Blood transfusions are used to replace lost blood during surgery or after a serious injury. An IV is used to insert the new blood into your body through the blood vessels. The overall procedure does not take long, but may depend on how much blood you need. The new blood just replaces what you have lost, but does not replace all of your original blood. Blood transfusions are fairly common as well. Many people in America have to receive transfusions each year. One of the most important factors involved in the transfusion process is blood type. There are four blood types and everyone in the world has one of those types. A, B, AB, O. There is also something called Rh-positive or Rh-negative that is attached to each persons blood type. When a person needs a blood transfusion the blood that they receive must match up. If the blood types do not match the antibodies in their blood will see the antibodies of the new blood as foreign, attack them resulting in sickness. So if you are type A blood your transfusion must come from another A blood type. There are some exceptions such as blood type O. People who have type O blood are also known as the universal donors. This means that any person in the world can receive type O blood as healthy transfusion blood. Type AB blood is known as the universal recipient and can receive any type of blood.
This was an informative post to allow some insight on blood transfusions. The transfusion process and why type O and AB blood are so critical to human life have always been topics I've continued to research. To read more about why blood types match up and details on blood transfusions read the article titled: What are Blood Transfusions?