Abstract
BACKGROUND: Intrapartum cesarean section (CS) after epidural labour analgesia (ELA) is usually managed by catheter top-up, yet some centres prefer repeat spinal anaesthesia (SA) for speed and density of block. The failure rate of this strategy and its dose-response relationship with prior epidural drug exposure remain uncertain. This retrospective cohort study aimed to determine the incidence and risk factors of failed repeat SA in parturients undergoing intrapartum CS after receiving ELA. METHODS: We reviewed all parturients who received ELA and subsequently underwent intrapartum CS at Peking University International Hospital (Jan 2024-May 2025). Among 167 eligible women, 102 received repeat SA while 64 received epidural top-up, one received general anaesthesia (GA). The primary outcome was failed repeat SA, defined as inadequate surgical block before skin incision requiring re-puncture, epidural rescue or conversion to GA. Multivariable logistic regression was used to identify independent risk factors of failed repeat SA. RESULTS: Eighteen of 102 repeat SA cases failed (17.6%; 95% CI 11.6%-26.1%), with 9 requiring conversion to GA (8.8%). No high or total spinal block was observed. The only independent predictor of failure was the total volume of epidural solution administered during labour (adjusted OR 1.020 per 1 ml increment, 95% CI 1.004-1.037, p = 0.016). Obesity, clinician top-ups were not significant in the adjusted model. CONCLUSIONS: Repeat SA following ELA carries a failure rate that exceeds accepted thresholds when cumulative epidural volume is high. The cumulative epidural volume is a readily quantifiable variable that can be integrated into risk-assessment algorithms. Prospective multicentre studies are warranted to validate this relationship and to test ancillary bedside measures (glucose reagent strips, pH testing or ultrasound) for confirming true subarachnoid placement before intrathecal injection.