What is a bone marrow aspiration?

A bone marrow biopsy removes a small amount of bone and a small amount of fluid and cells from inside the bone (bone marrow). A bone marrow aspiration removes only the marrow. These tests are often done to find the reason for many blood disorders and may be used to find out if cancer or infection has spread to the bone marrow. Bone marrow aspiration removes a small amount of bone marrow fluid and cells through a needle put into a bone. The bone marrow fluid and cells are checked for problems with any of the blood cells made in the bone marrow. Cells can be checked for chromosome problems. Cultures can also be done to look for infection. A bone marrow biopsy removes bone with the marrow inside to look at under a microscope. The aspiration (taking fluid) is usually done first, and then the biopsy.