When the PERC Rule Fails
Kline et al developed a clinical decision tool based on parameters that could be obtained from a brief initial assessment to reasonably exclude the diagnosis of pulmonary embolism (PE) without the use of D-dimer in order to prevent unnecessary cost and the use of medical resources. 1 Many of us have used the Pulmonary Embolism Rule-out Criteria (PERC) rule by now, but we should be clear on what it includes. Are we using it appropriately?