Medical Content Created by the Faculty of the
Harvard Medical School
Most patients have this test done by a hematologist in a clinic procedure area. You wear a hospital gown during the procedure. A sedative may be injected at this time. (If you are prescribed a sedative in pill form, you will be instructed to take it ahead of time.)
Most patients have bone marrow sampled from the pelvis. You lie on your stomach and the doctor feels the bones at the top of your buttock. An area on your buttock is cleaned with soap. A local anesthetic is injected to numb the skin and the tissue underneath the skin in the sampling area. This causes some very brief stinging.
A small cut is made in the skin to allow the biopsy needle to be placed through the skin. This needle is about half as wide as a pencil and has a handle on one end that your doctor holds while he or she moves it through your bone. The biopsy needle is moved through the bone with a twisting motion, as a corkscrew would be moved through a cork. When the needle has passed through the top layer of bone, your doctor uses a syringe to pull a liquid sample of your bone marrow cells through the needle. For most patients, the suction used in this liquid collection causes a pain in the buttock for a few seconds; this is why pain medicine is usually given in preparation for the biopsy.
After taking the liquid sample, the doctor carefully moves the needle a little bit further into the bone marrow to collect a second sample of marrow called a core biopsy. This core biopsy is a small solid piece of bone marrow, with not just the liquid and cells but also the fat and bone fibers that hold them together. After the needle is pulled out, this solid sample can be pushed out of the needle with a wire so that it can be examined under a microscope. Pressure is applied to your buttock at the biopsy location for a few minutes, until you are not at risk of bleeding. A bandage is placed on your buttock.