Avoid CT pulmonary angiography in emergency department patients with a low-pretest probability of pulmonary embolism and either a negative Pulmonary Embolism Rule-Out Criteria (PERC) or a negative D-dimer.

October 27, 2014

Advances in medical technology have increased the ability to diagnose even small blood clots in the lung. Now, the most commonly used test is known as a CT pulmonary angiogram (CTPA). It is readily available in most hospitals and emergency rooms. However, disadvantages of the CTPA include patient exposure to radiation, the use of dye in the veins that can damage kidneys and high cost.

Studies have demonstrated that certain findings in a patient’s medical history put them at very low risk for having a blood clot in the lung. In some cases, a blood test called a D-dimer may be additionally used to screen for the possibility of a clot. If patient historical factors and physical examination findings are negative, along with a negative D-dimer (if the physician chooses to order it), evidence shows that the risk of an undiagnosed blood clot is the same as if the patient had a negative CTPA. Such a strategy saves the risk of radiation, kidney injury and the high cost of a CTPA.


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