Lumbar Puncture

A lumbar puncture is a common procedure sometimes used in the diagnosis of childhood cancer and other childhood diseases and infections. It is also called an LP or a spinal tap.

During the procedure, a member of your health care team removes a small sample of fluid from around the spine using a thin needle.

The fluid is called cerebrospinal fluid or CSF. It surrounds and protects the brain and spinal cord. Testing the CSF can show if the patient has a disease or infection. The body makes CSF constantly. The patient’s body quickly replaces the small amount removed during the lumbar puncture.

The lumbar puncture procedure

• About an hour before the lumbar puncture, a health care provider may put numbing cream on the spot for the test. Your child may also get medicine to help them sleep through the test.
• If your child is awake, they may get an injection of liquid numbing medicine at the test spot. They either lie on their side or sit on the side of a bed.
• The health care provider will feel your child’s lower back to find the right place to put the needle. The provider will make sure your child’s back is clean and sterile. This prevents the chance of infection. It will probably feel cold as they clean your child’s back. The provider may put a plastic sheet called a drape over their back, so just the test area shows.
• Next, the provider will insert the needle in the appropriate spot. The needle is hollow with a smaller needle inside. When the larger needle is in place, the doctor takes out the smaller one. This process allows the fluid to go into test tubes. It takes 10 minutes or less to collect fluid. Then the provider takes out the needle, cleans the spot, and applies a bandage.

What your child feels

If your child is awake, they may feel a small pinch and some discomfort where the needle is inserted. Some people say the lumbar puncture procedure is not painful.

Results of the test

Talk to your health care team about when and how you will receive results.

Care after the procedure

Your child may stay lying in bed for 30 minutes or more after this procedure. They may also be given water or something else to drink. This helps to prevent headaches, which is a common side effect after this procedure

You can remove your child’s bandage after 24 hours.

Talk to your health care team about any pain medications your child can take for soreness. Watch your child for signs of infection, including:

• Increased pain, swelling, or redness where the puncture was done.
• Bad-smelling drainage from the site.
• A fever.

If your child shows signs of infection, contact your health care team right away.