What is the purpose of performing a lumbar puncture in suspected meningitis?

• A. To analyze CSF (cell count, glucose, protein, opening pressure) and obtain cultures
• B. To measure CSF oxygen
• C. To visualize brain structures
• D. To deliver antibiotics intrathecally

Answer: (A)

In suspected meningitis, the lumbar puncture is performed to obtain cerebrospinal fluid so you can analyze its composition and identify the causative organism. By examining the CSF, you determine the inflammatory response (cell count and type), measure glucose and protein levels, and assess opening pressure. These findings help distinguish bacterial from viral meningitis and indicate how severely the infection is affecting the CNS. Cultures and Gram stain (and often PCR) of the CSF are crucial for pinpointing the exact pathogen, which guides the choice and urgency of therapy. This diagnostic CSF analysis is the key reason for performing the procedure. The other goals listed—measuring CSF oxygen, visualizing brain structures, or delivering antibiotics intrathecally—are not the typical purposes of a diagnostic lumbar puncture in this context.