442 Gastroschisis (Greek for belly cleft) is a congenital paraum- bilical wall defect characterized by the protrusion of the intes- tines uncovered by peritoneum. The incidence of gastroschisis is approximately 1 in 10,000 live births.
GENETICS/BASIC DEFECTS
1. Precise etiology unknown 2. Inheritance
a. Isolated occurrence in most cases b. Rare autosomal dominant inheritance 3. Possible etiologies and risk factors
a. Vascular insult
i. Association of maternal smoking and maternal cocaine use with an increased incidence of gastroschisis
ii. The association of intestinal atresia and gastroschisis
b. Vascular disruption of the right omphalomesenteric artery
c. Premature atrophy or abnormal persistence of the right umbilical vein
d. In utero rupture of a hernia of the umbilical cord e. Risk factors for gastroschisis
i. Young maternal age (<20 years of age): the most striking epidemiological association with gas- troschisis (20–25%)
ii. Primiparous mothers
iii. Socially disadvantaged mothers iv. Maternal cigarette use
v. Use of vasoactive drugs (e.g., decongestant pseudoephedrine) early in pregnancy
vi. Recreational drug use (particularly the use of more than one drug)
4. Rare syndrome association
a. Omphalocele-exstrophy-imperforate anus-spinal defects (OEIS)
b. Amniotic band syndrome c. Limb body wall complex
5. Rare association with chromosome abnormalities a. Trisomy 21
b. Trisomy 13
CLINICAL FEATURES
1. Herniation of abdominal contents
a. Through a small abdominal wall defect
i. Lateral to the insertion of the umbilical cord ii. Most often to the right side of the umbilical cord b. Without covering sac
c. The herniated viscera floating freely in the amniotic cavity
d. Rare extrusion of the liver
e. Dilatation of bowel loops due to partial lymphatic and venous obstruction when they are mechanically com- pressed against the sidewall of the defect
f. Massive dilatation of the bowel secondary to volvu- lus, atresia and ischemia
2. The incidence of associated anomalies relatively infrequent except associated gastrointestinal anomalies (10–20%) a. Intestinal stenosis/atresia, often related to:
i. Intrauterine volvulus
ii. Strangulation of the blood supply to the extruded segment of intestine at the extremely tight abdominal wall defect
b. Adhesions c. Malabsorption d. Meckel diverticulum e. Protein-loosing enteropathy
f. Midgut volvulus g. Necrosis
h. Severe short gut syndrome i. Hypoperistalsis
3. Prognosis and complications a. Oligohydramnios
i. Associated with a high incidence of intrauterine growth retardation, which occurs in up to 60% of affected fetuses
ii. Possible secondary effects of severe oligohy- dramnios
a) Pulmonary hypoplasia b) Limb compression c) Cord compression
b. Polyhydramnios probably associated with reduced bowel motility or bowel obstruction
c. Fetal distress during labor d. IUGR
e. Small for gestational age f. Prematurity
g. Sepsis
h. Bowel damage i. Cardiac anomalies
j. Non-gastointestinal associated anomalies including occasional occurrence of amyoplasia and arthrogryposis k. Problems with absorptive and motility functions
l. Intraoperative complications m. Greater than 90% survival rate
n. Higher mortality rate (50%) associated with hernia- tion of the liver
o. Rare reports of spontaneous resolution of gastroschi- sis and closure of the anterior abdominal wall defect
DIAGNOSTIC INVESTIGATIONS
1. Routine blood work
2. Chromosome analysis rarely indicated (incidence of chro- mosomal anomalies <5%)
Gastroschisis
GASTROSCHISIS 443
3. Abdominal radiography 4. Abdominal ultrasound
5. Gastrointestinal investigations to rule out gastroe- sophageal reflux, abnormal intestinal absorption and motility, and Hirschsprung disease
6. Echocardiography
GENETIC COUNSELING
1. Recurrence risk
a. Patient’s sib: not increased unless a parent is affected with an autosomal dominant disorder
b. Patient’s offspring: not increased unless the patient is affected with an autosomal dominant disorder 2. Prenatal diagnosis
a. Elevated maternal serum alpha-fetoprotein (MSAFP):
MSAFP levels are greater in gastroschisis than in omphalocele
b. Prenatal ultrasonography
i. Demonstration of a mass adjacent to the anterior ventral wall representing the herniated viscera ii. Herniation almost always exit through the right
rather than the left lower quadrant
iii. Cord vessels observed to the left of the exiting bowel
iv. Dilated bowel loops within or outside the abdomen observed when the abdominal wall defect is small
v. Possible evisceration of stomach
vi. Possible evisceration of the urinary bladder with secondary hydronephrosis
vii. Polyhydramnios associated with bowel obstruction c. Amniocentesis
i. Elevated amniotic fluid alpha-fetoprotein ii. Positive acetylcholinesterase
iii. Chromosome analysis 3. Management
a. Counseling of parents
i. Inform 5–10% incidence of fetal or neonatal death ii. Inform long-term digestion problems associated
with short gut syndrome
b. No clear evidence indicating early cesarean section improve the outcome
c. Endotracheal intubation for respiratory distress in neonates
d. Avoid hypothermia, hypovolemia, and sepsis e. Fluid and electrolyte balance to prevent metabolic
acidosis commonly observed as a result of poor per- fusion related to hypovolemia
f. Insertion of an orogastric tube i. To prevent air swallowing ii. To aspirate intestinal contents g. Parenteral antibiotics
h. Surgical repair: primary repair versus staged repair with silastic silo
i. Total parenteral nutritional support for prolonged adynamic ileus
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444 GASTROSCHISIS
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GASTROSCHISIS 445
Fig. 1. A premature neonate had herniation of gastric antrum, small intestine and colon through the gastroschisis, right of intact umbilicus.
There was malrotation of the intestine.
Fig. 2. A stillborn with gastroschisis showing herniation of abdominal contents.
