blood disorders
Blood Donation Process
Introduction
Healthy people donate a small amount of their blood to be used for Overview of Blood Transfusion . People usually give 1 pint (about 450 milliliters, approximately less than 1/10th of the total amount of blood in the body) and often different components of the blood (see The entire process of donating whole blood (that is, blood with all component cells) takes about 1 hour. Blood donors must be at least 17 years old (16 in some places with consent of a parent or guardian) and weigh at least 110 pounds (50 kilograms). In addition, they must be in good health. Their pulse, blood pressure, and temperature are measured, and a blood sample is tested to check for low blood count ( Overview of Anemia ). Donors are asked a series of questions about their health, factors that might affect their health, and countries they have visited. Certain conditions and factors can permanently or temporarily disqualify people from donating blood. Disqualifying factors typically are those that might make donation dangerous for the donor or risk transmitting a disorder to the recipient. The decision to accept or disqualify a donor can be complicated. The American Red Cross provides detailed information on their web site (see Very few disorders permanently disqualify people from giving blood. Most people can eventually give blood even if they are disqualified at first because most conditions that disqualify donors are temporary. Donated blood is tested for many infections, so the chance of getting a disease from donated blood is very small. Generally, donors are not allowed to give blood more than once every 56 days. The practice of paying donors for blood has almost disappeared because it encouraged needy people to present themselves as donors and then sometimes to deny having any conditions that would disqualify them. A person who is deemed eligible to donate blood sits in a reclining chair or lies on a cot. A health care worker examines the inside surface of the person's elbow and determines which vein to use. After the area immediately surrounding the vein is cleaned thoroughly, a needle is inserted into the vein and temporarily secured with a sterile covering. A stinging sensation is usually felt when the needle is first inserted, but otherwise the procedure is painless. Blood moves through the needle and into a collecting bag. The actual collection of blood takes only about 10 minutes, but the whole process from health history to a brief recovery period takes about an hour. The standard unit of donated blood is about 1 pint (about 450 milliliters). Freshly collected blood is sealed in plastic bags containing preservatives and an anticlotting compound. A small sample from each donation is tested for some infectious organisms. 