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.

Duodenal atresia occurs when recanalization of the closed duodenum fails to occur or occurs only partially during the embryonic period (usually between the 8^th–10^th week of gestation). Because the development of the duodenum is connected to the growth of the pancreas and the hepatobiliary system, duodenal atresia is commonly associated with anomalies of these organs as well.

References:^[1]

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:^[1][3]

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:^[3][4]

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.

• Preoperative management
  • Parenteral nutrition via a central catheter shortly after birth
  • Fluid replacement and restoration of the electrolyte balance
  • Gastric decompression
• Surgery: bypass the atresia or stenosis
  • The exact procedure depends on the anatomic findings and associated anomalies
  • Common procedure: duodenoduodenostomy or duodenojejunostomy with a proximal transverse-to-distal longitudinal (diamond-shaped) anastomosis

References:^[5]

• If diagnosis and treatment occur quickly, the survival rate of isolated duodenal atresia (without further anomalies) is 95%.
• The presence of other anomalies worsens the prognosis.

References:^[2]