Caudal or penile block for hypospadias repair: similar fistula rates, fewer opioids with caudal

Design

Multicentre randomised non-inferiority trial, stopped early

Population

210 children ≤2 years having distal or midshaft hypospadias repair (161 followed to 3 months)

Primary outcome

Urethrocutaneous fistula within 3 months

Effect

8.9% vs 7.3%; RR 0.98 (95% CI 0.35 to 2.76)

Retrospective studies have linked caudal block to urethrocutaneous fistula after hypospadias repair, raising concern among surgeons. A randomised non-inferiority trial at 16 Pediatric Regional Anesthesia Network centres assigned children up to two years old having primary single-stage distal or midshaft repair to caudal or penile block with general anaesthesia.

Of 210 randomised, 161 completed three months' follow-up. Fistula occurred in 8.9% after caudal and 7.3% after penile block, with no significant difference. A more proximal meatus nearly tripled fistula risk. Children given caudal blocks needed intraoperative opioids less often (33% vs 56%), rescue opioids less often (4.9% vs 15.7%), and had lower recovery-room pain scores.

The trial stopped early and lost almost a quarter of participants to follow-up, so its interval is wide and a meaningful difference in fistula rates cannot be excluded. It does, however, weaken the case against caudal block and shows the hypospadias severity, rather than the block, drives most fistula risk.

• Consider caudal block for distal or midshaft hypospadias repair in children under two; this trial found no excess fistula.
• Expect less intraoperative and rescue opioid use with caudal than with penile block.
• Record meatal position, which was a stronger predictor of fistula than block type.
• Discuss the uncertainty openly with surgical colleagues; the trial was underpowered for small differences.

Why it matters

It is the first randomised evidence on a concern that has shaped block choice largely on retrospective data.

Don't overread it

The trial ended early with 23% loss to follow-up; the fistula comparison is too imprecise to establish equivalence.

The statistics, in plain English

A risk ratio of 0.98 with a 95% confidence interval from 0.35 to 2.76 means caudal block could plausibly reduce fistula risk by about two-thirds or nearly triple it. The trial cannot distinguish between those possibilities.

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