SHORT BOWEL SYNDROME

·         Definition-

o   Anatomical- presence of < 200 cm of residual small bowel in adults following intestinal resection.

o   Functional- insufficient intestinal absorptive capacity of the remaining small bowel in setting of intestinal resection leading to the clinical manifestations of diarrhea, dehydration, and malnutrition.

·         Intestinal failure- Inability to maintain nutrition without parenteral support.

·         Etiology- (most common causes listed)

o   Adults-

§  Acute mesenteric ischemia[due to atherosclerosis/thrombosis/vasculitides] (Single operation resection)

§  Malignancy

§  Crohn's disease (usually, Multiple operation resection)

§  Trauma

o   Pediatrics-

§  Intestinal atresia

§  Volvulus

§  Necrotizing enterocolitis

·         Pathophysiology-

o   The type and degree of symptoms depend on-

§  The specific segment (jejunum vs. ileum) resected.

§  The length of the resected segment.

§  The integrity of the ileocecal valve (risk of bacterial overgrowth)

§  Associated large intestine segment resection.

§  Residual disease in the remaining small and/or large intestine (e.g., Crohn's disease, mesenteric artery disease).

§  The degree of adaptation in the remaining intestine.

·         Clinical features

o   Steatorrhoea & diarrhea-

§  Severity- ileal resection with ileocecal valve resection > ileal resection > jejunal resection (because bile salts & Vit B₁₂ are absorbed in ileum)

§  Causes-

·         ↓intestinal absorptive area

·         Stimulation of colonic fluid & electrolyte secretion due to bile acids in colon

·         ↓intestinal transit time & bacterial overgrowth (in ileocecal valve resection)

·         Lactose intolerance (due to removal of lactase secreting segment)

·         Gastric hypersecretion

o   Hyperoxaluria & ↑ renal oxalate stones [seen in ileal resection with intact colon (bile acids and fatty acids increase colonic mucosal permeability thus, ↑oxalate absorption and ↑ binding of calcium by unabsorbed fatty acids, resulting in increased soluble oxalate that is then absorbed)]

o   ↑ cholesterol Gallstones- (due to ↓ bile acid pool size)

o   Gastric Hypersecretion

·         Treatment

o   Medical therapy

§  TotalParenteral Nutrition (TPN)

o   Surgical therapy

§  Non-transplant

·         Goal- To increase nutrient & fluid absorption by either slowing intestinal transit/↑intestinal length.

§  Intestinal transplantation

·         Most common indications-

o   Intestinal failure

o   Impending or overt liver failure

o   Thrombosis of major central veins

o   Frequent episodes of catheter-related sepsis

o   Frequent episodes of severe dehydration.

·         Transplant surgeries-

o   Isolated intestinal transplants (45%)- Isolated intestinal failure

o   Combined intestine/liver transplants (40%)- both intestinal and liver failure

o   Multivisceral transplants (15%)- indicated in giant desmoid tumors involving the vascular supply of the liver, pancreas & intestine, in diffuse GI motility disturbances, and in diffuse splanchnic thrombosis.