An omphalocele is a defect of the abdominal wall at the belly button through which abdominal contents protrude. The abdominal contents are covered by a “sac”. This problem is thought to start in the third week of development when the intestines are originally outside of the abdomen but do not completely re-enter the abdomen as in normal development. Babies born with omphaloceles often have multiple problems with other organs including the diaphragm, sternum, heart, bladder, rectum and spinal cord.
Omphaloceles occur in approximately 1 in 5000 live births and occur more frequently in boys than girls. Many children born with omphaloceles are premature.
When the omphalocele is located below the umbilicus (belly button) it is associated with a lower midline syndrome. This can include opening of the pelvic organs (bladder, rectum, uterus) outside of the abdomen with absence and lack of development of the colon, vagina, and anus. Children can also suffer from problems with the spinal cord and lower backbone.
An omphalocele above the umbilicus may be part of a syndrome called Cantrell’s pentalogy which includes an omphalocele, a hole in the diaphragm, an opening in the sternum, heart defects and occasionally a heart located outside of the chest.
The defect of the omphalocele may be between 1 to 4 inches in diameter. Smaller defects have better results and are easier to close. This may represent only a herniation of the umbilical cord and only contain small intestine. A large omphalocele may contain multiple intraabdominal contents including small intestine, liver, large intestine and stomach within the sac.
The diagnosis of an omphalocele may be made by ultrasound prior to birth. Early detection of the omphalocele allows for counseling, delivery planning and referral to a high-risk delivery center supported by a neonatal intenstive care unit and a pediatric surgeon. If the omphalocele defect is large, a cesarian section is often recommended, but with smaller defects, cesarian delivery has little advantage over vaginal delivery. Amniocentesis, or sampling of fluid surrounding the fetus, may also aid in the diagnosis of omphalocele.
At birth, newborns with omphalocele are treated by placing a tube through the mouth into the stomach to remove any swallowed air and prevent distension of the intestines. The intact omphalocele sac is kept covered and the infant kept in a heated environment. Intravenous fluids are given.
Approximately 10% of patients have a ruptured omphalocele sac which causes problems with fluid losses. These patients require more intravenous fluids and antibiotics.
The abdominal contents are covered by a sac, allowing multiple options available for management. Each patient’s case is unique and must be evaluated individually. Small defects can be managed by closing the muscle and the skin of the abdominal wall. Medium-sized defects are managed by careful removal of the sac with closure of the umbilical artery and vein and top of the bladder (urachus) going to the umbilical cord. The abdominal contents are placed into the abdomen. In patients with large omphaloceles and small abdomens, the abdominal wall cannot be closed right away. If the muscle cannot be brought together, the skin may be closed alone, leaving a hole in the muscle layer which can be closed at a later date.
If the omphalocele is very large, a staged abdominal wall closure is sometimes used with a silo to temporarily hold the abdominal organs. The sac contents may be reduced into the abdomen gradually over 3-10 days under sterile technique in the neonatal intensive care unit. The infant is returned to the operating room to remove the silo and close the muscle and skin.
In cases of sac rupture, the remaining sac and its contents may be covered by a biologic dressing.
Since omphaloceles often occur in conjunction with other fetal anomalies, treatment of the omphalocele may be delayed in order to take care of the more acute issues such as heart or lung problems. In some cases, antibiotic dressings or ointments are placed on the sac which allows skin to grow over the omphalocele. The omphalocele is then wrapped with an occlusive dressing in order to aid in reducing the sac contents.
After closing an omphalocele by an operation, infants continue have a risk of developing complications. Infection may occur. Some infants with omphalocele may have gastroesophageal reflux as a result of the increase in abdominal pressure with repair of the omphalocele. In few patients, an antireflux operation may be necessary.
The overall survival of infants with omphalocele depends on a variety of factors. These include if the size of the defect, whether an infant is premature, if the sac ruptures, and other associated abnormalities or chromosomal problems. Overall mortality rates range from 25-60% from various reports.