probability for finer risk communication.
Can the Wells score rule out PE by itself?
No. It estimates pretest probability; ruling out requires the D-dimer in PE-unlikely patients or imaging in PE-likely ones. The score alone never excludes or confirms.
Is there a simplified Wells score?
Yes: it rounds the 1.5-point items to 1 point, keeping the 3-point items, for easier mental math. Performance is nearly identical. This calculator uses the original weights for precision.
Does Wells work in pregnancy?
Less well; pregnancy changes D-dimer interpretation and the score was not derived in pregnant patients. Pregnancy-adapted algorithms exist and clinicians use them instead.
What is the subjective criterion?
Whether PE is the number one diagnosis or equally likely, worth 3 points. It captures clinical judgment and is among the most predictive items, but it must be answered honestly before deciding on imaging.
Who should use this calculator?
Clinicians evaluating suspected PE, plus students learning the rule. It reproduces a validated score for education. Suspected pulmonary embolism is an emergency; this page never replaces urgent care.