Bone Marrow Aspiration
A bone marrow aspiration may be done if your child’s doctor thinks cancer may have spread beyond the eye.
This test may be done once at diagnosis or later in the treatment journey. For example, after enucleation surgery if pathology shows there is a high risk of the cancer recurring. In this instance, the test may be repeated every few months for several years.
A special hollow needle is used to remove a sample of marrow from inside the hip bone. A pathologist examines the marrow under a microscope to look for signs of retinoblastoma.
Bone marrow aspiration can be done under local anaesthetic in an outpatient treatment room. The procedure is less traumatic for a young child when done under general anaesthetic. Many hospitals will co-ordinate so the sample can be drawn during an EUA when your child is asleep.
Marrow is usually taken from the top of the hip bone (pelvis), which is just under the skin and rich in marrow. Rarely, marrow is taken from other bones, such as the tibia (long bone in the lower leg) or sternum (breast bone).
During the Procedure
If bone marrow aspiration is done awake, your child may be given a mild sedative to reduce distress during the procedure. She will be asked to lay on her stomach or side on the procedure table. A cushion may be used to elevate her hip.
Wearing surgical gloves, the doctor or nurse practitioner will examine the bone and thoroughly sterilise the skin with antiseptic. Surgical paper will be placed on the skin: either several sheets, or one sheet with a window cut out for the aspiration site.
A local anaesthetic (usually lidocaine) may be injected into the skin and a small area of bone. This will sting for a few seconds, but the sensation passes quickly as the area becomes numb.
A hollow needle is passed gently through the skin into the bone. The doctor or nurse will then attach a syringe, and liquid marrow is sucked into it.
The whole procedure takes less than 20 minutes. Your child may feel some discomfort as marrow is drawn into the syringe, but this should only last a few seconds. She may feel bruised and achy for a few days afterwards. This can be eased with mild painkillers.
Children are often given a general anaesthetic for bone marrow aspirate, but with good child life support, even toddlers can complete this procedure awake. Some degree of sedation is usually important for these children, as is pre-treatment with a topical anaesthetic.
Consult with the doctor or nurse ahead of time so you can pre-treat the aspiration area with a numbing agent such as EMLA. Discussion with the doctor or nurse doing the procedure is important so that you put the topical anaesthetic in the correct area, and time the dose we