Bone marrow aspiration is the removal of a small amount of the liquid portion of the bone marrow through a needle inserted into the bone. It can be done to collect bone marrow for stem cell transplantation or chromosomal analysis, or to monitor treatment for certain types of blood disorders.

The bone marrow sample is examined under a microscope to obtain information to:

• Help diagnose conditions that affect the bone marrow, such as lymphoma and leukemia.
• Help determine the cause of abnormal blood tests.
• Measure the amount of iron, or other substances, that blood cells need for growth.

Additional tests of the bone marrow sample can also be done to see if an infection is present and to identify antibiotics that might be used to treat the infection.

A bone marrow biopsy is the removal of bone marrow tissue and is often done with a bone marrow aspiration. A biopsy allows close examination of the bone marrow's structure.