Lumbar puncture

A lumbar puncture (LP), often called a spinal tap, is a procedure in which a small amount of the fluid that surrounds the brain and spinal cord, called the cerebrospinal fluid (CSF), is removed and examined.

In infants and children, a lumbar puncture is typically done to look for meningitis, an infection of the meninges (the membrane covering the brain and spinal cord). Lumbar punctures also might be done to remove fluid and relieve pressure with certain types of headaches, to look for other diseases in the central nervous system, or to place chemotherapy medications into the spinal fluid.