Distinction In Stomach

Low Obstruction

Low intestinal obstruction is defined as one occurring in the distal ileum or colon. The symptoms are vomiting, abdominal distension, and failure to pass meconium.

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 atre-sia, Hirschsprung's disease, and functional immaturity of the colon that includes meconium plug

Stomach Collapsed

Fig. 1.17a,b. "Apple peel" mesentery. a Plain radiograph showing dilated proximal loops suggesting high obstruction. b Surgical specimen shows the dilated proximal segment and the collapsed distal segment, which is spiraled around its vascular supply and resembles an "apple peel". The mesentery is short

Fig. 1.17a,b. "Apple peel" mesentery. a Plain radiograph showing dilated proximal loops suggesting high obstruction. b Surgical specimen shows the dilated proximal segment and the collapsed distal segment, which is spiraled around its vascular supply and resembles an "apple peel". The mesentery is short

Dilated Bowel InfantAirless Abdomen

Fig. 1.18a,b. High intestinal obstruction. a Plain radiograph of a newborn infant that shows an airless abdomen with air only in the stomach. Despite the lack of intestinal air, there is distension of the flanks and elevation of the diaphragms. b Sonography demonstrates the abdominal distension to be produced by fluid-filled intestinal loops. At surgery, a proximal ileal atresia was found

Fig. 1.18a,b. High intestinal obstruction. a Plain radiograph of a newborn infant that shows an airless abdomen with air only in the stomach. Despite the lack of intestinal air, there is distension of the flanks and elevation of the diaphragms. b Sonography demonstrates the abdominal distension to be produced by fluid-filled intestinal loops. At surgery, a proximal ileal atresia was found b a syndrome and small left colon syndrome. Anorectal malformations are also an important cause of low intestinal obstruction, but are almost always evident on physical examination.

A low obstruction is usually obvious on the plain film. Plain radiographs in low obstructions are characteristic, always showing multiple dilated air-filled bowel loops, with air-fluid levels in the upright or horizontal beam radiographs. Whether or not a low obstruction is at the level of the distal ileum or at the level of the colon and, in this case, in what part of the colon, is usually impossible to determine from the plain film. The dilated loops occupy the entire abdominal cavity, and the small and large bowel cannot be distinguished from each other. This distinction can be readily made with a contrast enema. Virtually all neonates with evidence of low obstruction require a contrast enema. The critical differential diagnostic finding on the contrast enema of a newborn with low obstruction is the presence or absence of a microcolon. The term microcolon is synonymous with unused colon. The colon in low intestinal obstruction is small, owing to a lack of use rather than anatomic or functional abnormality (Berdon et al. 1968). The caliber ofthe colon depends on the passage of intestinal fluid and desquamate mucosal cells from the jejunum and proximal ileum. These small intestinal contents are termed succus entericus. If little or no succus entericus reaches the colon, it is tiny. In low intestinal obstructions, the fetal colon does not receive sufficient contents from the small intestinal to assume its normal caliber, and, therefore, at birth the colon is usually of very small caliber, generally less than 1 cm, and nondis-tensible. Proximal obstructions such as duodenal or jejunal atresias maintain normal colonic caliber by virtue of passage of succus entericus produced by the remaining small bowel distal to the atresia (Hernanz-Schulman 1999). Normally, meconium reaches the cecum in the fourth month of intrauter-ine life and is in the rectum by the fifth month. The development of obstruction at an early period will consequently prevent the passage of meconium into the colon, leaving this structure collapsed and narrowed, although potentially distensible. In cases of distal small bowel obstruction of relatively recent onset, the colon has had time to attain a normal caliber, and therefore a microcolon is not present. Thus, the presence of a microcolon is diagnostic of a long-standing distal small bowel obstruction, but a normal colon does not exclude this condition in all cases (Dana Veccma et al. 1998). The degree of microcolon in complete obstruction is variable, presumably due to the variable amount of meconium formed by internal secretions below the obstruction. The choice of contrast medium varies among different medical centers. We currently use a low osmolar water-soluble contrast medium.

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