Short bowel syndrome presents with a variety of symptoms that may require individualized therapy. Diarrhea is universal and multifactorial. Fat malabsorption (steatorrhea) and carbohydrate malabsorption induce an osmotic diarrhea, while hypersecretion of gastric fluid secondary to hypergastrinemia contributes to a secretory diarrhea. Mineral deficiencies often complicate short bowel syndrome, and vitamin B12 is especially common after ileal resection; however, other water-soluble vitamins are absorbed throughout the small intestine and deficiencies are not typical. Similarly, protein absorption is generally preserved.
Differential diagnosis
Causes of short bowel syndrome
The most common disorders in adults that lead to massive resection of the small intestine are vascular insults and Crohn’s disease (Table 25.1). Risk factors for vascular disease include advanced age, congestive heart failure, atherosclerotic and valvular heart disease, chronic diuretic use, hypercoagulable states, and oral contraceptive use. Less common adult causes include jejunoileal bypass, abdominal trauma, neoplasm, radiation enteropathy, and gastrocolic fistulae. Pediatric causes of short bowel syndrome are intestinal atresia, midgut or segmental volvulus, abdominal wall defects, necrotizing enterocolitis, Hirschsprung disease, hypercoagulable states, cardiac valvular vegetations, Crohn’s disease, and abdominal trauma.
Factors that influence absorption after intestinal resection
The amount of small intestine that remains after resection determines the transit time as well as the surface area available for nutrient, fluid, and electrolyte absorption. Approximately 50% of the small intestine can be resected without significant nutritional sequelae but resections of 75% or more almost invariably produce severe malabsorption that requires enteral or parenteral replacement therapy. Long-term survival has been reported with only 15–48 cm of residual jejunum in addition to the duodenum.
Table 25.1 Causes of short bowel syndrome
| Adult causes | Pediatric causes |
| Intestinal vascular insults Superior mesenteric artery embolus or thrombosis Superior mesenteric artery embolus or thrombosis Superior mesenteric vein thrombosis Volvulus of the small intestine Strangulated hernia Postsurgical causes Jejunoileal bypass Abdominal trauma with resultant resection Inadvertent gastroileal anastomosis for peptic ulcer disease Miscellaneous Crohn’s disease Radiation enteritis Neoplasms | Prenatal causes Vascular accidents Vascular accidents Intestinal atresia Midgut or segmental volvulus Abdominal wall defect Postnatal causes Necrotizing enterocolitis Trauma Inflammatory bowel disease Midgut segmental volvulus Hirschsprung disease Radiation enteritis Venous thrombosis Arterial embolus or thrombosis |
Resection of different small intestinal regions produces distinct consequences. Removal of the jejunum causes only limited defects in macronutrient, electrolyte, and water absorption. Jejunal resection reduces secretion of mucosal hormones that leads to gastric hypersecretion and pancreatic insufficiency. Removal of more than 100 cm of ileum usually precludes bile acid absorption and leads to bile salt-induced secretory diarrhea. The body compensates for this loss by increasing bile acid synthesis up to eightfold. Steatorrhea also results from loss of long ileal segments. The ileum is the primary site for vitamin B12 absorption. Malabsorption of vitamin B12
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