The National Heart Lung and Blood Institute defines a bone marrow test as a medical procedure used to gather information by sampling the tissue inside a person's bones. Bone marrow is a soft sponge-like tissue that manufactures blood cells.
Bone marrow tests are used by doctors to diagnose a number of bone and blood diseases including bone marrow disorders, myelofibrosis and leukemia.
The two types of bone marrow tests are aspiration and biopsy and are performed simultaneously.
According to the online Encyclopedia of Surgery, aspiration, or sampling, is the "removal by suction of the soft, spongy semisolid tissue (marrow) that fills the inside of the long and flat bones," usually taken from the hip bone. A biopsy is the removal of intact bone marrow from the sampling to reveal more in-depth information about the marrow structure.
The National Heart Lung and Blood Institute reports that bleeding and infection are the most reported side effects. These side effects are rare though.
Bone marrow tests are useful in providing important information about a variety of health conditions in a cancer patient.