This condition results from a prenatal ischemic event, which leads to complete or partial necrosis and aseptic resorption of a segment of bowel with its attached mesentery. Small bowel atresia is equally distributed between the jejunum and the ileum. The distal ileum is commonly affected. As a result of this insult, the fetal colon did not receive in utero sufficient intestinal content to allow it to distend to its normal caliber. At birth, the colon is narrow, small caliber and string-like in appearance; often termed as microcolon. The caliber is small due to disuse. Generalized abdominal distension and vomiting, which is sometimes bilious is the usual clinical presentation. Passage of meconium is limited and frequently delayed. In 25% of cases, there is an association with malrotation, volvulus, omphalocele, and meconium ileus. The occurrence is usually sporadic rarely inherited. The atresia may be single or multiple levels. The clinical presentation is dependent on the level of involvement; the higher the lesion is located, the earlier the onset of symptoms. Most infants present within 24 hours post delivery. Investigations in ileal atresia Plain abdominal film should be the first mode of investigation. The number of distended bowel loops is the key to diagnosing the level of the atretic segment. If the level is high, such as in duodenal atresia, only two air bubbles (the stomach and the proximal duodenum) will be seen; hence the description double bubble sign. If the level of involvement is lower, there will be more distended bowel loops. Sometimes amorphous intraabdominal calcifications scattered throughout the abdomen is seen. This is due to in-utero perforation of the bowel and there is extrusion of meconium within the peritoneal cavity. Intraperitoneal meconium calcify and sometimes as quickly as 24 hours. A contrast study using water-soluble media is the next investigation of choice. It will determine the cause of obstruction. In cases when lower lesion is suspected, water-soluble enema is indicated. As in this case, it demonstrated microcolon of the large bowel and outlined the appendix; the atretic distal ileum is also well demonstrated. |