The slow story of getting a second opinion on bloodletting
Do you like your barber? You trust their decisions with your appearance, maybe, but do they seem like the person to visit for medical treatment? It wasn’t that long ago that there wasn’t much choice in this matter— as keepers of sharp implements, a barber was many people’s source for medical care, because all they had to do was know how to cut you and help you safely bleed for a bit. You may find a barber pole quaint and folksy now, but it once stood for the blood and bandages that you’d expect to find there.
Medieval barbers weren’t the first people to come up with the idea of medicinal bleeding. There’s evidence that bloodletting was a form of treatment as far back as the ancient Egyptians. The ancient Greeks wrote about it as well, specifying the idea that the four humors (blood, black bile, yellow bile and phlegm) needed balance, and if you were sick it was probably just that you had too much blood in the mix. The best ways to reduce your blood was through leeches or a gentle slice in the arm or leg.
Expectations to evidence
With such a long tradition, it seems like something must have been working. Bloodletting couldn’t have lasted so long if it was just a chance to risk cardiac arrest or infection from unclean tools and an open wound. However, something like this has had an easier time persisting because for a long time medical science wasn’t the most scientific process. Germ theory wasn’t proposed until the 1500s. Medical autopsies were sporadically used and at times prohibited, leaving medical practitioners study animal anatomy as a proxy for their human patients. In the case of bloodletting, it’s quite possible that anecdotal evidence coupled with placebo effects and low expectations made the procedure seem successful.
In 1793, an outbreak of yellow fever started to shift doctors’ attitudes though. Benjamin Rush seemed to be attempting to bleed every last drop of fevered blood out of Philadelphia, to the point where bystanders became repulsed by the accumulated biomedical waste, shall we say. It prompted the gathering of medical statistics on the practice, which showed that bleeding patients wasn’t helping their outcomes. As more doctors were guided by data and not anecdotes, the practice mostly fell out of favor.
Not dead yet
Bloodletting isn’t completely abandoned though. There does seem to be some benefit to a narrow range of patients concerned with iron build-up in the blood, but nothing truly conclusive. The practice was recommended as recently as 1942 in western medical textbooks to fight pneumonia. And in India today, you can still find people lining up for a nick from a razor blade to cure everything from back pain to cancer. Hopefully the placebo effect hits hard for all of them.
Source: Bloodletting Is Still Happening, Despite Centuries of Harm by Erika Engelhaupt, Gory Details