Synonyms: stasis syndrome, stagnant loop syndrome.

In blind loop syndrome a portion of the small intestine becomes bypassed and thus cut off from the normal flow of food. The digestion of food becomes slow or stops leading to the growth of bacteria and malabsorption.

Pathophysiology

Obstruction to the normal passage of food through the affected segment leads to ineffective bile salt digestion of fats and fat soluble vitamins. The stagnant food ferments, with associated bacterial overgrowth.

Medical problems resulting from blind loop syndrome

• Fat malabsorption, e.g. steatorrhoea, blindness (from vitamin A deficiency), osteoporosis (from vitamin D deficiency)¹
• Inflammation of the small intestine wall leads to malabsorption of protein and carbohydrates
• Vitamin B12 deficiency resulting in a macrocytic anaemia
• Iron deficiency
• Osteoporosis from calcium and vitamin D deficiency

Causes

• Surgery, e.g. Billroth's operation II, Roux-en-Y procedure, gastric bypass for obesity²
• Inflammatory bowel disease, e.g. Crohn's disease
• Scleroderma
• Intestinal duplication
• Diverticulosis of the small intestine
• Diabetes mellitus
• Radiation enteritis

Presentation

• Loss of appetite and early satiety
• Dyspepsia
• Diarrhoea and steatorrhoea
• Bloating, flatulence
• Weight loss
• Nausea

Abdominal examination may reveal cachexia, abdominal distension and evidence of vitamin and mineral deficiencies.

Investigations

• Bloods may reveal:
  • Macrocytic anaemia (due to vitamin B12 deficiency)
  • Hypocalcaemia
  • Iron deficiency
  • Raised INR (due to vitamin K deficiency)
• Abdominal imaging including:
  • Abdominal X-ray
  • Abdominal CT scan
  • Barium studies
• Hydrogen breath test to detect bacterial overgrowth
• Specialised investigations looking at small intestine function:
  • D-xylose breath test
  • Faecal fat test
  • Bile acid breath test
• Small intestine aspirate with fluid culture - invasive and difficult

Specialised investigations and small intestine aspirates are rarely performed.

Management

• The underlying cause should be corrected if possible, e.g. surgical correction
• In many cases surgery is not an option and therapy has two aims:
  • Tackle bacterial overgrowth:
    • Antibiotics are used and may be required for long periods of time.
    • Commonest antibiotics used are the tetracyclines, e.g. oxytetracycline but it is estimated that up to 70% will fail to respond to this.
    • There have been some promising results with rifamixin, which is a non-absorbable antibiotic, but this is not more superior to metronidazole, which should be used as an alternative if there is lack of success with the tetracyclines.³
    • Development of resistance is a problem and antibiotics may need to be changed frequently.
    • Probiotics help in animal studies but their role in humans with bacterial overgrowth is yet to be established.⁴
  • Nutritional supplements - this can involve any of the following:
    • May require nutritional support in hospital or primary care.
    • Vitamin B12 injections.
    • Oral iron supplements.
    • Oral calcium and vitamin D supplements; other vitamin supplements.
    • Medium chain triglycerides (are more readily digested).

Complications

• Malabsorption leading to malnutrition and vitamin deficiencies
• Intestinal infarction
• Complete intestinal obstruction
• Perforation