Omphalocele

Developmental mechanisms and morphology

The pathogenesis of the disease directly depends on which specific organs comprise the contents of the hernia sac. The formation of the malformation is associated with early embryonic developmental disorders:

• Large defects (involving the liver): Formed when the lateral folds of the embryo's body fail to close properly. As a result, part of the liver ends up outside the normal abdominal cavity.
• Defects containing only intestine: Occur because the physiological umbilical hernia (a normal stage of intestinal tube development) fails to return into the abdominal cavity after the 10th week of gestation.

Special attention in clinical practice is paid to "giant omphalocele". This diagnosis is established if at least one of two criteria is met: liver tissue is visualized in the hernia sac, OR the transverse dimension of the abdominal wall defect exceeds 5 centimeters.

Antenatal diagnosis and associated syndromes

The malformation is successfully detected during screening ultrasound examination starting from the second trimester of pregnancy. The subsequent prognosis for the child's life and health primarily depends on the presence of associated pathologies, which occur in more than half of patients.

One of the best-known conditions associated with this defect is Beckwith–Wiedemann syndrome (Beckwith–Wiedemann syndrome). In classical literature, it also appears as the "EMG" syndrome, reflecting its main clinical triad:

1. Exomphalos (omphalocele).
2. Macroglossia (pathologically enlarged tongue).
3. Gigantism (excessive fetal growth).

Surgical strategy after the infant's birth varies depending on the volume of the hernia protrusion. Three main approaches are used: immediate radical defect closure, staged reduction of organs into the abdominal cavity, or delayed plasty performed after the hernia sac becomes epithelialized. It is important to remember that anatomically, intestinal malrotation is always present in omphalocele.

Omphalocele within the structure of complex syndromes (OEIS and cloacal exstrophy)

Omphalocele is frequently part of severe combined anomalies. In medical terminology, confusion sometimes arises between the concepts of OEIS complex (includes omphalocele, exstrophy, imperforate anus, and spinal anomalies) and cloacal exstrophy. In reality, these are different manifestations of the same pathological spectrum.

Cloacal exstrophy is the most severe, yet compatible with life, form from the epispadias-exstrophy spectrum. It results from abnormal development of the cloacal membrane and its premature rupture (prior to the 5th week of gestation). The malformation affects the gastrointestinal tract, urogenital system, central nervous system, and musculoskeletal system.

The clinical and anatomical picture includes:

• Omphalocele of various sizes.
• The cloaca opens directly onto the lower surface of the abdominal wall.
• An open blind-ending colon is located between the two separated halves of the urinary bladder.
• The terminal part of the ileum prolapses outward (on antenatal ultrasound, this yields a specific pathognomonic "elephant's trunk" sign — ‘elephant’s trunk’ sign).
• A short, blind-ending distal bowel.
• Ambiguous external genitalia.
• Frequent accompaniments: an "open book" pelvis (‘open book’ pelvis), bilateral inguinal hernias, spinal dysraphism (myelomeningocele), renal anomalies, and lower limb defects (e.g., clubfoot).

Strict predictors of cloacal exstrophy on prenatal ultrasound are considered to be the combination of omphalocele, myelomeningocele, and a non-visualized (absent on scans) urinary bladder.

Diagnosis and management of complex forms

In the early postnatal period, patients with cloacal exstrophy require comprehensive imaging:

• Ultrasound to assess the condition of the brain, spine, kidneys, urinary tract, and hip joints.
• MRI for detailed study of the pelvic anatomy (pelvic floor, reproductive tracts) and spinal structures.
• CT for planning pelvic bone reconstruction.
• Radiocontrast studies of the upper GI tract to map intestinal anatomy.

Surgical treatment in the early postnatal period requires a multidisciplinary approach. Primarily, surgeons perform fecal diversion (formation of a colostomy), closure or diversion of urine (bladder plasty or vesicostomy), reduction of organs and closure of the omphalocele, as well as repair of open neural tube defects. Reconstruction of the reproductive tracts is a complex multi-stage task usually postponed to an older age.

Associated GI issues: the choking neonate

When studying anterior abdominal wall and GI pathologies, one must also remember other critical conditions. The The Choking Neonate symptom complex manifests with profuse hypersalivation, gagging during feeding, cyanosis, and progressive respiratory distress.

Although the most frequent cause is gastroesophageal reflux, the physician must rule out severe foregut malformations arising in the first trimester:

• Esophageal atresia (EA) with or without tracheoesophageal fistula (TEF).
• Rarer pathologies: laryngeal clefts, diaphragmatic hernias, and vascular rings.

Esophageal atresia is frequently part of the VACTERL association, which shares a number of systemic defects with omphalocele and cloacal exstrophy (spinal, renal, limb anomalies, and anorectal malformations). The presence of polyhydramnios and the absence of a gastric air bubble on antenatal ultrasound should alert the physician to possible esophageal atresia.

Class and exam questions

What else to study on this topic

• Pathogenesis and differential diagnosis of gastroschisis
• Classification of types of esophageal atresia and tracheoesophageal fistulas
• Methods of surgical anterior abdominal wall plasty in neonates
• VACTERL association: diagnostic criteria and patient management
• Radiological signs of an H-type tracheoesophageal fistula

Other Topics in "Pediatric Diagnostic Radiology"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.