Pulmonary embolism probability scoring

The PERC rule is used to determine if any testing is needed, in those in who the diagnosis is unlikely. The Wells score is used to determine the probability of a pulmonary embolism based on a person's history and examination. There is additionally a Wells score for deep vein thrombosis.

PERC rule

PERC rule

Age > 49	1 0	+1
HR > 99/min	1 0	+1
Oxygen sats < 95%	1 0	+1
One leg swollen	1 0	+1
Previous VTE	1 0	+1
Coughing blood	1 0	+1
Surgery or trauma in last 4 wks	1 0	+1
Estrogen use	1 0	+1
Score

If the final score is 1 or more pulmonary embolism is not ruled out.

Wells score

Wells score

Symptoms of deep vein thrombosis	1 0	+3
Other diagnosis less likely	1 0	+3
Heart rate > 100/min	1 0	+1.5
Not moving ≥ 3 days OR surgery in last month	1 0	+1.5
Previous VTE	1 0	+1.5
Coughing blood	1 0	+1
Cancer in last 6 months	1 0	+1
Score

Traditional interpretation

• Score >6.0 — High (probability 59% based on pooled data)
• Score 2.0 to 6.0 — Moderate (probability 29% based on pooled data)
• Score <2.0 — Low (probability 15% based on pooled data)

Alternative interpretation

• Score > 4 — PE likely. Consider diagnostic imaging.
• Score 4 or less — PE unlikely. Consider D-dimer to rule out PE.