When the healthy stem cells come from you, the procedure is called an autologous transplant. If the stem cells come from another person called a donor, it is an allogeneic transplant. Blood or bone marrow transplants are most often used to treat blood cancers or other types of blood diseases that reduce the number of healthy blood cells in the body. These transplants can also be used to treat other conditions.

For allogeneic transplants, your doctor will try to find a donor whose blood cells are best for you. Your doctor will consider using cells from your close relatives, from people who are not related to you who are registered with the National Marrow Donor Program, or from publicly stored umbilical cord blood. While it is best to find a donor who is exactly right for you, new transplant procedures make it possible to use donors who are not exactly right for you.

Blood or bone marrow transplants are usually performed in a hospital. You will often need to stay in the hospital for one to two weeks before the transplant to prepare. During this time you will have a narrow tube in one of your large veins. You may be given medicines to make you sleepy during this procedure. You will also be given special drugs and possibly radiation to destroy your abnormal stem cells and weaken your immune system so that it doesn't reject donor cells after the transplant.

You will be awake on the day of the transplant and may be given medication to relax you during the procedure. The stem cells are given to you through the small tube in your vein. The stem cells travel through your blood to your bone marrow, where they start to make new healthy blood cells.

After the transplant, your doctor will check your blood count every day to see if new blood cells start to grow in your bone marrow. Depending on the type of transplant, you may be able to leave but stay close to the hospital, or you may have to stay in the hospital for weeks or months. The length of time depends on how your immune system recovers and whether or not the transplanted cells remain in your body. Before you leave the hospital, the doctors will give you detailed instructions to follow to avoid infection and other complications. Your doctor will monitor your recovery for up to a year.

While blood or bone marrow transplantation is an effective treatment for some conditions, the procedure can cause early or late complications. The medications and radiation needed can cause nausea, vomiting, diarrhea, fatigue, mouth sores, rashes, hair loss, or liver damage. These treatments can also weaken your immune system and increase your risk of infection. Some people can experience a serious complication called graft-versus-host disease if the donated stem cells attack the body. Other people can reject the donor stem cells after the transplant, which can be a very serious complication.