Congenital visceral malformations

Congenital visceral malformations develop during organogenesis, which occurs in the first 8 weeks after conception (embryonal period). Common malformations include anal atresia, omphalocele, gastroschisis, and biliary atresia. They may occur on their own or together with other malformations and syndromes. Anal atresia is characterized by an absent anal opening and failure to pass meconium, which may lead to an ileus or the formation of fistulas. An omphalocele is often associated with trisomies and manifests with the herniation of abdominal viscera through the abdominal wall into a hernia sac. In cases of gastroschisis, by contrast, herniated parts of the intestine are not covered by a sac, but exposed. All three conditions are clinical diagnoses and require surgery to prevent infections and further complications. In extrahepatic biliary atresia, the infant presents with prolonged neonatal jaundice, acholic stools, dark urine, and hepatomegaly. Conjugated hyperbilirubinemia and abnormalities on ultrasonography provide valuable clues for diagnosis. If extrahepatic biliary atresia remains undetected or surgery is delayed, the infant may die within the first two years of life, usually as a result of biliary liver cirrhosis.

• Definition: sporadically occurring malformation of the rectum with absence of an anal opening
• Epidemiology
  • Approx. 1:5,000 live births in the US
  • Sex: ♂ = ♀
• Etiology: associated with a number of conditions
  • Mesodermal defects (e.g., VACTERL syndrome)
  • Down syndrome
  • Maternal diabetes
  • Other malformations (e.g., vaginal or uterine anomalies, spinal cord or cardiovascular malformations)
• Clinical features ^[1][2][3]
  • Absence of anal opening
  • Thin anal membrane in place of anal opening through which meconium is visible
  • Obstipation, ileus
  • Fistulas that complicate defecation (e.g., rectovestibular, rectourethral, rectovaginal).
  • Small or missing anal dimple
  • In some cases, bucket-handle malformation
  • Flat bottom (absent or poorly developed midline groove between buttocks)
• Diagnosis
  • Clinical diagnosis
  • Lateral pelvic radiography or invertogram to determine position of the rectal pouch
  • Investigation of additional malformations (e.g., spinal ultrasonography, sacral x-ray)
  • Fistula screening
    • Examination of the genital area and the urethra (e.g., abdominal ultrasound)
    • Urinanalysis: meconium detectable in case of a rectourinary fistula
    • Augmented-pressure distal colostography to reveal fistulas.
• Treatment
  • IV hydration, no oral feeding
  • Anal reconstructive surgery (primary anoplasty) or temporary colostomy in more complex malformations

• Definition
  • Ventral wall defect that results in congenital herniation of abdominal viscera through the abdominal wall at the umbilicus.
  • The hernia sac is covered by the amniotic membrane and the peritoneum.
• Epidemiology
  • Approx. 1:4,000 live births in the US
  • Sex: ♂ > ♀
• Etiology
  • Frequently observed in trisomies (trisomy 21, trisomy 18, and trisomy 13) and Beckwith-Wiedemann syndrome
  • Often associated with additional malformations (e.g., cardiac, gastrointestinal, genitourinary, and neural tube defects)
• Pathophysiology: persistent herniation of the midgut derivatives due to impaired closure of the lateral umbilical folds
• Clinical features
  • Most commonly affects premature infants
  • Umbilical hernia sac (may contain intestine, liver, and gall bladder)
  • Features of associated conditions
• Diagnosis ^[4]
  • Clinical diagnosis at birth
  • Can be detected prenatally
    • Ultrasonography: polyhydramnios in utero
    • ↑ Maternal serum alpha-fetoprotein (MSAFP)
• Treatment
  • Cesarean delivery to prevent rupture of the sac
  • Wrapping of the hernia sac with sterile saline dressings covered with plastic wrap
  • Nasogastric suction
  • IV fluids to avoid abdominal distention and to compensate fluid loss
  • Surgery (within the first 24 hours of life)
    • Usually primary abdominal wall closure
    • Alternatively, secondary closure following:
      • Staged silo repair
      • Skin graft or dermal patch
• Complications
  • Rupture of hernia sac with infection (peritonitis)
  • Secondary intestinal wall atresia as a result of injury
• Prognosis
  • Dependent on the size of the defect and birth weight
  • Survival rate over 90% in the absence of additional malformations

• Definition: a ventral wall defect that results in paraumbilical herniation of the intestine through the abdominal wall without formation of a hernia sac
• Epidemiology: approx. 1:2,000 live births in the US
• Pathophysiology
  • Failed formation of a sufficiently large peritoneal cavity → growing bowel leads to rupture of the anterior abdominal wall at its weakest point → herniation of bowel sections
  • Because the malformation occurs relatively late in development, additional anomalies are rarely present (in contrast to omphalocele)
• Clinical features
  • Protrusion of intestinal content usually on the right side of the umbilicus
  • The intestine is not contained in a hernia sac and appears edematous, erythematous, and dull.
  • Shortened bowel
  • Malabsorption caused by mucosal damage
  • Peritonitis
  • Seen especially in premature infants and associated with cryptorchidism and gastrointestinal stenoses or atresia
• Diagnosis
  • Usually clinical diagnosis
  • Can be detected prenatally (see “Diagnosis” of omphalocele above)
• Treatment
  • Cesarean delivery has no advantage over vaginal delivery.
  • See “Treatment” of omphalocele above
  • Emergency surgery
    • Primary abdominal wall closure (success rate of 70%)
    • Alternative: staged silo repair (see “Treatment” of omphalocele above)
• Prognosis
  • Survival rates are generally high (> 90%).
  • Short bowel syndrome is a common complication.
  • 20% of children develop necrotizing enterocolitis. ^[5]

Unlike in cases of omphalocele, gastroschisis does not manifest with a hernia sac.

Omphalocele keeps your gut O-sealed (covered with peritoneum), but in Gastroschisis, the Gut freezes (herniates through the abdominal wall without being covered by peritoneum).

Biliary atresia

• Definition: obliteration or discontinuity of the extrahepatic biliary system, most commonly of the common bile duct
• Epidemiology
  • Approx. 1:10,000–15,000 live births in the US
  • ♀ > ♂
• Etiology
  • Exact etiology unknown, most likely an embryonal malformation or acquired lesion
  • Approx. 10–35% of cases involve additional anatomical malformations (e.g., situs inversus, asplenia, polysplenia, cardiac anomalies)
• Pathophysiology: discontinuity of the biliary system due to obliteration or fibrosis → obstruction of bile flow (cholestasis) → secondary biliary cirrhosis and portal hypertension
• Clinical features
  • Prolonged neonatal jaundice (> 2 weeks of life)
  • Acholic stools, dark urine
  • Hepatomegaly
• Diagnosis
  • Laboratory analysis
    • Conjugated hyperbilirubinemia
    • ↑ Aminotransferases and alkaline phosphatase
    • ↑ GGT
  • Ultrasonography
    • Absence of the gallbladder
    • No dilatation of the biliary tree
  • Liver biopsy
    • Active inflammation with bile duct degeneration and fibrosis
    • Bile duct proliferation
    • Portal stromal edema
  • Hepatobiliary scintiscanning (HBSS): failed excretion of the tracer into the bowel
  • Intraoperative cholangiography to confirm diagnosis
• Treatment
  • Kasai procedure (hepatoportoenterostomy): a connection is created between the liver and the small intestine to allow for bile drainage.
  • In cases of liver cirrhosis: liver transplantation (primary reason for liver transplantation in children)
• Complications
  • If undetected
    • Early biliary liver cirrhosis (at approx. 9 weeks of age)
    • Children may die within the first 2 years of life
  • Postoperative
    • Cholangitis in 50% of cases
    • Portal hypertension in > 60% of cases

Alagille syndrome

• Description: a genetic condition that is characterized by intrahepatic biliary duct aplasia or hypoplasia
• Epidemiology: Approx. 1:30,000–45,000 live births in the US
• Etiology
  • Autosomal-dominant inheritance
  • Mutation in the JAG1 gene on chromosome 20 in 90% of patients
• Clinical features
  • Hepatic manifestations
    • Cholestasis
    • Jaundice
    • Pruritus
    • Cirrhosis
  • Facial dysmorphism
    • Triangular face
    • Deep set eyes
    • Broad nasal bridge
  • Congenital heart defects (e.g., peripheral pulmonary stenosis)
  • Butterfly vertebrae
  • Posterior embryotoxon
  • Renal dysplasia
• Diagnosis
  • Laboratory findings
    • Conjugated hyperbilirubinemia
    • ↑ Serum aminotransferases
    • ↑ γ-GT
  • Liver biopsy: decreased number of interlobular bile ducts
  • Confirmation via genetic testing: detection of JAG1 gene mutation
• Treatment
  • Depends on the affected organ systems
  • Conservative management of cholestasis and pruritus (e.g., ursodeoxycholic acid, cholestyramine)

1. Levitt MA, Peña A. Anorectal malformations. Orphanet J Rare Dis. 2007; 2 : p.33. doi: 10.1186/1750-1172-2-33 . | Open in Read by QxMD
2. Imperforate Anus. https://rarediseases.org/rare-diseases/imperforate-anus/. Updated: January 1, 2007. Accessed: March 9, 2017.
3. Anal Atresia. http://www.msdmanuals.com/professional/pediatrics/congenital-gastrointestinal-anomalies/anal-atresia. Updated: October 1, 2016. Accessed: March 9, 2017.
4. Omphalocoele. https://radiopaedia.org/articles/omphalocoele. Updated: March 9, 2017. Accessed: March 9, 2017.
5. Jayanthi S, Seymour P, Puntis JW, Stringer MD. Necrotizing enterocolitis after gastroschisis repair: a preventable complication?. J Pediatr Surg. 1998; 33 (5): p.705-7.