Chapter 34: Congenital Abdominal Wall Defects

I. Intensive care

The two most common congenital wall defects are gastroschisis and omphalocele.

1. Gastroschisis

   1. Definition

      Gastroschisis is a full-thickness, typically right-sided, paraumbilical abdominal wall defect and primarily has the intestines and stomach protruding through the defect in the amniotic fluid.

   2. Incidence

      1. There has been a 10- to 20-fold increase in the birth prevalence of gastroschisis over the past two decades. The cause of this increase is poorly understood, but is a worldwide phenomenon.

      2. Currently, Gastroschisis occurs in one in 4000 live births.

      3. Gastroschisis occurs in males and females equally.

   3. Pathophysiology

      1. The etiology of gastroschisis has yet to be determined.

      2. There are several embryologic hypotheses that describe abnormal formation or weakening of the body wall followed by bowel herniation.

      3. The current accepted theory is that of failure of migration of the ventral folds on the right side causing the defect.

   4. Risk factors

      1. Gastroschisis has been strongly associated with maternal age younger than 21.

      2. Nulliparity has been associated with gastroschisis, independent of maternal age.

      3. Maternal exposure to vasoconstrictive drugs (cocaine, ephedrine, and pseudoephedrine), tobacco, aspirin, and ibuprofen may be associated with the development of gastroschisis.

      4. Maternal low bodyweight and genitourinary infections may also be associated with a greater risk of gastroschisis.

      5. Conversely, acetaminophen use in the first trimester may decrease the risk of gastroschisis.

   5. Clinical presentation

      1. Majority of patients are diagnosed prenatally in the United States.

         • Gastroschisis may first be identified by an elevated second trimester maternal serum α-fetoprotein level. An elevated maternal serum α-fetoprotein should be investigated further with a level 3 fetal ultrasound.

         • At 10 weeks of gestation, the midgut returns to the abdominal cavity, after this time point gastroschisis may be diagnosed with ultrasonography by visualization of freely floating intestine and a paraumbilical abdominal wall defect that is typically located to the right of the midline.

         • Gastroschisis may be associated with oligohydramniosis; polyhydramnios is less common and is associated with fetal bowel obstruction (atresia) or reduced bowel motility.

         • Bowel dilation is considered to be a prognostic marker for worse clinical outcome but has not been proven.

         • It may be challenging to differentiate a gastroschisis from a ruptured omphalocele prenatally.

      2. At birth, the intestines are noted to be outside the abdomen and are in varying degrees of being “matted” or thickened.

         • It is not uncommon to see these intestines to have meconium staining.

         • The ring in the abdominal wall may be excessively tight and the intestines may appear ischemic at times due to that.

         • Gastroschisis is labeled “complex” when there are additional intestinal abnormalities or ischemia and “simple” when it occurs in isolation.

         • The most common associated anomaly in gastroschisis is bowel atresia, with a reported rate of 6.9% to 28%. Gastroschisis is rarely associated with extraintestinal malformations.

   6. Diagnosis

      Gastroschisis is diagnosed clinically, as described above.

   7. Management

      1. Perinatal care

         • Advocates for cesarean delivery for fetuses with gastroschisis contend that vaginal delivery may injure the exposed bowel or increase the risk for infection. However, there is no ...