Blind loop syndrome occurs when part of the small intestine forms a loop that food bypasses during digestion. The presence of this "blind loop" means food may not move normally through the digestive tract.
Slowly moving food and waste products become a breeding ground for bacteria. The result — bacterial overgrowth — often causes diarrhea and may cause weight loss and malnutrition.
Sometimes called stasis syndrome or stagnant loop syndrome, blind loop syndrome is often a complication of stomach (abdominal) surgery. But blind loop syndrome can also result from structural problems and some diseases. Sometimes surgery is needed to correct the problem, but antibiotics are the most common treatment.
Signs and symptoms of blind loop syndrome often include:
- Loss of appetite
- Abdominal pain
- An uncomfortable feeling of fullness after eating
- Unintentional weight loss
When to see a doctor
Bloating, nausea and diarrhea are signs and symptoms of many intestinal problems. See your doctor for a full evaluation — especially if you've had abdominal surgery — if you have:
- Persistent diarrhea
- Rapid, unintentional weight loss
- Abdominal pain lasting more than a few days
If you have severe abdominal pain, get immediate medical care.
The small intestine is the longest section of your digestive tract, measuring about 20 feet (6.1 meters). The small intestine is where food mixes with digestive juices and nutrients are absorbed into your bloodstream.
Unlike your large intestine (colon), your small intestine normally has relatively few bacteria. But in blind loop syndrome, stagnant food in the bypassed small intestine becomes an ideal breeding ground for bacteria. The bacteria may produce toxins as well as block the absorption of nutrients.
The greater the length of small bowel involved in the blind loop, the greater the chance of bacterial overgrowth.
What triggers blind loop syndrome?
Blind loop syndrome can be caused by:
- Complications of abdominal surgery, including gastric bypass for obesity and gastrectomy to treat peptic ulcers and stomach cancer
- Structural problems in and around your small intestine, including scar tissue (intestinal adhesions) on the outside of the bowel and small, bulging pouches of tissue that protrude through the intestinal wall (diverticulosis)
- Certain medical conditions, including Crohn's disease, radiation enteritis, scleroderma, celiac disease, obesity and diabetes, can slow movement (motility) of food and waste products through the small intestine
Factors that increase your risk of blind loop syndrome include:
- Gastric surgery for obesity or ulcers
- A structural defect in the small intestine
- An injury to the small intestine
- An abnormal passageway (fistula) between two segments of bowel
- Crohn's disease, intestinal lymphoma or scleroderma involving the small intestine
- History of radiation therapy to the abdomen
- Diverticulosis of the small intestine
A blind loop can cause escalating problems, including:
- Poor absorption of fats. Bacteria in your small intestine break down the bile salts needed to digest fats. As a result, your body can't fully absorb the fat-soluble vitamins A, D, E and K. Incomplete absorption of fats leads to diarrhea, weight loss and vitamin deficiency disorders.
- Damage to the intestinal lining. Toxins that are released when bacteria break down stagnant food harm the mucous lining (mucosa) of the small intestine. As a result, most nutrients, including carbohydrates and proteins, are poorly absorbed, leading to serious malnourishment.
- Vitamin B-12 deficiency. Bacteria in the small intestine absorb vitamin B-12, which is essential for the normal functioning of your nervous system and the production of blood cells and DNA. A severe B-12 deficiency can lead to weakness, fatigue, tingling and numbness in your hands and feet, and, in advanced cases, to mental confusion. Damage to your central nervous system resulting from a B-12 deficiency may be irreversible.
- Brittle bones (osteoporosis). Over time, damage to your intestine from abnormal bacterial growth causes poor calcium absorption, and eventually may lead to bone diseases, such as osteoporosis.
- Kidney stones. Poor calcium absorption may also eventually result in kidney stones.