Gastroschisis and Omphalocele
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Direct answer
Gastroschisis and omphalocele are congenital abdominal wall defects through which abdominal contents protrude at birth. Gastroschisis is a full-thickness defect to the right of the umbilicus, with bowel exposed and no covering membrane, and it usually occurs in otherwise normal babies. Omphalocele is a central defect at the umbilical ring, with organs enclosed in a membranous sac, and it is frequently linked to chromosomal anomalies and other malformations.
What you must remember
- Gastroschisis: a full-thickness defect usually to the right of the umbilicus, with loops of bowel lying free in the amniotic fluid and no sac.
- Omphalocele: a central defect at the umbilical ring covered by amnion and peritoneum, and the liver may lie inside the sac.
- Associated anomalies: omphalocele is linked to trisomy 13, 18 and 21, cardiac defects and Beckwith-Wiedemann syndrome, whereas gastroschisis is usually an isolated lesion.
- Bowel damage: exposed bowel in gastroschisis may become oedematous, matted or shortened, and intestinal atresia is a recognised complication.
- Antenatal clue: raised maternal serum alpha-fetoprotein and fetal ultrasonography usually flag both defects before birth.
- Initial care: cover the exposed viscera with a sterile warm wrap, pass an orogastric tube and start fluids and antibiotics.
- Prognosis: gastroschisis generally has a good outcome, while omphalocele survival depends mainly on the associated anomalies.
Starting care in the first hours of life
Both defects need urgent protection of the abdominal contents, but the approach differs in detail. Early care lowers the risk of infection, fluid loss and hypothermia, and it prepares the baby for surgical repair.
- Delivery planning: The baby is delivered at a centre with paediatric surgical cover, and the route of delivery is decided on obstetric grounds, since vaginal delivery is usually acceptable in gastroschisis.
- Covering the viscera: The exposed bowel or sac is wrapped in a warm, moist, sterile covering, and the baby is nursed under a radiant warmer to prevent heat loss.
- Decompression: An orogastric tube is passed and kept on gentle suction to vent the stomach and reduce the risk of aspiration.
- Fluids and antibiotics: Isotonic fluids replace losses from the exposed bowel, and broad-spectrum antibiotics are started. In Beckwith-Wiedemann syndrome, blood glucose must be watched closely.
- Gastroschisis closure: Primary closure is attempted when the abdominal cavity can accommodate the bowel. If it cannot, a preformed silo is used for gradual reduction over several days.
- Omphalocele repair: Small sacs can be closed primarily, while large sacs are managed with staged reduction to avoid sudden raised intra-abdominal pressure.
- Monitoring after closure: Ventilation, renal output and venous return are watched closely, because tight abdominal closure can compromise all three.
Where the exam tries to catch you
Questions usually test whether the defect is central or lateral, and whether a syndrome is expected alongside it.
- Trap: calling any abdominal wall defect with bowel outside an omphalocele. Correct: gastroschisis lies lateral to the umbilicus without a membrane, whereas omphalocele is central and usually covered by a sac.
- Trap: treating gastroschisis and omphalocele as equally likely to carry chromosomal anomalies. Correct: chromosomal and cardiac evaluation matters most for omphalocele, because gastroschisis is usually isolated.
- Trap: assuming that a large omphalocele containing the liver is always fatal. Correct: outcome depends on the size of the defect and the associated anomalies, and staged repair has improved survival.
Frequently asked questions
Which abdominal wall defect is most strongly linked to chromosomal anomalies?
Omphalocele is most strongly linked to chromosomal anomalies, including trisomy 13, trisomy 18 and trisomy 21. Gastroschisis is usually an isolated defect, so karyotype testing is not needed for it in the same way. The presence of a sac and a central defect should prompt a full search for associated malformations.
What is the main difference between gastroschisis and omphalocele on examination?
Gastroschisis shows loops of bowel lying loose outside the abdomen to the right of an intact umbilical cord, with no membrane covering them. Omphalocele shows a central defect at the base of the cord, where the sac contains bowel or liver. Recognising the membrane is the key bedside distinction.
Why does gastroschisis cause bowel damage before birth?
Gastroschisis exposes the bowel to amniotic fluid throughout pregnancy, which can lead to thickening, oedema and matting of the loops. Intestinal atresia and shortened bowel can also occur in the same babies. This is why early covering and prompt surgical planning matter.
Can gastroschisis and omphalocele be diagnosed before birth?
Yes, both defects can be detected before birth by fetal ultrasonography and by raised maternal serum alpha-fetoprotein. Ultrasonography also helps tell them apart, since omphalocele is covered by a membrane and gastroschisis is not.