Let’s Think About… Blood Transfusions

While sitting in a hospital blood donation wing, filling out the form that you must complete every time you donate, I review the list of questions designed to determine if I’m eligible to donate.

Are you in good health generally and feel well today? “Yes.”

Have you had new or multiple sexual partners in the past three months? “Why even ask this if they’re going to test the blood for HIV no matter what?”

Have you ever had a positive test for Babesia?

“Why? How does that affect my ability to donate blood right now?” I have long been curious about this question asked of donors every session. Eventually I asked the phlebotomist why it matters if someone has ever been pregnant and why do they keep asking this instead of updating the computer records to reflect the donor’s pregnancy history? “Because when pregnant, the body can create an antibody that can kill other people if they receive it in a blood transfusion. We ask it every time because even if the body didn’t create the antibody in a previous pregnancy, it can in a later pregnancy, even if it doesn’t come to term.” Fascinating. Once I learned this, I went down a rabbit hole of information. The “killer” antibody is the Human Leukocyte Antigen (HLA) antibody, and it indeed is formed in some pregnancies but not in all. Studies have shown that 18 to 74% of women with a history of pregnancy have anti-HLAs and their prevalence increases with the number of pregnancies a woman has. According to Pregmune, HLAs are diverse proteins displayed on human cells like a barcode – unique for everyone. The immune system uses HLAs to differentiate “self” from “non-self.” This helps with pregnancy in a few ways, they help create immune tolerance between the mother and fetus, they help the mother’s immune system recognize pathogens, an organism that causes disease, and they help facilitate early fetal growth.

The HLA antibody, or anti-HLA is formed by the immune system as a response to the antigen. How do antibodies that help in the creation of life become a death sentence for others? Because HLAs are a main factor in the development of TRALI, transfusion-related acute lung injury, can occur from blood transfusions and can be fatal. TRALI occurs in about 1 in 5,000 transfusion cases and is the leading cause of transfusion-related death in the U.S. HLA antibodies that enter into a patient that receives that blood during a transfusion can bind to cells in the recipient’s lungs and lead to pulmonary edema, a condition where too much fluid builds up in the lungs.

A study published in 2017 shared that “plasma-containing components from female donors with leucocyte antibodies were responsible for the majority of TRALI fatalities before mitigation strategies were implemented.” While in the past few decades, hospitals and blood donation organizations have implemented measures to mitigate risk, like asking women if they’ve ever been pregnant and testing their blood, TRALI still holds the title of the most common cause of death from a blood transfusion in America, accounting for 30% of transfusion-related deaths.

But wait, that’s not all! Blood from a woman who’s been pregnant has been found to kill men at higher rates, but not from TRALI. Dutch researchers found in a 2017 study that men who received blood transfusions from women who had been pregnant were more likely to have died after three years than women who received blood transfusions and men who received transfusions from other men or women who had never been pregnant. The scientists also accounted for other health factors, like the severity of the medical issues that required the transfusions in the first place, and they still found the cause to be the blood from women who had been pregnant. Researchers don’t know what causes this death as TRALI occurs soon after a transfusion, and the deaths were recorded for three years post-transfusion. Due to a number of reasons, women were not required to be included in medical research until 1993 when Congress mandated the inclusion of women in research. This has led to women being underrepresented in clinical trials and medical research, as is the case with women making up 40% of research participants for medical issues that have been found to predominately affect women: cardiovascular disease, cancer, and psychiatric disorders. Pregnant people continue to be left out at higher rates due to safety issues.

This interesting fact about morbidity caused by blood from pregnant women just shows the continued need for more medical research that not only includes women but is done on women specifically.

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Situations we find ourselves in may result in us asking questions because they invite deeper reflection and uncover complexities that may not be immediately obvious. For example, an everyday event like a visit to the doctor can spark a range of questions about health, treatments, and personal well-being. A simple task, like filling out a questionnaire for a blood transfusion or blood donation, might prompt questions about why certain details are necessary, how the answers affect medical decisions, or what happens if something unexpected arises. These questions often arise because situations make us confront the unknown or challenge our assumptions. The more we explore a situation, the more angles we discover, and each new layer uncovers more uncertainty or curiosity. For instance, understanding a complex process, such as receiving medical treatment or navigating a social interaction, may lead us to ask, “What if things go differently than expected?” or “How did others handle similar situations?” These questions are not just about seeking immediate answers but are part of our natural curiosity and desire to understand the broader picture. Ultimately, asking more questions leads to deeper insights and can even inspire new perspectives or innovations.

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As published in Issue 2: United in Discovery. Click any page to view it full size.

First published in Issue 2: United in Discovery, the Innately Science newspaper.