Blind loop syndrome
Stasis syndrome; Stagnant loop syndrome; Small bowel bacterial overgrowthBlind loop syndrome occurs when digested food slows or stops moving through part of the intestines. This causes an overgrowth of bacteria in the intestines. It also leads to problems absorbing nutrients.
Causes
The name of this condition refers to the "blind loop" formed by part of the intestine that is bypassed. This blockage does not allow digested food to flow normally through the intestinal tract.
The substances needed to digest fats (called bile salts) do not work as they should when a section of the intestine is affected by blind loop syndrome. This prevents fat and fat-soluble vitamins from being absorbed into the body. It also leads to fatty stools. Vitamin B12 deficiency may occur because the extra bacteria that form in the blind loop use up this vitamin.
Vitamin B12
Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the bo...

Blind loop syndrome is a complication that occurs:
- After many operations, including subtotal gastrectomy (surgical removal of part of the stomach) and operations for extreme obesity
Gastrectomy
Gastrectomy is surgery to remove part or all of the stomach. If only part of the stomach is removed, it is called partial gastrectomyIf the whole sto...
ImageRead Article Now Book Mark Article - As a complication of inflammatory bowel disease
Inflammatory bowel disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
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Diseases such as diabetes or scleroderma may slow down movement in a segment of the intestine, leading to blind loop syndrome.
Diabetes
Diabetes is a long-term (chronic) disease in which the body cannot regulate the amount of sugar in the blood.

Scleroderma
Scleroderma is a disease that involves the buildup of scar-like tissue in the skin and elsewhere in the body. It also damages the cells that line th...

Symptoms
Symptoms include:
- Diarrhea
- Fatty stools
- Fullness after a meal
Fullness after a meal
Gas is air in the intestine that is passed through the rectum. Air that moves from the digestive tract through the mouth is called belching. Gas is ...
ImageRead Article Now Book Mark Article - Loss of appetite
Loss of appetite
A decreased appetite is when your desire to eat is reduced. The medical term for a loss of appetite is anorexia.
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Nausea
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up is forcing the contents of the stomach ...
ImageRead Article Now Book Mark Article - Unintentional weight loss
Unintentional weight loss
Unexplained weight loss is a decrease in body weight, when you did not try to lose the weight on your own. Many people gain and lose weight. Uninten...
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Exams and Tests
During a physical exam, the health care provider may notice a mass in, or swelling of the abdomen. Possible tests include:
- Abdominal CT scan
Abdominal CT scan
An abdominal CT scan is an imaging method. This test uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomog...
ImageRead Article Now Book Mark Article - Abdominal x-ray
Abdominal x-ray
An abdominal x-ray is an imaging test to look at organs and structures in the abdomen. Organs include the spleen, stomach, and intestines. When the ...
ImageRead Article Now Book Mark Article - Blood tests to check nutritional status
- Upper GI series with small bowel follow through contrast x-ray
Upper GI series
An upper GI and small bowel series is a set of x-rays taken to examine the esophagus, stomach, and small intestine. Barium enema is a related test th...
ImageRead Article Now Book Mark Article - Breath test to determine if there are excess bacteria in the small intestine
Treatment
Treatment most often starts with antibiotics for the excess bacteria growth, along with vitamin B12 supplements. If antibiotics are not effective, surgery may be needed to help food flow through the intestines.
Outlook (Prognosis)
Many people get better with antibiotics. If surgical repair is needed, the outcome is often very good.
Possible Complications
Complications may include:
- Complete intestinal obstruction
Intestinal obstruction
Intestinal obstruction is a partial or complete blockage of the bowel. The contents of the intestine cannot pass through it.
ImageRead Article Now Book Mark Article - Death of intestine (intestinal infarction)
Intestinal infarction
Intestinal ischemia and infarction occurs when there is a narrowing or blockage of one or more of the arteries that supply the small intestine....
ImageRead Article Now Book Mark Article - Hole (perforation) in intestine
- Malabsorption and malnutrition
Malabsorption
Malabsorption involves problems with the body's ability to take in (absorb) nutrients from food.
ImageRead Article Now Book Mark ArticleMalnutrition
Malnutrition is the condition that occurs when your body does not get enough nutrients.
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When to Contact a Medical Professional
Call your provider if you have symptoms of blind loop syndrome.
References
Harris JW, Evers BM. Small intestine. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice. 20th ed. Philadelphia, PA: Elsevier; 2017:chap 49.
Shamir R. Disorders of malabsorption. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 364.
Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
Stomach and small intestine - illustration
The stomach connects the esophagus to the small intestines and is where the majority of food digestion takes place.
Stomach and small intestine
illustration
Biliopancreatic diversion (BPD) - illustration
Malabsorptive operations, such as biliopancreatic diversion (BPD), restrict both food intake and the amount of calories and nutrients the body absorbs. In a BPD procedure, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, completely bypassing the upper part of the intestines. A common channel remains in which bile and pancreatic digestive juices mix prior to entering the colon. Weight loss occurs since most of the calories and nutrients are routed into the colon where they are not absorbed.
Biliopancreatic diversion (BPD)
illustration
Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
Stomach and small intestine - illustration
The stomach connects the esophagus to the small intestines and is where the majority of food digestion takes place.
Stomach and small intestine
illustration
Biliopancreatic diversion (BPD) - illustration
Malabsorptive operations, such as biliopancreatic diversion (BPD), restrict both food intake and the amount of calories and nutrients the body absorbs. In a BPD procedure, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, completely bypassing the upper part of the intestines. A common channel remains in which bile and pancreatic digestive juices mix prior to entering the colon. Weight loss occurs since most of the calories and nutrients are routed into the colon where they are not absorbed.
Biliopancreatic diversion (BPD)
illustration
Review Date: 10/17/2019
Reviewed By: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.