Understanding How Do You Lay for a Bone Marrow Biopsy?

September 25, 2025 •

4 min read

Knowing how do you lay for a bone marrow biopsy is crucial for patient comfort and procedural success, as positioning depends entirely on the sample site. A staggering number of these biopsies are performed annually, with the vast majority coming from the hip bone, dictating a specific prone or side-lying posture.

Quick Summary

The way you lie for a bone marrow biopsy is determined by the specific bone from which the sample is taken. For the most common site, the back of the hip bone, you will be asked to lie on your stomach or side. In less frequent cases involving the front of the hip or the breastbone, you will lie on your back during the procedure.

Key Points

Hip Biopsy (Posterior Iliac Crest): For the most common biopsy site on the hip bone, you will be positioned lying on your stomach (prone) or on your side (lateral decubitus).
Front of Hip (Anterior Iliac Crest): If the biopsy or aspiration is from the front of the hip bone, you will lie on your back (supine).
Breastbone (Sternum): Bone marrow aspirations (fluid samples) from the breastbone are performed with the patient lying on their back (supine), while core biopsies are not taken from this site in adults.
Infants and Young Children: In very young children, samples may be taken from the shin bone (tibia), requiring special positioning for that site.
Remain Still: Regardless of the position, it is vital to remain as still as possible throughout the procedure to ensure accuracy and minimize risk.
Communicate Discomfort: If you feel any significant discomfort or anxiety, inform the medical staff. Sedation options are available to help you relax.

Common Biopsy Site: The Hip Bone (Iliac Crest)

For the vast majority of bone marrow biopsies, the sample is extracted from the posterior iliac crest, which is the back of your hip bone. This is the preferred site because it is easily accessible, contains an excellent supply of marrow, and has a lower risk of complication compared to other areas. Depending on your comfort and the doctor's preference, two primary positions are used for this site:

Prone Position

When lying prone, you are on your stomach with your back facing up.

Access: This position provides clear access to both posterior iliac crests if samples are needed from both sides during the same procedure.
Stability: It offers excellent patient stability, as gravity helps keep you still against the examination table.
Comfort: While generally effective, some patients may find this position uncomfortable, especially those with pre-existing back problems or breathing difficulties.

Lateral Decubitus Position

In the lateral decubitus position, you lie on your side, often with your knees slightly bent in a fetal position.

Comfort: Many patients find this position more comfortable and relaxing than lying prone.
Stability: A non-dominant hand is used by the clinician to help stabilize the patient, who may otherwise feel unsteady when pressure is applied to the hip.
Support: A pillow may be placed between the legs for added comfort and alignment.

Less Common Biopsy Sites and Patient Positioning

In certain situations, a doctor may choose a different site for the biopsy. The positioning for these alternatives varies accordingly:

Anterior Iliac Crest

This is the front of the hip bone. When this site is used, typically only an aspiration (fluid sample) is taken. You will be asked to lie on your back, known as the supine position.

Breastbone (Sternum)

In adults and adolescents, the breastbone is sometimes used for a bone marrow aspiration (fluid) but not a core biopsy.

Positioning: You will be in a supine position, lying on your back, with your chest exposed.
Safety: This site requires extreme caution from the doctor due to the proximity of the heart and major blood vessels.

Shin Bone (Tibia)

In infants under 18 months, a sample can be taken from the shin bone. The child will be positioned to allow access to this area, usually on their side.

The Procedure: What to Expect While You Lay

Regardless of the position, the procedure follows a standard protocol to ensure safety and accuracy. Here is a general overview:

Preparation and Cleaning: After you are in the correct position, the biopsy site is cleaned thoroughly with an antiseptic solution to minimize the risk of infection.
Local Anesthesia: A local anesthetic is injected to numb the skin, underlying tissue, and the surface of the bone (periosteum). You may feel a brief stinging or burning sensation during this injection.
Aspiration: A needle is inserted through the bone into the marrow cavity. A syringe is attached to aspirate a sample of liquid bone marrow. A brief, sharp pain or pulling sensation is often felt at this stage as the suction is applied.
Core Biopsy: For a core biopsy, a different, larger needle is used to collect a small, solid piece of bone marrow tissue. You may feel more pressure during this part.
Remaining Still: Throughout the entire process, it is essential to remain as still as possible. The medical team will guide you and offer reassurance.

Comparison of Patient Positions for a Bone Marrow Biopsy


Position	Biopsy Site(s)	Typical Patients	Pros	Cons
Prone	Posterior Iliac Crest	Adults	Excellent stability, good access for bilateral biopsy	May be uncomfortable for some, especially those with cardiopulmonary issues
Lateral Decubitus	Posterior Iliac Crest	Adults, Older Children	More comfortable for most patients, good access	Patient may rock during pressure; requires stabilization by clinician
Supine	Anterior Iliac Crest (Aspiration), Sternum (Aspiration)	Adults, Adolescents	Clear access to front of body	Limited to aspiration only at sternum, higher risk at sternum
Side-Lying	Tibia (Lower Leg Bone)	Infants, Young Children	Best positioning for young patients	Site only suitable for infants/toddlers

How to Manage Anxiety and Discomfort

Preparing mentally for the procedure is just as important as physical preparation. Here are some tips to help:

Communicate: Talk to your doctor beforehand about your anxiety. They may offer additional options like light sedation or other medication to help you relax.
Relaxation Techniques: Practice deep breathing exercises. Focusing on your breathing during the procedure can distract you from any discomfort.
Comfort Measures: A pillow or wedge placed strategically can help maintain your comfort throughout the procedure, especially when lying on your side or stomach.
Stay Informed: Understanding each step of the process can make it less intimidating. Don't hesitate to ask questions. [For a detailed overview of the procedure, visit the Mayo Clinic website.](https://www.mayoclinic.org/tests-procedures/bone-marrow-biopsy/about/pac-20393117)

Conclusion

While the prospect of a bone marrow biopsy can be daunting, understanding the process, particularly how do you lay for a bone marrow biopsy, can help. The prone or lateral decubitus positions are standard for the most common hip site, ensuring optimal access and safety. Your medical team will ensure you are as comfortable and secure as possible throughout the procedure, and communicating your concerns is key to a smooth experience.

Frequently Asked Questions

Yes, your position during a bone marrow biopsy is determined by the specific bone being sampled, typically the back of the hip bone. The proper positioning is essential for the clinician's access, patient comfort, and the safety and accuracy of the procedure.

The most common position for a bone marrow biopsy is either prone (on your stomach) or lateral decubitus (on your side), as the procedure is most frequently performed on the posterior iliac crest, the back of the hip bone.

Lying on your side (lateral decubitus) is a common position for a bone marrow biopsy from the posterior iliac crest. Many patients find this position more comfortable than lying on their stomach, especially if they have respiratory issues or back pain.

Your position is generally decided by your doctor based on the biopsy site, but you can discuss your comfort level with them beforehand. For a hip biopsy, you may be offered the choice between lying on your stomach or your side.

If you are concerned about staying still, inform your medical team. They can provide sedation options to help you relax and remain calm throughout the biopsy. The doctor and nurses will also offer clear guidance and reassurance.

Yes, depending on your diagnosis, your healthcare provider may need samples from both hip bones. In such cases, the prone position is often used to allow easier access to both sides during the same procedure.

Aspiration (fluid sample) from the breastbone (sternum) is performed with the patient in the supine position (lying on their back). It is important to note that a core biopsy is not typically taken from the sternum.