Colon atresia

For practical purposes, the differential diagnosis of low intestinal obstruction in the neonate consists of five conditions. Two conditions involve the distal ileum and include ileal atresia and meconium ileus, and three involve the colon, which are colonic atresia, Hirschsprung s disease, and functional immaturity of the colon that includes meconium plug... 

Fig. 1.29a-d. Colon atresia, a Supine radiograph shows gaseous distension of howel. b,c Contrast enema, anteroposterior and lateral views show abnormally small colon (microcolon) with complete obstruction to retrograde flow of contrast material proximal to the middle transverse portion of colon, d Photograph at operation shows a distended colon up to the site of the atresia (arrow) and a microcolon distal to it... 

Bley W, Franken EA Jr (1973) Roentgenology of colon atresia. Pediatr Radiol 1 105-108... 

Poole GV (1990) Anatomic basis for delayed diagnosis of appendicitis. South Med J 83 771-773 Powell RW, Raffensperger JG (1982) Congenital colonic atresia. J Pediatr Surg 17 166-170... 

Fig. 6.11a,b. Colonic atresia and stenosis, a Colonic atresia in a neonate with a small distal colon and a blind upper end. b Colonic atresia showing a lower bowel well distended with contrast but with no connection to the more proximal bowel... 

Cocaine exposure in utero can affect various fetal organs. Gastrointestinal disorders, including ten cases of necrotizing enterocolitis (291), one of intestinal atresia, and one of spontaneous colonic perforation, have been reported (292). 

Fig. l.la,b. Pyloric atresia. Anteroposterior (a) and lateral (b) plain abdominal radiograph in a newborn infant that shows distension of the stomach (st) and absence of air in the small howel and colon, resulting in the characteristic single bubble image... 

The diagnosis is usually apparent on the plain films. The abdominal radiograph shows a few dilated bowel loops (three or four air bubbles), more than in the case of duodenal atresia and fewer than in ileal atresia or in other causes of low bowel obstruction (Fig. 1.14). The loop just proximal to the site of the atresia is frequently disproportionately dilated with a bulbous end. There is no air in the lower portion of the abdomen this is observed most clearly in the upright film (Rathaus and Grunebaum 1992) (Fig. 1.15). The colon cannot be identified and air... 

Plain film shows numerous dilated loops of bowel occupying the entire abdominal cavity, including the pelvic portion, and multiple air-fluid levels in upright film (Fig. 1.19). With this degree of distension the mucosal pattern of the small bowel is effaced and it is impossible to differentiate the small bowel from the colon (Winters et al. 1992). Examination of the colon is then warranted to disclose the presence or absence of a colonic lesion. In ileal atresia, the colon is normally placed but has an abnormally small caliber, the so-called functional microcolon typical of distal small bowel obstruction (Dalla Vecchia et al. 1998) (Fig. 1.19d,e). The presence of pneumoperitoneum indicates that perforation has occurred and a colon examination is contraindicated. Intraperitoneal calcifications, indicative of meconium peritonitis, are not uncommon in ileal atresia. 

Fig. 1.19a-e. Ileal atresia, a-c Supine, lateral, and upright abdominal radiographs show multiple dilated air-filled bowel loops occupying the entire abdominal cavity, with air-fluid levels in the upright radiograph. Note in (b) the absence of air in the rectum. With this degree of distension it is impossible to differentiate the small bowel from the colon. d,e Contrast enema outlines the minute size of the colon corresponding to an unused colon... 

The clinical presentation of patients with small left colon syndrome is very similar to that of patients with meconium plug syndrome. Air-fluid levels are often absent in the upright film, particularly prior to 48 h of life. Soap bubble meconium is typically seen in the collapsed left colon on the plain film, and the distended bowel tends to be less than that seen in atresias. The contrast enema reveals a normal or slightly dilated colon and rectum but... 

Winters WD, Weinberger E, Hatch El (1992) Atresia of the colon in neonates radiographic findings. AJR Am J Roentgenol 159 1273-1276... 

The radiological diagnosis of obstruction is usually visible on the conventional (plain) radiograph. In uncomplicated cases these radiographs of the abdomen are sufficient. The pre-atretic intestinal loops are dilated because of accumulation of large amounts of fluid and fluid levels are usually present on horizontal beam films. In case of jejunal atresia only a few loops of distended jejunum are present in the left upper abdomen, while in ileal atresia many dilated loops are identified. In complicated cases, especially with an abnormally distended and painful abdomen, a colon enema or US can be useful- particularly from the differential diagnostic point of view to exclude meconium ileus or meconium peritonitis. In case of atresia, a microcolon without the presence of meconium is usually found (Devos and Meradji 2003). 

In ultra-short segment Hirschsprung s disease the barium enema may show a large mega-rectum but no other specific findings. In NID, chronic intestinal pseudo-obstruction and total colonic agangiionosis the barium enema is often non-contributory. However, total colonic agangiionosis may sometimes have the appearance of a microcolon and therefore needs to be differentiated form ileal atresia and meconium ileus. 

Complete absence ofthe colon andrectumisextremely rare. However, segmental atresias or stenosis of the colon are seen more often and are believed to be secondary to an intrauterine vascular insult. Nevertheless they are still quite unusual and are seen much less commonly than atresias in the small bowel. The colon typically accounts for only 5%-15% of total... 

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