Which thermometer site is the second most accurate for core temperature?

• A. Oral
• B. Axillary
• C. Tympanic
• D. Temporal

Answer: (C)

Estimating core temperature relies on using a site that reflects the body's inner temperature rather than surface warmth. After rectal temperature, which is typically the most accurate, the tympanic site is considered a close and reliable option among common measurement sites because it mirrors core temperature via the ear’s proximity to central blood flow.

A tympanic thermometer reads infrared energy from the tympanic membrane, which shares blood supply with the brain. That connection helps the reading align with core temperature, and the method is quick and noninvasive, making it practical for routine use by CNAs. To get trustworthy results, use proper technique: gently insert the probe into the ear canal toward the tympanic membrane, ensure the ear is free of cerumen, and avoid measurements if there’s ear infection or drainage. Also be aware that ear conditions, loose fittings, or excessive ambient heat can affect accuracy.

So, the tympanic site is the best-choice second option because it provides a near-core readout with speed and ease, balancing accuracy with practicality in many care settings.