OMPHALOCELE GASTROSCHISIS
Category: Pediatric Surgery
Abstract : Omphalocele and Gastroschisis : The three most common abdominal wall defect in newborns are umbilical hernia, gastroschisis and omphalocele. Referral to tertiary centers with available neonatal intensive care is necessary in prenatally diagnosed cases. Changing the route of delivery does not affect outcome for either defect. Omphalocele has a high incidence of associated anomalies (cardiac, neurog
Omphalocele and Gastroschisis : The three most common abdominal wall defect in newborns are umbilical hernia, gastroschisis and omphalocele. Referral to tertiary centers with available neonatal intensive care is necessary in prenatally diagnosed cases. Changing the route of delivery does not affect outcome for either defect.
Omphalocele has a high incidence of associated anomalies (cardiac, neurogenic, genitourinary, skeletal, chromosomal syndromes) that are the cornerstones of mortality. Detailed search for associated anomalies, fetal echocardiogram and karyotyping should be performed always. Cesarean section is justified in large omphaloceles (> 5 cm) to avoid liver damage, sac rupture and dystocia.
Gastroschisis prenatal US appearance depends on gestational age and condition of extruded bowel. Fetal karyotyping testing is less important. Intestinal atresia complicates the defect, the result of an intrauterine vascular accident. Intestinal obstruction due to atresia or luminal constriction may cause polyhydramnios, fetal growth retardation and preterm labor, findings that can be monitored with serial US. No benefit has been found in recommending routine c-section for most cases of gastroschisis. Preterm deliveries by c-section have been found to prevent bowel damage in fetus with progressive bowel dilatation and thickening, a finding that has not been corroborated by others. Abnormal US appearance of fetal bowel is associated with more bowel edema, longer operative time and a higher incidence of postoperative complications. Omphalocele is a milder form of primary abdominoschisis
since during the embryonic folding process the outgrowth at the umbilical ring is insufficient (shortage in
apoptotic cell death). Bowel and/or viscera remains in the umbilical cord causing a large abdominal wall defect.
Defect may have liver, spleen, stomach, and bowel in the sac while the abdominal cavity remains
underdeveloped in size. The sac is composed of chorium, Wharton's jelly and peritoneum. The defect is
centrally localized and measures 4-10 cm in diameter. A small defect of less than 2 cm with bowel inside is referred as a hernia of the umbilical cord. There is a high incidence (30-60%)of associated anomalies in patients with omphalocele. Epigastric localized omphalocele are associated with sternal and intracardiac defects (i.e., Pentalogy of Cantrell), and hypogastric omphalocele have a high association with genito-urinary defects (i.e., Cloacal Exstrophy). All have malrotation. Cardiac, neurogenic, genitourinary, skeletal and chromosomal changes and syndromes are the cornerstones of mortality. Antenatal diagnosis may affect management by stimulating search for associated anomalies and changing the site, mode or timing of delivery.
Cesarean section is warranted in large omphaloceles to avoid liver damage and dystocia. After initial
stabilization management requires consideration of the size of defect, prematurity and associated anomalies. Primary closure with correction of the malrotation should be attempted whenever possible. If this is not possible, then a plastic mesh/silastic chimney is fashioned around the defect to cover the intestinal contents and the contents slowly reduced over 5-14 days. Antibiotics and nutritional support are mandatory. Manage control centers around sepsis, respiratory status, liver and bowel dysfunction from increased intraabdominal pressure.
The exact embryology of gastroschisis is unclear. The defect is always to the right of the midline with
a normally attached umbilical cord. Theories include failure of the right lateral somatopleure to form properly, intrauterine rupture and intrauterine vascular accident leading to ischemia of the right developing rectus. Associated anomalies are rare, with an 11% incidence of atresia. Treatment is identical to omphalocele except more urgent to avoid problems with the exposed bowel (dehydration and hypothermia). More than 90% babies survived. Prenatal diagnosis has brought a controversy toward optimal mode of delivery (Cesarean vs vaginal). The appearance of the bowel is edematous, matted and foreshortened due to exposure to amniotic fluid, and the constrictive vascular effects of a small defect.
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