Duodenal atresia

Prenatal diagnosis

The pathology can be suspected during pregnancy at the time of routine ultrasound screening. Characteristic findings include marked dilation of the fetal stomach and duodenal bulb (duodenal cap), as well as polyhydramnios (polyhydramnios). This anomaly is frequently accompanied by intrauterine growth restriction (IUGR). Due to the excessive accumulation of amniotic fluid, pregnancy frequently ends in preterm birth.

It is important to remember that the anomaly is rarely isolated. Patients require screening for components of the VACTERL association, and approximately 10% of cases additionally present with esophageal atresia (oesophageal atresia).

Postnatal clinical presentation

Characteristic symptoms develop in the infant as early as the early neonatal period. The primary manifestation is early vomiting. Since the obstruction is most commonly located below the major duodenal papilla (Ampulla of Vater), the vomitus contains bile (bilious vomiting). However, if the obstruction is proximal (pre-ampullary obstruction), bile will be absent from the vomitus. Visually, upper abdominal distension is noted in the newborn.

In cases of partial obstruction, such as a stenosis (narrowing in the second, descending part of the duodenum) or a congenital web (duodenal web), symptoms may be less pronounced. On contrast studies, a web appears as a thin filling defect crossing the intestinal lumen against the background of pre-stenotic dilation.

Diagnostic radiology

Plain abdominal radiography serves as the baseline method for confirming the diagnosis. The classic finding is the «double bubble» sign (double bubble), where one gas bubble corresponds to the distended stomach and the second to the dilated proximal duodenum.

• If there is no gas distal to the obstruction and the child's condition is stable, no additional instrumental imaging studies are required prior to surgery given this classic presentation.
• If distal gas is present, this indicates partial obstruction or, in rare cases, a duplication of the common bile duct (bifid common bile duct).

In controversial cases, especially when partial obstruction is suspected, an upper gastrointestinal contrast study is indicated. Ultrasound may be used additionally: giving the child clear fluid will distend the proximal segment, facilitating visualization.

Distinction from small bowel atresia

Unlike duodenal atresia, atresia of the jejunum (jejunum) and ileum (ileum) is more common. Their etiology is fundamentally different—they occur as a result of an intrauterine vascular accident (vascular accident). This blood supply disruption may be primary or secondary, for instance, developing secondary to volvulus (volvulus) or intussusception (intussusception).

In distal small bowel atresia, the clinical picture is supplemented by pronounced generalized abdominal distension and delayed meconium passage. Radiography shows multiple dilated loops. An important limitation of neonatal radiography is that it is impossible to differentiate the small intestine from the large intestine due to their identical diameter and poorly developed haustra in infants. If intrauterine perforation of a severely distended loop occurs, meconium peritonitis develops, leaving peritoneal calcifications.

Specific syndromes and management

A specific form of jejunoileal obstruction is the «apple peel» syndrome (apple peel syndrome). It is characterized by:

• Proximal jejunal atresia.
• Mesenteric agenesis and absence of the middle segment of the small intestine.
• Spiral twisting of the distal ileum around a narrow vascular stalk.
• Associated microcolon malrotation.

A contrast enema is used to differentiate low atresias from other conditions. Treatment for all forms is surgical (intestinal resection and primary anastomosis creation). The primary goal of the surgeon in multiple atresias is to preserve the maximum functional length of the intestine.

Class and exam questions

What else to study on this topic

• Pathogenesis and imaging findings of the «apple peel» syndrome
• Meconium peritonitis as a consequence of intrauterine perforation
• Differential diagnosis of neonatal intraabdominal masses
• Radiographic distinctions between high and low intestinal obstruction in infants
• Causes of abdominal distension in newborns: from pneumoperitoneum to necrotizing enterocolitis

Other Topics in "Pediatric Diagnostic Radiology"

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