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Spinal Duration Caesarean Section — FRCA Final MCQ

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ModerateObstetric AnaesthesiaSpinal Duration Caesarean SectionFRCA Final

A 40-year-old woman (ASA II) is undergoing an elective caesarean section under spinal anaesthesia. The spinal is sited at L3/4 with 2.2 mL of 0.5% heavy bupivacaine (11 mg) and diamorphine 300 mcg. Fifteen minutes later the block level is T3 bilaterally, the patient is comfortable, and BP is maintained with phenylephrine infusion. What is the expected duration of this spinal block?

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Correct answer: B — 90-150 minutes

Heavy (hyperbaric) bupivacaine 0.5% at a dose of 11 mg for caesarean section typically provides a surgical block duration of approximately 90-150 minutes (mean ~120 minutes). The addition of intrathecal diamorphine 300 mcg does not significantly extend motor block duration but provides excellent postoperative analgesia for 12-24 hours. Factors affecting block duration include patient height, position, baricity, dose, and individual variation. The surgical team should aim to complete the procedure within 90-120 minutes.

Reference: RCOA – 2023 – Obstetric anaesthesia; OAA – 2024 – Spinal anaesthesia for CS