Which procedure withdraws cerebrospinal fluid for analysis?

• A. Spinal Tap
• B. Nerve Conduction Velocity Test
• C. EMG Test
• D. CT Scan

Answer: (A)

The procedure to withdraw cerebrospinal fluid for analysis is a spinal tap, also known as a lumbar puncture. In this test, a needle is gently inserted into the lower back to reach the subarachnoid space surrounding the spinal cord. A small amount of CSF is then collected for lab analysis to look for infections, inflammation, bleeding, or other CNS issues, and opening pressure can be measured. This direct sampling of CSF is what makes it distinct from other tests: nerve conduction studies and EMG assess electrical activity of nerves or muscles, not fluid, while CT scans provide imaging of the brain and skull rather than sampling CSF.