What is an Omphalocele?
An omphalocele is a birth defect in which an infant's bowel, liver, and other abdominal organs stick out through the abdominal wall at the base of the belly button. These organs are covered by a clear sac which protects the organs. It is estimated that approximately 1 in every 4,000 to 7,000 babies born has this condition.
This birth defect occurs in utero. The abdominal cavity is formed between weeks three and four of pregnancy. If the omphalocele develops at this stage, it is very large in size. The intestines push out out from the belly into the umbilical cord between weeks six and ten. By the eleventh week, the intestines normally go back into the abdomen of the baby. A smaller omphalocele or a "hernia of the cord" develops at this stage of gestation.
The omphalocele is usually diagnosed around 20 weeks gestation. According to the Children's Hospital of Philadelphia, the following tests are performed in conjunction with diagnosis:
- Detailed level II fetal ultrasound — a noninvasive, high-resolution imaging study used to determine the amount and type of abdominal organs within the umbilical sac and possible rupture of the sac, as evidenced by free floating bowel or the liver outside of the abdomen. The possibility of other anatomic abnormalities is evaluated. Lung size can also be estimated.
- Ultrafast fetal MRI — an additional imaging technique advanced at CHOP that shows the omphalocele and the entire fetus. The MRI is used to confirm ultrasound findings and evaluate for the presence of any other anatomic abnormalities, especially central nervous system anomalies. Lung volumes are determined and compared to normal values at that gestational age (this comparison is called the observed-to-expected lung volume ratio, or O/E ratio).
- Fetal echocardiogram — an ultrasound of the fetal heart to look for heart defects. A unique collaboration with our specialized Fetal Heart Program, staffed by pediatric cardiologists with fetal expertise, ensures early diagnosis of heart defects.
The Centers for Disease Control has done research into risk factors that possibly contribute to a baby developing an omphalocele. Their findings were as follows:
- Alcohol and tobacco: Women who consumed alcohol or were heavy smokers (more than 1 pack a day) were more likely to have a baby with omphalocele.
- Certain medications: Women who used selective serotonin-reuptake inhibitors (SSRIs) during pregnancy were more likely to have a baby with an omphalocele.
- Obesity: Women who were obese or overweight before pregnancy were more likely to have a baby with an omphalocele.
Delivery of a Baby with Omphalocele
Babies with an omphalocele can be delivered vaginally or by C-section depending on the severity of the omphalocele. If the liver is contained within the sac, the baby is delivered by C-section to prevent rupture of the sac and stress on the newborn. After delivery, the omphalocele sac is wrapped in a sterile dressing. Many babies with an omphalocele have a smaller lung size; therefore, they may have increased difficulty breathing after delivery. The baby may need to be intubated after delivery to assist with their breathing.
Surgical treatment for an omphalocele occurs after birth. Each baby is different and an individualized treatment plan is developed based on the severity of the defect. If it is a smaller omphalocele, the baby can undergo a primary repair in which the abdominal organs are pushed back into the abdominal cavity and the defect is closed in one surgery.
Babies with a larger omphalocele may need to have a staged procedure performed. This requires multiple surgeries to move the abdominal organs back into the abdominal cavity. Sometimes newborns are required to wait and have their abdominal cavity grow in order to have enough room for the organs to fit. During this time period, there are special precautions taken to ensure that the abdominal sac is clean and safe.