Towards evidence-based emergency medicine: Best BETs from the Manchester Royal Infirmary. BET 3: Pulmonary embolism rule-out criteria (PERC) for excluding pulmonary embolism.

A short-cut review was carried out to establish whether the pulmonary embolism rule-out criteria (PERC) can safely exclude the diagnosis of pulmonary embolism (PE) in the emergency department (ED). One recent systematic review was directly relevant to the question and incorporated all the other relevant evidence identified. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are shown in table 3. The clinical bottom line is that PERC may be safely applied to patients aged 18-49 years presenting to the ED with chest pain and/or dyspnoea providing that the pre-test probability of PE is 7% or less (equivalent to a Wells score of <2).