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Rectal thermometry

Rectal thermometry is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rectal thermometry rather than just read about it. In short: Rectal thermometry is taking a person's temperature by inserting a thermometer into the rectum via the anus. This is generally regarded as the most accurate means of temperature-taking, although some may consider it to be an invasive or humiliating procedure.

Rectal thermometry — main illustration
Rectal thermometry — illustration

Key takeaways

  • Rectal thermometry belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Rectal thermometry to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Rectal thermometry from memory before moving on to harder problems.

Reference excerpt

Rectal thermometry is taking a person's temperature by inserting a thermometer into the rectum via the anus. This is generally regarded as the most accurate means of temperature-taking, although some may consider it to be an invasive or humiliating procedure. Thus, it is often used sparingly, and primarily on infants, children, or adults for whom taking an oral temperature would risk injury (e.g., an unconscious patient, a post-oral surgery patient, or a person suffering a seizure) or be inaccurate (due to recently ingested liquids or breathing through the mouth).

History The precise history of rectal thermometry is largely unknown, but medical thermometers have long been made in a tube shape that fits into the anus. Medical literature shows the practice dating back to at least the 18th century, and it is probable that rectal thermometry was thought to be a safer alternative to oral temperature-taking, due to the use of mercury and other toxic chemicals in early thermometers.

In 1966, Time Magazine noted: Near dawn every morning, a nurse walks into the hospital room, wakes the patient and subjects him to what for many remains a humiliating procedure, although it has become routine: insertion of a rectal thermometer. As thermometry-related technology improves in the 21st century, rectal thermometry is becoming less common, but it is still the preferred method for taking the temperature of infants and pets.

Use and procedure

Rectal thermometry remains widely used in pediatrics and veterinary medicine, where it is the preferred means of determining body temperature. It is also practiced by adults at home who want the most accurate possible temperature reading and are willing to overlook the invasive nature of the painless procedure. It is accomplished by inserting the tip of a thermometer, usually lubricated, to eliminate friction when pushed through past the tightly retentive anal sphincter, to a depth of 1.5 inches (3.8 cm) for an adult, or between .5 and 1 inch (1.3 and 2.5 cm) for a child. The thermometer tip must then be left in place until a reading can be derived, usually about 3 minutes for mercury thermometers and 1 minute for newer electronic types. Anal thermometers are often colored cherry red to differentiate them from oral or axillary thermometers. Their bulbs also have a shorter, squat shape similar to a pear. They are not meant to be used interchangeably with other types of thermometers.

References

Illustrations

Rectal thermometry: A nurse taking the rectal temperature of a child
A nurse taking the rectal temperature of a child
Rectal thermometry: For hygiene reasons, medical mercury-in-glass thermometers that were intended for rectal temperature used to be color-coded red. This differentiated them from thermometers for oral temperature, which were color-coded blue or green.
For hygiene reasons, medical mercury-in-glass thermometers that were intended for rectal temperature used to be color-coded red. This differentiated them from thermometers for oral temperature, which were color-coded blue or green.
Rectal thermometry: Different test prods: universal (top) and rectal (bottom)
Different test prods: universal (top) and rectal (bottom)

Worked examples

Example 1 — a first encounter with Rectal thermometry

Start with the simplest possible case. Write down what Rectal thermometry claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rectal thermometry before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rectal thermometry ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rectal thermometry

In research
Rectal thermometry appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Rectal thermometry in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Rectal thermometry is common in secondary-school and first-year university syllabi. It links to neighbouring topics Medical tests, Rectum, Thermometers, so understanding it makes those chapters shorter.
In everyday life
Look for Rectal thermometry outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rectal thermometry in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Rectal thermometry means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Rectal thermometry out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rectal thermometry in simple terms?

Rectal thermometry is taking a person's temperature by inserting a thermometer into the rectum via the anus. This is generally regarded as the most accurate means of temperature-taking, although some may consider it to be an invasive or humiliating procedure.

Why does Rectal thermometry matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rectal thermometry?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rectal thermometry.

Tags

  • Medical tests
  • Rectum
  • Thermometers

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