Clinical tool
Wells PE
Pre-test probability for pulmonary embolism.
Wells PE
0/ 12.5
Low probability
About 1 to 3% of patients in this group have PE. PERC, where applicable, or D-dimer is commonly used to decide on further testing.
- Two-tier reading
- PE unlikely. Score of 4 or less. D-dimer is commonly used; a negative result makes PE unlikely.
This score supports risk stratification and should be interpreted alongside the overall clinical context and current treatment guidance.
Score support, not a decision
What this calculates
Wells criteria for pulmonary embolism: seven weighted items giving a pre-test probability, from 0 to 12.5.
When to use it
In a haemodynamically stable patient with suspected PE, to decide between D-dimer and imaging.
How to interpret it
Three-tier: below 2 low, 2 to 6 moderate, above 6 high. Two-tier: 4 or less PE unlikely, above 4 PE likely. The 6.5 point threshold falls in the high group.
Important limitations
- The item for PE being the most likely diagnosis is subjective and the main source of variation.
- D-dimer is less useful in pregnancy, recent surgery, malignancy and older age, though age-adjusted cut-offs exist.
- Not for an unstable patient with suspected massive PE, who needs immediate resuscitation and imaging.
For practising medics only. Clinical tools support judgement, they do not replace it. Always verify results against current guidelines and the patient in front of you.