A spinal tap is a diagnostic procedure involving the insertion of a needle into the spinal canal to obtain cerebrospinal fluid. A needle is inserted in between the vertebrae of the lower back and a sample of spinal fluid is withdrawn and tested to determine the pressure and content of the fluid. A spinal tap is typically performed to diagnose brain or spinal cord infection, tumors, or hemorrhage. The procedure carries a risk of causing meningitis, an inflammation of the brain and spinal cord membrane. Physicians have largely replaced the use of spinal tap for diagnostic testing with noninvasive tests such as MRI and CAT scan.