Duodenal atresia is the complete occlusion or absence of the duodenal lumen.
Duodenal stenosis is an incomplete obstruction caused by narrowing of the lumen.
Epidemiology
20–25% of cases are associated with chromosomal abnormalities, especially Down syndrome.
Pathophysiology
Since the development of the duodenum is connected to the growth of the pancreas and the hepatobiliary system, duodenal atresia is also commonly associated with anomalies of these organs.
Duodenal stenosis or atresia prevents the fetus from swallowing and passing amniotic fluid.
Postpartum
Vomiting that is typically bilious
Distended upper abdomen and scaphoid lower abdomen
Delayed meconium passage
Diagnostics
Prenatal: ultrasound; Postnatal: x-ray
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.
If present, test for associated anomalies (e.g., karyotyping, microarray)
Risk factors: maternal smoking and/or use of vasoconstrictive agents (e.g., cocaine, MDMA) during pregnancy
Pathophysiology: vascular accident in utero (usually a disruption of superior mesenteric artery) → ischemic necrosis and reabsorption of the jejunum or ileum → discontinuous bowel → obstruction
Bilious vomiting and upper abdominal distention (postpartum)
Diagnostics: Abdominal x-ray shows a triple bubble sign (dilated small bowel loops and air-fluid levels; the three bubbles correlate with the distended stomach, duodenum, and jejunum proximal to the obstruction) and gasless colon.
