Prevalence: 1/5,000 to 1/10,000 live births. Parietal dehiscence that produces a more or less important hernia of the abdominal contents through a dilated umbilical orifice; the herniated organs are covered by a translucent avascular membrane, of the same nature as Wharton's jelly. This membrane insulates the intestinal loops from the surrounding environment and is centered by the umbilical cord. The extent of abdominal parietal dehiscence is highly variable: it can be limited to a large easily reducible umbilical hernia or, on the contrary, be large and contain small bowel, liver, spleen, bladder, stomach, gonads and sometimes even the heart (Cantrell's pentalogy). An omphalocele is associated with other congenital or chromosomal malformations in 2/3 of the cases.

The most common associated malformations are:

• other digestive malformations: malrotations, intestinal atresia and agenesis, imperforation, bile duct atresia; in small omphaloceles (diameter of the umbilical ring = 4 cm): residues of the omphalomesenteric canal and Meckel's diverticulum ;

• cardiac malformations: tetralogy of Fallot, dextrocardia, Cantrell pentalogy (epigastric omphalocele, bifid sternum,  anterior diaphragmatic hernia (Morgagni), absence of the diaphragmatic pericardium, and heart defects with cardiac ectopia and VSD);

• metabolic abnormalities: Wiedemann-Beckwith syndrome (visceral macrosomia, macroglossia, macrocephaly, neonatal hypoglycemia, polycythemia);
• genitourinary malformations: bladder exstrophy, renal abnormalities;
• craniofacial malformations: cleft lip and palate (SCHISIS association), hemangioma, ophthalmic abnormalities, meningocele, Donnai-Barrow syndrome (hypertelorism, broad fontanelle, irian coloboma, deafness, corpus callosum agenesis, mental retardation, diaphragmatic hernia and/or omphalocele, autosomal recessive transmission);
• chromosomal aberrations in 10 to 40 % of cases: trisomy 13, 15 and 18, but also 12 and 21.

Neonatal mortality is about 12 %. A factor of poor prognosis on fetal MRI is a measured pulmonary volume-to-expected pulmonary volume ration of less than 50 %: it is a sign of pulmonary hypoplasia and is predictive of a major risk of pulmonary arterial hypertension.

Parietal dehiscence is the result of an abnormality in the development of the embryonic mesoderm that does not ensure its normal tissue replacement function at the embryonic pedicle (base of the umbilical cord). Because the closure anomaly is on the middle part of the coelomic cavity, the omphalocele is referred to a "medial celosomia". The primary intestinal loop reintegrates only partially into the coelomic cavity and, at the time of birth, a variable part of the abdominal viscera is contained in a translucent sac made of Wharton's jelly and lined internally by the peritoneum. In 50 % of cases, the liver, spleen and gonads are located within the omphalocele, which is a factor of severity. When the parietal closure anomaly extends up to the sternum, it is referred to as "superior celosomia."

Giant omphalocele  (or "hepatocele") is when the pouch contains at least 75 % of the liver or when the diameter of the herniary orifice is > 5 cm: this presentation is often associated with hypoplasia of the thorax (narrow and elongated thorax) and, in about 1/3 of cases, pulmonary arterial hypertension. This makes perinatal management more complex and some of these children require chronic treatment of pulmonary arterial hypertension (NO, sildenafil etc.).

Neonatal care:

• if the sac is damaged broken: the management is similar to that of a laparoschisis (see this term)
• if the sac is intact, which is usually the case: it should be packed as quickly as possible in a sterile non-sticking protective dressing (Adaptic®, Xeroform®, Jelonet®) surrounded by swabs or a wet dressing and a supporting dressing (like Surgifix® or stretchable food film) taking care not to compress the sac. The dressing is intended to prevent bacterial contamination but also desiccation of the sac and resulting hypothermia.
• the newborn should be kept in a good hemodynamic and hydration state (150-300 mL/kg/day) and protected from infections with broad-spectrum antibioprophylaxis. Metabolic and acid-base disorder must be corrected, and diuresis should be monitored
• subsequent therapeutic management depends mainly on the size of the omphalocele and associated malformations

1. small omphaloceles (diameter of the umbilical opening ≤ 4 cm) are treated surgically as umbilical hernias with resection of the pouch, reintegration of the small bowel and primary parietal closure.
2. for large omphaloceles, the same 2 strategies for the reintegration of herniated viscera as those used for laparoschisis can be considered:

-        installing a prosthesis in silastic ("silo") in the neonatal intensive care unit to ensure a gradual reintegration of the content of the sac into the abdominal cavity (without anesthesia);

-        transfer to the operating room for trial of reduction in 1 stage or, depending on the size of the omphalocele and the hypoplasia of the abdominal cavity, the creation of a prosthesis in silastic or goretex allowing a gradual reduction (faster than in the previous case, but requiring anesthesia).

Surgical reduction is performed in the operating room under general anesthesia. It is carried out in the same way as for a laparoschisis and with the same monitoring. The main risk associated with the reduction of the hernia in a more or less hypoplastic abdominal cavity is to create excessive intraabdominal pressure that could:

• impede diaphragmatic movements (and thus ventilation);
• compromise the venous return (compression of the inferior vena cava);
• alter the kidney perfusion pressure, leading to renal failure;
• cause mesenteric ischemia.

The decision on whether or not to achieve a primary closure is based on the same principles as in the case of laparoschisis. In practice, reintegration in 1 stage is only possible for the small to moderate size omphaloceles (diameter of the parietal orifice between 4 and 6 cm or less than 3/5 of the abdominal perimeter). Giant omphaloceles must benefit from a progressive reintegration technique.

Anesthetic implications:

neonatal anesthesia; associated malformations (echocardiography: malformation ? pulmonary hypertension ? RV dysfunction ?), risk of difficult intubation (macroglossia) and hypoglycemia if Wiedemann-Beckwith syndrome; frequent presence of moderately high pulmonary blood pressure that can be very severe (iso- or suprasystemic) in case of giant omphalocele  (see above). NO and  milrinone are necessary in case of PAH with RV dysfunction. It may be necessary to place the newborn in the left lateral decubitus to avoid compression of the inferior vena cava. Prevention of hypothermia.

References :

-        Danzer E, Gerdes M, D'Agostino JA, Bernbaum J, Siegle J, Hoffman C, Rintoul NE, Liechty KW, Flake AW, Adzick NS, Hedrick HL.
Prospective, interdisciplinary follow-up of children with prenatally diagnosed giant omphalocele: short-term neurodevelopmental outcome.
J Pediatr Surg 2010; 45:718-23.

-         Partridge EA, Hanna BD, Panitch HB, Rintoul NE, Peranteau WH et al.
Pulmonary hypertension in giant omphalocele infants.
J Pediatr Surg 2014 ; 49 : 1767-70

-        Dal Col AK, Bhombal S, Hintz SR, Feinstein J, Altit G.
Comprehensive echocardiographic assessment of ventricular function and pulmonary pressure in the neonatal omphalocele population.
Am J Perinatol 2020 ; doi 10.1055/s-0040-1708048

Updated: December 2020