Blind loop syndrome, sometimes called stasis syndrome or stagnant loop syndrome, occurs from a complication of stomach surgery. The presence of “blind loop” means that the small intestine forms a loop that food avoids during digestion, leading to bacterial overgrowth. This in turn causes diarrhea, weight loss and undernourishment.


Symptoms regarding Blind loop syndrome can include:

  • Diarrhea
  • Stomach pain
  • Discomfort feeling of bloating after eating
  • Feeling nauseated
  • Inability to eat
  • Weight loss


Blind loop syndrome is caused by abnormal movement within the digestive tract, leading to bacterial overgrowth. The small intestine is where food mixes with digestive juices and nutrients, so when food is bypassed, it becomes an ideal area for bacteria to develop, causing blockage in the absorption of nutrients.

Blind loop syndrome can be caused by:

  • Structural problems found in or around the small intestine
  • Complications from major surgeries such as gastric bypass for obesity and gastrectomy to treat ulcers and stomach cancer
  • Medical conditions that slow movement of food and waste products through the small intestine. These include: Crohn’s disease, scleroderma, radiation enteritis, obesity and diabetes.


Complications arising from a blind loop may include:

  • Kidney stones (due to poor calcium consumption)
  • Bone diseases such as Osteoporosis
  • Malnourishment and damage to the small intestine when carbohydrates and proteins are poorly absorbed due to excess of bacteria.
  •  Incomplete absorption of fats (fat soluble vitamins A, D, E) can lead to an inability to eat, diarrhea, and vitamin deficiency disorders.
  • Vitamin B-12 deficiency: Bacteria in the small intestine absorb Vitamin B-12 in order for the nervous system and production of blood cells and DNA to properly function. A shortage of vitamin B-12 can lead to weakness, exhaustion, trembling and lack of feeling in the hands and feet, and in many advanced cases, to mental disorders.

Risk Factors

Factors leading to risks involved in Blind loop syndrome include:

  • Diabetes
  • Gastric surgeries for obesity or ulcers
  • Wound to the small intestine
  • Crohn's disease, intestinal lymphoma or scleroderma
  • Radiation treatments to the abdomen
  • Structural issues regarding the small intestine
  • Diverticulosis of the small intestine
  • Unusual movement in the canal between two segments of bowel