133: Surgical Diseases of the Newborn: Abdominal Wall Defects

GASTROSCHISIS

I. DEFINITION

A gastroschisis is a centrally located, full-thickness abdominal wall defect with 2 distinct anatomic features.

1. The extruded intestine is never covered by a protective sac.

2. The umbilical cord is an intact structure at the level of the abdominal skin, just to the left of the defect. Typically, the abdominal wall opening is 2–4 cm in diameter, and the solid organs (liver and spleen) reside in the peritoneal cavity.

II. PATHOPHYSIOLOGY

Exposure to irritating amniotic fluid renders the intestines edematous, indurated, and foreshortened. Appropriate peristalsis and effective intestinal absorption are significantly delayed, usually by several weeks. Associated congenital anomalies are rare.

III. CLINICAL PRESENTATION

The infant is born with varying amounts of intestine extruding through the defect. An inflammatory peel is often found on the intestines. Up to 10% of neonates with gastroschisis will have an associated intestinal atresia.

IV. DIAGNOSIS

Although readily apparent in most cases, gastroschisis must be differentiated from ruptured omphalocele. Increasingly, prenatal ultrasonography identifies gastroschisis

V. MANAGEMENT

1. General considerations. Infants with gastroschisis should be delivered at a neonatal center capable of providing definitive care. Both vaginal and cesarean deliveries have been shown to be safe and should be left to the obstetrician's discretion.

2. Specific measures

   1. Fluid resuscitation. Venous access should be obtained promptly and aggressive fluid resuscitation should be initiated to combat the large evaporative fluid losses from the exposed bowel.

   2. Temperature regulation. Immediate attention should be directed toward maintenance of normal body temperature. The tremendous intestinal surface area exposed to the environment puts these infants at great risk for hypothermia.

   3. Protective covering/position. To prevent evaporative heat loss, the bowel should be covered with a moist, clean dressing. The abdomen should be wrapped in layers of cellophane, or the baby's abdomen, bowel, and legs should be placed in a plastic bag. The newborn should be laid on its side to prevent “kinking” the intestine's vascular pedicle while awaiting surgical intervention.

   4. Nasogastric/orogastric decompression. This is helpful.

   5. Broad-spectrum antibiotic coverage. Appropriate given the unavoidable contamination.

   6. Total parenteral nutrition. Delayed bowel function should be expected, and appropriate intravenous nutritional support must be provided.

   7. Surgical correction. As soon as the infant's condition permits, operative correction should be undertaken. In some babies, reduction of the herniated intestine and primary closure of the abdominal wall can be performed. Others require placing the intestines in a protective silo with subsequent staged reduction. Central venous access is usually part of the surgical intervention.

OMPHALOCELE

I. DEFINITION

An omphalocele is a herniation of abdominal contents into the base of the umbilical cord. The gross appearance of omphalocele differs from that of gastroschisis in 2 important respects:

1. The malpositioned abdominal contents are covered by a protective membrane (unless ...