Bone marrow is a spongy tissue within the bones. It is present inside the hip bone, ribs, sternum, and thigh bone. It is a semisolid tissue containing fluid and solid portions. Bone marrow contains stem cells that produce blood cells:
- White blood cells (WBCs): fight against infections
- Red blood cells (RBCs): carry oxygen and nutrients
- Platelets: responsible for blood clotting
Bone marrow biopsy and aspiration are procedures usually performed together to collect and examine bone marrow for helping in diagnosis of blood disorders and other conditions. In a bone marrow biopsy, a special biopsy needle is used to extract a sample of the solid portions of the bone marrow. In bone marrow aspiration, a special aspiration needle is used to withdraw (aspirate) a sample of the fluid portion.
Why is bone marrow biopsy and aspiration done?
Bone marrow analysis is one of the most important diagnostic tools for evaluating blood disorders and other conditions. It helps in the diagnosis, staging, and therapeutic monitoring of blood cancers. Some common conditions that indicate bone marrow biopsy and aspiration are:
- Chronic myeloid leukemia and acute myeloid leukemia: Cancer arising from myeloid cells in the bone marrow which form WBCs (white blood cells), RBCs (red blood cells) and platelets
- Acute lymphocytic leukemia and acute lymphocytic leukemia: Cancer arising from the lymphocyte cells, a type of WBC present in the bone marrow
- Hodgkin and non-Hodgkin lymphoma (cancer of the lymphatic system)
- Hairy cell leukemia (slow growing cancer of B cells, a type of WBC)
- Multiple myeloma (cancer of plasma cells, also called B cells, a type of WBC)
- Idiopathic thrombocytic purpura (low level of platelets due to an unknown cause)
- Cytopenia (decreased level of one or more blood cell types)
- Thrombocytosis (increased level of platelets)
- Undiagnosed anemia (decreased RBCs)
- Nutritional deficiencies
- Infections that may infiltrate the bone, e.g., tuberculosis and fungal infections.
- Fever of unknown origin
- Metastatic cancer (cancer that has spread to other parts of the body)
- Metabolic disorders
What happens during bone marrow aspiration and biopsy?
The most commonly used bone for a biopsy is the iliac crest (thick curved upper border of the hip bone, present on both sides of the hip). It is easily accessible and associated with lesser complications. A biopsy sample may be obtained from one or both iliac crests. Sampling from the iliac crest may be contraindicated in obese patients.
The sternum (breastbone) is sampled as the last resort in those older than 12 years of age and in those who are obese. Sternum has a higher risk of complications.
Before the procedure:
The doctor obtains a detailed medical history, performs a physical assessment, and advises complete blood and radiological analysis to understand the disease better. Biopsy helps in confirming the diagnosis.
During the procedure:
It is a short procedure performed under local anesthesia. Children or patients who do not cooperate require general anesthesia or intravenous sedation. Hence, there is no pain. Bone marrow aspiration to extract fluid portion of the marrow is usually performed first. A small incision is made through which an aspiration needle is inserted into the bone and then into the bone marrow. Following this, bone marrow biopsy is performed. A larger biopsy needle is used to extract a solid part of the bone marrow tissue. The samples are sent to the pathologist for analysis.
After the procedure:
Wound dressing would remain for 24 to 48 hours. In case of local anesthesia, patients can go home soon after the procedure and resume normal activities. Patients who had general anesthesia or intravenous sedation may take a day to fully recover from anesthesia. Patients may experience pain, swelling, and bruising which usually resolve in a week. Pain killers and antibiotics may be prescribed.