Tests and Procedures

Lumbar puncture (spinal tap)

What you can expect

A lumbar puncture is usually done in an outpatient facility or a hospital by a doctor or a nurse. Your doctor or nurse will talk to you about the potential risks, and any discomfort you might feel during the procedure.

If a child is having a lumbar puncture, a parent may be allowed to stay in the room in some cases. Talk to your child's doctor or nurse about whether this will be possible.

Before the procedure

You may be asked to change into a hospital gown, although in some cases you may have the procedure while wearing your own clothing. There are a few possible positions for this test. Usually, you lie on your side with your knees drawn up to your chest, or you sit and lean forward on a stable surface. These positions flex your back, widening the spaces between your vertebrae and making it easier for your doctor to insert the needle.

For an infant or young child, someone will hold the child in position during the procedure.

Your back is washed with antiseptic soap or iodine and covered with a sterile sheet.

During the procedure

  • A local anesthetic is injected into your lower back to numb the puncture site before the needle is inserted. The local anesthetic will sting briefly as it's injected.
  • A thin, hollow needle is inserted between the two lower vertebrae (lumbar region), through the spinal membrane (dura) and into the spinal canal. You may feel pressure in your back during this part of the procedure.
  • Once the needle is in place, you may be asked to change your position slightly.
  • The cerebrospinal fluid pressure is measured, a small amount of fluid is withdrawn and the pressure is measured again. If needed, a drug or substance is injected.
  • The needle is removed, and the puncture site is covered with a bandage.

The procedure usually lasts about 45 minutes. Your doctor or nurse may suggest lying down after the procedure.

Sometimes, an ultrasound may be used as a guide during the procedure on infants and young children. The ultrasound can help prevent inserting the needle too far.

After the procedure

  • Plan to rest. Don't participate in strenuous activities the day of your procedure. You may return to work if your job doesn't require you to be physically active. Discuss your activities with your doctor if you have questions.
  • Take a pain medication. A nonprescription pain-relieving medication that contains acetaminophen can help reduce a headache or back pain.