Exomphalos is a birth anomaly where the abdominal organs, such as the intestines and sometimes the liver, protrude outside the baby’s body at the base of the umbilical cord. This condition is classified as an abdominal wall defect, occurring early in fetal development when the abdominal wall fails to close completely. The organs that have moved outside are contained within a protective, translucent sac, which is formed by the peritoneum and amnion. Although rare, this congenital condition requires specialized care and surgical intervention soon after birth.
What is Exomphalos?
Exomphalos occurs due to a failure in embryonic development. Normally, the intestines temporarily move into the umbilical cord between the sixth and tenth weeks of gestation, returning to the abdominal cavity by the twelfth week. In exomphalos, they remain outside. The defect is located at the center of the abdomen, through the umbilical ring, and its size determines the condition’s classification.
The condition is divided into two types based on the size of the defect and the organs involved. Exomphalos minor typically involves a small opening (less than four or five centimeters) and contains only the intestine and omentum. Exomphalos major, or giant exomphalos, is characterized by a larger opening (greater than four or five centimeters) and often includes the liver in addition to the bowel. The presence of the liver in the sac is a factor in treatment planning, as it indicates a smaller fetal abdominal cavity volume.
Exomphalos must be distinguished from gastroschisis, another abdominal wall defect. The defining feature of exomphalos is the protective sac covering the herniated organs, continuous with the umbilical cord. In gastroschisis, the defect is typically smaller, located to the right of the umbilical cord, and the bowel loops are exposed directly to the amniotic fluid without a membrane covering. While the sac protects the organs from amniotic fluid damage, exomphalos is more commonly associated with other congenital abnormalities.
Causes, Risk Factors, and Associated Conditions
The cause of exomphalos is not fully understood, but it is believed to result from a combination of genetic and environmental factors affecting early fetal development. Advanced maternal age has been noted as a potential risk factor associated with the condition.
A significant number of exomphalos cases are linked to other congenital abnormalities, which influence the overall prognosis. Associated defects are observed in up to 72% of neonates. These comorbidities include structural defects in other organ systems, most notably cardiac anomalies, which are present in 30% to 50% of cases.
Chromosomal abnormalities are commonly found, occurring in about 15% of live-born infants. The most frequently observed conditions are Trisomy 18 (Edwards Syndrome) and Trisomy 13 (Patau Syndrome). Exomphalos is also a characteristic feature of several genetic syndromes, including Beckwith-Wiedemann Syndrome (BWS), a growth disorder linked to approximately 10% of cases. The long-term outcome is often more dependent on the severity of these associated conditions than on the size of the abdominal wall defect.
Diagnosis and Immediate Postnatal Stabilization
Exomphalos is most frequently detected during routine prenatal care, usually via an ultrasound scan performed around the 12-week or 20-week mark of the pregnancy. The ultrasound allows specialists to visualize the midline defect and the membrane-covered organs protruding from the fetal abdomen. If the defect is diagnosed early, a detailed ultrasound examination, including a fetal echocardiogram, is performed to check for associated heart defects and other structural anomalies.
Invasive testing, such as chorionic villus sampling or amniocentesis, may be offered to determine if a chromosomal anomaly is present for parental counseling and planning. Delivery is typically planned for around 38 weeks of gestation at a specialized hospital equipped with a neonatal intensive care unit and pediatric surgery team. The mode of delivery is usually vaginal, unless the exomphalos is giant or contains a large portion of the liver, which may necessitate a Caesarean section to avoid sac rupture.
Immediate care focuses on stabilizing the infant and protecting the sac and its contents. The sac must be protected with a non-adherent dressing and an occlusive covering (such as a plastic bag or wrap) to minimize fluid loss and prevent infection. Maintaining the baby’s temperature is also a priority, as heat can be rapidly lost from the exposed viscera. A nasogastric tube is placed to continuously drain the stomach, decompress the bowel, and prevent aspiration.
Surgical Management and Long-Term Prognosis
The definitive management of exomphalos is surgical, but the approach depends heavily on the size of the defect and the presence of any other anomalies. For exomphalos minor, which involves a small defect and only contains bowel, a primary closure is often performed soon after birth. This single operation involves gently placing the organs back into the abdomen and surgically closing the abdominal wall layers.
For exomphalos major, the large volume of herniated organs, especially the liver, means the abdominal cavity is too small to accommodate everything at once without causing respiratory or circulatory compromise. In these cases, a staged repair is necessary. This can involve a temporary protective covering called a silo, which is a pouch or mesh attached to the defect edges. The silo holds the viscera outside while allowing gravity to slowly reduce the contents over several days to weeks.
An alternative approach for giant exomphalos is conservative management, where the sac is treated with a topical antimicrobial agent and dressings. This method encourages the sac’s membrane to toughen and epithelialization to occur, creating a large hernia covered by skin. The definitive repair of this ventral hernia is performed months or years later, once the child has grown and the abdominal cavity has expanded sufficiently. Following repair, the infant may require total parenteral nutrition (TPN) until bowel function returns to normal.
The long-term prognosis is varied, but for those with an isolated defect and no associated conditions, the survival rate is high, often exceeding 90%. The main determinants of a poorer outcome are severe chromosomal anomalies, such as Trisomy 18, and significant heart defects. Even after successful repair, some children may experience complications like gastrointestinal issues or the later development of a hernia at the repair site. However, most children who survive the neonatal period lead normal lives, though they may require long-term follow-up care.