A brief history of rectal temperatures

Andrew Katz
6 min readJan 1, 2021

Because someone had to write it.

Rectal Temp Bum Cake ©Katherine Dey at Deviant Desserts, LLC

The lowly rectal temperature.

It’s been a dreaded component of medical encounters, a new parent’s worst nightmare and the inspiration (don’t say butt … don’t say butt…) for countless stand-up comedy routines. Historically it doesn’t appear to date as far back as one would imagine. After all, the first mercury thermometers were a foot long and took about twenty minutes to register. It wasn’t until the turn of the 19th century that Dr Charles Allbutt (no, I’m not making that up) patented a practical-to-use clinical thermometer.

Dr Allbutt’s patented clinical thermometer © Library of Congress

Preferred sites then were the mouth or axilla (armpit). The rectum was considered, but it’s likely that not enough studies had been done at that point to support its reliability. And, anyway, it wasn’t most people’s first choice.

Rectal temps seem to have come into widespread use shortly before or during the Second World War. William Manchester, for example, in his memoir of the Pacific Theater, Goodbye Darkness, recounts having his rectal temp checked by a corpsman (whether that was for the sake of accuracy, policy or due to his injuries is not made clear) while being invalidated home. By the 1950s rectal temps had become the universal gold standard of body temperature measurement. In some hospitals policy was to use rectal temperatures on all patients unless there was some ano-rectal pathology present. Others mandated rectals for any patient under 18, or any patient admitted to pediatrics. ICU patients and those in CCU with acute MI (heart attack), or under seizure precaution, were also monitored with rectal temps well into the 1980s.

What’s the difference between oral and rectal temps? The taste!

Rectal temps were also in common use among women charting their basal body temperatures to predict ovulation, either to promote pregnancy or as a church-friendly method of contraception.

Born in the late 50s, I had the usual experience with rectal temps. My last one was about age six. I recall being at an unfamiliar doctor’s office. I don’t remember why. But the nurse had me pull down my…



Andrew Katz

LA born & raised, now I live upstate. I hate snow. I write on healthcare, politics & history. Hobbies are woodworking & singing Xmas carols with nonsense lyrics