What is the connection between the blood type and the blood transfusion?
In blood transfusions, medical staff must ensure that the patient receives blood from a compatible donor. The relationship between blood type and blood transfusion is very important because incorrect blood could cause serious disease. If possible, the patient who needs blood will be written and compared to the care provider to determine what kind of blood to be given. If it is an emergency situation and the patient needs blood immediately, the doctor may allow a blood transfusion from an almost generally compatible donor.
There are a number of different blood groups systems, broken by different types of structures found on individual blood cells and plasma. Two of the most important are ABO and Rhesus groups, determined by surface molecules on blood and plasma antibodies. Patient with type A blood antibodies against B blood and cannot receive transfusions from patients with B or AB with blood. Conversely, patients with type B type respond to A and AB while patients with AB blood can receive blood from patients type A or B. They are considered "universal donors" because they can give everyone blood. However, they can only receive blood from other people with type O because they will respond to type A, B or AB blood.
Rhesus blood group and blood transfusions also have an important relationship. Some patients have Rhesus D antigen in their blood, while others don't. This adds a layer of complexity to compare donors with ABO. If the patient has antigen Rhesus D, he may receive blood from a patient who shares it or does not have antigen at all. However, patients without antigen may be ill if they receive blood from the donor who carries it.
The patient could therefore have A, B, AB or blood may be positive or negative, depending on the presence of Rhesus antigen. O Blood is only a universal donor when the patient is negative because blood can be safely inflated into almost anyone. AB positive people are universal recipients because they won't be REAGrvate on blood A, B or O and can obtain a transfusion from a donor with or without rhesus antigen. This relationship between blood type and blood transfusion is important for care providers because they must choose the most suitable blood for their patients.
One of the problems focusing on the blood group ABO and Rhesus and blood transfusion problems is that there are a number of other compounds classified in different group systems. They are much more rare and tend to be primarily concerned about specific human populations. If the patient and donor have a conflict under one of these less used systems, seemingly compatible transfusions may actually cause reaction.