skip to main content

CSF vs Epidural Fluid Differentiation — FRCA Final MCQ

Instant feedback + full explanation. One question, done properly.

HardRegional AnaesthesiaCSF vs Epidural Fluid DifferentiationFRCA Final

A 50-year-old man has an epidural catheter placed at T9/10 for post-operative analgesia. Two hours after surgery, his nurse notes clear fluid leaking from the epidural site dressing. How can you differentiate epidural fluid from cerebrospinal fluid at the bedside?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — There is no bedside test – send fluid for beta-2 transferrin assay

Bedside glucose testing cannot reliably differentiate epidural infusate from CSF because both contain glucose (most epidural infusions contain fentanyl/bupivacaine without glucose, but contamination renders bedside testing unreliable). The definitive test is a beta-2 transferrin assay – beta-2 transferrin is found exclusively in CSF, perilymph, and aqueous humour. This takes 24-48 hours. Clinical assessment (volume of leak, block density, and presence of headache on sitting) may be more immediately useful. If CSF leak is suspected, the epidural should be removed.

Reference: RCOA – 2023 – Regional anaesthesia module; Association of Anaesthetists – 2013 – Neuraxial complications