Description
Omphalocele, also known as exomphalos, is a congenital anterior abdominal wall defect at the base of the umbilical cord. In omphalocele, the intestines, liver, and occasionally other organs remain outside the abdomen in a sac, covered by a thin, translucent layer of peritoneum and amnion.
Pathogenesis
Omphalocele is believed to result from a failure of the midgut to return to the abdominal cavity during the physiological herniation phase of development.
Epidemiology, Risk Factors & Associations
- The incidence of omphalocele is approximately 1 in 4000 to 7000 births.
- An increased incidence is seen with advanced maternal age.
- Omphalocele is often associated with chromosomal abnormalities (approximately 30% of cases), especially: Trisomies 13 (1-2%), 18 (10%), and 21 (less than 1%).
- It is also seen in several syndromes such as Beckwith-Wiedemann syndrome, Pentalogy of Cantrell (a rare condition characterised by defects in the diaphragm, abdominal wall, pericardium, heart and lower sternum), and OEIS (omphalocele, exstrophy, imperforate anus, spinal defects) complex.
Clinical Features
The key clinical feature is a central abdominal wall defect at the base of the umbilical cord with herniated organs covered by a translucent sac. The size of the omphalocele can range from small, with only a portion of the intestines involved, to large, with most of the abdominal organs, including the liver, outside the abdomen.
Complications
Complications may include rupture of the omphalocele sac, infection, organ damage, pulmonary hypoplasia, and other congenital anomalies or syndromes. There is also a risk of long-term complications such as gastroesophageal reflux disease and malabsorption.
Subtypes
Omphalocele can be classified based on the size (small or giant) and the organs involved (liver-containing or liver-free).
Pathological Features
Histopathology
Examination of the sac can show a lining of amniotic epithelium and underlying connective tissue, with the absence of musculature confirming the diagnosis of omphalocele.
Radiological Features
General Features
- Location: Central abdominal wall defect at the base of the umbilical cord.
- Morphology: Herniated organs covered by a sac.
- Associated Findings: Other congenital anomalies may be identified.
US
- Can usually identify omphalocele by the second trimester of pregnancy.
- Shows a central abdominal wall defect with herniated abdominal organs covered by a membrane.
MRI
- Useful for defining the anatomy and assessing the size of the defect and extent of organ involvement.
- Can also help to identify associated anomalies.
Grading and Staging
There is no specific grading or staging system for omphalocele.
Differential Diagnosis
- Gastroschisis: A congenital defect usually to the right of the umbilicus with herniated abdominal organs that are not covered by a sac. There are no associated chromosomal anomalies.
Management
- Management is multidisciplinary, involving neonatology, paediatric surgery, and genetics consultation. The approach to management is often based on the size of the omphalocele and the presence of associated anomalies.
- The mainstay of treatment is surgical, which may be a primary closure for small defects or a staged closure for large defects.
- Preoperative care includes protecting the sac, maintaining thermoregulation, and providing supportive care.