A 58-year-old woman presents with sudden-onset 'worst headache of her life,' vomiting, and neck stiffness. CT head is normal. Lumbar puncture performed 14 hours after onset shows xanthochromic supernatant after centrifugation. Which finding most strongly supports the diagnosis?
- A Opening pressure >25 cm H2O
- B RBC count that does not fall from tube 1 to tube 4 ✓
- C CSF glucose <2.2 mmol/L
- D Neutrophilic pleocytosis >1000 cells/μL
Correct answer: B. RBC count that does not fall from tube 1 to tube 4
Explanation
Xanthochromia (yellow supernatant after centrifugation) indicates hemoglobin breakdown from lysed RBCs and is the hallmark of subarachnoid hemorrhage, detectable from about 6 hours and persisting for 2-4 weeks. A constant RBC count across tubes 1 and 4 rules out traumatic tap. Neutrophilic pleocytosis and low glucose suggest bacterial meningitis. Elevated opening pressure is nonspecific. Harrison 21st edition confirms xanthochromia as the key CSF finding for SAH when CT is negative.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.