Because someone had to write it.
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.
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 drawers and in it went. I didn’t like it because my mother had switched me to oral temps a few months prior. But it wasn’t that big a deal, either. Kids wanted to feel grown-up. Had things been the other way around — if babies got oral temps and grown-ups rectals — we’d have had our pants down sooner than you could say pass me the Vaseline.
I didn’t encounter them again until 1971. Believing I was both suicidal and all-around asshole, my parents checked me in, against my will, to a psychiatric hospital. I began my stay in the facility’s ICU. One of my roommates, a man in his fifties who, I think, was being treated for alcoholism, developed a fever. I was standing by the door to our room, chatting with another patient when the orderly, Leonard, came by. He held up an object that looked like a pocket watch with a button on one side and a meat thermometer spike on the other.
I stick it in like this, Leonard said, with a sharp, upward motion, pull the button, and two seconds later, it registers.
We nodded. Ahh, the wonders of technology!
He did that to my roommate several times, usually while the rest of us were on hand to watch.
Whether this was an effort to be more precise, or out of fear that ICU patients might bite down on glass thermometers, or, as in One Flew Over the Cuckoo’s Nest, to establish psychological dominance, I never found out. For the rest of my time in ICU I made it my business never to show any sign of illness. Out in the residential unit temp checks were done orally.
What did the nurse say when she found a rectal thermometer in her pocket? Some asshole has my pen!
Fast forward, 1978. I was working nights as a nurse’s aid in long term care. Many of our patients required rectal temps because their level of consciousness didn’t permit oral temps. Some of the older nurses requested rectals on all the patients. None ever complained. They were an elder population, and it was what they had come to expect while being in the hospital. A new NA started. She had no experience working in hospitals. One night, after the charge nurse asked her to check a patient’s temperature, she came back with a reading way, way off the scale.
Rectal thermometers don’t read that low, we teased her.
The one I use on myself does, she countered.
You use a rectal thermometer on yourself? I asked.
She means the one she uses for her daughter,” another aid said. For we knew she was the mother of a toddler.
No. No, I use it on myself,” she insisted.
That’s how I learned about BBTs. She and her husband had been trying to conceive without success. Her fertility doctor proposed BBT charting.
No doctor is going to tell you to use oral temps, right?” she explained.
When I mentioned this to my girlfriend at the time, she nodded. She was also doing rectal BBTs, in her case as a form of birth control.
Was that why she had never spent the night?
A few years later I was in nursing school. A representative from Planned Parenthood gave us an in-service on contemporary birth control and fertility treatments. When she came to BBTs, she stated categorically they were done orally.
Why the seeming disconnect? Perhaps because both the NA from long-term-care (who became my good friend and was in the same nursing class) and my girlfriend were from less developed countries, where women’s access to education lagged, and people submitted more readily to the authority of doctors and other professionals. But even in more developed countries, such as France and Sweden, rectal temps remained popular well into the 90s.
My first job after school was in a burn center. Burns are open wounds, leaving the victim vulnerable to sudden onset infections, which make temperature monitoring crucial. Most of the nurses, and not just the older ones, used oral temps on the non-critical patients, but switched to rectal readings whenever one developed a fever. Usually, after hearing this in report at the start of my shift, I’d switch them back to oral. Studies at the time backed me up, promoting oral temps as closer to the gold standard of reflecting core body temperature (which is defined as the temperature of the superior pulmonary artery) than rectal. Besides, I’m naturally diffident. I guard my body space and respect that of others. That’s not always the best quality in a nurse, but it made me popular with my patients.
If you come into our store without a mask, we will have to take your temperature. And we only have rectal thermometers!
Measuring temps rectally has become uncommon enough for someone to ask on Quora if non-veterinary rectal temperature reading was an urban legend.
But don’t count them out entirely. Recent literature suggests that in infants and small children tympanic and contact thermometers occasionally miss dangerous fevers. In that age range, the rectal temperature method is still the gold standard (though not, obviously, necessary for routine screening). Same for basal body temperature monitoring. As often happens in healthcare, new studies contradict previous studies, which contradicted the studies that came before. Oral temps, some suggest, don’t graph as accurately as rectals. Today, however, women have the choice of vaginal temps, which the same studies suggested, are as accurate as rectals, but simpler to perform, or even wrist bands that record skin temperatures with reliability comparable to more invasive methods.
In conclusion, you’re not entirely off the hook because your nurse still decides where and how to take your temperature.