A lumbar puncture or spinal tap is an image-guided procedure performed on the lower back to obtain a sample of spinal fluid – the liquid that surrounds the brain and spinal cord to examine it for cancer cells or infection.

The cerebrospinal fluid or CSF is a clear liquid that delivers nutrients to the brain and cushions both the spinal cord and the brain, protecting it from exterior injury. The fluid is produced and reabsorbed in the brain on a continuous basis. CSF is composed of cells, water, proteins, sugars, and other vital substances that are essential to maintain equilibrium in the nervous system.

A lumbar puncture may also be performed to inject anticancer medication directly to the brain and spinal cord. Children and adolescents are usually given anaesthesia or sedation before a lumbar puncture is performed.

The video below demonstrates a lumbar puncture in a child undergoing cancer treatment. This video was designed to educate parents and caregivers by showing an actual patient being accessed for treatment.

This activity is supported by a contribution from Lilly USA, LLC.

Performing the Procedure

A child will usually lie on his or her side in a curled position, chin tucked to the chest and knees pulled up to the chest. A member of the medical team will assist the child to get into this position and to maintain it throughout the procedure. Older children can, in some cases, sit up and curl the back by tucking their chin to their chest.

spinal tap

When the back is in a curved position, a needle is inserted between the small bones of the spine (vertebrae) into the fluid space around the spinal cord and a sample of the spinal fluid is extracted, collected into a tube and sent to a laboratory to be tested.

Lying still for this test can be rather stressful for children, so it may be a good idea to rehearse this with your child before the test so that they can feel more in control and understand what he or she needs to do.

A lumbar puncture may also be used to deliver chemotherapy into the spinal canal through the same needle after the cells are removed for testing.

Potential Complications of a Lumbar Puncture

While the risk is small, because this procedure involves the spinal cord and brain, there may be some risk, including the following:

  • A small amount of CSF can leak from the needle insertion site. This can cause headaches after the procedure. If there is a persistent leak the headache can be severe.
  • There is a slight risk of infection because the needle breaks the skin’s surface, providing a possible portal of entry for bacteria.
  • A temporary pain or numbness to the legs or lower back pain may be experienced.
  • There is a risk of bleeding in the spinal canal.

There may be other risks depending on the specific medical condition. Be sure to discuss any concerns with your child’s doctor prior to the procedure.