A client has clear fluid leaking from the nose followed a basilar skull fracture. Which finding would alert the nurse that cerebrospinal fluid (CSF) is present?

A basilar skull fracture can result in a tear in the dura mater, allowing cerebrospinal fluid (CSF) to leak through the nose (rhinorrhea) or ears (otorrhea). Identifying CSF leakage is important because it increases the risk of meningitis and indicates a breach in the protective barriers of the central nervous system. CSF has specific characteristics that differentiate it from other body fluids. Nurses use both visual and laboratory clues to confirm its presence. A. Turbid fluid that is positive for leukocytes suggests infection rather than cerebrospinal fluid leakage. CSF in a basilar skull fracture is typically clear unless infected, and the presence of leukocytes indicates inflammatory or purulent drainage. This finding would raise concern for meningitis rather than confirm CSF. B. Fluid that separates into concentric rings (halo or “double ring” sign) and tests positive for glucose is characteristic of cerebrospinal fluid. Basilar skull fracture can disrupt the meninges, allowing CSF to leak through the nasal passages. CSF contains glucose, unlike normal nasal secretions, and the halo sign helps distinguish it from blood or mucus. C. Fluid testing positive for nitrates is not associated with cerebrospinal fluid. Nitrate presence is not a diagnostic marker for CSF leakage. This finding would not help confirm a diagnosis of CSF rhinorrhea following a skull fracture. D. Sero-sanguinous fluid with a low pH is not characteristic of CSF. CSF is typically clear and slightly alkaline rather than acidic. Blood-tinged drainage may occur with trauma, but it does not confirm CSF presence and requires further diagnostic testing to differentiate from other fluids.