Criteria
Pulmonary Embolism Rule-Out Criteria (the PERC rule)
If you have a low clinical suspicion of PE, use the Pulmonary Embolism Rule-Out Criteria (the PERC rule).[76]
In patients who meet all of the criteria (age <50 years; initial heart rate <100 bpm; initial oxygen saturation >94% on room air; no unilateral leg swelling; no haemoptysis; no surgery or trauma within last 4 weeks; no history of venous thromboembolism; no oestrogen use), the risk of PE is considered to be lower than the risk of testing, and no further testing is indicated. Patients who do not meet the PERC rule can be stratified using the Wells (or Geneva) score.[76]
One meta-analysis of studies that assessed the accuracy of the PERC rule to exclude PE reported a sensitivity of 97%.[145]
Wells and Geneva scores
If you have a high clinical suspicion of PE or the patient does not meet the PERC rule, use the original Wells criteria (modified), simplified Wells criteria (modified), original Geneva score (revised), or the simplified Geneva score (revised) to determine a clinical (pre-test) probability that corresponds to confirmed PE prevalence.[146][147] [ Pulmonary Embolism Wells Score Opens in new window ] [ Revised Geneva Score for Estimation of the Clinical Probability of Pulmonary Embolism in Adults Opens in new window ] Each of these clinical decision tools assigns a value (a single point, or points) to a series of historical and physical examination features, the sum of which determines whether PE is likely or unlikely.
[Figure caption and citation for the preceding image starts]: Original and simplified Wells criteria (modified)Created by BMJ Knowledge Centre [Citation ends].
[Figure caption and citation for the preceding image starts]: Original and simplified Geneva score (revised)Created by BMJ Knowledge Centre [Citation ends].
The simplified versions of the modified Wells criteria or revised Geneva score may be preferred in clinical practice because of their ease of use.[148] Both simplified versions have been validated; neither has been shown to be superior to the other.[100] However, the Geneva score is based entirely on objective clinical items and may be more reproducible (the Wells criteria [original and simplified] include the subjective clinical item 'alternative diagnosis less likely than PE').[149]
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