Congenital anomalies of the small intestine, colon, and rectum.

Congenital anomalies of the gastrointestinal tract are a significant cause of morbidity in children and, less frequently, in adults. These abnormalities include developmental obstructive defects of the small intestine, anomalies of the colon, anomalies of rotation and fixation, anorectal anomalies, and intestinal duplications. Neonates with complete high intestinal obstruction do not usually require further radiologic evaluation following radiography, whereas those with complete low obstruction should undergo a contrast material enema examination. An upper gastrointestinal series must be performed in all patients with incomplete intestinal obstruction because management is different in each case. In low intestinal obstruction, ultrasonography (US) may help differentiate between small bowel obstruction and colonic obstruction. In addition, US can help correctly identify meconium ileus and meconium peritonitis and is useful in the diagnosis of enteric duplication cysts. In malrotation and anorectal anomalies, computed tomography (CT) and magnetic resonance (MR) imaging can provide superb anatomic detail and added diagnostic specificity. Intestinal duplications manifest as an abdominal mass at radiography, contrast enema examination, or US. At CT, most duplications manifest as smoothly rounded, fluid-filled cysts or tubular structures with thin, slightly enhancing walls. At MR imaging, the intracystic fluid has heterogeneous signal intensity on T1-weighted images and homogeneous high signal intensity on T2-weighted images. Familiarity with these gastrointestinal abnormalities is essential for correct diagnosis and appropriate management.