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Anaes TopicsNeuraxial anaesthesia

Anaes · Neuraxial anaesthesia

Caudal epidural anaesthesia

Also known as Caudal anaesthesia · Caudal block · Caudal epidural · Sacral epidural · Caudal analgesia · Single-shot caudal

Caudal epidural anaesthesia injects local anaesthetic into the epidural space through the sacral hiatus — the most caudal access to the neuraxis. It is the commonest regional block in children, providing sacral and lumbar anaesthesia for lower-abdominal, perineal and lower-limb surgery, and it is used in adults for chronic-pain caudal epidural steroids. Its safe practice rests on the sacral-hiatus anatomy, the needle angle and the aspiration test, and its place is now compared against the newer erector spinae plane blocks.

high6 referencesUpdated 26 July 20268 min readVerification in progress

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Red flags

  • The dural sac terminates at S2 in the adult and lower in the infant; advancing the needle beyond the sacral hiatus risks a dural puncture and a total spinal — keep the needle below S2 and aspirate before injecting.
  • The sacral canal is highly vascular; an intravascular injection of local anaesthetic can cause systemic toxicity — aspirate for blood and inject incrementally with a needle that allows aspiration.
  • An unintended intrathecal injection (CSF on aspiration) converts a caudal into a spinal; if unrecognised, a full caudal dose produces a high or total spinal.
  • Infection of the sacrococcygeal area (pilonidal disease, local sepsis) is a contraindication because the needle can carry infection into the epidural space.
  • Caudal block masks the signs of surgical complications (urinary retention, haematoma, compartment syndrome) in the lower body; ensure the surgical team plans postoperative monitoring accordingly.
  • A high volume of local anaesthetic in a small child can spread to the thoracic dermatomes and produce hypotension or respiratory compromise; dose by weight.
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Practise this topic8 MCQs with explanations

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ANZCAFRCAABAEDAICFCAIFCA_SA

Red flags

  • The dural sac terminates at S2 in the adult and lower in the infant; advancing the needle beyond the sacral hiatus risks a dural puncture and a total spinal — keep the needle below S2 and aspirate before injecting.
  • The sacral canal is highly vascular; an intravascular injection of local anaesthetic can cause systemic toxicity — aspirate for blood and inject incrementally with a needle that allows aspiration.
  • An unintended intrathecal injection (CSF on aspiration) converts a caudal into a spinal; if unrecognised, a full caudal dose produces a high or total spinal.
  • Infection of the sacrococcygeal area (pilonidal disease, local sepsis) is a contraindication because the needle can carry infection into the epidural space.
  • Caudal block masks the signs of surgical complications (urinary retention, haematoma, compartment syndrome) in the lower body; ensure the surgical team plans postoperative monitoring accordingly.
  • A high volume of local anaesthetic in a small child can spread to the thoracic dermatomes and produce hypotension or respiratory compromise; dose by weight.
The one-line answer

Caudal epidural anaesthesia approaches the epidural space through the sacral hiatus — the most caudal access to the neuraxis. It is the commonest regional block in children, providing sacral and lumbar anaesthesia for lower-body surgery — taught place; [4] owns the paediatric caudal comparison — and safe practice rests on the sacral-hiatus anatomy, the needle angle that keeps the tip below S2, and the aspiration test before every injection.[4]

Meet the patient

A 3-year-old for circumcision is anaesthetised and turned lateral. You palpate the sacral cornua, advance a cannula through the sacrococcygeal membrane, feel the pop, flatten the angle, aspirate — clear. The legs spread within minutes, the heart rate holds, and the surgeon operates without a general anaesthetic deep enough to risk the airway. This is the caudal block in its element — taught vignette; [4] owns the paediatric caudal comparison.[4]

The question every trainee must answer before the pop is felt: where is the dural sac, and what happens if the needle goes past it? The answer — S2 in the adult, lower in the infant, and a total spinal if you breach it — is reason aspiration test is non-negotiable — taught anatomy.[4]

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References6ShowHide
  1. [1]Hasoon J, Abd-Elsayed A, Viswanath O, et al. The Utility of Caudal Epidural Steroid Injections: A Comprehensive Review. Orthop Rev (Pavia), 2026.PMID 42299144
  2. [2]Agarwal S, Agrawal S, Kamal G, et al. A comparative study of clonidine and dexmedetomidine as an adjuvant to levobupivacaine for caudal analgesia in children undergoing below umbilical surgeries: A randomized double-blind controlled trial. Agri, 2026.PMID 41609323
  3. [3]Samaan PME, Shawky EAM, Ghallab MAEA, et al. Comparative Study of the Effect of Continuous Caudal Epidural With General Anesthesia Versus General Anesthesia on Intraoperative and Postoperative Analgesic Requirements for Lumbar Fixation. Anesthesiol Res Pract, 2026.PMID 42147357
  4. [4]Bagri V, Manickam A, Parameswari A, et al. Analgesic efficacy of ultrasound-guided pudendal nerve block versus caudal block for penile surgeries in children. J Anaesthesiol Clin Pharmacol, 2026.PMID 42088184
  5. [5]Masiero BB, Lombardi RA Response to Letter to the Editor: Erector spinae plane block versus caudal block in children: similar analgesia, different stories beneath the surface. Braz J Anesthesiol, 2026.PMID 42331224
  6. [6]Kankal S, Bozdana M, Turan Eİ, et al. Comparison of sacral erector spinae plane block and caudal epidural block for postoperative analgesia in pediatric hypospadias surgery: a prospective observational study. Perioper Med (Lond), 2026.PMID 42265792

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