Blind loop syndrome, also called stagnant loop syndrome, is a rare condition that occurs when food stops moving through or slows down through part of your small intestines. Bacteria can overgrow in the stagnant part of your intestines.

Blind loop syndrome can occur as a complication of:

  • abdominal surgery
  • anatomical differences
  • gastrointestinal disorders that impede the mobility of food through your gut

Blind loop syndrome can lead to nutritional deficiencies and other problems like diarrhea or anemia. The outlook varies widely depending on the underlying cause. You may require surgery to treat the underlying condition and nutritional support to correct nutritional disorders.

Read on to learn more about blind loop syndrome, including causes, symptoms, and treatment options.

Blind loop syndrome is rare, and there’s insufficient research to estimate how common it is since it often goes undiagnosed or misdiagnosed. It may be confused with other digestive conditions like:

Signs and symptoms of blind loop syndrome are vague and can often be mistaken for those of another gastrointestinal condition. They can include:

Blind loop syndrome usually develops due to anatomic abnormalities, including:

  • surgical side effects like scarring, fistulas, or stricture (narrowing of your intestines)
  • afferent loop syndrome, a complication of stomach surgery
  • jejunal diverticulosis, small pouches in the middle section of your small intestines
  • anastomosis, the surgical attachment of two parts of your intestines

It can also develop due to mobility or inflammatory diseases, such as:

Blind loop syndrome can lead to small intestine bacterial overgrowth (SIBO), which can impair fat absorption and the absorption of some vitamins and minerals. Potential complications of the nutrient deficiencies include:

Nutrient deficiencyComplications
Vitamin Axeropthalmia, a progressive eye disease
night blindness
Vitamin D• secondary hyperparathyroidism
muscle weakness
Vitamin Kbruising
black stools
blood in urine
irregular menstruation
Vitamin Eneuropathy
nystagmus, involuntary and rapid eye movements
• trouble with muscle function
Calciumbrittle bones
• heart rhythm problems

Other complications include:

  • muscle spasticity or paraplegia due to chronic vitamin B12 deficiency
  • softening of your bones
  • retroperitoneal hemorrhage, a life threatening condition where fat malabsorption depletes vitamin K stores and impairs blood clotting. It has a mortality rate of around 18%.

Blind loop syndrome is difficult to diagnose because it requires a high degree of suspicion to rule out other potential causes of your symptoms.

Imaging plays an important role in diagnosing blind loop syndrome. Potential imaging tests you might receive include:

Breath tests and bacteria cultures can help rule out other conditions and support the diagnosis. They include:

Treatment goals for blind loop syndrome treatment are:

  • reducing the overgrowth of bacteria in your gut
  • correcting nutritional deficiencies
  • managing other symptoms


The traditional antibiotic treatment to resolve bacterial overgrowth has been tetracyclines, but newer research suggests that rifaximin and metronidazole may be more effective. Usually, antibiotics are prescribed for 7–10 days.

Blind loop syndrome surgery

Surgery may be required if an anatomical difference is causing your symptoms. You may need surgery to remove a blockage in your gut or to remove stagnant sections of your intestines.

Blind loop syndrome diet

Nutritionists or dietitians often recommend a high calorie and low fat diet for people with blind loop syndrome. You may also need intramuscular vitamin B12 injections or oral vitamin and mineral supplements.

It’s important to contact a doctor if you have frequent and concerning gastrointestinal problems or unexplained weight loss. It’s particularly important if you’ve recently had abdominal surgery, to rule out potential complications.

Here are some frequently asked questions people have about blind loop syndrome.

Why is it called blind loop?

The name “blind loop” refers to a section of your small intestine that food bypasses. This area is called a blind pouch.

Is blind loop syndrome the same as SIBO?

Blind loop syndrome is characterized by food bypassing part of your small intestines, which often leads to bacterial overgrowth. SIBO is the overgrowth of bacteria in your small intestines and a potential characteristic of blind loop syndrome.

What’s the difference between afferent loop syndrome and blind loop syndrome?

Afferent loop syndrome is a complication of stomach surgery where your digestive juices become trapped in your upper small intestines and can back up into your stomach.

Blind loop syndrome is a rare condition characterized by stool bypassing or slowing down through a section of your small intestines. It can lead to bacterial overgrowth and nutritional deficiencies.

Treatment for blind loop syndrome may include antibiotics, surgery, and nutritional support. It’s important to see a doctor any time you have persistent gastrointestinal symptoms, especially if you’ve recently had abdominal surgery.