Short Bowel Syndrome



Short Bowel Syndrome


Carlos H. Lifschitz



Short bowel syndrome can be caused by prenatal events, such as volvulus, small bowel atresia, gastroschisis or malformation. Acquired causes of the syndrome include necrotizing enterocolitis, volvulus, meconium ileus, massive trauma to the abdomen and, although rarely in children, Crohn disease (Box 359.1). Because most cases occur in the perinatal period, the remaining bowel must be capable of adapting to provide sufficient absorption of water and electrolytes to maintain homeostasis and nutrients sufficient to sustain growth. Compensatory intestinal growth dominated by villous hyperplasia usually occurs within
3 years after resection. In the more severe cases, various degrees of nutrient malabsorption may persist, rendering it impossible for affected patients to sustain life or growth without additional intravenous nutrition. In addition, poor peristalsis as a result of damaged bowel from the initial insult or from narrowing of intestinal surgical anastomosis or peritoneal fibrosis or both may impair enteral nutrition.


Ultimately, total oral or enteral nutrition may be feasible if at least 20 to 30 cm of small bowel remains and the ileocecal valve is intact. During the adaptation period, and sometimes during periods of accelerated growth, the administration of intravenous nutrition may be mandatory. Some patients may tolerate enteral feedings only when they are administered as a constant infusion through a gastrostomy. The degree of nutrient malabsorption that results from a short bowel is related to the extent of the resection, the topography of the segment of bowel resected, and the existence of the ileocecal valve. Removal of the ileocecal valve complicates the clinical condition because it facilitates bacterial overgrowth. In some cases, however, intestinal peristalsis may be affected, and nutrient absorption can be impaired, even when a reasonable length of bowel remains functional.


CLINICAL MANIFESTATIONS AND COMPLICATIONS

Although disaccharidases are more abundant in the jejunum, they occur also in the ileum, and carbohydrate malabsorption may not be severe if the jejunum is resected. Carbohydrate malabsorption can be secondary to decreased surface absorptive area and diminished disaccharidase activity as a result of diminished bowel length, mucosal irritation resulting from gastric hypersecretion (frequently observed in the early phase of extensive small bowel resections), accelerated transit time, and/or small bowel bacterial overgrowth. In the last situation, bacteria may use the carbohydrate before it is absorbed, causing the formation of gas and diarrhea.

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Jul 24, 2016 | Posted by in ORTHOPEDIC | Comments Off on Short Bowel Syndrome
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