You’re pretty lucky if you can go through life without needing a blood transfusion. That said, you’re also pretty lucky if you can get a blood transfusion if you need one. Blood transfusions are literally lifesaving, and they’re easily one of the most important medical advances in history.
The Early Beginnings of Blood Transfusions
Ancient medicine had a much different understanding of blood and the body than we do now, and they believed a healthy body required a delicate balance of the four humors: blood, phlegm, black bile, and yellow bile. This led to the common practice of bloodletting to treat common ailments.
The modern understanding of blood was forever transformed in 1628 by British doctor William Harvey, who discovered the circulation of blood in the body. It was Dr. Harvey who observed that the heart pumped the blood, and that valves in the veins pushed blood in only one direction.
In his book De Motu cordis, Dr. Harvey wrote, “It must therefore be concluded that the blood in the animal body moves around in a circle continuously and that the action or function of the heart is to accomplish this by pumping. This is [the] only reason for the motion and beat of the heart.”
This new understanding of blood and the circulatory system paved the way for transfusions, and the first occurred a few decades later by yet another Brit.
British physician and surgeon Richard Lower, who was a follower of Dr. Harvey, saw the value of transfusing blood from one individual to another for medical emergencies. He performed the first successful blood transfusion—not between two humans—but instead between two dogs.
According to science historian Elizabeth Yale, this early transfusion was “gruesome,” and involved tying down the dogs, opening up the arteries and veins in the necks, and extracting and inserting the blood using goose feather quills. The “emittent” dog, meaning the one doing the (involuntary) donating, fainted and eventually died; however, it was still considered a success.
Dr. Lower wanted to see how he could transfuse blood to a human, but because the donor was likely to die, he used a sheep instead. In 1667, Dr. Lower and Jean-Baptiste Denis performed separate successful transfusions from sheep to humans.
Human-to-Human Blood Transfusions
The first blood transfusion between two humans didn’t occur until 1818, when British obstetrician James Blundell successfully transfused blood in order to treat a woman’s blood loss following childbirth. Dr. Blundell used blood from the arm of the woman’s husband, according to an article he later penned for The Lancet.
The 20th century was a remarkable time for medical advancements, and it brought many improvements to blood transfusions. One big moment was the discovery of blood types by Austrian Karl Landsteiner in 1901. Dr. Landsteiner not only came up with the blood groups of A, B, AB, and O, but he also demonstrated that transfusions could only be successful between people of the same blood types, and he earned a Nobel Prize in 1930 for the discovery.
Another important discovery was anticoagulants—blood thinners—in 1914. Previously, blood donations had to be used immediately, but Adolf Hustin found that sodium citrate could be added to blood, which allowed blood to be stored for longer periods of time. Storing blood became crucial on the battlefield during World War I.
In 1940, another breakthrough was made: the discovery of the Rh blood group. The “Rh factor” is a protein present in some blood types, and it was recognized as the cause of most bad transfusion reactions. Finding out if a patient was Rh-positive or Rh-negative made transfusions much safer.
Blood Banks + Blood Cleanliness
The American Red Cross began a national blood collection program in the 1940s. Blood donations became the norm, but it was quickly realized that serious infections could be transmitted through this blood supply.
One of the most notable cases of contaminated blood was in Ryan White, the first child diagnosed with AIDS. White had hemophilia, which limits the blood’s ability to clot and can cause severe bleeding from small injuries. White became infected with AIDS in 1984 after receiving a contaminated blood donation. (He died in April 1990 before his high school graduation.)
White’s story was significant because it helped break the stigma of AIDS and urged researchers to find a treatment—but it also highlighted the need to screen blood donations. Blood started to be screened for hepatitis B in 1971, HIV in 1985, leukemia in 1987, hepatitis C in 1990, and West Nile virus in 2005.
Blood Transfusions Today
On average, 36,000 units of red blood cells are needed on a daily basis in the United States, and nearly 7 million Americans donate annually, according to the American Red Cross, which provides 40 percent of blood products in the U.S. However, donations don’t always keep up with demand, especially for rare blood types.
Today, donating blood is considered safe, as long as you’re more than 110 pounds and in good health. Want to donate blood? Here are the 7 best and worst things to eat beforehand.