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Blood Transfusion Reactions- Etiology, Epidemiology, Pathophysiology, and Management

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Adverse reactions to transfusions of whole blood or one of its components are referred to as transfusion reactions. They might be minor or life-threatening.

Medically reviewed by

Dr. Kaushal Bhavsar

Published At May 16, 2023
Reviewed AtSeptember 19, 2023


Adverse occurrences connected to the transfusion of whole blood or one of its components are referred to as transfusion reactions. They could be minor to life-threatening in intensity. Responses can occur during the transfusion (acute transfusion reactions) or days to weeks later (delayed transfusion reactions) and may be immunologic or non-immunologic. Because of the non-specific, frequently overlapping symptoms that reactions can present with, they can be challenging to diagnose.

Fever, chills, urticaria (hives), and itching are among the most typical warning signs and symptoms. Some symptoms go away with little to no treatment. Nevertheless, signs of a more serious reaction include respiratory difficulty, a high fever, hypotension (low blood pressure), and red urine (hemoglobinuria).

Before the transfusion is initiated, a detailed understanding of the patient's health and medical history is required. During intervals of 15 minutes, vital signs are monitored and normally recorded. Vital signs may slightly fluctuate during transfusions; this is normal. The following variations are possible: a temperature variation of plus or minus 0.5 C, a respiration rate variation of plus or minus 5, a heart rate variation of plus or minus 10 beats per minute, and a blood pressure variation of plus or minus 20 mm Hg.

It is crucial to remember that changes greater than these thresholds do not necessarily indicate a transfusion reaction; rather, they indicate that the bedside nurse should be more watchful in looking for one. Hormonal reactions can cause hives and itching.

What Is the Etiology of Blood Transfusion Reactions?

Immune-mediated transfusion responses frequently result from a mismatch or incompatibility between the recipient and the transfused substance. These include antibodies produced in response to foreign antigens (alloantibodies) as well as antibodies created naturally by the blood recipient (such as anti-A and anti-B, which are often in charge of acute hemolytic transfusion reactions).

Many reactions, such as mild allergic, febrile non-hemolytic, acute hemolytic, and anaphylactic, are caused by these alloantibodies. Transfusion-associated lung injury (TRALI) is hypothesized to be caused by antibodies, which can potentially cause responses.

Non-immunologic reactions are typically brought on by disease transmission or the physical effects of blood components. For instance, bacterial contamination of a blood product results in septic transfusion reactions and is brought on by bacterial and endotoxin contamination. Bacteria in the blood of the donor at the time of collection, poor blood donor arm cleaning, incorrect product handling after collection, or the presence of germs in the donor's circulation could all be to blame for this.

Moreover, transfusion responses can happen independently of blood-related causes. They include hypothermia and transfusion-associated volume overload (TACO).

What Is the Epidemiology of Blood Transfusion Reactions?

Mild allergy and febrile non-hemolytic transfusion responses are relatively common, although severe reactions are rare (anaphylaxis, acute hemolytic, and sepsis). The majority of adverse reactions with TRALI have been known to be fatal, and long-term or later reactions are frequently brought on by the spread of an illness.

The type of transfusion reaction, the prevalence of disease in the donor community, and the level of post-transfusion treatment the patient receives all influence the severity and incidence. The hazards and fatalities connected with the transfusion of blood products are steadily declining because of advances in testing, automated data systems, and donor screening.

What Is the Pathophysiology of Blood Transfusion Reactions?

Depending on the transfusion reaction, the pathophysiology varies.

Acute Transfusion Reactions:

  • Mild Allergic: Attributed to a donor product's foreign protein-induced hypersensitivity.

  • Anaphylactic: Comparable to a little allergic reaction, but with a more serious outcome. When a patient with IgA deficiency develops alloantibodies against IgA and subsequently receives blood products containing IgA, this can occasionally happen.

  • Febrile Non-hemolytic: Generally believed to be brought on by cytokines secreted from leukocytes of blood donors (white blood cells).

  • Septic: Caused by bacteria or bacterial metabolites that may contaminate blood, such as endotoxin.

  • Acute Hemolytic Transfusion Reactions: Depending on the exact etiology, it may cause intravascular or extravascular hemolysis (cause). Recipient antibodies to blood donor antigens can cause immune-mediated responses. There is a chance of non-immune reactions when red blood cells are harmed before transfusion.

  • Transfusion-Associated Circulatory Overload (TACO): This takes place when the amount of the transfused component results in hypervolemia (volume overload).

  • Transfusion-Related Acute Lung Injury: Human leukocyte antigen or human neutrophil antigen antibodies in the donor product interact with antigens in the recipient to cause acute lung damage. The immune system of the receiver reacts and releases mediators that result in pulmonary edema. Clinical conditions that predispose the patient, such as an infection, recent surgery, or inflammation, could be a factor in this.

Delayed Transfusion Reactions

  • Delayed Hemolytic Transfusion Reaction: Usually brought on by a patient's anamnestic reaction to a foreign antigen that they had previously been exposed to (generally by prior transfusion or pregnancy).

  • Transfusion-Associated Graft-Versus-Host Disease: Results from the engraftment of donor lymphocytes—often present in cellular blood products—into the bone marrow of an immunosuppressed recipient. The donor lymphocytes react against the recipient's body after identifying the patient as an outsider. The foreign lymphocytes cannot be eliminated by the patient's immune system. Though uncommon, this can be fatal.

What Is the Management of Blood Transfusion Reactions?

The transfusion should be discontinued right away if a transfusion reaction is suspected, and the intravenous line should be kept open with the proper fluids (often 0.9 % saline). Examining the product bag and confirming the patient's identity should be done as a clerical check. At intervals of 15 minutes, the patient's vital signs should be observed and noted.

Whenever possible, the bag and tubing should also be sent to the lab along with a post-transfusion blood sample. To rule out a transfusion that is incompatible, the blood bank typically conducts extra testing and administrative procedures.

The most common form of treatment for certain transfusion reactions is support. For a nonhemolytic febrile transfusion reaction, an antipyretic can be administered, as can antihistamines for a moderate allergic reaction.

The type of component being transfused, the storage needs, and the patient's co-morbid conditions at the time of transfusion are only a few of the variables that affect transfusion reactions. The best possible patient care is ensured by knowing how to immediately recognize transfusion reactions and treat the patient accordingly.


In medicine, blood transfusions are frequently required, and all healthcare professionals must be knowledgeable about transfusion reactions. Any patient can undergo a blood transfusion on any ward, and all nurses must be aware of any potential issues and how to handle them. Most blood transfusion responses are the result of a nursing or office error. Many transfusion reactions are benign, while some can be severe and fatal. Although they are extremely rare, anaphylactic responses following a blood transfusion frequently result in death.

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Dr. Kaushal Bhavsar
Dr. Kaushal Bhavsar

Pulmonology (Asthma Doctors)


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