Blind Loop Syndrome

• • Intestinal stasis and bacterial overgrowth related to disruption of propulsive forces or other factors that limit bacterial growth

  • Proliferating bacteria deconjugate bile acids, making micellar formation inadequate resulting in increased colonic fatty acids and steatorrhea

  • Megaloblastic anemia results from malabsorption of vitamin B12 .

  • Treatment should be geared toward correcting the anatomic defect predisposing to bacterial overgrowth, or decreasing bacterial concentration through antibiotic treatment

Epidemiology

• • Caused by the disruption of the mechanisms that limit bacterial growth

  • -Peristalsis

    -Interdigestive migrating motor complex

    -Gastric acidity

    -Immunoglobulins

    -Prevention of reflux of colonic contents by the ileocecal valve

  • Strictures, diverticula, fistulas, or poorly emptying segments of intestine cause stagnation and permit bacterial proliferation

  • Stasis of intestinal contents may also result from a functional abnormality of motility (eg, scleroderma)

Symptoms and Signs

• • Steatorrhea

  • Diarrhea

  • Malnutrition

Laboratory Findings

• • Megaloblastic anemia

  • Hypocalcemia

  • Impaired absorption of orally administered vitamin B12

  • Quantitative culture of upper intestinal aspirates (> 105/mL are abnormal)

  • 14C-d-xylose breath test: Anaerobic bacteria in the small bowel metabolize xylose, releasing 14CO2, which is detected in the breath

Imaging Findings

• • Upper GI contrast radiographic study or CT scan: May reveal blind intestinal loop, intestinal stricture, or fistula

• • Steatorrhea is the consequence of bacterial deconjugation and dehydroxylation of bile salts in the proximal small bowel, resulting in micelle formation that is inadequate to solubilize ingested fat

  • Hypocalcemia occurs because calcium is bound to unabsorbed fatty acids in the intestinal lumen

  • Macrocytic anemia is due to malabsorption of vitamin B12 , largely because of binding of the vitamin by anaerobic bacteria

Rule Out

• • Other causes of malabsorption (short bowel syndrome, small intestinal lymphoma, pancreatic exocrine insufficiency, inflammatory bowel disease)

• • CBC

  • Peripheral blood smear

  • Serum calcium

  • Upper GI aspirate with culture

  • 14C-d-xylose breath test

  • GI contrast radiography or CT scan for defining anatomic defects

When to Admit

• • Severe malnutrition

• • Surgical treatment of underlying fistula, blind loop, diverticula, or other lesion

  • In others, treatment consists of broad-spectrum antibiotics and drugs to control diarrhea

Surgery

Indications

• • Anatomic defects amenable to treatment: Fistula, diverticulum, blind loop

Medications

• • Antibiotics

  • Antidiarrheal agents

Treatment Monitoring

• • CBC count

  • Symptomatic control (diarrhea, steatorrhea, malnutrition)

Prognosis

• • Good if anatomic defect can be identified and corrected

References