ABSTRACT
Advanced fetal diagnostic techniques (e.g., chorionic villous sampling, amniocentesis) and serial imaging (e.g., ultrasound, magnetic resonance imaging) have led to an increased understanding of the natural history and outcome of many fetal anomalies. As a result, the majority of fetuses with anomalies amenable to surgery are best served by planned delivery and care after birth. There is, however, a small proportion of fetuses for whom an untreated anomaly will result in death in utero or shortly after birth. Prenatal intervention has, in large part, been predicated on those anomalies that cause either low-output or high-output cardiac failure resulting in hydrops, defined as skin and/or nuchal edema or fluid accumulation in two of three body cavities (pleura, pericardium, peritoneum). Examples include fetuses with hydrops from a space-occupying chest mass (e.g., cystic adenomatoid malformation, pericardial teratoma, tension hydrothorax), sacrococcygeal teratoma (SCT), select heart defects, twin-twin transfusion syndrome, and twin reversed-arterial perfusion (TRAP) sequence. Pulmonary and kidney failure can be predicted in a subset of fetuses with complete and early gestation urinary tract obstruction (e.g., posterior urethral valves) and may benefit from ultrasound-guided vesicoamniotic shunt placement. Fetuses with threatened postnatal airway obstruction from a cervical teratoma or lymphangioma may benefit from the ex utero intrapartum treatment (EXIT) strategy. Controversial areas of maternal-fetal intervention include non-lethal anomalies such as laser therapy for amniotic band syndrome and repair of a myelomeningocele.
