This may be because the rectum contains no thermoreceptors and thus is heated or cooled as an effect of hypothalamic control, rather than in response to it. Even under the best of circumstances, without proper depth and dwell time, rectal temperature readings will be inaccurate. The axilla and groin When oral and rectal sites are inaccessible or inappropriate, the axilla or the groin may be used. The site doesn't reflect temperature fluctuations as well as other sites. The site and nearby areas are at risk for exposure to surrounding air.
Peripheral vasoconstriction occurs in shock.
Because of the risk of perforation, the rectum isn't used in neonates. The skin Adults' temperatures rarely are measured by their skin, though this quick technique may help track a trend. At best, it provides a peripheral body temperature with measurements that may vary widely because of vasomotor activity and ambient temperatures. These drawbacks particularly apply when using single-use chemical thermometers to measure temperature at the forehead, a site constantly exposed to ambient temperatures. A valid use of skin temperature is with incubated newborns.