Abstract
INTRODUCTION: Despite increasing incidence of impacted fetal head at cesarean birth and associated injury, it is unclear which techniques are most effective for prevention and management. A high quality evidence review in accordance with international reporting standards is currently lacking. To address this gap, we aimed to identify, assess, and synthesize studies comparing techniques to prevent or manage impacted fetal head at cesarean birth prior to or at full cervical dilatation. MATERIAL AND METHODS: We searched MEDLINE, Emcare, Embase and Cochrane databases up to 1 January 2023 (PROSPERO: CRD420212750016). Included were randomized controlled trials (any size) and non-randomized comparative studies (n ≥ 30 in each arm) comparing techniques or adjunctive measures to prevent or manage impacted fetal head at cesarean birth. Following screening and data extraction, we assessed risk of bias for individual studies using RoB2 and ROBINS-I, and certainty of evidence using GRADE. We synthesized data using meta-analysis where appropriate, including sensitivity analyses excluding data published in potential predatory journals or at risk of retraction. RESULTS: We identified 24 eligible studies (11 randomized and 13 non-randomized) including 3558 women, that compared vaginal disimpaction, reverse breech extraction, the Patwardhan method and/or the Fetal Pillow®. GRADE certainty of evidence was low or very low for all 96 outcomes across seven reported comparisons. Pooled analysis mostly showed no or equivocal differences in outcomes across comparisons of techniques. Although some maternal outcomes suggested differences between techniques (eg risk ratio of 3.41 [95% CI: 2.50-4.66] for uterine incision extension with vaginal disimpaction vs. reverse breech extraction), these were based on unreliable pooled estimates given very low GRADE certainty and, in some cases, additional risk of bias introduced by data published in potential predatory journals or at risk of retraction. CONCLUSIONS: The current weaknesses in the evidence base mean that no firm recommendations can be made about the superiority of any one impacted fetal head technique over another, indicating that high quality training is needed across the range of techniques. Future studies to improve the evidence base are urgently required, using a standard definition of impacted fetal head, agreed maternal and neonatal outcome sets for impacted fetal head, and internationally recommended reporting standards.