**2.1 Epidemiology**

Congenital duodenal obstruction accounts for 50% of all intestinal atresia cases [1, 2]. The incidence of the disease varies from 1 in 5000 to 1 in 10,000 newborns [5–8]. Limited information is available about hereditary forms of CDO. Unlike other types of congenital intestinal obstruction, duodenal obstruction has a high association with other anomalies; such concomitant anomalies are reported in 38% of patients with CDO [9, 10]. The most common associated disease reported is Down syndrome registered in 25–46% of cases [11–13]. Other associated anomalies include intestinal malrotation (54%), congenital cardiac anomalies (32–48%), esophageal atresia (9%), renal anomalies (5%), and anorectal malformations (7%) [14–20]. These anomalies can be part of VACTERL syndrome or isolated [13]. Spigland et al. reported that 12% of patients with duodenal atresia have an associated anomaly of the biliary tract, such as biliary atresia [21, 22]. Associated diseases tend to determine the postoperative course in patients with duodenal atresia. In patients with associated esophageal atresia or cardiac defects—most often a complete atrioventricular septal defect—high mortality rates have been reported [13, 23].
