Gastrointestinal Tract | Abdominal wall defect - Omphalocele
Omphalocele is a rare defect of the abdominal wall whereby the baby’s bowel, liver and abdominal organs are contained in a sac that protrudes outside the abdomen. Babies can be carried to full term and their mode of delivery depends on the size of the omphalocele. Once the baby is delivered, surgery is required to repair the defect.
- In cases of omphalocele, the babies’ abdominal organs protrude outside the abdomen, into the base of the umbilical cord.
- Omphaloceles can usually be detected by ultrasound from approximately 12 weeks onwards.
- The baby will need to be delivered in hospital and the mode of delivery (vaginal vs caesarean section) will be determined by the size of the omphalocoele. Larger lesions will usually be delivered by caesarean section.
- Overall survival is approximately 80%.
Omphalocele occurs in approximately 1 in 5,000 live births.
The diagnosis is made by ultrasound in the second trimester of pregnancy.
Omphaloceles are different from gastroschisis. The herniated organs (outside the abdomen) are covered by the omphalocele sac, a thin, clear membrane (unless it has ruptured). Omphaloceles tend to occur in older mothers, as opposed to gastroschisis, which often affects younger mothers.
Recurrence rate is less than 1%, unless due to a chromosomal cause. Most omphaloceles are sporadic.
Once the condition is diagnosed, care includes a detailed ultrasound, fetal echocardiography, and genetic counselling and testing. Some fetuses (approximately 40%) with an omphalocele will have associated chromosomal, genetic or cardiac conditions. All patients are seen in a joint clinic at Mount Sinai Hospital by maternal-fetal medicine, neonatal and paediatric surgical staff.
At birth, the omphalocele is wrapped with a sterile dressing. Stabilization of the baby is a priority, especially respiratory support and initial resuscitation as necessary.
Surgery can be offered after birth as a primary repair (one surgery) for smaller lesions or as a staged repair (multiple surgeries) for larger lesions. A staged repair is done in multiple steps whereby the abdominal organs are slowly replaced back into the abdomen with the aid of a mesh, before closing the defect surgically once all organs have been replaced into the abdomen.
However, it may also be delayed for several months depending on the overall health of the baby, its respiratory status and growth, size and degree of liver herniation. In extremely large omphaloceles, the membrane may be painted and converted into a kind of skin, to facilitate repair of the abdominal wall. When all the organs can be replaced in the abdomen, the opening is closed.
The size of the omphalocele will largely determine the course and outcomes after birth. Babies without associated defects generally do the best. However, those with associated anomalies (40-50%), such as brain, spine, heart, intestinal, renal defects, or chromosomal abnormalities or genetic syndromes have a poorer prognosis. If the liver is herniated, the abdomen and lungs are usually smaller, thus affecting surgical treatment and post-natal complications. Pulmonary hypoplasia (underdevelopment of the lungs) can not only cause respiratory difficulties for the newborn, but can also affect function of the heart, feeding ability and overall growth and development.