PERC Rule
It is important to note that the PERC rule was never intended to be applied to anything but a low risk group of patients determined either by clinical gestalt or by the Wells PE score - Jason West MD
HWN Suggests
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. 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... So who are the CT-PE or V/Q positive patients who could have been falsely “PERC ruled out?” Is there data on false PERC rule negative patients as determined by a positive CT-PE or V/Q scan?
Featured
PERC Rule
Rules out PE if no criteria are present and pre-test probability is ≤15%.
Pulmonary Embolism Rule-Out Criteria: A Clinical Decision Rule That Works
A clinical decision rule that gives a 99% clinical probability of no PE, allowing the physician to avoid workup (e.g., d-dimer test, CT), is impressive. In comparison, 14 validation studies of the Wells Criteria revealed that 1.3% to 27.9% of patients deemed to be low risk had a PE.5 It appears that the PERC rule is far more sensitive.
Articles of Interest
Puzzling out the PERC rule
Because his head is still spinning from yesterday’s ‘D-dimer talk’, the intern decides to talk you about how to rule out a pulmonary embolism in this patient. You take a deep breath, crack your knuckles, and prepare yourself for the ‘PERC rule’ talk….
PERC Rule for Pulmonary Embolism
There is no need to apply the PERC Rule to those patients who are not being evaluated for PE. If the patient is considered low risk, the PERC Rule may help avoid further testing. If the patient is moderate or high risk, then PERC Rule cannot be utilized.
PERC Rule in the Evaluation for Pulmonary Embolism in Low-Risk Patients
The PERC (Pulmonary Embolism Rule-out Criteria) rule can be used in the initial evaluation for pulmonary embolism (PE) in low-risk patients to exclude the diagnosis of PE based on historical and physical examination data alone. A patient's low-risk risk status can be determined by either clinician judgement or by using Wells Criteria. If a patient fails to meet any of the below criteria then a D-dimer can be done to aid in the decision of whether or not the patient should get a CT angiography of the chest to rule out the presence of a PE.
PERC – Still (Mostly) Useless
…except, perhaps, in a risk-management sense – but, only if we keep beating it down into its narrowest application due to its terrible specificity. As an aside, in this era of over-testing and over-diagnosis of PE, the diagnosis of PE isn’t necessarily the ideal endpoint – what we should be following are patient-oriented outcomes such as death/heart failure in untreated PE in PERC-negative patients to truly make it a valid tool.
PERCs of the Wells Score
In patients that are low risk based on either WELLS or clinical gestalt, another option is to use the PERC rule instead of a d-dimer to rule out PE. This can help avoid the problem of dealing with a positive d-dimer in a patient whom you really do not think has a PE. The PERC rule was created in 2004.
Pulmonary embolism rule-out criteria (PERC) in pulmonary embolism—revisited: A systematic review and meta-analysis
Because of the high sensitivity and low negative likelihood ratio, PERC rule can be used confidently in clinically low probability population settings.
