Which type of transfusion reaction is characterized by fever without hemolysis?

A febrile reaction is the correct choice as it specifically refers to an increase in body temperature following a blood transfusion, typically manifested by fever and chills. This type of reaction is commonly caused by the recipient's immune system responding to leukocytes or other components present in the transfused blood products. Unlike hemolytic reactions, febrile reactions do not involve the destruction of red blood cells (hemolysis), which makes them notably different in their presentation and underlying mechanisms.

In contrast, hemolytic reactions are associated with the destruction of red blood cells and present with symptoms such as fever, chills, back pain, and hemoglobinuria, making them more severe and potentially life-threatening. Allergic reactions, while they may cause symptoms like hives, itching, or anaphylactic reactions, typically do not present primarily with fever. Anaphylactic reactions are acute and severe responses that can lead to respiratory distress and circulatory collapse, often occurring within seconds to minutes after exposure to the allergen, such as proteins in the blood product.

Understanding the unique characteristics of each type of transfusion reaction is crucial for accurate diagnosis and management during transfusion therapy.