Lumbar Puncture Fact Sheet 

Your healthcare provider has advised you to have a lumbar puncture. This test is also called a spinal tap. This test is done to see if you have an infection in your spinal fluid (meningitis) or your brain (encephalitis) or other problems . The test can also find bleeding from a blood vessel on the surface of the brain. It can also look for tumor cells in your spinal fluid. Lumbar puncture can be used to look for signs of inflammation such as multiple sclerosis and to measure spinal fluid pressure to diagnose other disorders. Lumbar puncture can be used to remove fluid to treat conditions in which the pressure is too high.

What happens during the procedure

A lumbar puncture is common and safe. It usually isn’t any more painful than getting a shot. Your skin will be cleaned with an antiseptic solution. The healthcare provider will then use medicine to numb a small area of skin on your lower back. He or she will insert the spinal needle there. In babies, the numbing medicine usually isn’t used. This is because the infant spinal needle is very small and usually hurts less than the sting of the numbing medicine.

The provider will place the spinal needle between the bones of your lower spine, and into the spinal canal below the end of the spinal cord. There is no danger of harming the spinal cord during the procedure. Your doctor will take out less than a teaspoonful (about 5 milliliters) of spinal fluid. Once the spinal fluid is removed, a simple dressing will be placed on the place where the needle was inserted. The procedure usually takes about 10 to 15 minutes. Bit it can take longer because of problems related to positioning during the procedure or because degenerative changes in the spine.

Risks of the procedure

Any medical procedure carries some risk. Your doctor is telling you to have this test because the risks are very small. Making a definite diagnosis of your condition is very important.

Side effects are quite uncommon after a lumbar puncture. They may include:

  • Bruising. It’s possible to break a small blood vessel near the skin during the procedure. There may be bruising. This is not a serious condition. It will go away on its own like any other bruise.

  • Infection. Skin bacteria can infect the puncture site or spinal fluid. To help prevent this, your skin is sterilized with an antiseptic solution. Only sterilized and single use equipment is used during this procedure.

  • Headache that gets worse. Once in a while, the lumbar puncture itself may cause a headache. Or it can cause an existing headache to get worse. This may happen if spinal fluid leaks internally from the puncture in the spinal canal. When you get home, rest as your healthcare provider tells you to. Lie flat and drink plenty of fluids. This may help ease a headache if one occurs.  Rarely, headaches continue longer than expected. Some of your own blood may be used to patch the leaking fluid.

  • Bleeding. You have a small risk of minor bleeding where the needle is put through the skin. This bleeding usually stops with mild pressure by your healthcare provider. You also have a small risk of bleeding around the spinal canal, but this is rare.

  • Back pain. You may have back pain, usually where the needle is inserted. This can happen after the procedure. This usually goes away after 1 to 2 days. You can treat it with an over-the-counter pain medicine.

  • Herniation. Although rare, brain herniation can happen if this procedure is done while there is swelling in the brain. Herniation means that part of the brain is compressed and damaged because of swelling in the brain. Your healthcare provider will make sure you have no brain swelling before doing a lumbar puncture.

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