Gastroschisis is the herniation of the intestines through an opening in the abdominal wall. It is a congenital defect that can be detected prenatally using imaging technologies, mainly ultrasonography. In most cases, the surgical intervention is performed on the first day after birth. In complicated cases, the repair is done in stages using a pouch (a silo) to contain extruded bowels, and wall closure is achieved over one or two weeks.
There are several types of congenital abdominal wall defects that result in the extrusion of bowels and other organs, with gastroschisis being the most frequent. Gastroschisis and omphalocele are both examples of an abnormal opening in the abdominal wall that results in the bowels protruding out of the abdomen into the amniotic sac, but they are different, well-defined conditions. Omphalocele is associated with chromosomal aberrations and malformations in several other organs; in this condition, a membrane surrounds the externalized intestines. Gastroschisis does not tend to be associated with chromosomal abnormalities or problems with other organs, and there is no membranous covering on the extruded bowels.
Gastroschisis is a relatively common congenital defect affecting about 1 in 2000 births . There has been a recent increase in its prevalence. The opening in the abdominal wall is mainly to the right of the umbilical cord. The herniated organ is most often the small bowel, which is not rotated. The bowels are exposed to the amniotic fluid, which may lead to a decrease in its functional capacity. Exposure to the amniotic fluid also results in increased levels of maternal alpha-fetoprotein, the detection of which may lead to the discovery of gastroschisis. Other clues for gastroschisis are fetal growth retardation and polyhydramnios . Gastroschisis may also be discovered by chance during a second-trimester sonography. Fetal abdominal circumference is low in gastroschisis, making the assessment of the age of the fetus difficult . Very low abdominal circumference and an abnormal gastric bubble are among the indicators for increased perinatal death or serious bowel injuries such as necrotizing enterocolitis . In one study, babies with gastroschisis delivered between 35 and 37 gestational weeks were found to have the fewest perinatal complications .
The most important imaging tool for the diagnosis of gastroschisis is antenatal ultrasonography, which is the cornerstone of imaging in pregnancy because it is noninvasive and not associated with exposure to radiation. Radiography is only used in the postnatal period and, for the same reason, the application of computerized tomography (CT) is inappropriate antenatally.
Ultrasonography allows for the detection of the location and features of the abdominal faults and differentiates amongst the different types of abdominal anomalies . In the case of gastroschisis, the herniated bowels have no membranous covering; thus, the image shows free-floating bowel loops with irregular shapes. Although the small bowel is most frequently extruded, other organs may also be found floating in the amniotic fluid, such as the large intestines, stomach, urinary bladder, uterus, fallopian tubes, and testes. The extruded intestines may be inflamed and swollen.
Various studies have examined the value of fetal intestinal and other features detected by ultrasonography in predicting later complications. In addition to the signs mentioned above in connection with adverse outcomes, several other characteristics have been studied as predictors of complications. Intra-abdominal bowel dilatation and polyhydramnios were both associated with bowel atresia . The predictive value of extra-abdominal dilatation is questionable: although one recent study found a significant association between extra-abdominal bowel dilatation and morbidity, a large percentage of patients with this type of anomaly were free from complications . Magnetic resonance imaging (MRI) is used mainly in complicated cases or where ultrasound results are equivocal.