For the diagnosis of certain ailments, a rectal exam may be done. Suppositories may be inserted into the rectum as a route of administration for medicine. The endoscopic procedures colonoscopy and sigmoidoscopy are performed to diagnose diseases such as cancer.
Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital thermometer until it "beeps", not more than 25 mm (1 inch) into the rectum via the anus. Due to recent concerns related to mercury poisoning, the use of mercury thermometers is now discouraged. Normal rectal temperature generally ranges from 97.6 to 100.4 °F (36 to 38 °C) and is about 1 °F (0.5 °C) above oral (mouth) temperature and about 2 °F (1 °C) above axillary (armpit) temperature. On average, the rectal temperature is 0.7 °F (0.4 °C) higher than oral temperature. Many pediatricians recommend that parents take infants and toddler's temperature in the rectum for two reasons: (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical. (2)Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults. In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy and modesty have led some parents and doctors to discontinue taking rectal temperatures.
