Duodenal atresia and stenosis

Duodenal atresia is a complete occlusion or absence of the duodenal lumen, whereas duodenal stenosis refers to an incomplete obstruction caused by narrowing. Both conditions present with signs of obstruction, including a distended upper abdomen, delayed meconium passage, and vomiting. If the defect is located proximal to the major duodenal papilla, nonbilious vomiting occurs, whereas a defect occurring distal to the papilla causes bilious vomiting. Evidence of polyhydramnios on prenatal ultrasonography may lead to an early diagnosis of duodenal obstruction. An abdominal x-ray typically shows the double bubble sign. Duodenal atresia and stenosis generally have a favorable prognosis and may be surgically treated through duodenoduodenostomy.

• Around 1/5000–10,000 live births
• ∼ 50% of cases are associated with further anomalies, e.g., bile duct and VACTERL association.
• 20–25% of cases are associated with chromosomal abnormalities, especially Down syndrome.

References:^[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Intrauterine

• Polyhydramnios

Postpartum

• Vomiting, that is typically bilious if the stenosis is distal to the major duodenal papilla
  • Atresia or high-grade stenosis: vomiting few hours after birth
  • Mild stenosis: vomiting after a few days
• Distended upper abdomen and scaphoid lower abdomen
• Delayed meconium passage

References:^[3][1]

Prenatal

• Ultrasound
  • Polyhydramnios
  • Dilation of the stomach and duodenum (proximal to the obstruction) is common.
  • Double bubble sign

Postnatal

• X-ray of the abdomen
  • Double bubble sign: air and fluid build up proximal to the obstruction and are separated by the pyloric sphincter, which resembles two bubbles on imaging – one in the stomach and one in the duodenum
  • Gasless distal bowel

References:^[4][3]

Jejunal atresia and Ileal atresia

• Definition: absence of the jejunal lumen or ileal lumen
• Epidemiology: less common than duodenal atresia
• Pathophysiology
  • Vascular accident in utero (usually a disruption of superior mesenteric artery) → ischemic necrosis and reabsorption of the jejunum/ileum → discontinuous bowel
  • Risk factors: vasoconstrictive drugs (e.g., cocaine, MDMA, or cigarettes) during pregnancy
• Clinical features: similar to duodenal atresia
  • Polyhydramnios (intrauterine)
  • Bilious vomiting and upper abdominal distension (postpartum)
• Diagnosis: abdominal x-ray shows a triple bubble sign (dilated small bowel loops and air-fluid levels) and gasless colon
• Treatment: surgical correction with bypass of the occluded part of bowel is always required

The differential diagnoses listed here are not exhaustive.