Blood Transfusion

When a person is given a blood transfusion, that person is really only receiving part of the blood that has been donated for his or her use. The transfusions typically transfuse only the red blood cells that have been donated.

Blood transfusions are used to correct two main, major types of problems. The first problem is acute and massive blood loss. This empties the blood vessels to the degree that the heart cannot maintain enough blood pressure to move the blood through the body. The second problem is severe anemia. Severe anemia is when there is enough blood volume in the body but not enough red blood cells in the blood to get oxygen to the body's tissues.

Physicians have to carry out compatibility test before blood transfusion to their patient. Cross-Matching, is a test done by physicians to determine if the donated blood matches the recipient's blood that is in dire need of a blood transfusion. There are two ways to do cross-match test: Electronic and Manual.

Electronic Cross-Matching: You simply inject the donor's blood and the recipient's blood into a machine which connects to a computer. If all the necessary components of the blood are compatible, the computer prints off a sheet that tells you that it is safe to do a transfusion with this blood. The physician can then safely perform the transfusion of the blood. This is an important factor during emergencies when a patient has lost a lot of blood.

Serological Cross-Matching: When the electronic method is not available, serological cross-matching is the second choice. In this method, the physician or the blood technician at hand has to manually do the test in order to verify whether the blood of the recipient matches the blood of the donor. Blood is collected from the recipient. Plasma from the blood is extracted via centrifuge method. The plasma is then injected with a syringe into test tubes with the donor blood. If agglutination occurs, then that means that the patient's plasma contains antibodies against the donor's blood. If there is no agglutination, then a match is made and the blood is safe to transfuse.

For getting more details & case studies of blood transfusion, read internal medicine teaching by Professor EBM.