Blood – The Doctor Giveth and the Doctor Taketh: Myths, Beliefs and Evidence

This Country Doctor learned something interesting at Grand Rounds the other day. One of the Cityside hematologists gave a talk about blood transfusions that made me think about how slow the medical profession is to change its beliefs and its practice, even when faced with overwhelming evidence that we are doing the wrong thing.

It turns out our profession has been wrong about the benefits of transfusing anemic patients, just like our predecessors were wrong in their belief that bloodletting was helpful.

For thousands of years medical practitioners used bloodletting, drawing off sometimes very large quantities of blood, as a treatment for various illnesses. After this treatment was proven useless and dangerous in 1628 by Harvey, the practice continued for more than 200 years. It is said to have brought on George Washington’s death in 1799 after 9 pints of his blood was withdrawn. Samuel Hahnemann, the physician who founded Homeopathy, looking for kinder, gentler treatments for his patients, wrote in 1809:

“The more refined humoralists, in addition to the impurities in the blood, alleged, besides, the existence of a pretended, almost universal, plethora, as an excuse for their frightful, merciless bloodlettings.”

Analyzing why it took so long to eliminate this type of treatment, Kerridge and Lowe wrote in 1995:

“That bloodletting survived for so long is not an intellectual anomaly—it resulted from the dynamic interaction of social, economic, and intellectual pressures, a process that continues to determine medical practice.”

Legend has it that early adopters of non-bloodletting didn’t dare to withhold this “treatment” for their sickest patients. They, like modern day physicians, were afraid of “doing nothing”.

Today, bloodletting is only used for a handful of conditions where the patient actually has too many red blood cells or too much iron in the blood. But we have gone too far in the opposite direction, thinking that most anemic patients could benefit from a couple of extra units of blood.

In 1999 The New England Journal of Medicine wrote authoritatively about several negative effects from transfusions. Since then the evidence has continued to mount against transfusion in medical patients with anemia. Bleeding surgical patients are in a different category.

But for many years we transfused our sickest patients in hope of helping them do better. When they didn’t, we usually didn’t blame the transfusion, but thought they were just too sick to fully benefit from transfusion. This is exactly what happened in the days of bloodletting.

The new findings about the negative effects of transfusion were ignored, perhaps even swept under the carpet. After all, giving blood seemed like such an obvious thing to do.

Even though we know that anemic patients are more likely to suffer for example heart attacks due to low oxygen delivery to their tissues, it turns out that blood transfusion to correct anemia actually further decreases oxygen delivery to heart muscle tissue. Transfused patients have a greater risk for illness and death than non-transfused patients, all the way down to degrees of anemia that usually raise the hair on every physician’s back. Even our own (autologous) blood donation has this effect due to changes in blood cells and plasma caused by handling and storage. Transfused blood cells have a tendency to be less flexible and slippery than normal blood cells and have been proven to block tiny blood vessels and thereby keeping patients’ own, healthy, blood cells from getting through.

A chilling fact is that even though blood between 30 and 42 days old carries a dramatically greater risk of negative effects than blood less than 30 days old, we still continue to offer it to patients without informing them of the additional risk we subject them to.

The increased risk for illness and death extends well beyond the immediate period after transfusion: We are now seeing an increased cancer risk in people who have received blood transfusions several years ago.

The International Consensus Conference on Transfusion and Outcomes issued this statement in 2009:

“There is little evidence to support a beneficial effect from the greatest number of transfusions currently being given to patients. The vast majority of studies show an association between red blood cell transfusions and higher rates of complications such as heart attack, stroke, lung injury, infection and kidney failure and death.”

At Cityside and many other hospitals, the threshold for transfusion in medical patients has been lowered, and surgical patients sometimes have their operations postponed in order to manage anemia with iron infusions and erythropoietin injections to allow the patient to build up their own blood supply before surgery. And if transfusions are given, they are kept to a minimum.

Such changes in practice are likely to happen in other areas of medicine if we are willing to really practice evidence based medicine and not just do what sounds like a good idea. Too many things have sounded good and turned out bad to make that a defensible strategy.

I can’t help thinking about how uncomfortable many doctors have been over the years when treating Jehovah’s Witnesses, whose religion forbids them to accept blood transfusions. That belief may actually have saved many lives.

Medicine is an ever-changing practice, and it is humbling to realize how doctors sometimes harm their patients by doing what seems to be the right thing to do.

Dr. Martin H. Fischer said it well:

”It is not hard to learn more.  What is hard is to unlearn when you discover yourself wrong.”  

6 Responses to “Blood – The Doctor Giveth and the Doctor Taketh: Myths, Beliefs and Evidence”


  1. 1 Jewell Burke June 4, 2012 at 2:08 pm

    Thank you for an insight that will take many more years for Doctors to accept!

  2. 2 Blood Management (@BloodManagement) June 7, 2012 at 6:24 pm

    Thank you- this is one of the better summaries I have read regarding the shift in transfusion risks and benefits. I also appreciated and enjoyed the historical perspective regarding bloodletting. It turns out that modern bloodletting plays into anemia management, since drawing too many lab test for hospitalized patients can actually lead to blood transfusions! If you are interested in staying current on the topic of appropriate blood use and transfusion safety, you can follow our blog at http://www.thebloodytruth.com . Thanks again- Tim Hannon, MD, MBA

  3. 3 totally critical June 10, 2012 at 3:12 am

    “That belief may actually have saved many lives.”

    What about the lives it has COST?

    This article completely lacks a critical perspective. You’re going to quote Hahnemann? Really? His medical legacy is one of the most persistent bits of superstitious nonsense around to this day! Do a comparison of the literature supporting homeopathy with that supporting blood transfusions.

    “The new findings about the negative effects of transfusion were ignored” Even Wikipedia has a long list of blood transfusion risks. Their anemia article states that doctors try to avoid blood transfusions for anemia because of the risks involved. That’s how “ignored” the risks are..

    Do blood transfusion risks sometimes outweigh the benefits? Sure they might, but it’s the same medical community you criticize for “ignoring the risks” that FOUND the risks in the first place! And it’s up to them to evaluate the risks, not up to religious people who point fingers and say “I told you so” based on the interpretation of a 2000 year old book translated from a long extinct language. .

    No matter how you look at it, Blood transfusions now are safer then they have ever been! Does it mean we can’t try to find safer alternatives? Of course not, but it is no different to any other medical treatment in that regard. When was the last time you saw a treatment that was 100% safe and effective? Does that mean blood transfusion hasn’t actually saved thousands of lives over the last century?

    How about the surgery and organ transplant procedures we have today? Which equally have saved thousands of lives. Would they be around if we never used transfusions? Would we even be discussing, let alone developing “blood-less” alternatives without the techniques blood transfusions allowed us to develop over the last several generations?

    It’s just how science works: we discover risks, we try to mitigate them. But does just one study showing risks outweigh a hundred years of experience and many more studies showing benefits of blood transfusions? Is that called “sweeping it under the rug”? No, that’s called building consensus. When the evidence mounts, only THEN it becomes reasonable to act on it.

    The people that sit on the sidelines saying “I told you so” before there was sufficient evidence have no rational justification for doing so. They have no evidence to base their belief on, if they turn out to be right in some way, it was only by accident.

    • 4 Humble June 13, 2012 at 10:27 pm

      Am nt a doctor u may be,u realy regard d bible as an old book?While u ar right but remember its nt jst a religious group old book but a book from d oldest,wisiest nd d highest scientist in d whole universe.Isn’t he d right person to tell us wat we need to know in advance b4 they happen?.Over 2thousand yrs nw he say “it wl prosper to u gud health”if u abtain 4m blood.Act 15:28,29.No scientist 2da know better than d creator.Blood missuse or transfusion is jst as 1 who smoke.He get a little benefit but at d longrun pay a higher price of hs action.U ar accountable to God of hw u make use of blood.

    • 5 critical thinker July 7, 2012 at 10:07 pm

      “What about the lives it has COST?” Problem with this affirmation. there are patients that have died WITH blood transfusions. It is easy to blame a religious group for their beliefs but what about the medics that have wanted to introduced this treatment by force? Who is the bad guy here? “No matter how you look at it, Blood transfusions now are safer then they have ever been!” Yes but problem with this is that there are NOT all types of test for all sickness out there related to blood. Please, we are in 2012, not in the 1900’s. Not everyone can even donate blood, even if they wanted to. The medicine has advanced enough to still continue to use such an obsolete method like this on.

  4. 6 Nick June 11, 2012 at 9:56 pm

    Excellent article. Good research, thanks for covering this important topic.

    Please take a look at this trailer for a documentary film about blood transfusion, the should be out sometime this year.

    http://www.asiageographic.com/primum/trailers.htm

    http://www.asiageographic.com/html/nomansblood.pdf


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