- Emergencies
- Pulmonology
- Vascular medicine
PERC score
Check eight criteria in a patient with a low clinical probability of pulmonary embolism
The PERC rule is designed for a specific situation: a patient in whom the clinician already considers the pre-test probability of pulmonary embolism to be low. When all eight criteria are negative, it can help avoid additional testing as part of a validated algorithm. It must not be applied to an intermediate- or high-risk patient.
- Number of questions
- 8 criteria
- Approximate duration
- ≈ 1 minute
- Population
- Adults with suspected low clinical probability pulmonary embolism
- Modality
- clinical rule
QuestionnairePERC
CLINICIAN SCORE
The patient must meet all of the following conditions at the same time. Only to be used in patients whose pre-test probability of pulmonary embolism is already deemed low.
Are you patient?
PERC is not a test for the general public: it is only relevant after an initial clinical probability assessment by a healthcare professional.
Question 1 / 8
Age < 50 years
Terms of contract
The PERC rule only applies after a prior clinical assessment has deemed the probability of pulmonary embolism to be low (less than 15% according to NICE), with other plausible diagnoses considered. Oxygen saturation must be measured on room air and all eight criteria must be completed; an unknown criterion cannot be assumed negative. The surgery/trauma criterion applies to the past four weeks requiring hospitalisation. PERC is only used following a low prior clinical assessment; it is not a general screening tool.
Score interpretationPERC
Each unfulfilled condition counts as a positive criterion (1 point). Total of 0 to 8 positive criteria.
Total score
First reading
0 to 0
8 negative criteria + low prior clinical probability: negative PERC.
1 to 8
At least 1 positive criterion: positive PERC.
0 positive criteria (8 negative criteria) with low pre-test clinical probability: PERC negative; at least 1 positive criterion: PERC positive.
Off-label use increases the risk of false reassurance. Oxygen saturation, medical history, and pre-test risk assessment must be properly established.
Frequently asked questions
Sources and references
Kline JA et al.
Kline JA et al., J Thromb Haemost, 2004
Questionnaires and associated scores
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