Bone Marrow Biopsy

Why we do a bone marrow biopsy

Your bone marrow is the factory floor where all blood cells are made. When the blood looks abnormal — unexplained low counts, abnormally high counts, abnormal-looking cells on a smear, a suspected blood cancer — we sometimes need to look at the factory itself, not just the finished products in the bloodstream.

A bone marrow examination gives us several pieces of information at once: how cellular the marrow is, what proportion is each cell type, whether abnormal cells are present, the architecture and any scarring, the chromosomes and genetic mutations of the cells, and the iron stores. No single blood test can replace this.

The two samples we take

Both are usually done at the same sitting, through the same skin nick, so you have one procedure rather than two.

Where on the body — the back of the hip

The standard site is the posterior iliac crest — the bony prominence at the back of the hip, just above and to the side of the buttock. It's chosen because the bone is close to the skin, the marrow space is generous, and there are no important structures nearby. You'll lie on your side or on your front. The site is marked, cleaned with antiseptic, and draped.

Occasionally — when the back of the hip isn't accessible (very rarely in adults) — the front of the hip (anterior iliac crest) or the breastbone (sternum, for aspirate only) is used.

"Almost every patient I've ever biopsied has said the same thing afterwards: 'That was nowhere near as bad as I'd built it up in my head.' The fear of it is genuinely worse than the doing of it."

The procedure — step by step

1. Arrival and consent. We'll go through the procedure, the reasons for it, and the small risks, and you'll sign a consent form. Bring someone with you if you can — to drive you home and for company.
2. Positioning. You'll lie on your side or face-down on the couch, comfortable, with the site exposed.
3. Cleaning and draping. The skin is cleaned with antiseptic — it can feel cold — and a sterile drape is placed.
4. Local anaesthetic. A small needle is used to numb the skin (a brief sting, like any local) and then the deeper tissue down to the bone surface (a few seconds of pressure). We wait for the numbness to take effect.
5. The aspirate. A specialised needle is passed through the numbed area into the marrow cavity. When the liquid marrow is drawn into the syringe, you may feel a brief, deep, drawing sensation — sharp for a few seconds, like a strong pull, then gone. This is the part most patients describe as "uncomfortable" rather than painful. Some clinicians use a brief whiff of inhaled sedation for this moment.
6. The trephine. A slightly larger needle is then advanced to take the core. You'll feel pressure and a crunching sensation as the needle works through the bone — this is normal and not dangerous. It takes about a minute.
7. Pressure and dressing. Firm pressure is held for several minutes to stop any oozing, and a small dressing is applied.
8. Recovery. You'll rest for 15-30 minutes. You can eat and drink. Most patients walk out feeling fine.

From start to finish, the procedure itself takes about 20-30 minutes. The actual sampling — the part where you might feel discomfort — is usually under two minutes.

What it actually feels like — honestly

The local anaesthetic stings briefly. After that, the skin and the layers above the bone are numb. The surface of the bone takes the local well too. What the local cannot completely numb is the inside of the marrow cavity — that's why the aspirate moment can feel like a deep, drawing pull for a few seconds. It's brief, and it passes. The trephine portion is more about pressure than pain.

Most patients rate the worst moment as a 3-5 out of 10. A small minority find it more uncomfortable; a small minority feel barely anything at all. We can offer additional pain relief or light sedation (such as inhaled gas-and-air, or a small oral premed) if you prefer — please tell us in advance if you're particularly anxious.

After the procedure

• Keep the dressing dry for 24 hours, then remove it.
• You may have a dull ache at the site for one to three days — paracetamol is usually enough.
• Avoid heavy lifting, intense exercise and vigorous sport for 48 hours.
• It's safe to drive home if you've had local anaesthetic only; not if you've had sedation.
• Showers are fine after 24 hours; avoid baths and swimming until the small skin nick has fully sealed (about a week).

Risks — what to know, honestly

Bone marrow biopsy is a very safe procedure when done by an experienced operator. Serious complications are rare but worth being aware of:

• Bruising and soreness at the site — common, settles in a few days.
• Bleeding — rarely significant; we check your platelets and clotting beforehand if there's concern.
• Infection at the puncture site — very rare with sterile technique.
• Persistent pain — uncommon, usually settling within two weeks.
• Vasovagal episodes (feeling faint) — managed by lying you flat for a few minutes.

When the results come back

Different parts of the test take different lengths of time.

We'll arrange your follow-up appointment for when the key results are back, and explain everything together — what was found, what it means, and what the plan is from there.

Common fears, answered honestly

"Will I be paralysed?" No. The procedure is done at the back of the hip, well below the spinal cord. The spinal cord ends much higher up, in the mid-back.

"Will I be put to sleep?" Usually not — a local anaesthetic is enough for almost everyone. Sedation is available if you prefer, but most patients don't need it.

"Can I refuse?" Yes — but we only ever recommend the test when the information it gives genuinely changes what we can do for you. If you're unsure, ask: "What will this test tell us that we can't learn any other way?" — and we'll give you a straight answer.

"Will it have to be repeated?" Sometimes — for certain diseases we repeat the biopsy to assess response to treatment. We try to combine repeat biopsies with other tests where possible to minimise procedures.

"What if my platelets are very low?" Bone marrow biopsy can usually be done safely even with low platelets, because the bony site is easy to press firmly. If counts are extremely low, we may give a platelet transfusion first.

"Can I eat before?" Yes — for local-anaesthetic-only procedures, eat and drink normally. If you're having sedation, we'll ask you not to eat for 6 hours beforehand.

What to bring on the day

• A list of your current medications — particularly blood thinners, which may need adjustment before the procedure.
• Your most recent blood test report.
• Comfortable clothing — loose trousers are easier.
• A companion to take you home, especially if any sedation is planned.