(Also see Overview of Congenital GI Anomalies.)
The duodenum can be obstructed by atresia, stenosis, and pressure due to an extrinsic mass.
This anomaly is the 3rd most common atresia of the GI tract. The estimated incidence is 1 in, 5,000 to 10,000 live births. Duodenal atresia is due to the failure of canalization of the embryonic duodenum. This failure may be related to an ischemic event or genetic factors.
Duodenal atresia, unlike other intestinal atresias, is commonly associated with other congenital anomalies such as Down syndrome, which is present in 25 to 40% of cases. Other associated anomalies include VACTERL (vertebral anomalies, anal atresia, cardiac malformations, tracheoesophageal fistula, esophageal atresia, renal anomalies and radial aplasia, and limb anomalies), malrotation, annular pancreas, biliary tract abnormalities, and mandibulofacial anomalies.
Diagnosis of duodenal atresia can be suspected prenatally if there is polyhydramnios, dilated bowel, ascites, or a combination.
Postnatally, infants with duodenal atresia present with polyhydramnios, feeding difficulties, and emesis that may be bilious. The diagnosis is suspected by symptoms and classic double-bubble x-ray findings—one bubble is in the stomach and the other is in the proximal duodenum; little to no air is in the distal gut. Although an upper GI series provides definitive diagnosis, it must be done carefully by a radiologist experienced with doing this procedure on children to avoid aspiration and is not typically necessary if surgery is to be done immediately. If surgery is to be delayed (eg, because other medical issues, such as respiratory distress syndrome, need to be stabilized), a contrast enema should be done to confirm that the double-bubble sign is not due to malrotation. Once the disorder is suspected, infants should receive nothing by mouth, and an NGT should be placed to decompress the stomach.
Surgery is the definitive therapy.
A choledochal cyst may obstruct the duodenum by extrinsic pressure. There is some evidence that the incidence of choledochal cysts is increasing.
Infants with choledochal cyst classically present with a triad of abdominal pain (a very difficult finding to infer in the neonate), right upper quadrant mass, and jaundice. If the cyst is large, it may also manifest with variable degrees of duodenal obstruction. Neonates can present with cholestasis. These cases are relatively rare and occur most commonly in neonates of Asian descent.
Choledochal cyst is most commonly diagnosed by ultrasonography. These cysts can be further defined by using magnetic resonance cholangiopancreatography, ERCP, or endoscopic ultrasonography.
Treatment of choledochal cyst is surgical and requires complete excision of the cyst because of the high risk (20 to 30%) of developing cancer in the cyst remnants. The surgical procedure most commonly used is a Roux-en-Y hepaticojejunostomy.
Annular pancreas is a rare congenital anomaly (5 to 15 per 100,000 live births), often associated with Down syndrome, in which pancreatic tissue encircles the 2nd portion of the duodenum, causing duodenal obstruction.
About two thirds of affected individuals remain asymptomatic. Of those who do develop symptoms, most present in the neonatal period, but manifestation may be delayed until adulthood. Neonates present with polyhydramnios, feeding problems, and emesis that may be bilious.
The diagnosis of annular pancreas can be suggested by an x-ray of the abdomen showing the same double-bubble sign seen in duodenal atresia. The diagnosis can also be made by an upper GI series and is more definitively made with CT or magnetic resonance cholangiopancreatography. ERCP can be done in older children.
Treatment of annular pancreas is surgical bypass of the annular pancreas with duodenoduodenostomy, duodenojejunostomy, or gastrojejunostomy. Resection of the pancreas should be avoided because of the potential complications of pancreatitis and pancreatic fistula development.