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Spinal tap

Preparation for a spinal tap

A spinal tap is usually performed in a hospital and takes about 45 minutes. You should plan to rest after the procedure but will most likely be able to go home the same day. 

During a spinal tap procedure, you can expect to lie on your side with your knees drawn up toward your chest. You may also sit on the edge of the exam table with your legs dangling and your chin tucked. Your doctor will carefully cleanse the puncture location with an antiseptic liquid. You may receive an injection of numbing medication, which could sting for a moment. This will keep the rest of the procedure from being painful. 

Your doctor will then insert a thin spinal needle. You may feel pressure or brief pain as the needle punctures the tissue surrounding the spinal cord. Once the needle is in place, your doctor will record the CSF pressure and withdraw a sample of fluid. Your doctor also will inject any necessary medications at this time. Your doctor will then remove the needle and cover the puncture site with a bandage. 

It may be uncomfortable to stay in position for the test, but it is crucial to do so because movement could lead to serious injury of the spinal cord.  


Because a lumbar puncture involves the risk of bleeding around the spinal cord, your doctor will monitor you for several minutes after the procedure. You will have to lie flat on your back in order to put pressure on the puncture site and reduce the risk of bleeding or leaking CSF. You may need to rest for the remainder of the day at home. 

Headache is the most common complication of a spinal tap. This likely occurs from the temporary change in intracranial pressure caused by the spinal tap. You should report a headache or any other side effects to your doctor at Dignity Health. Often, drinking caffeinated beverages can help alleviate your headache. Your doctor will share the results with you in a few days.  


Your doctor will let you know the results of your test. They will talk through what your specific results mean for your condition. CSF samples are evaluated based on general appearance, protein, white blood cells, glucose levels, microorganism presence, and presence of cancer cells. 

Your CSF should look clear and have the consistency of water. If the CSF is cloudy, that could mean there is a buildup of protein or white blood cells. Red could indicate bleeding or spinal cord obstruction. Orange, brown, or yellow could indicate previous bleeding or an increased CSF protein.  

Your test will measure pressure. Increased CSF pressure may be due to an increase in pressure within the skull, while decreased CSF pressure could be from a spinal block, dehydration, CSF leakage, or fainting.  

Your test will also report protein and glucose levels. CSF protein levels can indicate diabetes, bleeding, tumor, injury, or an inflammatory or infectious condition. Decreased protein is a sign of rapid CSF production. Increased CSF glucose means that you have high blood sugar, while decreased glucose may be due to low blood sugar, infection such as meningitis, or tuberculosis. 

A spinal tap will tell you about white and red blood cells. Increased white blood cells could be a sign of infection, illness, tumors, meningitis, or multiple sclerosis. Red blood cells are generally a sign of bleeding or the result of a traumatic lumbar puncture. 

The results of a spinal tap come with a lot of information. Do not hesitate to ask your doctor if you have questions or need clarification on what any of the test results mean or indicate for your condition. 

The information contained in this article is meant for educational purposes only and should not replace advice from your healthcare provider.