American Board of Internal Medicine (ABIM) Certification Practice Exam

What must be done prior to lumbar puncture in patients with suspected meningitis who exhibit altered mental status?

1. Administer antibiotics immediately

2. Perform a noncontrast head CT scan

3. Get a blood culture

4. Start IV fluids

The correct answer is: Perform a noncontrast head CT scan

In patients with suspected meningitis exhibiting altered mental status, performing a noncontrast head CT scan prior to lumbar puncture is critical. This imaging study is essential to rule out the presence of increased intracranial pressure, which may lead to the risk of brain herniation if a lumbar puncture is performed without first assessing for it. Altered mental status can indicate a potentially life-threatening condition such as cerebral edema or mass effect from a lesion, and these conditions necessitate careful evaluation. The noncontrast CT scan helps clinicians visualize the brain and identify any abnormalities that could contraindicate a lumbar puncture. Thus, it is a standard practice to ensure patient safety by assessing the need for further interventions based on the CT findings. In this scenario, while administering antibiotics and managing other supportive care like IV fluids are crucial steps in the management of suspected meningitis, they are not the immediate priorities that address the increased risk associated with altered mental status. Blood cultures are important for diagnosing the causal organism in cases of meningitis, but they do not directly address the critical need for imaging in the setting of altered mental status.