What is the diagnostic study of choice for confirming meningitis?

The diagnostic study of choice for confirming meningitis is a lumbar puncture. This procedure involves the insertion of a needle into the spinal canal to collect cerebrospinal fluid (CSF). Analyzing the CSF is crucial for diagnosing meningitis, as it allows healthcare providers to assess various parameters, including white blood cell counts, glucose levels, protein concentrations, and the presence of bacteria or viruses.

This analysis can differentiate between types of meningitis, such as bacterial, viral, or fungal, based on the characteristics of the CSF. For instance, bacterial meningitis typically presents with a high white blood cell count, predominantly neutrophils, elevated protein levels, and low glucose concentrations compared to blood glucose. In contrast, viral meningitis often shows a lymphocytic predominance with normal glucose levels.

Other imaging studies, such as CT scans or MRIs, may be used to rule out other complications or conditions affecting the brain, but they do not provide direct evidence of meningitis. Blood cultures can help identify systemic infections but do not specifically confirm the presence of meningitis. Therefore, the lumbar puncture is the definitive test for diagnosing this condition.