Caudal block did not cause hypospadias fistulas - the meatal position did

Design

Multicentre randomised non-inferiority trial across 16 centres, terminated early

Population

161 children aged 2 years or under completing follow-up after primary single-stage midshaft or distal hypospadias repair

Primary outcome

Urethrocutaneous fistula within 3 postoperative months

Effect

8.9% caudal vs 7.3% penile block (RR 0.98, 95% CI 0.35-2.76); proximal meatal position RR 2.8 (1.48-5.30); caudal reduced intraoperative opioid 33% vs 56%

Retrospective series have argued for years about whether caudal block raises the risk of urethrocutaneous fistula after hypospadias repair, usually without accounting for how severe the hypospadias was. Sixteen Pediatric Regional Anesthesia Network centres randomised children aged two or under having primary single-stage midshaft or distal repair to caudal or penile block alongside general anaesthesia. Of 210 randomised, 161 completed three-month follow-up.

Fistula occurred in 7 of 79 caudal patients (8.9%) and 6 of 82 penile block patients (7.3%), a risk ratio of 0.98 with a confidence interval from 0.35 to 2.76. What did predict fistula was anatomy: a proximal meatal position carried a risk ratio of 2.8 (95% CI 1.48-5.30, P = 0.002). Caudal block came with clear analgesic advantages - intraoperative opioid given to 33% against 56% (P < 0.001), rescue opioid to 4.9% against 15.7% (P = 0.01), and lower mean recovery-room FLACC scores (0.49 against 1.14, P = 0.03).

The trial terminated early with incomplete enrolment and nearly a quarter lost to follow-up, and the authors are explicit that it should be read as exploratory. That framing is right, and it still moves the argument. The retrospective signal that generated the concern was never adjusted for severity; here, when severity is measured, it is severity that carries the risk and the block does not. A confidence interval reaching 2.76 cannot exclude harm, but it no longer supports the routine avoidance of caudal block that some units adopted.

• Record meatal position explicitly - it was the variable that predicted fistula
• Caudal block halved intraoperative opioid exposure and reduced rescue opioid threefold
• Do not treat the fistula question as settled; the confidence interval still admits meaningful harm
• Counsel families on fistula risk using the anatomy, not the anaesthetic technique
• An early-terminated trial with 23% loss to follow-up is exploratory evidence, and should be described that way

Why it matters

Units that avoid caudal block for these repairs are acting on retrospective data that never adjusted for hypospadias severity.

Don't overread it

Early terminated with 23% loss to follow-up - a wide confidence interval means clinically important harm cannot be excluded.

The statistics, in plain English

A risk ratio of 0.98 sounds reassuringly neutral until the confidence interval is read: 0.35 to 2.76 means the data are compatible with caudal block reducing fistula risk by two-thirds or nearly tripling it. That is what happens when 13 events are split across 161 children. The analgesic outcomes are on much firmer ground because opioid administration is common rather than rare - 33% against 56% is a real and precisely measured difference. The proximal meatal position result, with an interval from 1.48 to 5.30, is the finding that survives scrutiny, and it points at anatomy rather than anaesthesia.

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