Fig. 37.1
Clinical photograph showing omphalocele. Note the location of the omphalocele in the center of the umbilical cord
Fig. 37.2
Abdominal x-ray showing omphalocele and a clinical photograph showing ruptured omphalocele
The incidence of omphalocele is variable but generally occurs in 2.5/10,000 births. Small omphaloceles on the other hand occur with a rate of 1 case in 5000 live births. Large omphaloceles occur with a rate of 1 case in 10,000 live births.
The mean size of omphalocele defect is 2.5–5 cm (4–12 cm).
Omphalocele is classified into two types: minor and major.
Minor omphalocele: There is protrusion of a small portion of the intestine only and the size of the defect is < 5 cm in diameter.
Major omphalocele: There is protrusion of the intestines, liver, and other organs and the diameter of the defect is > 5 cm.
The omphalocele sac is ruptured in 10–20 % of cases. This may occur in utero or during delivery (Fig. 37.2b).
Etiology
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The exact etiology of omphalocele is not known.
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Various theories have been postulated; these include:
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Failure of the bowel to return into the abdomen by 10–12 weeks
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Failure of lateral mesodermal body folds to migrate centrally
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Persistence of the body stalk beyond 12 weeks’ gestation
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A defect in the development of the muscles of the abdominal wall.
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Diagnosis
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Omphalocele is usually detected antenatally during routine ultrasonographic evaluation.
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An omphalocele is diagnosed when an anterior midline abdominal mass is demonstrated on fetal ultrasonic evaluation.
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The mass consists of abdominal contents that have herniated through a midline central defect at the base of the umbilical cord insertion. The mass usually has a smooth surface and contains abdominal viscera, usually the liver, intestines, and stomach.
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Diagnostic amniocentesis is indicated when an omphalocele is demonstrated on antenatal ultrasound evaluation. This is to detect associated chromosomal abnormalities.
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The finding of an omphalocele should prompt a detailed ultrasonographic evaluation to detect associated anomalies.
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Fetal echocardiography and karyotyping should also be performed.
Associated Anomalies
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Omphaloceles are associated with other anomalies in 70−80 % of the cases.
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Fig. 37.3Clinical photograph showing ruptured omphalocele with ruptured Meckel’s diverticulum
Fig. 37.4Plain abdominal x-ray showing features of intestinal obstruction in a patient with omphalocele (a) and a clinical photograph showing intestinal atresia in a patient with omphalocele (b)
Fig. 37.5Plain x-ray showing skeletal malformations in a patient with omphalocele-
Congenital heart disease (25 %): Most commonly ventricular septal defect, atrial septal defect, and tetralogy of Fallot.
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