When is a lumbar puncture indicated and what are key contraindications?

• A. Indicated for suspected meningitis; contraindicated with mass effect.
• B. Indicated for headaches; contraindicated in infection.
• C. Indicated for dehydration; contraindicated in high BP.
• D. Indicated for suspected meningitis, subarachnoid hemorrhage evaluation, or CSF analysis; contraindicated with suspected increased ICP/mass effect or bleeding diathesis.

Answer: (D)

The main point here is when a lumbar puncture (LP) is appropriate and when it should be avoided. An LP is the key test to obtain cerebrospinal fluid for analysis when you suspect meningitis, to help evaluate for subarachnoid hemorrhage (especially when CT is negative or inconclusive), and to perform CSF studies for diagnostic purposes. These are the core indications because CSF analysis provides direct information about infection, bleeding, or inflammatory/immune processes in the CNS.

The procedure is contraindicated when there is a risk that removing CSF could cause harm. If there is suspected increased intracranial pressure with a mass effect, or any mass lesion, an LP can precipitate brain herniation due to abrupt pressure changes. Bleeding diathesis or known coagulopathy raises the risk of spinal or intracranial hemorrhage during needle passage or CSF withdrawal. These are the primary safety concerns that limit its use.

So, the best choice reflects using LP for suspected meningitis, SAH evaluation, or CSF analysis, while avoiding it when increased ICP/mass effect or bleeding risk is present.