Why is rectal temperature measurement considered more accurate?

Rectal temperature measurement is considered more accurate because it is taken from a location that is fully internal within the body. The rectum is a stable environment for temperature measurement, typically reflecting the core body temperature better than other sites such as oral or axillary (underarm) sites. This is due to the fact that the rectum is less affected by external factors such as ambient temperature, recent food or drink intake, and the presence of circulation issues that can impact readings from peripheral sites.

Moreover, the rectal cavity is closer to the internal body temperature, which provides a more consistent and reliable measure of the body's true temperature, making it particularly useful in clinical settings for diagnosing fever or other body temperature abnormalities. Other methods can be influenced by external factors or may take longer to stabilize, which is not the case with rectal measurements.