Bone marrow test for CLL

Rarely, your specialist may want to look at a sample of bone marrow as well as a blood sample.  You may hear this test called a bone marrow aspiration, a bone marrow biopsy or a trephine biopsy.

You have this test to check whether there are cancer cells in your bone marrow. Bone marrow is spongy tissue and fluid that is inside some of your bones. It makes blood cells.

A doctor or specialist nurse removes an area of bone marrow in one piece, from your hip. Doctors can then look at the tissue under a microscope.

Diagram showing a bone marrow biopsy

You have the test in the outpatient department of the hospital. 

You have a local anaesthetic to numb the area.This means you are awake.

Some people may have medicine to make them drowsy (sedation). Some hospitals may use gas and air (Entonox) to help relax you instead of sedation. 

Types of biopsy

There are 2 main types of bone marrow test: 

  • bone marrow aspiration
  • bone marrow trephine biopsy

Aspiration means the doctor or nurse sucks some liquid bone marrow up into a syringe.

A bone marrow trephine means that they remove a very thin 1 or 2cm long core of bone marrow in one piece.

You usually have both of these tests done at the same time. They give some of the same information to the doctor, but there are differences. The bone marrow trephine shows the structure of the bone marrow inside the bone, whereas the aspiration takes just the bone marrow cells.

Preparing for your bone marrow test

Your nurse or doctor will tell you how to prepare for the bone marrow test if you are in hospital. If you are an outpatient your appointment letter will explain what you need to do.

You are usually able to eat and drink beforehand if you aren't having sedation. If you’re having sedation you’ll get specific instructions about when to stop eating and drinking before the test.

Take your medicines as normal unless told otherwise. If you are taking any blood thinning medicines, you might need to stop these before the test. Your doctor will tell you when to stop taking them.

What happens?

Your doctor or nurse gives you information about the procedure and asks you to sign a consent form. This is a good time to ask any questions you have.

You change into a hospital gown and lie on your side with your knees tucked up into your chest. Usually your doctor or nurse takes the sample from the back of your hip bone.

Your doctor or nurse first cleans the area with some antiseptic fluid, which can feel cold. You then have an injection into the skin over the biopsy site to numb the area. They put a thin needle through the skin into the hip bone. This might be uncomfortable but this only lasts a short time. 

Your doctor or nurse sucks a small amount of liquid bone marrow into the needle, using a syringe. You feel a pulling sensation when they start drawing the bone marrow cells out. 

They take the needle out and put in a second one if you're having a trephine biopsy as well. The aim is to get a small amount of marrow out in one piece.

The whole test takes around 30 minutes.

After your bone marrow test

If you have a sedative, you need to stay at the hospital for a few hours until it has worn off. And you need someone with you so that you don't have to go home on your own. You can go home that day if you are feeling well enough.

The area is looked at by the nurses before you go home. You have a dressing over the area, which you should keep on for 24 hours. If you notice any bleeding, apply pressure to the area. You can do this by lying on your back. Contact the hospital if the bleeding doesn't stop.

After the test, your hip might ache for a couple of days. You may need some mild painkillers such as paracetamol to take at home.

Possible risks from bone marrow test

A bone marrow test is very safe and any risks are small. 

During the procedure there is a very small risk of damage to nearby structures, but this is very rare.  


It's not unusual to have a small amount of bleeding from the area where the needle went in. If you notice any heavy bleeding, apply pressure to the area. If it doesn't stop, contact the hospital.


Sometimes blood leaks out of the vein and collects under your skin. This can look like a small dark swelling under the skin (haematoma). Pressing hard once the needle is removed can help


There is a small risk of getting an infection in the wound. Tell your doctor if you have a temperature or if the area becomes red and sore. 


Some people feel uncomfortable and have pain after the local anaesthetic has worn off. Your nurse will tell you what painkillers to take. If you have severe pain or it's getting worse then you should contact the hospital.

Tingling in your leg

You may have some tingling in your leg which wears off with time.

Getting your results

Waiting for test results can be a very worrying time. You might have contact details for a specialist nurse and you can contact them for information if you need to. It can help to talk to a close friend or relative about how you feel.

You can also contact the Cancer Research UK nurses on freephone 0808 800 4040. The lines are open from 9am to 5pm, Monday to Friday.
Last reviewed: 
18 Sep 2021
Next review due: 
18 Sep 2024
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