Three weeks after head trauma, a 28-year-old man reports continuous clear watery discharge from the right nostril, worse on bending forward. When the fluid drips onto his handkerchief over the blood-stained centre, a lighter ring spreads around it. Which investigation best confirms the nature of this fluid?

• A Fluid glucose estimation above 60 mg/dL
• B Detection of beta-2 transferrin in the fluid ✓
• C High-resolution CT cisternography with intrathecal contrast
• D Culture for Haemophilus influenzae

Explanation

The double ring or halo sign on a handkerchief suggests CSF mixed with blood, but the definitive confirmatory test is detection of beta-2 transferrin, a protein found almost exclusively in CSF and ocular fluid. Glucose testing was traditionally used but is unreliable because tears and nasal secretions contain glucose and contaminated samples give false results. Cisternography localizes an active leak once the diagnosis is established biochemically, and culture adds nothing to identifying the fluid.

Reference: Scott-Brown's Otorhinolaryngology and Head and Neck Surgery, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.