As you palpate the carotid artery, you may detect vibrations, or thrills, like the throat vibrations of a cat when it purrs. Proceed to auscultation.

Auscultate both the carotid arteries to listen for a bruit, a murmur-like sound arising from turbulent arterial blood flow. Ask the patient to stop breathing for ∼15 seconds, then listen with the diaphragm of the stethoscope, which generally detects the higher frequency sounds of arterial bruits better than the bell. Note that higher-grade stenoses may have lower frequency or even absent sounds, more amenable to detection with the bell. Place the diaphragm near the upper end of the thyroid cartilage below the angle of the jaw, which overlies the bifurcation of the common carotid artery into the external and internal carotid arteries. A bruit in this location is less likely to be confused with a transmitted murmur from the heart or subclavian or vertebral artery bruits.

Listen for bruits in older patients and patients with suspected cerebrovascular disease.

Because auscultation has low sensitivity and specificity for detecting asymptomatic carotid disease (46% to 77% and 71% to 98%) and there are high rates of false positives with ultrasound, the USPSTF recommends against routine screening. Consider further evaluation for high-risk groups.

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