Blind 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.
The name of this condition refers to the "blind loop" formed when part of the intestine 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.
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
- As a complication of inflammatory bowel disease
Exams and Tests
During a physical exam, the health care provider may notice a mass in, or swelling of the abdomen. Possible tests include:
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.
Many people get better with antibiotics. If surgical repair is needed, the outcome is often very good.
When to Contact a Medical Professional
Contact your provider if you have symptoms of blind loop syndrome.
Stasis syndrome; Stagnant loop syndrome; Small bowel bacterial overgrowth
Gan T, 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. 21st ed. St Louis, MO: Elsevier; 2022:chap 50.
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.
Review Date 10/26/2021
Updated by: Michael M. Phillips, MD, Emeritus 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.