Which diagnostic test helps distinguish cerebrospinal fluid drainage from nasal mucus after transsphenoidal hypophysectomy?

Which diagnostic test helps distinguish cerebrospinal fluid drainage from nasal mucus after transsphenoidal hypophysectomy?

• A. Lower the head of the bed
• B. Test the drainage for glucose
• C. Obtain a culture of the drainage
• D. Continue to observe the drainage

Answer: (B)

Distinguishing CSF drainage from nasal mucus after transsphenoidal hypophysectomy relies on a characteristic chemical difference: CSF contains glucose, while nasal mucus does not in a reliable way. CSF glucose is typically about 60% of the plasma glucose level, so a drainage sample that shows measurable glucose strongly suggests CSF. A quick bedside glucose test on the drainage therefore provides a direct, practical way to confirm a CSF leak versus mucus. Lowering the head of the bed is a management step to reduce pressure and potential leaking but does not tell you whether the drainage is CSF or mucus. Culturing the drainage would look for infection, not differentiate CSF from mucus. Simply observing the drainage over time does not provide the diagnostic distinction needed.

Distinguishing CSF drainage from nasal mucus after transsphenoidal hypophysectomy relies on a characteristic chemical difference: CSF contains glucose, while nasal mucus does not in a reliable way. CSF glucose is typically about 60% of the plasma glucose level, so a drainage sample that shows measurable glucose strongly suggests CSF. A quick bedside glucose test on the drainage therefore provides a direct, practical way to confirm a CSF leak versus mucus.

Lowering the head of the bed is a management step to reduce pressure and potential leaking but does not tell you whether the drainage is CSF or mucus. Culturing the drainage would look for infection, not differentiate CSF from mucus. Simply observing the drainage over time does not provide the diagnostic distinction needed.