Omphalocele (exomphalos): a birth defect of the abdominal wall

In early pregnancy the intestine develops inside the umbilical cord and usually moves into the abdomen a few weeks later. Great Ormond Street Hospital explains that in exomphalos the intestines, and sometimes organs such as the liver, stay inside the cord but outside the abdomen. The Scottish neonatal surgery network describes it as a weakness of the abdominal wall where the umbilical cord joins it, with the contents held in a loose sac around the cord. Because the contents lie outside, the abdominal cavity often does not develop properly and may stay small.

Omphalocele and exomphalos are two names for the same condition; the UK children's hospitals cited here mostly say exomphalos. Gastroschisis is a different abdominal wall defect and has its own page.

GOSH says it is not known what causes exomphalos. Royal Manchester Children's Hospital says it is not caused by anything the parents did or did not do in pregnancy, can sometimes be associated with conditions such as Beckwith-Wiedemann syndrome or trisomies, is not inherited, and that any future pregnancy is not at an increased risk.

Estimates of how common it is differ between sources. The Scottish network says it occurs in about 1 in 4,000 pregnancies, Manchester says around 1 in 8,000 babies, and GOSH says around two in every 5,000 children born each year. This difference is worth knowing about if you read several leaflets.

Manchester says exomphalos is usually diagnosed during a routine antenatal scan, and occasionally a small one is found after birth. If it is found in pregnancy, families are offered antenatal care with a specialist team, regular checks that the baby is growing, tests for associated genetic conditions and an appointment with a neonatal surgeon and neonatologist. GOSH says early diagnosis gives time for discussions and planning for when and where to give birth.

GOSH says that generally babies are born vaginally, although some, especially those with a very large exomphalos, may need a caesarean section. Manchester says it is likely a baby will be born by caesarean and that a planned delivery is offered at a specialist centre, and that earlier delivery may be needed if the fetal medicine team detect problems.

Hospitals classify exomphalos by size and contents. GOSH uses a cut-off of 4 cm; Manchester uses 5 cm. Either way, minor exomphalos has a smaller opening and contains only bowel, and major exomphalos has a larger opening and/or contains the liver.

GOSH says exomphalos is a serious condition that needs prompt treatment soon after birth, with babies usually transferred to a specialist centre within a few hours if born elsewhere. If the covering membrane is intact the baby is kept warm and hydrated until transfer.

For a small exomphalos, GOSH says the surgeon replaces the contents inside the abdomen and closes the base of the cord, usually in one operation soon after transfer. Manchester adds that for minor exomphalos the sac is removed, the bowel is pushed back in, and the opening in the abdominal wall is closed, normally within the first few days of life, with recovery in neonatal intensive care and feeding within the first few days.

For larger or liver-containing defects, there may not be enough room in a newborn's abdomen. GOSH says doctors may place a silo or pouch over the intestines which is closed over days to weeks, then close the skin and muscles in a second operation. Manchester says that for major exomphalos it may be better to wait until the baby is larger, protecting the sac with special dressings until skin grows over it, with surgery months or even years later while the baby is at home.

GOSH explains that bowel function can take a while to start after the operation, so children may need to be fed intravenously with total parenteral nutrition (TPN) before milk is gradually introduced through a tube and then by breast or bottle. Some babies have breathing problems that need longer support. Babies go home or return to their local hospital once feeding properly and gaining weight, and may have a contrast scan to check the position of the intestines.

GOSH says the outlook depends on the size of the defect and any other problems, and that many children grow up to live normal lives. Some need TPN for longer to gain weight, may seem smaller than other children of the same age for the first few years, and the majority catch up. There is a very small chance that the intestines do not absorb nutrients properly, called intestinal failure, which needs long-term TPN.

Manchester says that after surgery most babies with exomphalos alone do not have serious ongoing problems, whereas babies with associated genetic conditions can have problems related to those conditions and need ongoing medical care. GOSH adds that children who have had a repair may develop hernias in the years afterwards because the abdomen has fewer muscles than usual, and that any new bulge in the abdomen should be mentioned to a doctor.

GOSH suggests that if the child is unwell after discharge, they should be taken to a local hospital, where doctors can discuss concerns with the specialist team. Follow-up arrangements, including health visitor or community paediatric nurse visits, are normally explained before discharge.