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Pain pathway anatomy-physiology — FRCA Primary MCQ

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HardPhysiologyPain pathway anatomy-physiologyFRCA Primary

A labour epidural initially works bilaterally, then produces dense unilateral analgesia after the patient changes position. Aspiration is negative and the catheter is 6 cm within the epidural space. What is the most appropriate first rescue manoeuvre?

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Correct answer: E — Withdraw the catheter one to two centimetres and cautiously redose

The best answer is “Withdraw the catheter one to two centimetres and cautiously redose”. A catheter threaded deeply can migrate laterally or through an intervertebral foramen, producing unilateral block. After reassessment and exclusion of intrathecal or intravascular placement, withdrawing it one to two centimetres and cautious redosing is a rational first rescue. Persistent failure should prompt replacement rather than repeated large boluses.

Reference: Arendt and Segal, Why epidurals do not always work: https://pmc.ncbi.nlm.nih.gov/articles/PMC2505163/