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Intestinal atresia, a congenital complete obstruction of the lumen of the intestine, is one of the most frequent causes of bowel obstruction in the newborn, and can occur at any point in the gastrointestinal tract. Approximately one-half of the cases involve the duodenum; most other cases affect the jejunum or ileum, with a small percentage in the colon.

Duodenal atresia is thought to be caused by an interruption of normal gastrointestinal tract development. Jejunal and ileal atresias are acquired in utero, resulting from vascular disruption leading to ischemic necrosis of the fetal intestine. Causes of the vascular disruption include intestinal volvulus, intussusception, internal hernia, gastroschisis, meconium ileus, and interruption of the segmental mesenteric blood supply.

Findings on prenatal ultrasound that suggest the possibility of intestinal atresia include polyhydramnios, dilated bowel, or increased bowel echogenicity. Duodenal atresia is suggested by the "double bubble" formed by the dilated proximal duodenum and stomach. Prenatal ultrasonography is not always accurate, and plain radiographs and contrast examinations should be obtained after birth to confirm the diagnosis.

Infants with intestinal atresia typically present with signs and symptoms of intestinal obstruction (abdominal distension and vomiting), usually beginning in the first two days of life. The presentation may be delayed for days or weeks in infants with stenosis (partial obstruction) of the intestine rather than atresia. Associated findings vary by anatomical site, and include:

Duodenal atresia – Vomiting may or may not be bilious. About 30 percent of newborns with duodenal atresia have Down syndrome. In infants without Down syndrome, other congenital malformations are common, including gastrointestinal (biliary atresia, agenesis of the gall bladder), cardiac, renal, and vertebral anomalies.

Jejunal and ileal atresia – Vomiting is typically bilious. Hyperbilirubinemia is common. About 10 percent of infants with jejunal or ileal atresia have cystic fibrosis and meconium ileus.

On plain abdominal film, a double bubble sign strongly suggests duodenal atresia; with rare exceptions, distal gas is absent. Jejunal or ileal atresia typically appears as dilated loops of small bowel with air-fluid levels. The bowel distension is most prominent in more distal atresias. 

Additional evaluation for most infants includes contrast radiographs to confirm and better define the anomaly, plain chest films for vertebral anomalies, and laboratory studies to assess the infant's clinical condition including complete blood count and differential, serum electrolyte concentration, blood urea nitrogen (BUN), and creatinine.

Additional tests to assess for associated conditions are indicated in patients with duodenal atresia (echocardiogram and renal ultrasonography); Down syndrome (echocardiogram, and rectal biopsy to evaluate for Hirschsprung disease); and meconium plugs (testing for cystic fibrosis).

Preoperative management for an infant with intestinal atresia includes withholding feedings and placement of a nasogastric or orogastric tube to continuous suction. Intravenous access should be established, and parenteral fluids should be provided. Abnormalities in fluid and electrolyte balance should be corrected. Broad-spectrum antibiotics (eg, ampicillin and gentamicin) are typically given to prevent postoperative infection.

The surgical approach depends upon the site of the atresia. In every case, the possibility of a second or multiple atresias should be considered.

From Up To Date: Intestinal atresia 

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