Lumbar puncture ( LP ), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to help diagnose diseases of the central nervous system, including the brain and spine.

A lumbar puncture (often called spinal tap, by non-doctors) is a medical method to collect a sample of cerebrospinal fluid (fluid from the brain ). This can be done to analyse the sample, to find some hints to diseases. It can also be done to lower the pressure of the fluid inside the skull . This short article about medicine can be made longer.