Learn about lumbar puncture, which removes a sample of cerebrospinal fluid to find infections, bleeding and other problems. It is also called spinal tap.
A lumbar puncture (spinal tap) is a test used to diagnose certain health conditions. It's performed in your lower back, in the lumbar region. During a lumbar puncture, a needle is inserted into the space between two lumbar bones (vertebrae) to remove a sample of cerebrospinal fluid. This is the fluid that surrounds your brain and spinal cord to protect them from injury.
A lumbar puncture can help diagnose serious infections, such as meningitis; other disorders of the central nervous system, such as Guillain-Barre syndrome and multiple sclerosis; bleeding; or cancers of the brain or spinal cord. Sometimes a lumbar puncture is used to inject anesthetic medications or chemotherapy drugs into the cerebrospinal fluid.
During a spinal tap, known as a lumbar puncture, you typically lie on your side with your knees drawn up to your chest. Then a needle is inserted into your spinal canal — in your lower back — to collect cerebrospinal fluid for testing.
A lumbar puncture (spinal tap) may be done to:
Information gathered from a lumbar puncture can help diagnose:
Although lumbar puncture (spinal tap) is generally recognized as safe, it does carry some risks. These include:
Post-lumbar puncture headache. As many as 25% of people who undergo a lumbar puncture develop a headache afterward due to fluid leaking into nearby tissues.
The headache typically starts several hours up to two days after the procedure and may be accompanied by nausea, vomiting and dizziness. The headaches are usually present when sitting or standing and resolve after lying down. Post-lumbar puncture headaches can last from a few hours to a week or more.
Before your lumbar puncture (spinal tap), your health care provider takes your medical history, does a physical exam, and orders blood tests to check for bleeding or clotting disorders. Your provider may also recommend a CT scan or MRI to determine if you have any abnormal swelling in or around your brain.
Your health care provider will give you specific instructions about food, drink and medications.
Tell your provider if you're taking blood-thinning or other anticoagulant medications. Examples include warfarin (Jantoven), clopidogrel (Plavix) and apixaban (Eliquis). Also, tell your provider if you're allergic to any medications, such as numbing medications (local anesthetics).
A lumbar puncture (spinal tap) is usually done in an outpatient facility or a hospital. Your health care provider 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 health care provider about whether this will be possible.
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 a lumbar puncture (spinal tap). 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 health care provider to insert the needle. Your back is washed with antiseptic soap or iodine and covered with a sterile sheet.
For an infant or a young child, someone will hold the child in position during the procedure.
The procedure usually lasts about 45 minutes. Your health care provider may suggest lying down after the procedure.
Sometimes, an ultrasound may be used as a guide during a lumbar puncture on infants and young children. The ultrasound can help prevent inserting the needle too far.
The spinal fluid samples from the lumbar puncture (spinal tap) are sent to a laboratory for analysis. Lab technicians check for a number of things when examining spinal fluid, including:
Lab results are combined with information obtained during the test, such as spinal fluid pressure, to help make a possible diagnosis.
Your health care provider generally gives you the results within a few days, but it could take longer. Ask when you can expect to receive the results of your test.
Write down questions that you want to ask your health care provider. Don't hesitate to ask other questions that may come up during your visit. Questions you may want to ask include: