Aspiration and Biopsy: Bone Marrow

What It Is

Bone marrow aspirations and biopsies are performed to examine bone marrow, the spongy liquid part of the bone where blood cells are made.

In a bone marrow aspiration, a small amount of liquid marrow is taken from inside the bone so the cells can be examined under a microscope.

In a bone marrow biopsy, a small piece of intact bone marrow is removed so the structure of the bone marrow inside its bony framework can be examined. Occasionally, only an aspiration is needed; other times, both tests are done.

The aspiration and biopsy are done by a trained medical practitioner (nurse or doctor) using a small needle inserted into a bone. Usually the back of the hipbone (iliac crest) is used.

Why It's Done

Doctors perform bone marrow aspirations and biopsies when they're concerned about a problem in the bone marrow. The tests can help to diagnose:

the cause of anemia (too few red blood cells, which carry oxygen through the body)
the cause of thrombocytopenia (too few platelets, which help the blood to clot)
the cause of an abnormal number of white blood cells, which fight infections
cancers of the blood, such as leukemia
whether cancers that started elsewhere have spread to the bone marrow (the assessment of how much a cancer has spread is called staging, and is important in determining treatment and prognosis)
viral, bacterial, or fungal infections in the bone marrow that might be causing a lasting fever or other symptoms
certain genetic diseases (such as lipid storage diseases)

They also might be done to collect a bone marrow sample for procedures (such as stem cell transplantation) or other testing (such as chromosomal analysis).

Preparation

After the procedure is explained and all of your questions have been answered, your parent or guardian will be asked to sign an informed consent form (this states that you and your parents understand the procedure and its risks, benefits, and alternatives and give permission for it to be performed).

The person performing the bone marrow aspiration and biopsy will know your medical history, but might ask additional questions, such as what medicines you're taking or whether you have any allergies. Be sure to report any bleeding tendencies, and whether you might be pregnant.

Numbing cream may be placed on the aspiration and biopsy site about 30 minutes before the procedure. You will probably receive sedation just before the procedure begins. You will be asked to stop eating and drinking at a certain point earlier to make sure the stomach is empty. Sedation medications are usually given through an IV line (intravenous line). IVs are a way to get fluids or medicines directly into a person's vein. Sedation medications help patients stay asleep during the entire procedure.

Your parent or guardian might be able to stay in the room with you during the procedure for reassurance and support or they will be just outside in a waiting area.

Procedure

A bone marrow aspiration and biopsy usually takes about 30 minutes.

You may be asked to change into a cloth gown, and then you'll be positioned on an exam table on your stomach or side. The skin will be cleaned with a special soap to sterilize the skin.

If you're sedated, your vital signs (heart rate, blood pressure, temperature, and blood oxygen level) will be monitored during the procedure. You may have a cuff around your upper arm to measure blood pressure and a small fingertip clip to monitor the blood oxygen level.

A small amount of anesthetic medicine will be injected through the numb spot on the skin to prevent pain as the bone marrow needle is inserted through the skin and soft tissues.

For the bone marrow aspiration, the doctor or nurse will carefully insert a needle into the biopsy site and will then attach a syringe to draw out a sample of fluid from inside the bone.

For the biopsy, a different kind of needle will be inserted into the same area to remove a small sample of bone. A bandage will then be applied to the biopsy site.

bone_marrow_biopsy_illustration

What to Expect

If you're drowsy, the injected anesthetic might sting a bit for a minute or two and you might also feel the pressure of the biopsy needle pushing in. Some people feel a quick sharp cramp as the liquid bone marrow is withdrawn for the aspiration or as the sample of bone marrow is removed for the biopsy. This cramp only lasts for a few seconds. In many cases, sedation is used to put patients into a deep sleep so they won't feel anything.

Depending on the doctor's recommendations, you might have to lie down for a while after the procedure. If sedated, you may need a few hours to rest and to allow the medications to wear off.

The biopsy site may feel slightly sore the day after the procedure and might have a small bruise. The bandage should be left in place for as long as instructed by the doctor.

Getting the Results

A doctor with expertise in interpreting bone marrow biopsies (also called a pathologist) will look at the biopsy sample under a microscope and then give the information to your doctor, who will review the results with you and your parents.

In an emergency, the results of a biopsy can be available quickly. Otherwise, they're usually ready in 1-2 days. Results can't be given directly to the patient or family at the time of the test.

If a bacterial infection is suspected, a culture is sent to a lab and results are usually available in 48 hours. A doctor might start antibiotic treatment while waiting for the results of the culture.

Risks

A bone marrow biopsy is considered a safe procedure with minimal risks. Complications are rare. In some instances, there may some discomfort or pain at the biopsy site for 1-2 days. In rare cases, infection or bleeding can happen.

If you're sedated, there's a slight chance of reaction to the medicine (for example, an allergic reaction), or slowed breathing due to the medications. If there are any problems with the sedation, the medical staff will treat them right away.