Bone marrow test in children — what to expect

Knowing exactly what to expect reduces fear — for you and for your child. Here is a step-by-step account of how a paediatric bone marrow aspiration and biopsy typically unfolds.

1. 1

   Fasting and arrival

   Your child will be asked to fast for a set number of hours before the procedure (typically four to six hours for food and two hours for clear fluids, though the anaesthetist's specific instructions take priority). Arrive at the time the hospital gives you — registration, weight, and a brief clinical check happen before anything else. Bring the child's comfort object, whether that's a favourite toy, a blanket, or a tablet loaded with their favourite show.

2. 2

   Meeting the anaesthetist

   Before the procedure, the anaesthetist will meet your child and you to explain what sedation or general anaesthesia involves, ask about allergies and previous reactions to anaesthesia, and answer your questions. This is the right time to mention if your child has had breathing problems or any past difficulties with sedation. In many paediatric centres, a parent is permitted to be present right up until the child is asleep — ask the team whether this is possible at your hospital.

3. 3

   Going to sleep

   Anaesthesia is typically given through a small cannula (a thin plastic tube) placed in the back of the hand or arm, or sometimes as a breathing gas through a mask for younger children who are distressed by needles. The child usually falls asleep within 30 to 60 seconds. They feel nothing from this point forward, and they will have no memory of the procedure itself.

4. 4

   The aspiration and biopsy

   Once the child is fully asleep, the haematologist or oncologist cleans the skin over the posterior iliac crest (the rounded bone at the back of the hip) with an antiseptic solution and makes a tiny skin puncture — no stitches needed. A hollow needle is advanced through the bone into the marrow space, and the liquid aspirate is drawn out. If a biopsy core is also needed, a slightly larger trephine needle takes the small solid sample. The whole procedure typically takes 15 to 20 minutes. A small sterile dressing is applied, and the anaesthesia is reversed.

5. 5

   Waking up and recovery

   Children usually wake within 15 to 30 minutes in the recovery area. They may be groggy, a little tearful, or nauseous for a short time — this is normal. Once the child is awake, drinking, and their observations are stable, they move to a ward or day-care bay. Most children go home within two to four hours of the procedure. Mild soreness at the needle site for one to two days is expected; the dressing should be kept dry for 24 hours. Paracetamol or ibuprofen (as directed by the doctor) is usually sufficient for comfort.

6. 6

   When to call the hospital after going home

   Contact the team if your child develops a fever above 38.5°C in the 48 hours after the procedure, if bleeding from the site does not stop with gentle pressure, if there is increasing redness, swelling, or warmth around the dressing, or if your child complains of worsening pain rather than improving pain. These are uncommon but important to report promptly. Your discharge paperwork will include a direct number to call — keep it accessible.

7. 7

   Understanding and waiting for results

   Results arrive in stages. The initial morphology report — what the cells look like under the microscope — is typically available in 24 to 48 hours, and your oncologist may call you with early findings. Flow cytometry results (identifying the exact cell type) usually follow in two to four days. Cytogenetics and molecular testing, which look for specific chromosomal changes that guide which treatment protocol is used, may take one to two weeks. The wait is hard. Write your questions down as they occur to you so you are ready for the results appointment. At CION, our team is available to answer questions between appointments — you do not have to sit alone with your worry.