Stricture of the small intestine (Intestinal atresia)
SYSTEM: GASTROINTESTINAL TRACT
FREQUENCY: 1 in 1000, roughly 50% occur in the duodenum and 50% in the jejunum or ileum
PATIENT HISTORY: This baby died soon after birth having been unable to retain any food. There was frequent vomiting.
The level of the obstruction is at the duodeno-jejunal junction. Distal to this there is a collapsed small bowel, while proximally there is marked dilatation of the stomach and duodenum.
Intestinal atresia refers to complete occlusion of the lumen of the intestine or the absence of a segment of intestine. In congenital intestinal stenosis the bowel lumen is very much narrowed, over a short or long length of bowel. The presentation depends on the level of the obstruction; duodenal or jejunal atresia may cause polyhydramnios due to inability of the foetus to absorb swallowed amniotic fluid. There will be vomiting and abdominal distension within 24 hours of birth, or these symptoms may be delayed somewhat if the obstruction is more distal.
The South African surgeon Chris Barnard showed through experimental work on puppies still in the uterus, that intestinal atresia could be caused by interruption of the blood supply (via the mesenteric vessels) to the bowel, with consequent infarction and then scarring or resorption of a segment of bowel. His discovery led to the successful surgical repair of these lesions; since the blood supply on either side of the atretic segment is poor, at surgery a wide excision margin is essential.
In the case of duodenal atresia, another explanation is that it is a failure of the duodenum to recanalise after the solid cord stage of duodenal development very early in gestation. There is a strong association of duodenal atresia with Down's syndrom.
Jejuno-ileal atresia may be associated with cystic fibrosis.
There are also gene mutations that have been implicated in intestinal atresia, especially in cases with multiple atresias.