Chapter 396. Abdominal Wall Defects

Gastroschisis is congenital abdominal wall defect though which intraperitoneal contents protrude (Fig. 396-1). The defect occurs to the right of the umbilical cord and can range in size from 2 to 5 cm. The bowel typically appears edematous and inflamed and may be covered by a fibrinous peel. The most commonly eviscerated organs include the intestines and gonads. Gastroschisis occurs in younger mothers,1 with a total incidence of one in 3000 live births.2 Several studies have reported a recent increase in the incidence of gastroschisis.3-5

Pathogenesis

Gastroschisis occurs during the sixth or seventh week of gestation. The right umbilical vein naturally involutes, leaving one umbilical vein and two umbilical arteries. It is hypothesized that the right abdominal wall suffers from vascular compromise, which results in gastroschisis.6,7 This explains why gastroschisis always occurs to the right of the umbilicus. Two other hypotheses exist for the formation of gastroschisis. One involves the defective development of the mesenchyme on the anterior abdominal wall. Anecdotally, omphalocele membrane rupture and subsequent growth of skin to the right and lateral to the umbilicus was documented by ultrasound; the newborn appearance was that of a gastroschisis.8

Epidemiology

Maternal and environmental factors have been implicated in the development of gastroschisis. In animal models, folic acid deficiency, maternal hypoxia, and salicylates have been linked to abdominal wall defects.9 The use of vasoconstrictive agents, such as pseudoephedrine, cocaine, and cigarettes, in early pregnancy have been postulated to increase the risk of gastroschisis.10 Maternal use of salicylates and acetaminophen has also been implicated in the development of gastroschisis.11 Elevated atrazine levels, a chemical found in pesticides in drinking water, has recently been correlated with a regional increased incidence of gastroschisis in the United States.12

Infants with gastroschisis tend to be born prematurely. There is some evidence that gastroschisis infants allowed to deliver after 36 weeks have a stillborn rate of approximately 10%.13 Consequently, mothers of gastroschisis infants are induced to deliver at 36 to 37 weeks, when lung maturity is reached.

Ten percent of infants with gastroschisis have an associated intestinal atresia of varying lengths. It is thought that the atresia results from in utero segmental intestinal volvulus. This is made more likely by the fact that the intestines float in the amniotic fluid without the protection of the peritoneal cavity. Occasionally, the gastroschisis defect closes completely around the mesenteric pedicle, causing the midgut to be ischemic and reabsorbed prior to birth.

The intestines of infants with gastroschisis have an inherent dysmotility. In most gastroschisis infants, this manifests as a prolonged ileus after closure of the abdominal wall. The average time to start feeds after abdominal wall closure is ...