Block Level for Instrumental Delivery — FRCA Final MCQ

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ModerateObstetric AnaesthesiaBlock Level for Instrumental DeliveryFRCA Final

A 26-year-old primigravida at 40 weeks' gestation is transferred to the obstetric theatre for a trial of forceps delivery. Her labour epidural is being extended, and the team is prepared to proceed immediately to caesarean birth if the forceps attempt is unsuccessful. What is the minimum upper sensory block level, assessed bilaterally using loss of cold sensation, that should be achieved before the forceps attempt begins?

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Correct answer: E — T4

The correct answer is E, T4. The stem describes a trial of forceps in theatre with immediate conversion to caesarean birth if unsuccessful. The epidural therefore needs to be extended to a caesarean surgical block before the attempt; for cold testing, the conventional bilateral endpoint is loss of cold to T4, corresponding approximately to T5 with light-touch testing. A dense sacral component must also be confirmed. T6 is not an adequate cold endpoint here; levels quoted using touch and cold are not interchangeable. T10 covers the visceral afferents associated with uterine contractions and may support labour analgesia, but not operative anaesthesia with possible laparotomy. T8 is not an accepted endpoint. S2 represents part of the pudendal and perineal supply, but a saddle or pudendal block alone does not provide the required cephalad surgical block.

Reference: Plaat F, Stanford SER, Lucas DN, et al. Prevention and management of intra-operative pain during caesarean section under neuraxial anaesthesia: a technical and interpersonal approach. Anaesthesia. 2022;77:588-597. Recommendations on neuraxial block assessment. https://www.rcoa.ac.uk/media/19926