Fetal Surgery

Abstract

The extraordinary advances in molecular genetics and the ongoing technologic innovations in medical imaging now make it possible to prenatally diagnose virtually any condition with a high level of confidence. This has afforded the opportunity to consider prenatal treatment for an ever-expanding list of conditions and to avoid or minimize irreparable organ injury or death that can occur if treatment is delayed until after delivery. Fetal therapy has expanded the list of conditions that are considered for medical treatment including high-risk congenital pulmonary airway malformations (CPAM), fetal arrhythmias, congenital adrenal hyperplasia (CAH), and congenital diaphragmatic hernia (CDH). The indications for open fetal surgery have expanded with the development of interventions for myelomeningocele (MMC), sacrococcygeal teratoma (SCT), bladder outlet obstruction (BOO), and CPAM. Perhaps the most striking area of growth in fetal intervention has come in the field of fetoscopic techniques, which are used to treat conditions such as twin–twin transfusion syndrome (TTTS), twin reversed arterial perfusion (TRAP) sequence, and CDH.

Appendices

Summary Points

Fetal intervention requires precise high-quality prenatal imaging, a complete maternal history, strict selection criteria, and techniques that are safe for both mother and fetus.

The most common indication for fetal surgery currently is twin–twin transfusion syndrome, which is usually treated by fetoscopy.

Antenatal medical treatment options remain limited and include steroid administration for the treatment of congenital pulmonary airway malformations, rapidly involuting congenital hemangiomas, and complete heart block due to maternal lupus, and transplacental treatment of fetal tachyarrhythmias with antiarrhythmic medications.

Fetoscopic surgery is currently used to treat: twin–twin transfusion syndrome, twin reversed arterial perfusion, amniotic band syndrome, congenital high airway obstruction syndrome due to tracheal atresia, bladder outlet obstruction due to posterior urethral valves, and, in experimental studies, congenital diaphragmatic hernia.

Open fetal surgery is rarely indicated but is considered in conditions with a high mortality such as congenital lung lesions or sacrococcygeal teratoma with hydrops, and certain highly morbid conditions such as bladder outlet obstruction and myelomeningocele.

Anesthetic and tocolytic techniques are currently quite effective but continually being refined.

Editor’s Comment

Centers that specialize in fetal diagnosis and intervention are becoming increasingly common. Due to the efforts of experts in the field, the technology is advancing rapidly; though currently the indications for actual in utero fetal intervention remain few. Nevertheless, fetal diagnostic and surgical centers serve several important roles and, as such, have contributed greatly to the care of newborns with congenital anomalies: (1) genetic and obstetrical counseling, (2) state-of-the-art imaging and interventional diagnostics available in one location, (3) a source of reliable information for pregnant women and their families when a congenital anomaly has been identified antenatally, (4) the opportunity to pursue in utero intervention when indicated, (5) the ability to make plans for appropriate medical and surgical therapeutics for when the baby is born, and (6) the option of actually ­delivering the child in a children’s hospital where care can be delivered without the delay associated with transfer (which at this time is available at only one center in the US).

Despite the fact that the results of fetal surgery for congenital diaphragmatic hernia have been disappointing in that the results have been no better than that achieved by the standard of care, the work has nonetheless contributed greatly to the understanding of this condition and effective fetal interventions appear to be finally within grasp. Operations for other conditions (congenital lung disease, sacrococcygeal teratoma, cervical masses) have proven somewhat more successful but only when the life of the fetus is in jeopardy. Several technical problems encountered early on have been resolved, including achieving hemostasis of the hysterotomy incision, maintaining uterine volume and temperature during the procedure, balancing the needs of the mother and the fetus related to anesthetic issues, and avoiding injury to the placenta, which occupies a large proportion of the internal surface area of the uterus. Postoperative preterm labor remains a common and frustrating occurrence after fetal intervention. Nevertheless, it is inevitable, however, that someday soon fetal surgery will become more routine as the few remaining hurdles are removed.

Fetal operations, including procedures performed using the EXIT approach, involve a large team of dedicated specialists all working together to maintain the health and well-being of the fetus(es) and, most importantly, the mother. The planning and coordination of the team are clearly important to achieving this goal. During a typical fetal operation or EXIT procedure, the operating theater is filled with personnel, more than for any typical operation, each contributing something specifically important to the task at hand: pediatric surgeons, obstetricians, anesthesiologists, neonatologists, and nurses representing each of the specialties involved. Two operating rooms are usually required, one for the mother and another for the infant. The result is a tense but well-orchestrated process and usually a successful outcome. Eventually, it is likely that nearly every congenital anomaly will be detectable antenatally, in which case newer and better treatments will become available because of the ground-breaking work of the select few who are today’s fetal surgeons.