1. Diagnostic Imaging Test
An omphalocele is a defect in the abdominal wall that allows the internal organs to protrude into the umbilical cord, sometimes covered by a membranous sac. If your child has an omphalocele, it will probably be diagnosed during a prenatal ultrasound. This is particularly true if the omphalocele is large in size and several organs are bulging out of your child's belly. Because fetal sonogram technology has advanced so much in recent years, your doctor will probably be able to get a very good look at your child's omphalocele. Depending on the particulars of your case, your doctor may order an MRI (magnetic resonance imaging) to see the omphalocele in more detail and examine other systems in your child's body. Specifically, an MRI may be used to see your baby's heart to look for deformities there. As many as 47 percent of babies with omphaloceles also have cardiac defects.
2. Prenatal Tests to Identify Other Conditions
As many as 70 percent of children born with omphaloceles also have other medical conditions, such as chromosomal abnormalities and heart malformations. Before your baby is born, your doctor will offer you the opportunity to screen for these defects as well. A blood test called an MSAFP, maternal serum alpha-fetoprotein test, is a common test that is usually done between 15 and 20 weeks. It tests for a variety of congenital conditions and may be the first indication of an omphalocele if it is done before the omphalocele is discovered via ultrasound. This test can also indicate whether other genetic conditions are a concern or not.
If your child is diagnosed with an omphalocele in the womb, you will probably be asked whether you want to have an amniocentesis to test for additional birth defects. An amniocentesis tests the amniotic fluid around the baby for abnormalities. This test is usually recommended if the MSAFP reveals elevated AFP levels, as it can provide more concrete information about genetic abnormalities. Whether or not you want to get an amniocentesis done, however, is a personal choice. Unlike ultrasounds and blood tests, an amniocentesis does pose a threat to the health of your baby. As many as one in 200 tests result in a miscarriage.
3. Differential Diagnoses
It can be difficult for doctors to identify an omphalocele positively in early pregnancy because there are several other conditions that look similar on an ultrasound. If your baby has a physiologic midgut herniation, that can be misdiagnosed as an omphalocele initially. MSAFP testing and amniocentesis can help to differentiate between these two conditions. Gastroschisis is a condition similar to an omphalocele in which the internal organs protrude from the abdomen but not the umbilicus. This usually looks very different on the ultrasound, unless the sack that surrounds the omphalocele breaks. Babies with gastroschisis do not usually have other chromosomal problems, however.
