Congenital abdominal wall defects.
The objectives of this chapter are to review the resuscitation and perinatal management of neonates with abdominal wall defects.
Congenital abdominal wall defects (AWD), with an increasing incidence over the last several decades, represent one of the more commonly encountered neonatal surgical conditions. While often considered together, they can be divided into two distinct clinical entities; namely omphalocele and gastroschisis. AWD in gastroschisis is typically <4 cm in size, located to the right of the umbilical cord, and lacks a covering sac. Consequently, the exteriorized abdominal contents, most frequently midgut derivatives (rarely part of the liver, gonads, and bladder), are exposed to amniotic fluid during gestation. In contrast, an omphalocele is characterized by a defect typically >4 cm in size, located at the base of the umbilical cord, and the exteriorized intra-abdominal contents are typically covered by a sac made by the layers of the umbilical cord. Multiple additional congenital anomalies can be associated with AWD. Up to half of neonates with omphalocele may have an associated cardiac anomaly; other associations include chromosomal anomalies and musculoskeletal and neural tube defects. In contrast, gastroschisis is most commonly associated with intestinal atresias (5% incidence), while other extra-intestinal malformations are encountered relatively less frequently. As a result, despite numerous advances in neonatal and surgical care, considerable morbidity and mortality remains associated with AWD. Moreover, certain aspects of management, such as the timing and mode of delivery, utility of fetal interventions, and the timing and type of repair performed for AWD remain controversial.
Optimal timing of and mode of delivery for both types of AWD are controversial and have been debated considerably. In patients with gastroschisis, exposure of the exteriorized bowel to the amniotic fluid is thought to lead to the development of an inflammatory peel, which in turn causes bowel dysmotility and delayed transition to full enteral nutrition. However, multiple studies and a Cochrane review failed to demonstrate any significant advantage of elective preterm delivery. Similarly, the perceived risk of injury to the viscera in the birth canal during vaginal delivery led to an interest in performing routine cesarean sections. However, multiple studies as well as a systematic review of the literature do not demonstrate any advantage to cesarean section for AWD in the absence of obstetrical indications. In patients with omphalocele, the timing and mode of delivery is a little less controversial; in the absence of obstetrical indications, term vaginal deliveries are more universally advocated. Cesarean deliveries, however, may be considered in the case of giant omphaloceles with liver in the sac, ruptured omphaloceles, ectopia cordis, and cloacal exstrophy. Therefore, the recommendation is a term vaginal delivery in the absence of any fetal issues, with close monitoring....