The bone marrow is an organ, and organs are formed by cells that perform a similar function to a certain degree. The main function of the bone marrow is the production of blood cells whether they are red blood cells, white blood cells or platelets. When a disease affects the bone marrow, the patient usually has abnormalities in the production of such components. Bone marrow biopsy is one of the most commonly ordered hematological investigations because the bone marrow is the main manufacturing plant of blood cells. Since it is hidden under a layer of thick bone, we need special techniques to obtain a sample for investigations. After birth and as the human advances in age, the percentage of the active “red” marrow decreases, and by late childhood and early adulthood, it becomes almost completely replaced by the inactive “yellow” marrow. The active marrow becomes limited to the axial bones, especially the sternum or “breastbone”, ribs, hip bone and the proximal ends of long bones. In other words, the parts near the center of the body.
Bone marrow biopsy is ordered for the following conditions:
- An unexplained anemia, alarmingly decreased platelets or increased white blood cells.
- The diagnosis, staging and monitoring of the treatment of hematological malignancies whether they are leukemias, myelodysplastic disorders, lymphomas or multiple myeloma.
- Fever of an unknown origin.
- Some rare metabolic diseases, such as Nieman-Pick and Gaucher, which are related to the storage of fats and glycogen in our bodies.
- Metastatic cancers from elsewhere in the body and staging of other granulomatous diseases, including sarcoidosis and tuberculosis.
Bone marrow biopsy types
There are two main types of bone marrow biopsies: aspiration biopsy and trephine biopsy.
In bone marrow aspiration, the doctor will push a needle through the thick bone -under local anesthesia-, and then aspirate a small amount of the marrow, this procedure is used in the case of some bone cancers to get a general look on the cellular components of the bone marrow.
Trephine bone marrow biopsy on the other hand involves the sampling of a small part of the bone with the marrow underneath with special needles and technique. It is more accurate than the standard bone marrow biopsy, and the only option in cases where bone marrow aspiration can’t be performed as in cases of aplastic anemia -which is a type of anemia due to the inability of the bone marrow to produce red cells-, and metastatic cancers.
Bone marrow biopsy is usually carried out either in a hospital or an outpatient clinic, and the doctor will usually administer local anesthesia with antianxiety medications.