Bloodletting

We all need someone we can bleed on And if you want it, why don't you bleed on me? Bloodletting is a formerly widespread medical treatment. It is famous as one of the most common treatments of prescientific humoristic medicine, which postulated that disease was caused by imbalance of the body's humors: black bile, yellow bile, blood, and phlegm. If a person had a disease which indicated too much blood, bloodletting was used to correct the problem. Bloodletting was even thought to be a cure for anaemia.

Bloodletting has a long, venerable history of use in traditional and pre-scientific medicine as a panacea of sorts, and patients liked it so much, they had to be convinced not to be bled. As such, it should come as no surprise that general-purpose bloodletting is still used in alternative medicine as part of Unani, Ayurveda, and traditional Chinese medicine. One naturopathic textbook lists all three of these systems as being acceptable bases for naturopathic practice.

In modern medicine, bloodletting is known as therapeutic phlebotomy and is used in a few, very specific circumstances, such as polycythemia vera (in which the bone marrow produces excess red/white blood cells) and haemochromatosis (iron overload), to reduce the number of red blood cells. Bloodletting is not to be confused with lancing, a proper medical technique in which pus is drained from an abcess, boil, etc.

History
Bloodletting is known to have been used for about 3000 years. Initially, disease was thought to be caused by malevolent supernatural entities, and bloodletting and trepanation were used to expel these spirits from the patient's body. As time went on, however, physicians became more sympathetic to naturalistic explanations for disease, and this resulted in the Greek Theory of The Four Humors, in which imbalance of the four humors (black bile, yellow bile, blood, and phlegm) was considered the root cause of all diseases. (Bloodletting use also developed independently in India, with the bloodletting technique Sravana being described in approximately the 6th or 7th century B.C. in the Ayurvedic surgery treatise Sushruta Samhita). Greek humorism spread, gradually became Europe's chief medical practice, and arrived in Asia, where it was adopted by Islamic cultures and adapted in the form of Unani in about the 10th century A.D.

Anecdotes
Fast-forward a few centuries. In 1793, there was a yellow fever epidemic in Philadelphia, and Benjamin Rush, a physician and signatory of the Declaration of Independence, believed he could effectively fight the disease by relieving patients of up to 75% of their blood, because he treated himself this way and got better. His work A Defence of Blood-letting, as a Remedy for Certain Diseases (published in Volume 4 of Medical Inquiries and Observations ) contains anecdotes like the following:

Sure, all those women recovered, but what about the ones who died after being bled? Rush would probably weakly argue that the people who died after bleeding did so only because they were too ill to be cured, so it couldn't be helped.

"Someone who had been in a coma for an unspecified amount of time came out of the coma an unspecified amount of time after he was bled. Therefore, bloodletting works." That's just not a convincing argument. It wouldn't be convincing even if the person woke up just a few minutes later–since Rush probably bled hundreds, if not thousands, of people, coincidences like this are to be expected. Maybe most of his coma patients didn't get better, and this one was just part of the lucky minority. Without statistics, there's no way of knowing.

"And absolutely none of the kids I treated died. Ever. At all. Just trust me." Also, "appeared to be saved" is right.

Now, Rush obviously thinks it is inconceivable that these people could have gotten better without bloodletting. Of course, this is fallacious; thanks to statistics, we now know that about 30% of smallpox patients live. Even in Rush's day, when such detailed numbers weren't available, it was probably known that smallpox wasn't always fatal, so his belief is unjustified.

Note also that when people afflicted by smallpox die even after being bled, he simply handwaves those anecdotes away. Later in the book, Rush claims again that "moderate bleeding" is harmful, and that only "heavy" bloodletting works, giving examples of people losing from a few pounds to over 100 ounces of blood before being cured. But it must be noted that despite this, Rush was perfectly content to use an instance of "moderate" bloodletting in the coma anecdote described previously, in which only 12 ounces of blood were drained from the patient. In other words, Rush claims light bleeding is ineffective only when it is used in failed cases; if light bleeding is performed in a "successful" anecdote, he has absolutely no qualms about using that testimonial in favor of bloodletting. He thus uses this argument as an escape hatch, which he uses only when it suits him.

Positive results must be due to bloodletting and not natural improvement (despite the fact that many of the conditions he lists, including smallpox, can resolve on their own), and negative outcomes simply don't matter, because Rush said so. If someone dies, it's just because they weren't bled enough; if they had lost more blood, they would have lived. This is one of the characteristics of pseudoscience: there is no falsifiability. Every outcome only confirms the original hypothesis, and no possible result will ever disprove it. With this sort of "logic", you can believe in anything from flat earthism to mercury pills (indeed, Rush actually promoted mercury in this book in addition to bloodletting).

Just like the temporary worsening and detox symptoms of homeopathy and naturopathy! What a coincidence.

"Really, he was. Cured, that is."

The basis for this claim is probably testimonials along the lines of "I've used bloodletting for a long time, and I haven't had a cold in years!" Of course, these sorts of anecdotes don't clarify if people who didn't get bled were more likely to get colds.

Any reduction in pain can be easily explained as the result of the placebo effect. The supposedly shortened duration of childbirth can be accounted for by confirmation bias or by his relying on a subjective sense of time (as opposed to timing and recording the durations precisely on paper). Also, Ignaz Semmelweis would probably have a few choice words to say about sticking unsterilized sharp objects in pregnant women.

In volume 5 of Medical inquiries and observations, there are yet more anecdotes, including ones which supposedly demonstrate that bloodletting can cure rabies.

Science
In the 19th century, however, bloodletting use declined, as a result both of statistical studies on bloodletting's efficacy being conducted (as the medical profession became more scientific and less anecdotal in outlook), as well of research on bloodletting's actual physiological effects on disease.

The credit for bloodletting's disproval is often attributed to Pierre Charles Alexandre Louis, a French doctor known as "the father of medical statistics", who invented the "numerical method", a precursor to modern clinical trials, and who once said "without the aid of statistics nothing like real medicine is possible." However, his work on bloodletting, though revolutionary for its time, suffered from a rather small sample size and from some methodological flaws, so that it only enabled him to conclude that bloodletting was less effective than previously thought. But:

Though Louis' conclusions were not that disruptive to the status quo, he was nevertheless criticized by anecdotally minded doctors who refused to believe that statistics could be superior to personal experience. The idea that truly effective medicine was only now being developed, with the advent of statistics, and that the previous thousands of years of medical practice were essentially worthless, was very controversial. Doctors objected that:

[R]esults obtained by analyses of large groups of patients were not universally applicable to the single individual presenting in their examining room.

In addition:

These views grew out of fashion, and medicine dropped its reliance on anecdotal evidence. One author writing in 1875 noted,

Bloodletting's image declined, so that it became known as one of the most famous examples of the barbaric ineffectiveness of pre-modern medicine. Except in traditional medicine, where it is still, even now, considered a panacea.

Modern use
In alternative medicine bloodletting is an important part of Unani, Ayurveda, traditional Chinese Medicine, and Hildegard medicine. In all four of these systems, bloodletting can also involve cupping.

Unani is one of the few forms of alternative medicine in which bloodletting is used according to humoristic principles. Because of this, bloodletting and leeching are used quite often, owing to the fact that there are supposedly many diseases resulting from excess blood. In Unani, bloodletting is considered a good way of detoxifying the blood. Unani is probably the closest thing to the backwards, old-fashioned medicine people usually think of when they hear the word "bloodletting". Some of the diseases treated by bloodletting include headaches, migraines, eczema, conjunctivitis, cataracts, asthma, angina, pneumonia, ulcers, tonsillitis and glaucoma.

In Ayurveda, bloodletting is known as Raktamoksha(na) and is claimed to be good for detoxing and stimulating the immune system. It is used for conditions such as excessive drowsiness, baldness, urticaria, rash, eczema, acne, scabies, leucoderma, chronic itching and hives, enlarged liver, spleen, gout, tumors, and genital infections. But it doesn't stop there: bloodletting is also used in Panchakarma, which is an Ayurvedic therapy that involves bloodletting, vomiting, purging, enema, and herbal steam inhalation in order to clear the body of toxins and balance its energy. What's interesting is that Panchakarma is supposed to be done four times a year, even by people who are perfectly healthy, because it's supposedly necessary for maintaining one's health. Bloodletting is thus used not only as a treatment, but also as a preventative!

Traditional Chinese use of bloodletting is the least drastic; it is used in the context of acupuncture and only involves draining a few drops of blood. This is supposed to be good for, among other things, sore throat, epistaxis, pain of fingers, mental disorders, numbness of fingers, loss of consciousness [compare with Rush's coma anecdote], cardiac pain, irritability, aphasia with tongue stiffness, heat stroke, infantile convulsions, feverish sensation of the palm and sole, headache, redness of eyes, stiffness of the tongue, febrile disease, irritability, pain in chest, corneal disease, abdominal distention, uterine bleeding, prolapse of uterus, hernia, enuresis, facial swelling, toothache, distending sensation of chest and abdomen, cold in leg and foot, dream disturbed sleep, mental confusion, pain in vertex of the head, dizziness, blurring of vision, aphonia, dysuria, dyschesia, deafness, pain in the hypochondriac region, nasal obstruction, epistaxis, ophthalmalgia, and shingles.

Hildegard medicine is an obscure humoristic system of medicine invented by St. Hildegard von Bilgen. It has only a few hundred practitioners, mostly in Germany. In this system, bloodletting is used to detoxify the blood and remove "bad" black bile. Hildegard medicine supposedly came to St. Hildegard in visions from God, so apparently this means God approves both of detoxing and bloodletting. Go figure.

Leeching
Leeching (also known as hirudotherapy) is a form of bloodletting that uses leeches to remove blood from a person instead of a knife and cup. Leeching has, surprisingly, been found to be effective for a number of conditions, and is a part of modern medicine. (As with all such treatments, it should be done under proper medical supervision, as there can be issues with hygiene. Also use of leeches on certain parts of the body is not advisable. A leech's mouth contains anti-coagulants.)

Alternative medicine, however, uses it for completely inappropriate conditions. In Ayurveda and Unani, leeching is claimed to be good for (among other things) baldness. Also, because leeching is a form of bloodletting, it is thought to be good for detoxifying. (According to one pro-Ayurveda source, "Ayurvedic medicine has had an obsession with these creatures for centuries." )

"Leech" is also a Middle English word for a physician or surgeon.

Recreational bloodletting
Naturally some weirdos alternatively orientated folk like bloodletting for non-medical purposes. Here are some examples:


 * Extreme sado-masochists - that's gotta hurt! Still, no pain, no gain, as they say.
 * "Real" vampires - why be sucked off by someone when you can have someone sucking your blood? (Through a straw.)
 * War mongering - bloodletting on an industrial scale and not much fun for most of the participants.
 * Corporal mortification as a religious practice.

Some forms of self-harm may involve bloodletting too.

Conclusion
Just because a treatment is extremely popular and has many testimonials in favor of it does not necessarily mean that it is effective. Proponents of bloodletting, arguing for the utility of bloodletting, gave as examples many cases from their personal experience which they believed demonstrated its efficacy. They told tales of "miraculous" cures, and of patients recovering some period of time (and sometimes very soon after) the use of bloodletting, with the implication being that these recoveries must have been due to bloodletting, and that they cannot have been coincidences or due to other causes.

But anecdotal evidence suffers from a number of problems which render it untrustworthy. For instance, improbable things happen, and unlikely coincidences can and do occur all the time. Rush likely treated thousands upon thousands of patients, many of whom he probably treated several times. Out of this very large population of cases, it is certain that many unlikely and coincidental events occurred. Even incurable diseases can sometimes resolve on their own, a phenomenon known as spontaneous improvement. In addition, a patient, misdiagnosed with a disease they do not have, may attribute their survival to the treatment they used, when in fact they had either no disease, or a disease that resolved on its own.

Over the course of history, countless treatments have been considered cure-alls, including not just bloodletting, but mercury (a favorite of Rush's), lead (used in Ayurvedic and traditional Chinese medicine), tobacco, and birthwort. Many of these alleged panaceas are based on theories that contradict one another. For instance, of the many currently-used systems of hands-on healing, such as Reiki, therapeutic touch, and quantum touch, many claim to be the only effective one. Similarly, homeopaths may claim that only homeopathic water is effective for curing illness, and that ordinary water is useless, while others may claim that ordinary water can indeed cure everything. The fact that supposedly "miraculous" anecdotal evidence is invoked in support of so many contradictory therapies would indicate that it is not all that useful.

Modern forms of alternative medicine rely on the same type of pseudo-evidence as bloodletting. Just as bloodletters rejected statistics because they contradicted their personal experience, modern naturopaths and other practitioners claim that their preferred unproven and disproven treatments can cure serious diseases such as cancer or hepatitis, due to their belief that personal observation trumps numbers. Arguing that homeopathy, a treatment based on anecdotal evidence, is an effective treatment, while simultaneously stating that bloodletting, a treatment also based on by anecdotes, is ineffective, is nothing more than special pleading. Cherry picking cases that very well could be attributed to coincidence or other causes cannot be considered a reliable base on which to construct a system of medicine. One cannot just reject science and pick and choose the parts of reality that seem palatable. Down that road lies a return to humorism and the barbaric ineffectiveness of pre-scientific medicine.

Skeptical

 * Bloodletting works, Steven Novella
 * Cupping is a thing? Really? PZ Myers on bloodletting
 * Acupuncture and Modern Bloodletting, Steven Novella, Science-Based Medicine
 * California Forbids Chinese Bloodletting, Ben Kavoussi, Science-Based Medicine

General

 * History of bloodletting by phlebotomy.
 * Medical Antiques, includes photographs of some of the actual equipment used.
 * The last Illness and Death of Lord Byron - His last Poem
 * LA Times article on Bloodletting
 * Youtube videos of Ayurvedic bloodletting (not for the faint of heart)
 * Youtube videos of TCM bloodletting (not for the faint of heart)