Question and Answer: Is It Possible For My Character to Commit a Murder by Causing a Transfusion Reaction?

19 Apr

Q: In my story, an elderly and seriously ill man is murdered by a nurse who switches the blood he is to receive, causing a reaction, which kills him. How does this reaction occur and what symptoms would the victim have?

A: Transfusion reactions come in many varieties. They may be as mild as a rash or perhaps chills and fevers or may be so severe as to cause death. First let’s look at why these reactions occur.

The red blood cells (RBCs) are the carriers of Oxygen (O2) from the lungs to the tissues and of Carbon Dioxide (CO2) from the tissues to the lungs. This is accomplished by using the hemoglobin inside the RBCs. The RBCs also have Antigens on their surface. It is these antigens that cause the problem.

These antigens are designated either A or B. From these our blood typing system (ABO System) has been derived. Type A blood has only A antigens, Type B only B antigens, Type AB both, and Type O neither.

Simple so far. But, the serum of the blood (the liquid part) also carries antibodies. It is the reaction of these antibodies with the antigens of the transfused blood that causes problems.

Type A serum (that is the serum of people with Type A blood) has Anti-B antibodies. Type B has Anti-A antibodies. Type AB has neither. Type O has both Anti-A and Anti-B antibodies.

TYPE            Antigens on RBCs            Antibodies in Serum
A                             A                                       Anti-B
B                             B                                       Anti-A
AB                        AB                                      None
O                       Neither                           Anti-A and Anti-B

Reactions occur when blood with the right Antigen is given to a person with its corresponding antibody. For example, if a Type A person (who has Anti-B antibodies in the serum) receives Type B blood (which has the B antigen on its RBCs) or Type AB blood (which has both A and B antigens) an adverse reaction will occur because the Anti-B antibodies in the recipients serum will react with the B antigens on the transfused RBCs. This is a transfusion reaction. The result is agglutination, or “clumping,” of the blood cells and the release of several harmful chemicals, which cause the symptoms and signs of this basically “allergic” reaction.

It gets more complicated than this because there are a multitude of other antigen-antibody problems with blood matching. Antigens like the well-known Rh Factor, which is either Positive or Negative, and many others, mostly named after the physicians that discovered them. Your “blood type” is typically expressed only in terms of the ABO and Rh systems. For example, a person who is A-Positive has Type A blood and the Rh Factor Antigen is present, while a person who is O-Negative had Type O blood and the Rh Factor is absent.

Because of the multitude of potentially problematic antigens, prior to transfusion blood is “Typed and Cross Matched.” This is done to test the donor’s blood directly against the recipient’s blood for any antigens and antibodies that might cause the blood to be “incompatible” and thus, lead to reactions. In very emergent situations such as gun shots, stabbings, or automobile accidents where the victim is bleeding to death and there isn’t time to do a complete Cross Match, “type specific” blood is given. A person’s blood type can be determined in a few minutes but cross matching may take hours. In these cases, a Type A person receives Type A blood and everyone hopes for the best.

Another option in these situations is to give “Universal Donor” blood. This is Type O Negative. Since Type O RBCs have no surface antigens they are the least likely to cause a reaction regardless of the recipient’s blood type. Reactions can still occur due to other antigens but in an emergent situation, as I said above, you give the best blood type available and hope for the best.

In your story, I would suggest that you have your victim be Type A and have the nurse switch the blood for Type B. This could definitely cause a reaction. The patient would develop fever, chills, and a diffuse, irregular red rash over his entire body. This could begin within minutes or might be delayed for a few hours. He might develop a full blown anaphylactic allergic reaction, which would be the above symptoms plus, shortness of breath, low blood pressure, and severe shock with pallor, cold and clammy skin, and a bluish tinge to his lips and fingers and toes. Since this represents the severest form of allergic reaction, it would develop fairly quickly and could lead to cardiac arrest and death. If the victim survived all this, it is possible that his kidneys would be severely and irreparably damaged, even requiring dialysis.

Note: This is a very complex topic. If you want to know more, start HERE.


Posted by on April 19, 2011 in Uncategorized


11 responses to “Question and Answer: Is It Possible For My Character to Commit a Murder by Causing a Transfusion Reaction?

  1. BethAnne

    April 19, 2011 at 6:26 pm

    Don’t forget to tell your author that the processes and regulatory policies require two licensed professionals to sign off on each unit of blood hung. They have to assure that it is the right patient and right unit of blood. Both sign. In the lab, each tech must sign their contact and procedures too and there are multiple re-checks. The murderer would have to find a way to compromise or corrupt one of those processes. I can’t wait to see what the author creates on this one!


    • D.P. Lyle, MD

      April 19, 2011 at 6:44 pm

      Good points. Thanks. Of course if she was the one to actually give the blood, brought in a bag from outside, and swapped it while no one is looking, which is not that difficult to do, it could work. Of course labeling and signatures could cause her some problems later. But if she could then swap the bags back again–particularly if the reaction is delayed 30 minutes or so–and get rid of the outside bag she just might pull it off. This way the empty bag would be the one from the lab with all the signatures, labels, etc, and no one would be the wiser. Even if the ME tested the residual blood in the bag, he would have no way to know that it had been switched. Or she could simply hang the right bag and then inject some blood of the wrong type with a large syringe–again some she brought from outside. This might or might not be enough to cause a severe reaction but that’s the case with hanging the wrong blood, too. Some people get the wrong blood and nothing happens. Luck is involved in everything. Some people get the wrong blood and a reaction occurs in minutes. Bad luck is involved in everything too. Thanks for your comments. Isn’t storytelling fun?


      • Laura Mitchell

        April 20, 2011 at 8:25 am

        But isn’t there a possibility that injecting the wrong blood will cause an immediate and visible reaction within the bag (e.g. injecting Type B+ into a Type A- bag)? Also, since blood bags don’t have injection ports like an IV bag does, injecting something into them exposes you to the blood The ports of a blood bag are for spiking only. Just a thought.


      • D.P. Lyle, MD

        April 20, 2011 at 9:01 am

        Possible but not likely. To avoid any reaction in the blood bag and to avoid leaving needle marks on the bag and contaminating the blood in the bag (so the ME wouldn’t be able to find it if he looks) simply inject the wrong blood into another IV.


      • Laura

        December 14, 2014 at 11:05 am

        The transfusion has to be started within 30 minutes of the blood leaving the lab, or they have to return it, so they wouldn’t be able to delay it that long. There would be no way to get all of the labels from the blood center off of the old bag and onto the new one, at least not in that time period, and definitely not without it being obvious that it had been done.
        Injecting it through another IV site would have to be the way to go, but then when they do the reaction workup on the unit, they will find that it was fine, just as it was when they did the crossmatch, and have absolutely no idea why she had a reaction. If everything from the reaction and the post – reaction blood looks like she got the wrong blood type, but the unit is right, eventually someone will have to suspect foul play and start to look at the nurse.


      • D.P. Lyle, MD

        December 14, 2014 at 2:04 pm

        And excellent from a plotting point of view.


  2. Laura Mitchell, RN

    April 19, 2011 at 7:03 pm

    Most facilities require that 2 licensed people (usually RNs) verify that everything is correct (blood bank documents match the issued unit, patient identifiers, etc.). So, with this in mind, at least one other person knows that there is a transfusion going. Plot question: how are you going to prevent another nurse from intervening to minimize the transfusion reaction (stopping it)? Also, while it does happen, it’s pretty difficult (at least in the US) to intentionally give incompatible blood in non-emergent situations. Perhaps your character can give the patient something that would mimic a transfusion reaction? Or have your victim suffer from a delayed transfusion reaction?


  3. BethAnne

    April 20, 2011 at 2:50 am

    Yes it is fun! I thought that maybe the author would develop a scene outside the clinical setting. I can’t wait to read what happens!


  4. Laura Mitchell

    April 20, 2011 at 4:52 pm

    Yeah, you can put in the saline line and just flush it through.


  5. Laura

    December 14, 2014 at 10:54 am

    The med tech in me is cringing at the thought of someone writing a book where a nurse can just switch out a bag of blood to kill someone. Unrealistic portrayal of blood bank situations drives me nuts in tv shows and books, simply because it reinforces the idea people already have from doctors and nursing personnel blaming everything on the lab (“oh, we’re sorry, you’ve been here five hours because we don’t have that CBC back yet. The lab is slow” – when it took them four and a half hours to order it) that the lab is made up of incompetent, uneducated idiots who can never do anything right. When even nurses have been known to say “you mean there’s a school for the lab?” to techs who have masters degrees, a plot like this is not helping.


    • D.P. Lyle, MD

      December 14, 2014 at 2:03 pm

      But it works nicely for crime writers and that’s who I answer questions for.



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