Using a rectal thermometer is safe, simple, and requires no forethought, and is considered the gold standard for diagnosing exertional heat stroke. In fact, it can be boiled down into twelve simple steps:

1. Remove the athlete from the playing field, if appropriate, to a shaded area (such as an EZ-Up tent, locker room/athletic training room, or tree shade).
   1. Note: it is recommended that a second adult (e.g. assistant, coach, parent, etc.) is present for performing the skill
2. Drape the patient appropriately (with towels or sheets) for privacy, if possible.
3. Position the patient on their side with their top knee and hip flexed forward.
4. Make sure the thermistor probe is cleaned with isopropyl alcohol.
5. Lubricate the probe.
6. Make sure the probe is plugged into the thermometer.
7. Turn the thermometer on.
8. Insert the probe 15 centimeters past the anal sphincter.
9. If you meet resistance while inserting, stop and remove the probe, then try again.
10. Leave the probe in for the duration of treatment.
11. After treatment has ended, remove the probe gently.
12. Discard the probe after use.

Thermometer refers to a rigid device used to measure and read/record small changes in temperature, but does not allow for continuous temperature monitoring as the device must be removed after each reading is obtained.

Thermistor refers to a flexible or non-rigid device used to measure small changes in temperature and allows for continuous temperature monitoring since it may stay in place during treatment.

Updated as of: August 10, 2026