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Introduction Antenatal Postnatal West Midlands Data

Gastroschisis is the intrauterine evisceration of fetal intestine through a paraumbilical anterior abdominal wall defect, nearly always on the right side of the umbilicus. In addition to the evisceration of the intestine the stomach, bladder and gonads are often extra-abdominal. The liver does not herniate from the defect. There is no surrounding sac and so the intestines are exposed to the amniotic fluid during pregnancy. The bowel usually becomes shortened, thickened and dilated and is often matted together with adhesions.

Gastroschisis is thought to originate from a relatively late event in development since there are few associated anomalies. It may arise from an isolated vascular event involving the right side of the abdominal wall. This abnormality occurs sporadically and has a low recurrence rate. It is therefore extremely doubtful that a genetic cause is responsible for gastroschisis so the possibility of a nutritional or environmental aetiology remains. Associations with young mothers and low social class are established but not understood. Smoking has been suggested as a possible risk factor and an increased risk for gastroschisis has been described in women using recreational drugs before or in early pregnancy.

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In gastroschisis the maternal serum AFP level is elevated in approximately 75% of cases, values of 4-5 multiples of the median are common. The diagnosis is made on ultrasound by visualising the free loops of bowel that herniate through the anterior abdominal wall into the amniotic fluid. Click for picture Image

Although the risk of aneuploidy is low, a detailed ultrasound examination should be performed with early karyotyping if indicated. Cases of ruptured exomphalos have been reported and can be confused with gastroschisis.

Serial ultrasonography allows the measurement of fetal growth and intestinal assessment looking for dilatation and abnormal peristalsis. The amniotic fluid is either normal or slightly diminished unless there is associated gastrointestinal atresia when polyhydramnios may develop. Consideration should be given to fetal assessment with umbilical artery Doppler velocimetry because of the association with stillbirth.

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The choice of timing, mode and unit of delivery are controversial. There is a balance between the ultrasound findings of the bowel and indices of fetal well-being with the risks associated with preterm delivery. A vaginal delivery should be contemplated unless there is an obstetric contraindication. Immediate postnatal treatment includes resuscitation, transfer and operative reduction.

In gastroschisis, survival is around 90% and at least 80% have a single operation to repair the abdomen. The umbilicus is usually preserved. Forcing the intestines into too small an abdominal cavity can affect ventilation, vascular blood supply and renal perfusion. If this is the case a silo is fashioned and delayed closure performed after gradual reduction over 3-10 days. This is necessary if the abdomen is small particularly in the baby with intrauterine growth retardation. Patients require intravenous nutrition with normal feeding established in most cases at between 20 and 40 days but support may last for 6 or more months.

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WM Data

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© Perinatal Institute 2011