What is the expected outcome when a person with O phenotype is transfused with A type blood?

When a person with O phenotype is transfused with A type blood, a possible hemolytic reaction can occur due to the presence of A antigens on the transfused red blood cells. Individuals with blood type O have naturally occurring anti-A antibodies in their plasma. This means that, upon receiving A type blood, their immune system can identify the A antigens as foreign and mount an immune response against them.

This immune response can lead to agglutination of the transfused red blood cells, followed by hemolysis, which is the breakdown of red blood cells. Such a reaction can cause serious complications, including fever, chills, shock, and even kidney failure due to the rapid destruction of red blood cells in the bloodstream.

In comparison, blood type O is often referred to as the universal donor but only in the context of red blood cell transfusions where O negative is indeed suitable for most recipients. However, this universal donor status does not apply when a person with blood type O receives blood from another type, particularly A, as their antibodies will react against the A antigen present in type A blood. Therefore, the anticipated outcome in this scenario aligns with the potential for a hemolytic reaction.