What is the proper technique for obtaining a tympanic temperature measurement in adults and children, including preparation, positioning, probe insertion depth, and contraindications?

How to Take Tympanic Temperature

Critical Caveat: Tympanic Infrared Thermometry is Unreliable for Clinical Decision-Making

Tympanic infrared thermometers should not be used as a reliable method for temperature measurement in clinical settings, as they consistently underestimate core temperature and show poor agreement with accurate methods. 1, 2

The Society of Critical Care Medicine and Infectious Diseases Society of America explicitly recommend against using infrared tympanic thermometers in critical care settings due to their unreliability. 2 These devices measure ear canal temperature rather than true tympanic membrane temperature, resulting in systematic underestimation of core body temperature by 0.4-0.8°C with wide variability (±0.6-0.7°C). 3, 4

Hierarchy of Temperature Measurement Methods

When choosing a temperature measurement method, follow this evidence-based hierarchy from most to least accurate: 1, 2

Most Accurate (Core Temperature):

• Intravascular thermistors (pulmonary artery catheter)
• Esophageal thermistors
• Bladder catheter thermistors

Acceptable Alternatives:

• Rectal thermometers (avoid in neutropenic patients)
• Oral thermometers (sublingual placement)

Unreliable and Not Recommended:

• Tympanic infrared thermometers
• Temporal artery (no-touch) thermometers
• Axillary measurements (underestimate by 1.5-1.9°C)
• Chemical dot thermometers

1, 2

If Tympanic Infrared Thermometry Must Be Used: Proper Technique

Despite its limitations, if no other method is available, follow these steps to minimize measurement error: 3, 4

Preparation

• Remove obstructing cerumen if present, as it may interfere with readings (though studies show mixed results on this effect). 1, 4
• Ensure the device lens is clean and free of debris or earwax. 5
• Allow at least 90-120 seconds between consecutive measurements in the same ear to prevent artificially low readings from cooling the ear canal. 3, 4

Positioning

• Position the patient's head to straighten the ear canal: pull the pinna up and back in adults, down and back in children. 3
• Hold the thermometer grip in the "telephone handle position" (60-degree angle following the mandibular ramus), as rotation away from this position significantly decreases accuracy. 3, 4
• Insert the probe 3.5 cm into the ear canal to approximate the distance to the tympanic membrane. 1

Measurement Technique

• Take the temperature reading immediately upon positioning the probe—do not dwell in the canal for more than 0-5 seconds before measurement, as this cools the canal and lowers readings. 3, 4
• Ensure an adequate seal to prevent ambient air from affecting the reading. 1
• Record the measurement site (tympanic) with the temperature value in the medical record. 1

Contraindications and Limitations

• Do not use if inflammation of the auditory canal or tympanic membrane is present. 1
• Do not use if external canal obstruction prevents proper probe placement. 1
• Note that cerumen impaction does not meaningfully affect infrared tympanic temperature measurements according to otolaryngology guidelines. 1
• Tympanic temperatures can be influenced by convective air currents during resuscitation efforts. 1

Clinical Implications of Inaccurate Measurement

Temperature discrepancies of 1-2°C from actual core body temperature commonly occur with infrared tympanic methods. 2 In 10% of patients, the difference between rectal and tympanic infrared measurements exceeds 1°C. 6 Among patients with rectal temperatures ≥38.5°C, only 60% were identified as febrile by infrared tympanic thermometry. 6

Missing fever or hypothermia can have mortality implications, as patients with serious infections may present with hypothermia rather than fever, and inaccurate temperature measurement could delay recognition and treatment of life-threatening conditions. 2

Recommendation for Clinical Practice

If neither central thermometry nor oral/rectal measurements are feasible, any temperature obtained from infrared tympanic methods is unreliable and should not guide clinical decisions. 2 In such cases, base clinical assessment on other signs of infection (hemodynamic instability, altered mental status, leukocytosis, elevated lactate) rather than relying on the temperature value itself. 1, 2

A new onset temperature of ≥38.3°C or ≤36.0°C should trigger clinical assessment but not necessarily automatic laboratory or radiologic evaluation for infection. 1