Omphalocele is a midline anterior abdominal wall defect where abdominal organs (bowel, liver, spleen) protrude outside the abdomen at the umbilical ring level within a sac covered by amniotic membrane. Incidence is approximately 1/4000-6000 live births. Omphalocele results from failure of lateral folds (somatic plicae) to close at the midline during 10-12 weeks of embryonic development. Being covered by a membrane is the most important morphological feature distinguishing omphalocele from gastroschisis. Omphalocele has strong association with chromosomal anomalies — risks of trisomy 13, 18, 21, and Turner syndrome are elevated. It may also be associated with Beckwith-Wiedemann syndrome and pentalogy of Cantrell. Usually detected by prenatal ultrasound in the first trimester. Classified as giant omphalocele (containing liver) and small omphalocele (containing only bowel) — prognosis and treatment vary according to this distinction. Treatment is primary surgical closure or staged closure (silo technique) for large defects.
Age Range
0-0
Peak Age
-
Gender
Equal
Prevalence
Rare
Omphalocele results from failure of closure of lateral body folds during embryonic development, which begins at 3-4 weeks and should complete by 10-12 weeks. In normal development, four body folds (cephalic, caudal, right lateral, left lateral) unite at the midline and close the abdominal wall. When lateral folds fail to close, a midline defect remains and abdominal organs protrude in a sac covered by amniotic membrane. The membrane consists of three layers: outer amnion, inner peritoneum, with Wharton's jelly between — this forms the structure of the omphalocele sac. The umbilical cord attaches to the apex of the sac — this is the pathognomonic anatomical relationship for omphalocele. Defect size determines organ herniation: in small defects (<4 cm) only bowel loops, in large defects (>4 cm) liver and other organs protrude. Chromosomal anomaly association is explained by body wall closure genes being located on the same chromosomes — in trisomy 18, body wall closure genes are affected. Beckwith-Wiedemann syndrome (BWS) association is explained by disruption of the IGF-2/H19 imprinting region — BWS typically presents with macrosomia, macroglossia, and omphalocele triad.
Pathognomonic finding combination for omphalocele: midline abdominal wall defect + herniated organs covered by amniotic membrane + umbilical cord inserting at sac apex. The combination of these three findings confirms omphalocele and clearly distinguishes it from gastroschisis (right paraumbilical defect, no membrane, cord in normal position).
Prenatal ultrasound reveals a defect at the midline level of the fetal anterior abdominal wall. Abdominal organs (bowel +/- liver) protrude outside the abdomen within a sac covered by amniotic membrane. The umbilical cord inserts at the apex of the sac — this is the pathognomonic anatomical relationship for omphalocele. The membrane appears as a thin, smooth, hyperechoic line and sac contents are seen surrounded by this membrane. If liver herniation is present, the sac size is large and the liver is identified as a heterogeneously echogenic structure.
Report Sentence
A midline anterior abdominal wall defect is seen on prenatal US with abdominal organs protruding within a membrane-covered sac; the umbilical cord inserts at the sac apex; findings are consistent with omphalocele.
In giant omphalocele, the liver is seen herniated within the sac. The liver is identified on US as a homogeneous intermediate echogenic structure and hepatic veins may be traced within the sac by Doppler. Liver herniation indicates a defect >4 cm. Besides the liver, bowel loops, spleen, and sometimes stomach may also herniate. Giant omphalocele is associated with worse prognosis, higher chromosomal anomaly risk, and more difficult surgical repair.
Report Sentence
Liver herniation is seen in the omphalocele sac, consistent with giant omphalocele; detailed evaluation for chromosomal anomaly and additional malformations is recommended.
On fetal MRI, T2-weighted images evaluate the omphalocele sac and contents with high resolution. Bowel loops and liver show different signal characteristics on T2 — bowel lumen is T2 hyperintense (intraluminal fluid), liver shows intermediate signal. The membrane appears as a thin hypointense line. Fetal MRI provides better soft tissue contrast than US and is superior for evaluating additional anomalies (cardiac, renal, cerebral). MRI is also used to calculate abdominal cavity volume for assessing postnatal surgical closure possibility.
Report Sentence
On fetal MRI T2-weighted images, a midline abdominal wall defect with herniated organs within a membrane-covered sac is seen; consistent with omphalocele.
Doppler ultrasound confirms umbilical cord insertion at the sac apex. Umbilical arteries (x2) and umbilical vein (x1) are confirmed with flow within the cord. This finding is the pathognomonic anatomical relationship for omphalocele and critical for differentiation from gastroschisis — in gastroschisis, the umbilical cord is in normal position and the defect is right paraumbilical, independent of the cord.
Report Sentence
Doppler examination confirms umbilical cord insertion at the apex of the omphalocele sac; this anatomical relationship supports the diagnosis of omphalocele.
When omphalocele is detected, screening for additional anomalies is mandatory. Cardiac anomalies (30-50%) are the most commonly associated anomaly — VSD, ASD, tetralogy of Fallot. Renal anomalies (15-20%), cerebral anomalies (10%), and extremity anomalies should also be screened. Increased NT, nasal bone hypoplasia, or other soft markers increase chromosomal anomaly risk. Beckwith-Wiedemann syndrome findings (macroglossia, macrosomia, nephromegaly) should be sought.
Report Sentence
Omphalocele has been detected and detailed fetal screening for associated cardiac, renal, and cerebral anomalies has been performed; amniocentesis for chromosomal anomaly evaluation is recommended.
Criteria
Defect >4 cm, liver herniation present, liver + bowel + other organs in sac
Distinct Features
Primary closure usually not possible → staged closure (silo), pulmonary hypoplasia risk, higher mortality, more frequent chromosomal anomaly
Criteria
Defect <4 cm, only bowel herniation, liver not herniated
Distinct Features
Primary surgical closure usually possible, better prognosis, but chromosomal anomaly risk still elevated
Criteria
Omphalocele + macroglossia + macrosomia triad, 11p15 imprinting defect
Distinct Features
Normal karyotype (85%), neonatal hypoglycemia risk, hepatoblastoma/Wilms tumor screening needed, usually giant omphalocele
Distinguishing Feature
Gastroschisis is right paraumbilical defect (omphalocele midline); no membrane in gastroschisis (present in omphalocele); umbilical cord in normal position in gastroschisis; additional anomaly rate is low in gastroschisis (10-15% vs 50-70%)
Distinguishing Feature
Physiological bowel herniation (midgut herniation) is normal at 8-12 weeks; >12 weeks or >7 mm sac size should suggest omphalocele; liver does not herniate in physiological herniation
Distinguishing Feature
Umbilical cord hernia is a smaller defect (<2 cm) containing only bowel; distinguished from large omphalocele by defect size and absence of liver herniation; additional anomaly rate in umbilical cord hernia is low
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralWhen omphalocele is detected, a multidisciplinary approach is required. Prenatally: (1) karyotype analysis via amniocentesis is mandatory — for trisomy 13, 18, 21, and Turner syndrome; (2) detailed fetal anatomy survey — cardiac anomaly evaluated with echocardiography; (3) fetal MRI recommended for anatomical detail in giant omphalocele. Delivery planning: cesarean delivery recommended for giant omphalocele (membrane rupture risk); vaginal delivery may be possible for small omphalocele. Postnatal treatment: primary surgical closure for small omphalocele; staged closure (silo technique) or paint-and-wait strategy for giant omphalocele. Prognosis: isolated small omphalocele survival >90%; significantly worsens with giant omphalocele + additional anomalies.
Chromosome analysis and detailed anomaly screening are mandatory in omphalocele diagnosis (cardiac, renal, cranial). Small omphaloceles undergo primary surgical repair. Giant omphaloceles (liver herniation) may require staged closure (silo technique) or conservative management (allowing epithelialization). In trisomy-associated cases, prognosis depends on the underlying genetic anomaly.