The "PERC Rule" is used to assess a patient's risk for probability of PE in the emergency department.It involves evaluating the presence or absence of 8 clinical criteria to arrive at a pretest probability. And remember, this rule is supposed to be used for patients with really low pretest probability where you weren't concerned about PE to begin with. Some experts claim that "PERC negative" on the chart proves you considered PE in the differential diagnosis. But the test isn't designed to be used on EVERY patient as a means to rule out PE. Only use if you thought about the disease in a low risk patient and didn't plan on getting a d-dimer or further testing.
The criteria are (all must be YES):
age < 50 years
heart rate less than 100 beats per minute
room air oxygen saturations 95% or greater
no prior deep venous thrombosis [DVT] or PE
no recent trauma or surgery (4 weeks)
no hemoptysis
no exogenous estrogen
no clinical signs suggestive of DVT (Unilateral leg swelling on visual inspection
