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Omphalocele

diagram of an omphalocele Click To Enlarge

diagram of
an omphalocele
Click To Enlarge

What is an omphalocele?

An omphalocele is an abdominal wall defect characterized by an absence of the abdominal muscles, fascia and the skin in the central abdomen. The size of the defect or "hole" is variable, with a spectrum from small to giant. As a result of the defect, some of the abdominal contents which may include the bowel, stomach and the liver remain outside the body protected by a membranous sac. The umbilical cord is inserted through the outside of this sac. The defect occurs between the 3rd and 4th week of gestation during which time there are 3 areas of infolding occurring simultaneously. A disruption in any one of these areas results in an omphalocele with its own unique anatomic features.

The incidence of omphalocele is approximately 1 in every 5,000 births and is more common in boys than girls. It is often linked to maternal age greater than 35 years. An omphalocele is associated with other defects in greater than 50% of cases. Heart defects are present in approximately 30% of cases. In addition, chromosomal abnormalities are present in as many as 30% of cases.

What testing is recommended during the pregnancy?

Serial ultrasounds will monitor the baby's growth and the defect. The protective sac can tear in about 10% of the cases which would expose the contents to the amniotic fluid and can cause damage to the bowel.

A fetal echocardiogram is recommended for all babies with this condition.

An amniocentesis is recommended, given the high incidence of chromosomal abnormalities. In cases of giant omphalocele, a fetal MRI may be performed to evaluate lung volumes.

Are there special considerations planned for the delivery?

The delivery should be planned at a hospital that is prepared for high-risk deliveries, including a neonatal intensive care and pediatric surgical team. Obstetrical, neonatal and pediatric surgical interventions can be coordinated in this setting. There is a slightly higher risk for preterm labor associated with an omphalocele.

Commonly, a Cesarean section is required for the delivery of an infant with a giant omphalocele or those with a defect greater than 5 cm containing liver to avoid dystocia. Each birth plan is based on the individual situation.

Is there fetal treatment for an omphalocele?

There is no fetal treatment for an omphalocele.

What is the treatment for an omphalocele?

There are many surgical options for treating an omphalocele. There are two problems that need to be addressed: closure of the abdominal wall defect and decreased abdominal domain. Small omphaloceles may be closed primarily with one surgical procedure. Medium sized omphaloceles may require a stages procedure and possibly a patch closure. Large and giant omphaloceles often have associated pulmonary hypoplasia and require a thoughtful surgical strategy. If babies have severe pulmonary hypoplasia, they may require prolonged mechanical ventilation. Initial treatment may consist of application of antibacterial ointment to the sac and circumferential wrapping to gently reduce abdominal contents and enlarge the abdominal domain. These babies are often discharged from the hospital and parents continue wrapping the omphalocele while the sac epithelializes (forms a skin-type coating). These infants are repaired electively when there is sufficient abdominal domain. This strategy may avoid multiple operations and a prolonged initial hospitalization.

Are there other health problems that are more common among babies with an omphalocele?

Babies diagnosed with an omphalocele may have other health issues involving the heart, bowel, kidneys, or the central nervous system. Imaging studies are repeated after birth to exclude other anomalies.

However, even babies with an isolated omphalocele may have long-term health issues. Babies with giant omphaloceles generally have more severe problems. Most infants will have some degree of feeding difficulties. This is largely due to prolonged ventilatory needs and a lack of positive oral stimulation, which results in disorganization of the muscles used to suck and swallow. A feeding specialist can assess the baby and develop a program to correct the problem. In addition, some babies have difficulty tolerating formula, and have trouble gaining weight.

Some babies will develop gastroesophageal reflux after the repair. It is often managed with medication, but may require an additional surgical procedure. A small group of infants with a giant omphalocele may have underlying pulmonary hypoplasia (under-developed lungs). These babies may need prolonged ventilator support.

Babies that require an extensive stay in the neonatal intensive care are often delayed in their motor skills. An infant development specialist will evaluate the baby when he can tolerate activity. The goal is to create plan of exercises and experiences to assist the baby in meeting his developmental goals.

Can this happen again with another pregnancy?

The risk of an omphalocele occurring in another pregnancy is related to the underlying cause. If a chromosome abnormality or genetic syndrome is present, the recurrence risk is dependent on the inheritance pattern of the underlying cause. Prenatal diagnostic testing may be available. If nonsyndromic (isolated), omphalocele is generally thought to be a sporadic event without a significant recurrence risk. Your doctor and a genetic counselor will review the risk in your family.