What Is a Lumbar Puncture?

A lumbar puncture (also called a spinal tap) is a procedure in which a thin needle is carefully inserted into the lower back to access the cerebrospinal fluid (CSF) that surrounds the spinal cord and brain.

Doctors use it to collect fluid for lab testing, measure fluid pressure, or sometimes inject medication. A radiologist or trained physician typically performs the procedure, often with fluoroscopic (X-ray) guidance for accuracy.

Why Might I Need a Lumbar Puncture?

Your doctor may recommend a lumbar puncture if you have:

• Symptoms that suggest infection, inflammation, or bleeding involving the central nervous system
• Need to analyze cerebrospinal fluid for diagnostic purposes
• Need to measure CSF pressure
• Certain conditions where medication needs to be delivered into the spinal fluid

How Do I Prepare?

Typical preparation includes:

• Medications: Tell your doctor about all medications, especially blood thinners. Certain blood thinners may need to be stopped for a short period (only as directed).
• Hydration: You may be asked to drink extra clear fluids the day before.
• Eating: Follow any instructions about fasting or clear liquids.
• Allergies: Inform the team of any allergies to local anesthetics.
• Transportation: Arrange for someone to drive you home.

How Is the Procedure Performed?

The procedure is usually done on an outpatient basis and takes about 20–40 minutes (plus recovery time).

Typical steps:

1. You lie on your side or stomach. The lower back is cleaned with an antiseptic solution.
2. Local anesthetic is injected to numb the skin.
3. Using fluoroscopic guidance when available, a thin needle is carefully advanced into the spinal canal in the lower lumbar region.
4. A small amount of cerebrospinal fluid is collected for testing, and/or pressure is measured.
5. The needle is removed, and a small bandage is applied. You will be observed afterward.

What Should I Do for Aftercare?

Immediate Recovery

• You will need to lie flat for several hours after the procedure. This helps reduce the risk of a cerebrospinal fluid leak and post-procedure headache.
• Drink plenty of fluids to help rehydrate.
• Most patients go home the same day after observation.

Activity Guidelines

• Rest for the remainder of the day. Avoid strenuous activity, heavy lifting, and bending for 24–48 hours.
• You may usually return to light activity the next day if you feel well.

What to Expect

• Mild backache at the puncture site is common.
• A headache that is worse when sitting or standing and better when lying down can occur. Extra fluids, rest, and caffeine sometimes help. Contact your doctor if the headache is severe or persistent.

What Are the Risks?

Lumbar puncture is generally safe when performed by experienced physicians. Possible risks include:

• Post-procedure headache (most common side effect)
• Back pain or discomfort at the puncture site
• Bleeding or infection (rare)
• Rarely, nerve irritation or other neurological symptoms

Your physician will discuss the specific risks and benefits for your situation.

When Should I Call My Doctor?

Contact your healthcare provider if you experience:

• Severe or persistent headache that does not improve with lying down
• Fever, stiff neck, or increasing redness/swelling at the puncture site
• New numbness, tingling, or weakness in the legs
• Difficulty urinating or controlling bowel/bladder function