Spinal Tap (Lumbar Puncture)

Test Overview

A spinal tap (also called a lumbar puncture) is a procedure to collect and look at the fluid (cerebrospinal fluid, or CSF) that surrounds the brain and spinal cord.

During a spinal tap, 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 container with a growth substance. This is called a culture. If any bacteria or fungi grow in the culture, an infection may be present. The pressure of the CSF also is measured during the procedure.