Congenital anomalies have a wide array of presentations, from almost unnoticeable variations to remarkable dysmorphology. They may be detected at first breath of life or several weeks to months later. The causes of congenital anomalies are also as varied as their presentations. Genetic mutations, toxin-induced syndromes, and mechanical in utero effects drive the majority of anomalies; yet in others, the causes remain unknown.

The clinical management of all congenital anomalies involves a multidisciplinary approach to the patient. Due to the altered physiology of congenital anomalies, many different specialties including neonatology, critical care, surgery, and genetics work in concert to provide optimal outcomes for each individual patient. This chapter will examine several of the most common congenital anomalies and address their pathology, diagnosis, and management.

BACKGROUND

Gastroschisis and omphalocele are the most common abdominal wall defects in neonates. In the United States, the incidence of gastroschisis has seen a 10- to 20-fold increase over the past 20 years.¹ Currently, the incidence of gastroschisis is 1 in 4000 live births while omphaloceles have an incidence of 1 in 4000 live births.¹

Pathophysiology

During normal fetal development, the gut protrudes from the umbilical ring and then retracts back into the abdominal cavity by the 11th week of gestation.¹ When the series of events needed to complete this process fail to occur, abdominal wall defects result. Gastroschisis is not commonly associated with other congenital anomalies, with the exception of localized abnormalities such as intestinal atresia (10% to 28%) and cryptorchidism (up to 15%).^1,2

An omphalocele results from failed growth and fusion of the lateral folds early in gestation. This creates a central defect of the umbilical ring and allows the bowel to remain herniated. Over 50% of patients with omphalocele have associated anomalies, which are usually midline.¹ These include cardiac defects (30% to 50% of infants), colonic atresia, imperforate anus, sacral and vertebral anomalies, and genitourinary malformations such as bladder exstrophy or cloacae.¹ Syndromes associated with omphalocele include the Pentalogy of Cantrell (sternal cleft; pericardial, cardiac, and diaphragmatic defects), Beckwith-Wiedemann syndrome (macroglossia, macrosomia, and hypoglycemia), and trisomy 13, 15, 18, and 21; chromosomal abnormalities occur in up to one-third of cases.^1,2,3

CLINICAL PRESENTATION

Patients with gastroschisis are often premature. They commonly present with a defect to the right of the umbilicus and herniation of the abdominal contents through the umbilical ring (Figure 126-1). The bowel is not contained within a sac therefore it is often thickened, with a fibrous peel, due to prolonged intrauterine exposure to amniotic fluid.² Complications of gastroschisis include intestinal macroglossia, volvulus, stenosis, or atresia.²

An omphalocele presents as a central defect in the abdominal wall, commonly inferior to the umbilical ring. The opening is generally greater than 4 cm, and a membranous sac covers the contents, unless it ruptured before delivery. The liver and intestines herniate through the opening in 10% of these patients, resulting in a giant omphalocele.² In contrast to gastroschisis, infants with omphalocele typically have normal gastrointestinal function.

DIAGNOSTIC EVALUATION

These abdominal wall defects can be detected prenatally on ultrasound examination which allows delivery of these neonates at centers that can provide the intensive care needed during the perinatal period. A physical examination should be performed immediately after birth to detect any associated anomalies that require urgent evaluation.^1,2,3 Radiographic studies, echocardiography, renal ultrasound, and chromosomal analysis should be obtained.

MANAGEMENT

The initial management of an infant with either gastroschisis or omphalocele is similar. Treatment is aimed at bowel decompression, replacement of insensible fluid losses, avoidance of hypothermia, and a thorough search for concurrent anomalies. To this end, in gastroschisis, the abdominal contents should be wrapped in warmed, sterile saline-soaked gauze.² Care should be taken to prevent kinking of the mesenteric vessels.² The patient should be wrapped in a large bowel bag to prevent evaporative heat and fluid losses. Intravenous fluids at one and a half times the maintenance rate should be initiated.³ For patients with omphalocele, intravenous fluid replacement and prevention of hypothermia also apply, but due to the sac covering the bowel the risks of hypothermia and evaporative fluid losses are less than those in gastroschisis.³ Nasogastric tube placement aides in bowel decompression and rectal examination coupled with rectal irrigation can aide in the evacuation of meconium.² Parenteral antibiotics that cover bowel flora should be administered (e.g. ampicillin + gentamicin + metronidazole or ampicillin-sulbactam + gentamicin). Once the patient is hemodynamically stable, nutrition is started. While enteral feeding is preferable to parenteral nutrition, these patients often have delayed bowel motility—especially with gastroschisis—and therefore parenteral nutrition is often necessary initially.

ADMISSION AND DISCHARGE CRITERIA

After initial stabilization, newborns with abdominal wall defects require prompt transfer to a neonatal intensive care unit (NICU). Discharge criteria include adequate surgical coverage of the intra-abdominal organs, resolution of any sepsis, and recovery of bowel function with tolerance of full enteral nutrition.

CONSULTATION

Consultation with a pediatric surgeon is indicated for either primary repair of the defect or silo placement with reduction of the bowel and then delayed repair² (Figure 126-2).

BACKGROUND

Congenital diaphragmatic hernia (CDH) represents one of the most challenging conditions in neonates. Prior management used to include immediate surgical correction of the CDH, but as our understanding of this disease has evolved, initial management now focuses on stabilization of the patient with delayed surgical repair.² The incidence of CDH is 1 in 2000 to 5000 live births, and the majority present on the left side.² Despite recent advances in critical care and surgical interventions the overall survival rates have remained at 70% to 90%.³

Pathophysiology

In utero compression of the developing lung by the bowel may result in pulmonary hypoplasia as well as pulmonary hypertension.

CLINICAL PRESENTATION

Initially, the patients may have a “honeymoon period” with adequate respiratory effort.³ Gradually though, as respiratory function worsens, neonates with CDH present with respiratory distress, which can include tachypnea, grunting, chest wall retractions, cyanosis, and pallor.^2,3 Physical examination reveals a scaphoid abdomen and bowel sounds within the chest. Heart sounds can be heard on the right with breath sounds decreased bilaterally. Persistent fetal circulation may be demonstrated by the difference in pre- and postductal oxygen saturation measurements thus giving an idea of the degree of shunting occurring within the lungs.³ The Oxygenation Index (OI) is the most valuable parameter that can be used to predict survival of patients with significant shunting caused by the pulmonary hypoplasia associated with CDH. The OI is calculated using the preductal partial pressure of arterial oxygen (P_aO₂) with the formula:

An OI less than 6 is associated with a survival of 98%, with higher OI values indicating worse lung hypoplasia and therefore a worse prognosis.²

DIFFERENTIAL DIAGNOSIS

Many neonatal conditions can present with respiratory distress. Some conditions include pulmonary sequestrations, bronchogenic cysts, congenital pulmonary airway malformations (formerly known as congenital cystic adenomatoid malformations), meconium aspiration, pleural effusions, pulmonary consolidations, cystic teratomas, and neurogenic tumors.

DIAGNOSTIC EVALUATION

CDH is frequently diagnosed by fetal ultrasonography.² At birth, radiographs of the chest and abdomen (i.e. “babygram”) reveal multiple gas-filled bowel loops within the chest, mediastinal shifting as well as an intrathoracic gastric bubble² (Figure 126-3). A nasogastric tube, placed for gastric decompression, frequently coils in the chest cavity; this is also identified on x-ray. Echocardiography and renal ultrasonography should be performed to assess for any associated anomalies.²

MANAGEMENT

Initial stabilization, treatment of pulmonary hypertension, and delayed surgical intervention constitute the principal management strategies for CDH. Treatment of respiratory distress includes endotracheal intubation and mechanical ventilation.² Nasogastric tube decompression of the stomach prevents bowel distention which would compromise respiratory function.³ Maintenance of euvolemia and avoidance of acidosis and hypoxemia are paramount in the treatment of the pulmonary hypertension which is found in these patients. Patients with respiratory failure and persistent hypoxemia may require extracorporeal membranous oxygenation (ECMO).²

ADMISSION AND DISCHARGE CRITERIA

After initial stabilization, newborns with CDH require prompt transfer to a NICU. These lesions used to be treated as surgical emergencies but multiple studies have shown that delayed repair results in improved survival rates. As a result, initial care focuses of respiratory management and stabilization of the pulmonary hypertension and repair is often performed once both ventilatory status and pulmonary hypertension has stabilized or improved. Patients are ready for discharge once their CDH is surgically repaired, they are off ventilatory support, and they are able to demonstrate adequate growth on enteral nutrition.