A rectal temperature is often considered more accurate than an oral or axillary temperature, due to potential alterations in the mouth temperature from beverage intake and alterations in skin temperature due to ambient conditions. There are many types of thermometers available on the market today. For a rectal temperature, a digital thermometer with a probe cover is recommended. A normal rectal temperature is 99.6 degrees F., one degree higher than a normal oral temperature. Taking a rectal temperature is contraindicated for certain conditions.
Rectal temperatures should not be taken in most people with a heart condition. According to "Taking Vital Signs," a rectal probe can stimulate the vagus nerve, which surrounds the anus. This can cause a dangerous heart arrhythmia and fainting.
Recent rectal, anal, vaginal and prostate surgeries are all contraindications for taking a rectal temperature due to the risk of damage from the thermometer. A different route must be used until the patient has healed from surgery.
Diarrhea can change the temperature inside the rectum. Also, inserting the temperature probe inside the rectum of someone experiencing diarrhea can cause that person to have another bowel movement while you are trying to get the temperature reading.
Hemorrhoids are considered a contraindication for taking a rectal temperature. This is true whether the hemorrhoids are external or internal. This contraindication is due to the risk of the temperature probe harming the tissues. Additionally, if the probe is placed near hemorrhoids, the temperature reading could be incorrect.
Certain Intestinal Conditions
Colitis is considered to be a contraindication for taking a rectal temperature due to the chance of damage to the rectum from the thermometer. Bleeding from the rectum is another contraindication. Sometimes, it is because the cause of the bleed is unknown and adding the possibility of causing bleeding by inserting the thermometer can confuse the diagnosis. Secondly, the bleeding could be due to a condition that could be further harmed by the insertion of the probe.
Drugs.com relates that rectal temperatures are contraindicated in people who have a tendency to bleed easily. Patients with a low platelet count or hemophilia fall into this category. Patients who take blood-thinners may also need to avoid getting a rectal temperature. This is due to the possibility of injuring the rectum and causing a bleed that is difficult to control.
Rectal temperatures should not be performed on people with a fecal impaction (a large, firm stool that is caught in the large intestine or rectum due to an inability to pass it) for two reasons: the thermometer may go into the stool, causing an inaccurate reading, and the tissue in the rectum may be compromised by a large fecal impaction, increasing the odds that a temperature probe will cause damage to the tissue.
Some practitioners recommend that only medical personnel take a rectal temperature in an infant under one month old. Others recommend avoiding rectal temperatures in people over 80 years of age. Both of these recommendations are based on the increased likelihood of damage to the tissues of the rectum.