skip to main content

Unilateral Epidural Block — FRCA Final MCQ

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

ModerateObstetric AnaesthesiaUnilateral Epidural BlockFRCA Final

A 34-year-old woman at 38 weeks' gestation has an epidural inserted at L3/4 for labour analgesia. Thirty minutes after the loading dose, the left-sided sensory block extends to T8, but there is no demonstrable block on the right and she has persistent right-sided pain. The catheter is secured with 5 cm within the epidural space and aspiration is negative for blood and CSF. Positioning her with the right side dependent and administering an incremental rescue bolus produces no improvement after 15 minutes. What is the most appropriate next action?

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

Reveal the answer and explanation

Correct answer: C — Withdraw the catheter by 1–2 cm and administer a further incremental epidural bolus

Explanation lettering: B = shown as A · E = shown as B · A = shown as C · C = shown as D · D = shown as E

The correct answer is A. A persistent unilateral block usually reflects excessive catheter length in the space, with the tip lying laterally or passing through an intervertebral foramen. UK obstetric epidural troubleshooting guidance sequences management as a top-up with the unblocked side dependent first, then catheter withdrawal if this fails. Here the dependent-position rescue bolus has already failed, so the next step is to withdraw the catheter 1–2 cm under sterile conditions (5 cm indwelling means at least 3 cm remains) and re-dose incrementally after repeat aspiration. Resiting (B) is reserved for failure of catheter adjustment. Repeating the unchanged manoeuvre (C) will not correct a laterally sited tip. Increasing the infusion rate (D) deepens the existing left-sided block without restoring right-sided spread. A single-shot spinal (E) is time-limited and unsuitable for ongoing labour analgesia; if resiting were needed, a fresh epidural would be placed.

Reference: East Anglian Obstetric Anaesthetists Group / Health Education England. Epidural Troubleshooting Guide for Obstetric Anaesthesia, section: Common Patterns of Inadequate Labour Analgesia – Unilateral block. 2019. https://heeoe.hee.nhs.uk/sites/default/files/eaoag_epidural_troubleshooting_2019_-_final.pdf