Blood transfusions are fairly common and people receive them for numerous reasons. For example, a person may have had surgery and lost blood that needs to be replaced. Some people may need them because of an infection that has made it difficult for their body to make blood. Or, they may have a bleeding disorder, such as hemophilia.
There are many precautions that must be taken before undergoing a blood transfusion. First of all (and the most important), blood needs to be typed and matched. If a person gets blood that they are not compatible with they could die. Also, sometimes people have allergic reactions to blood so this needs to be monitored as well.
Another key precaution that has to be taken in the process before giving someone a transfusion is that the doctor or nurse has to establish whether or not there are any blood disorders that could complicate the transfusion. Hemophilia is one of the more common blood disorders and transfusions can still be given but only if clotting factor is added or serious bruising/bleeding may occur. It is also common after a person has received a large number of transfusions that the blood refuses to clot on its own.
You would also have to establish whether or not a person had any alergies to the iodine used to sterilize the plce on the arm for the IV. While this doesn't happen very often, you don't want an allergic reaction starting when a person is needing blood, as that's a fairly life-critical procedure.
Most doctors also check to see if there are "needle tracks" or evidence of IV drug use, which can compromise veins to the point they can't be used, and signal increased risk of infectious diseases already being present. Everyone in the room needs masks and gloves, so that no blood contact is made, and the risk of infection is minimized.
For donors, the process of giving blood is very safe. Only sterile equipment is used and there is no chance of catching an infection from the equipment. There is a slight chance of infection at the puncture site if the skin is not properly washed before the collection needle is inserted. Some donors feel light-headed upon standing for the first time after donating. Occasionally, a donor will faint. Donors are advised to drink lots of liquids to replace the fluid lost with the donated blood. It is important to maintain the fluid volume of the blood so that the blood pressure will remain stable. Strenuous exercise should be avoided for the rest of the day. Most patients have very slight symptoms or no symptoms at all after donating blood.
For recipients, a number of precautions must be taken. The blood given by transfusion must be matched with the recipient's blood type. Incompatible blood types can cause a serious adverse reaction (transfusion reaction). Blood is introduced slowly by gravity flow directly into the veins (intravenous infusion) so that medical personnel can observe the patient for signs of adverse reactions. People who have received many transfusions can develop an immune response to some factors in foreign blood cells. This immune reaction must be checked before giving new blood. Infectious diseases can also be transmitted through donated blood.