Blood transfusion is a tricky business. Transfusion with wrong blood type is rare. But it has happened before and can happen again. To understand how it feels to have a wrong type of blood running through your bloodstream, you first have to understand how blood type and transfusion works. A person’s blood type is determined by his red blood cells. When a baby is born, doctors analyse his red blood cell properties and determine the blood type from A, B and O. Exceptions to this is the AB type, where the RBC shows properties of both A and B types.