Congenital intestinal atresias, stenosis, and webs typically present early in neonatal life due to the associated obstructive symptoms. The reported incidence of congenital intestinal atresias, stenosis, and webs is 1 in 5000 to 10,000 births in the United States. These malformations can occur throughout the intestinal tract but are most commonly found in the duodenum (50%) and the jejunum or ileum (35–40%). A colonic location is identified in 5% to 10% of atresias, and rarely, pyloric or gastric lesions are present (< 1%).
Pyloric atresia is the rarest of intestinal atresias, occurring in 1 in 100,000 live births. The exact mechanism of development for pyloric atresia is not yet known. Several theories have been proposed: vascular accident, failure of lumen to recanalize, or developmental arrest. The most likely etiology is a developmental defect occurring between the 5th and 12th week of fetal development. Duodenal atresia, on the other hand, is attributed to a failure of the recanalization process in the 11th week of gestation. It is associated with anomalies including trisomy 21, congenital heart disease, malrotation, esophageal atresia, imperforate anus, genitourinary disorders, and gallbladder agenesis. In contrast, the most commonly accepted etiology for jejunoileal and colonic atresias involves intrauterine mesenteric ischemia from a variety of vascular accidents, encompassing umbilical cord infarcts, volvulus, internal hernias, fascial defects, intussusception, and intestinal perforation. The affected segment is then believed to be reabsorbed.
Genetic links and familial patterns of intestinal atresias (mostly autosomal recessive) are also well described, although the specific genes or mutations involved have yet to be identified. Recently, an autosomal recessive syndrome comprising neonatal diabetes mellitus, intestinal atresias, and gallbladder agenesis has been described. An autosomal recessive genetic disorder called Herlitz syndrome is linked to some cases of pyloric atresia. Patients with this syndrome suffer from epidermolysis bullosa lethalis, which results in severe vesiculobullous lesions after minimal skin friction. Gastrointestinal defects and immunodeficiency syndrome (GIDID) is characterized by multiple intestinal atresias, which can occur at various levels throughout the small and large intestines. Some patients exhibit features of very early onset inflammatory bowel disease (IBD). Surgical outcomes are poor.
The majority of infants with intestinal atresia present as newborns with signs and symptoms of intestinal obstruction, including vomiting (which may be bilious), varying degrees of abdominal distension depending on the level of obstruction, and often failure to pass meconium.
Antral and Pyloric Atresia and Webs
Three types of antral and pyloric atresias have been described, based on extent of disruption between the stomach and duodenum. Type I, the most common form of such atresia (57%), is characterized by the development of a mucosal and submucosal web or membrane without involvement of the muscular layer. The membrane can become redundant over time and prolapse into the pyloric channel, creating a classic “windsock” deformity. Type II (34%) involves ...