What is a spinal tap (lumbar puncture)?

Cervical spine, thoracic spine, lumbar spine

To perform a spinal tap (also called a lumbar puncture), your healthcare provider inserts a needle into your lower back to get a sample of cerebrospinal fluid. Cerebrospinal fluid is the clear liquid that surrounds your spine and brain. A lab tests the fluid sample to check:

  • Presence of bacteria, fungi or abnormal cells.
  • Glucose (blood sugar) levels.
  • Protein types and levels.
  • White blood cell types and levels.

Why do healthcare providers perform spinal taps (lumbar punctures)?

Your healthcare provider may perform a spinal tap to test for:

Healthcare providers also use spinal taps to:

  • Administer regional anesthesia, such as an epidural to block pain in the lower part of the body.
  • Inject dye for an X-ray diagnostic test (myelogram).
  • Inject cancer medications or muscle relaxers.
  • Relieve intracranial (head) pressure.

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