Supplementary Material for: The Evolution of Cephalocentesis in Contemporary Obstetric Practice: From Emergency Intervention to Planned Procedure

Objective: To analyze the evolution, indications and outcomes of cephalocentesis over a 38-year period at two tertiary fetal medicine centers. Methods: Retrospective review of 70 cephalocentesis procedures (1985-2023) at Mount Sinai Hospital, Toronto and the National Maternity Hospital, Dublin. Cases were divided into pre-2002 (n=37) and 2002-onwards (n=33) cohorts in order to evaluate practice evolution. Results: Mean gestational age at diagnosis was 32.7 ± 5.4 weeks with severe hydrocephalus in 95.7% (67/70) and hydranencephaly in 4.3% (3/70) of cases. Pre-2002, 94.6% (35/37) of procedures were performed intrapartum; 2002-onwards, this shifted to 66.7% (22/33) pre-labor planned procedures with 84.8% (28/33) using a transabdominal approach. Concurrent fetal analgesia and potassium chloride to achieve fetal asystole was introduced in 2002. Vaginal delivery was achieved in 95.7% (67/70) of cases. Perinatal mortality (excluding KCl cases) was 91.8% (45/49). All four survivors (5.8%) demonstrated neurodevelopmental impairment. Conclusion: Cephalocentesis has evolved from an intrapartum intervention to a planned procedure with standardized protocols. Our findings support reserving this procedure for cases where there is no expectation of postnatal survival, with the primary purpose of facilitating vaginal delivery when caesarean section could unnecessarily increase maternal morbidity.