Also known as:
A lumbar puncture (also called a spinal tap) is a procedure to collect and look at the fluid (cerebrospinal fluid, or CSF) surrounding the brain and spinal cord.
During a lumbar puncture, a needle is carefully inserted into the spinal canal low in the back (lumbar area). Samples of CSF are collected. The samples are studied for color, blood cell counts, protein, glucose and other substances. Some of the sample may be put into a special culture cup to see if any infection, such as bacteria or fungi, grows. The pressure of the CSF also is measured during the procedure.