**Question:** Common reaction to blood transfusion may include all except:

A. Anaphylaxis
B. Hemolysis
C. Acute kidney injury
D. Infection

**Core Concept:** Blood transfusion is a procedure where blood components or whole blood is given to a patient who is experiencing severe blood loss or hemoglobin deficiency. While blood transfusion is a lifesaving procedure, it can sometimes lead to adverse reactions due to various reasons.

**Why the Correct Answer is Right:**

The correct answer, **Acute kidney injury (AKI)**, is not mentioned as a common reaction to blood transfusion because the primary purpose of this question is to identify reactions that are directly related to the transfusion process or the transfused blood components. AKI is a complication that could result from other factors, such as hypovolemia, sepsis, or pre-existing kidney disease, rather than inherent to the transfusion procedure itself.

**Why Each Wrong Option is Incorrect:**

1. **Anaphylaxis (A)**: This is a systemic allergic reaction that can occur during or immediately after blood transfusion. It is a common adverse reaction due to the presence of anti-HLA antibodies in the transfused blood, causing histamine release and leading to symptoms such as hypotension, bronchospasm, and hypoxia.

2. **Hemolysis (B)**: This refers to the breakdown of red blood cells (RBCs) after transfusion. Hemolysis can be caused by incompatible blood units, storage lesions, or the presence of anti-RBC antibodies. While hemolysis is a transfusion-related complication, it is not specifically excluded in this question, as it is a common complication and not a reaction unique to blood transfusion.

3. **Infection (D)**: Blood transfusion carries a risk of transmitting pathogens, such as viruses, bacteria, and parasites, particularly if the blood is obtained from an infectious donor. In this question, "Infection" is not directly related to the transfusion process but rather to the potential risk of using an infectious blood unit.

4. **Acute kidney injury (AKI)**: As explained earlier, AKI is not an inherent reaction to blood transfusion but rather a consequence of hypovolemia, sepsis, or pre-existing kidney disease.

**Clinical Pearl:** It is essential for healthcare professionals involved in transfusion medicine to be aware of the common complications and reactions associated with blood transfusion, including anaphylaxis, hemolysis, and infection. Transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO) are also potential complications; however, they are not explicitly excluded in this question, as they are transfusion-related complications rather than reactions unique to blood transfusion. Understanding these complications and reactions will help healthcare professionals provide safer and more effective transfusion therapy to patients.