Impacted Fetal Head During Second Stage Caesarean Birth: A Prospective Observational Study

The rate of cesarean delivery (CD) at full cervical dilation in the second stage of labor is rising. During this stage, the risk of maternal and neonatal complications is greater because the baby's head may be engaged deeply in the pelvis, a condition known as impacted fetal head. Delivery in this situation may be challenging because the obstetrician may not be able to pass their hand between the pelvis and fetal head or a vacuum effect may occur making head elevation difficult. Also, extending the uterine incision may be more likely because the uterus is thinned and stretched. Neonatal complications of this condition may include bony fractures, hypoxic brain injury, and death. Because the definition of impacted fetal head is subjective, the reported incidence at cesarean birth varies from 1.5% in women undergoing CD and 63% in women undergoing CD at full dilation. Although there are a number of disimpaction techniques that have been advocated, including the fetal pillow, the Patwardhan method, the push technique, reverse breech extraction, and tocolysis and the Tydeman tube, there are few data on their frequency of use and effectiveness. A Cochrane review of 4 trials comparing reverse breech extraction and the push technique found no difference in birth trauma and lower rates of endometritis and blood loss with reverse breech extraction, although the quality of evidence was low. Two small trials suggested that the preventative use of the fetal pillow reduced adverse events compared with other techniques, but these studies had methodological weaknesses such that the UK National Institute for Clinical Excellence could not recommend the pillow outside of clinical trials. Yet, the use of the fetal pillow is gaining popularity despite a large retrospective trial finding no significant benefit to maternal and neonatal outcomes. The aim of this study was to determine the incidence and complications rates of impacted fetal head at full dilation cesarean delivery and review the disimpaction techniques used. This was a prospective, observational study using data from theUKObstetric Surveillance System, which collects population-based data about rare pregnancies from all 194 maternity hospitals in the United Kingdom. Nominated clinicians were asked to notify UK Obstetric Surveillance System of women with singleton pregnancies in cephalic presentation who underwent CD during the second stage of labor between March and August, 2019. Additional data were collected when a disimpaction technique was used, or the operating surgeon experienced "difficulty" delivering the head. A total of 557 second-stage CDs from 159 hospitals were included in the analysis. The push technique, ranked as the first technique used in cases with difficulty delivering the fetus' head, was used as treatment in 167 cases and as a preventive measure in 68 cases. The fetal pillow was used as treatment in 34 cases and as a preventive measure in 142 cases. Tocolysis was used in 54 cases as treatment and 13 cases as a preventative measure. Among maternal complications, blood loss >1000 mL occurred in 26% of cases, followed by extension of uterine incision (22%) and admission to intensive care (6.1%). A total of 15 (2.7%) babies died or sustained severe injury, with 2 deaths directly attributable to impacted fetal head. Injuries included fractures (7), brachial plexus injury (2), and facial palsy (1). There were 3 babies with hypoxic ischemic encephalopathy and 7 who underwent cerebral cooling. Neonatal care admission occurred in 12% of cases. In this study, cases involving impacted fetal head had significant maternal and neonatal complications. The push technique and fetal pillow were the 2 most often used techniques.