Testing Clear Nasal Drainage After a Head Injury

Neurological · Question from the ATI RN Medical-Surgical 2023 Proctored Exam study set

Correct answer: B. Test for glucose

Why this is the answer

Cerebrospinal fluid contains glucose, while ordinary nasal mucus does not — so a positive glucose test on the drainage (often alongside a "halo sign" on a gauze pad) helps confirm the fluid is CSF from a dural tear rather than simple nasal secretions. Checking for protein (A) isn't the standard, quick bedside screen used for this. Checking for bacteria (C) would require sending a culture and take time, and doesn't quickly distinguish CSF from mucus at the bedside. Measuring pH (D) isn't a reliable or standard way to differentiate the two fluids either.

The bigger concept

A CSF leak from the nose or ear after a head injury is a serious finding because it creates a direct path for bacteria to reach the meninges, so confirming it quickly (glucose test, halo sign) matters — the patient is then watched closely for signs of meningitis and generally not packed or irrigated in a way that could push contaminants inward.

Related Neurological practice questions

• The 'Halo Sign' After a Head Injury
• What a Positive Kernig's Sign Means
• Positive Babinski Sign in an Adult
• Positive Brudzinski's Sign: The Nurse's Immediate Action
• A Halo Sign on the Bedsheet: What Comes Next

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