Which transfusion reaction can occur with only a few milliliters of blood infused and typically presents without a fever?

An anaphylactic transfusion reaction is a severe allergic reaction that can occur quickly after the infusion of even a small volume of blood, typically just a few milliliters. This type of reaction is characterized by rapid onset of symptoms such as difficulty breathing, swelling, hives, and sometimes gastrointestinal symptoms, rather than the elevated body temperature associated with febrile reactions.

In cases of anaphylaxis, the immune system reacts excessively to proteins in the donor blood, leading to the release of histamines and other chemicals that cause the symptoms. Unlike febrile reactions that often coincide with temperature increases due to the immune response against white blood cells or cytokines, anaphylaxis can occur independently of fever and is notably linked to IgE-mediated hypersensitivity reactions.

Transfusion-related circulatory overload typically results from excessive volume rather than an immune-mediated response, leading to symptoms like dyspnea and hypertension, while hemolytic reactions, especially acute ones, generally involve larger volumes of blood and present with fever as well as signs of hemolysis. Neither of these responses fits the described characteristics of an anaphylactic reaction.