Omphalocele is the herniation of abdominal viscera at the base of the umbilical chord. The viscera are wrapped up internally by the peritoneum and externally by the amnion, being at times separated by Wharton’s jelly. The defect is central, and the umbilical chord is inserted over the membranous sac with sizes ranging from 2 to 12 cm. It has an incidence of 1/4,000 live births and still a high incidence of prematurity (33 to 52 percent) as well as of associative malformation (30 to 88 percent) (Nicolaides, 1992).
The ultrasonographic diagnosis is an easy performance over the second trimester (Table 1). However, the diagnosis happens to be more complicated because of a physiological herniation of the intestinal loops until the 12th week. Both the diagnosis and the differentiation from gastroschisis can be done at the end of gestation with difficulty by either ultrasonography or magnetic resonance. This is due to physiological reduction of amniotic fluid alongside some fetal static, often inadequate.
The most frequent associations are: cardiac anomalies (30% to 50%), skeleton anomalies, renal anomalies (40%), cleft spine and hydrocephaly (39%). A restrict in fetal growth has been detected in 20 percent of cases. Moreover, there is still an association with chromosomal anomalies especially trisomies 13 and 18, of 20 to 54 percent (Nicolaides, 1992; Isfer, 1996). In a few cases, there might be a rupture of membrane, hindering the distinction between omphalocele and gastroschisis.
Table 1: Differential diagnosis between omphalocele and gastroschisis
| || |
| Localization || Umbilical cord wrapping || To the right of umbilical cord |
| Membrane || Yes || No|
| Herniated structures || Intestines and/or liver || Mostly intestines|
| Chromosomal disorders || Frequent || Infrequent|
| Associative syndromes || Yes || No|
Gastroschisis is an evisceration to the right of the umbilical chord normally inserted. It has an incidence of 1/10,000 to 1/15,000 births. It has a heterogeneous etiology, resulting in many cases from either an accident or vascular insult in the development of the right omphalomesenteric artery, what leads to necrosis of the base of the umbilical chord. The umbilical chord remains intact, medially to the defect. The defect size varies from 2 to 5 centimeters. According to the literature studied, the frequency of associated deformities might vary from 0 to 20 percent. The most frequent associations are: rotation anomalies and intestinal atresias. There is still a small association with certain chromosomal anomalies (Isfer, 1996).
Pentalogy of Cantrell
Pentalogy of Cantrell consists of an extensive defect of the thoracoabdominal wall, which has nearly always a lethal prognosis. The defect is characterized by the association of five anomalies: omphalocele, cardiac ectopia, absence of the distal portion of the sternum, absence of the anterior diaphragm and absence of the parietal pericardium. It has a rare frequency of about 1/100,000 births. There is a common association with cardiac anomalies, such as defect of the ventricular septum, Ebstein’s anomaly, tricuspid atresia, tetralogy of Fallot, single atrium, atrioventricular canal, mitral atresia, anomaly of pulmonary circulation, single ventricle, pulmonary stenosis, pulmonary atresia, aortic stenosis, coarctation of aorta, transposition of great vessels, etc. (Sanders, 1996).