A rectal temperature measures the body’s internal temperature by inserting a thermometer into the rectum. This method is the most precise way to assess core body temperature, especially when other methods are less reliable. While often associated with infants, it can be necessary for adults. Rectal temperatures typically register slightly higher than oral temperatures, usually by about 0.5 to 1 degree Fahrenheit (0.3 to 0.6 degrees Celsius).
Essential Preparation
Gathering the necessary supplies ensures a smooth and hygienic process. You will need a digital thermometer specifically designed for rectal use, a water-soluble lubricant, disposable probe covers, and clean gloves. Ensure the thermometer is clean and functioning correctly; if reusable, clean and disinfect it before and after each use. Creating a private and comfortable environment for the individual helps them relax.
Administering a Rectal Temperature
Proper positioning ensures comfort and accessibility. The individual should lie on their side with the upper leg flexed towards the chest, often called the Sims’ position, to expose the anal area. Maintain privacy and warmth by exposing only the necessary region.
Attach a disposable probe cover to the digital thermometer and apply a generous amount of water-soluble lubricant to the tip, covering about 1 to 1.5 inches (2.5 to 3.8 cm). Gently clean any feces or secretions around the anal area before proceeding.
Gently part the buttocks to expose the anus. Ask the individual to take a slow, deep breath and relax. Carefully insert the lubricated thermometer tip into the rectum, aiming towards the belly button, to a depth of approximately 1 to 1.5 inches (2.5 to 3.8 cm) for adults. Do not force the thermometer if resistance is felt, as this could cause injury.
Hold the thermometer steady until it beeps, signaling the reading is complete. This typically takes about 15 seconds to a minute. Carefully remove the thermometer. Dispose of the probe cover and wipe the anal area clean of any lubricant or residue.
Understanding Readings and Important Considerations
Read the digital display on the thermometer. A normal rectal temperature for adults typically falls between 97.6°F to 100.6°F (36.4°C to 38.1°C). A rectal temperature of 100.4°F (38°C) or higher generally indicates a fever.
Never force the thermometer during insertion, as this can cause trauma or damage to the rectal tissue. Rectal temperature measurement should be avoided in individuals who have recently undergone rectal surgery, have hemorrhoids, or have certain cardiac conditions, as insertion could stimulate the vagus nerve. This method should also be avoided in individuals with bleeding disorders or low platelet counts due to the risk of bleeding.
Seek medical advice if a fever is 103°F (39.4°C) or higher, lasts more than a day or two, or is accompanied by severe symptoms like a stiff neck, confusion, or difficulty breathing. After use, clean the thermometer thoroughly with antibacterial soap and cool water, then disinfect the probe with rubbing alcohol or an alcohol-based wipe, allowing it to air dry completely before storage.