In about 20 percent of cases, bone marrow is collected from the pelvic bone under a full anesthetic using a thin, sterile needle. As a rule, two small incisions at the back of the pelvic bone are all that is required. The riskiest part of the procedure is essentially the anesthetic. About 5 percent of the bone marrow is removed, which the body fully regenerates. Some donors experience localized pain from the incision, which often feels like bruising. The donor spends 3 days in hospital. On the first day you check in, on the second you have the procedure, and on the third you are discharged.