Chapter 42

### Key Points

1. Intestinal atresia is a life-threatening cause of intestinal obstruction in the newborn.

2. Atresia can occur throughout the intestinal tract but is common in the small intestine.

3. The surgical goal is to establish intestinal continuity.

4. Duodenal atresia can be associated with Down syndrome, cardiac defects, and malrotation.

5. Jejunoileal atresia can be associated with cystic fibrosis, gastroschisis, and short gut syndrome.

6. Colonic atresia is uncommon, but does occur.

Intestinal atresia is a congenital absence of the bowel lumen, which results in obstruction. It becomes evident during prenatal ultrasonography or presents in the early neonatal period. If not corrected, the anomaly will result in death from losses of gastrointestinal (GI) fluids, pulmonary aspiration, and malnutrition. Thus, surgical creation of a continuous lumen with as much functional bowel as possible is the mainstay of management. Not until surgical technique was complemented by the ability to support the neonate through the perioperative period with nutrition and ventilation was long-term survival possible.

Atresias are classified into 3 types with variations depending on etiology and the location of the obstruction. Type I has mural continuity with a membranous luminal obstruction. In Type II atresia, a residual fibrous cord connects a dilated proximal segment to the unused smaller distal segment. Type III atresia finds a gap between the proximal and distal bowel with a mesenteric defect. The level of the obstruction is reflected in the etiology, incidence, clinical presentation, differential diagnosis, and surgical technique.

Many theories exist for the development of intestinal atresia. They can be simplified into 2 categories: an ischemic event causing necrosis and resorption of the involved bowel, or failure of the lumen to develop from the embryologic cord stage. Because of the fixation of the first and second part of the duodenum and its dual blood supply from the celiac axis and the superior mesenteric artery, it is less susceptible to vascular accidents. Therefore, the most likely etiology for duodenal atresia is failure of luminal recanalization after the cord stage. Because of the mobility of the jejunum and ileum with the potential for compression or volvulus, and the anatomy of the arcades, these areas are more likely to suffer vascular ischemia. The presence of a mesenteric defect with Type III atresias also supports this etiology. Statistically, the more distal the atresia, the less frequent is the incidence. Realizing that the last embryonic segments to recanalize are the duodenum and the sigmoid colon, the rare occurrence of colonic atresia remains relatively discrepant and deserves further attention.

When a neonate presents with a bowel obstruction, locating the site of the lesion becomes most important in the sequence of clinical investigation and management. The approaches are quite different for the proximal lesion compared to a distal ileocolonic obstruction. A duodenal or jejunal obstruction is more likely to be atresia, and once other significant systemic anomalies are excluded, the baby is prepared more promptly for the operating ...

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