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  • Writer's pictureD. P. Lyle

Criminal Mischief: Episode #54: 15th Century Blood Transfusions


Q and A: How Could My Time-traveling Physician Save the Life of My 15th Century Heroine With a Blood Transfusion?

Q: I am writing a time travel where one of the characters is a modern doctor who is sent back in time (15th century) with his family. I want to have him do something medical to save the life of the heroine (I was thinking heroine needs blood transfusion which would require a blood typing system) Any idea how it could be accomplished? I was also thinking that the heroine has rare blood type. Would that be Type B?

A: This is an interesting scenario in that you have someone with modern knowledge transported back to medieval times. This means he would have all the medical knowledge of transfusions––which of course did not exist then––but no scientific equipment to help. Not to mention that merely bringing it up might get him killed by the church––but that’s another issue.

The first human transfusion took place in France in 1667 when Jean-Baptiste Denis successfully transfused sheep blood into a fifteen year old boy. The first human to human transfusion was in 1818 and was performed by James Blundell on a patient suffering from postpartum bleeding. Even he had no way of matching the blood and, in fact, didn’t understand that there were blood proteins that made transfusions incompatible between many people and successful between others. It wasn’t until 1901 that Karl Landsteiner discovered the ABO blood groups and begin to understand the nature of transfusions and transfusion reactions. In 1939, the Rh factor was discovered, also by Landsteiner along with several other physicians, thus refining the process further.

So your time-traveling doctor would know all of this and would also know that transfusions are only successful if the donor and recipient match one another as far as blood type is concerned. But he would have no way of testing the donor and recipient for blood type and compatibility, which of course is essential to avoid harming or killing the recipient. But, there is a way around this. He would know that two compatible bloods could be mixed and no reaction would occur while if they were not compatible clumps would form. We call this agglutination and it is the basis of a transfusion reaction. He could simply mix the blood of the donor with that of the recipient––which is more or less the way it’s done today––and look for this reaction. The problem? This agglutination can only be seen microscopically and there were no microscopes in the 15th century.

The microscope was discovered in 1590 by two Dutch spectacle makers–Zacharias Janssen and his son Hans. They employed the glass lenses they used in their spectacle making, which had been around since the 13th century. When they placed these lenses in tubes, they discovered that they magnified any image viewed through the tube. This was the precursor of the true microscope which was developed nearly 70 years later (1660s) by Anton van Leeuwenhoek. So, your modern physician would know this and could perhaps fashion his own crude microscope from spectacle lenses. This would allow him to see any agglutination that might occur. He could then simply take the recipient’s blood and test it against several potential donors and see which one had the least reaction. This would be crude cross matching but it could work. He would then know whose blood to use in the transfusion process.

This question appeared in MWA’s The Third Degree December 2022



The two most important components of blood from a forensics point of view are the red blood cells and the serum. Using these two components, we can determine the ABO type of a blood sample and most bloodstains.

The red blood cells are the cells that contain hemoglobin, which is the molecule that transports oxygen from the lungs to the tissues. The hemoglobin resides within the red blood cell. On the surface of the red blood cells are other extremely important molecules called antigens. These antigens deter- mine the blood type.

There are only two types of antigens; they are designated as either A or B. A person with type A blood will have A antigens on his red blood cells; type B blood has B antigens; type AB blood has both A and B antigens; and type O blood possesses neither antigen.

Landsteiner also discovered another antigen in the blood, the D antigen. Whether a person has this antigen is known as the rhesus or Rh factor because Landsteiner’s studies were performed in rhesus monkeys. The presence of this factor in a person’s red blood cells means he has Rh-positive blood, and if not, it is Rh-negative blood. Thus, a person with type A positive blood possesses the A antigen and the Rh (D) antigen on their red blood cells. Per- sons who are type O negative have neither the A, B, nor Rh antigen on his red blood cells.

Another important factor is that the serum contains specialized proteins called antibodies. The key point in understanding blood typing is that for every antigen there is a corresponding antibody. An antibody is highly specific in that it only recognizes and reacts with its specific antigen and not with any other. When an antibody meets its matching antigen, it combines with it to form an antigen-antibody complex. This reaction is what causes transfusion reactions and is the basis for the blood-typing procedure.


As stated above, the surfaces of red blood cells possess either A or B antigens, both, or neither. The serum contains antibodies that are termed either anti-A or anti-B, depending upon which antigen they recognize. That is, if an anti-A antibody comes into contact with an A antigen, a reaction will occur. Since it is highly specific for the A antigen, it will not react with a B antigen.

These anti-A and anti-B antibodies are found in the serum, but which one, if any, a person has depends upon his blood type. Logically, a person with type A blood cannot possess anti-A antibodies, since this would lead to an antigen- antibody reaction that would be deadly. So, each person has antibodies that are directed against the blood antigens that differ from the ones on her own red blood cells.

That is, if a person has antigen A on his red blood cells (type A blood), he then has anti-B antibodies in his serum (see Figure 9-1). If he has antigen B (type B blood), then he has anti-A antibodies in his serum. Likewise, a person with both A and B antigens (type AB blood) has neither anti-A nor anti-B antibodies. And a person with neither A nor B antigens (type O blood) has both anti-A and anti-B antibodies.

But Type O blood is considered the be the “universal donor.” This means that in situations where time does not allow for cross matching, type O is given. But, even though type O possesses both anti-A and anti-B antibodies, it does not react with blood types A, B, and AB because the red blood cell antigens of the donor react with the serum antibodies of the recipient to cause transfusion reactions. Since type O has no red blood cell antigens, no reaction occurs.

The reaction of the recipient’s serum antibodies with the red blood cell antigens of the donor’s blood is what causes transfusion reactions. For example, a person with type A blood cannot receive a transfusion of type B blood without risking a severe reaction; he has anti-B antibodies in his serum, so if he is given type B blood, these anti-B antibodies will immediately react with the B antigens on the red blood cells of the donor’s blood. This is a transfusion reaction and results is agglutination, or clumping, of the blood cells, which can lead to rashes, kidney damage, and death.

Agglutination occurs because the serum antibodies are bivalent. This means that they have two reactive ends. If each end of the antibody re- acts with a red blood cell surface antigen, it forms a complex of two red blood cells and one antibody. Sort of like a dumbbell, with the red blood cells being the two end-weights and the antibody the handle. As the re- action continues, the red blood cells are bound into a latticework and clump together.

Blood typing makes use of this reaction. Serum that contains anti- bodies is called antiserum (plural is antisera). If the serum contains anti- A antibodies, it is called anti-A se- rum; if it contains anti-B antibodies, it is anti-B serum. In the lab, these two types of antisera are used to determine blood type.

For example, if a given blood sample agglutinates when exposed to anti-A serum but not with anti-B se- rum, the cells contain only antigen-A and the blood type of the sample is A.

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