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Anatomic Problems of the Lower GI Tract

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About the Lower GI Tract

Anatomic problems of the lower gastrointestinal (GI) tract are problems related to the structure of the lower GI tract. The parts of the lower GI tract may be in the wrong place, may not be shaped normally, or may not connect normally to other parts of the body.

female doctor examining baby

Anorectal Malformations

Anorectal malformations are birth defects of a child’s anus or rectum that interfere with the normal passage of stool. Anorectal malformations occur when the anus and rectum don’t develop normally before birth.

Colonic Atresia & Stenosis

Colonic atresia is a birth defect in which part of the colon is completely blocked or missing. Colonic stenosis, which may be a birth defect or may develop later in life, is a condition in which part of the colon is more narrow than normal.


Malrotation is a birth defect that occurs when the intestines do not correctly or completely rotate into their normal final position during development. People born with malrotation may develop symptoms and complications, most often when they are babies but sometimes later in life.


Intussusception is a condition in which part of the intestine folds into itself, much like a collapsible telescope. Intussusception is the most common cause of intestinal obstruction in babies and young children, and the condition is rare in adults.

Colonic & Anorectal Fistulas

A colonic fistula is an abnormal tunnel from the colon to the surface of the skin or to an internal organ. An anorectal fistula is an abnormal tunnel from the anus or rectum to the surface of the skin around the anus. Colonic fistulas are usually a complication of surgery, diverticulitis, Crohn’s disease, cancer, or radiation. Anyone can get an anorectal fistula, which arises from an infection in an anal gland.

Rectal Prolapse

Rectal prolapse occurs when the rectum drops down through the anus. Among adults, rectal prolapse is more common in those older than age 50 and more common in women than in men. Rectal prolapse is rare in children.

Colonic Volvulus

Colonic volvulus occurs when the colon twists around the tissue that holds it in place. The most common types of colonic volvulus are sigmoid volvulus and cecal volvulus. Colonic volvulus is more common in older adults.

Clinical Trials

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Your Digestive System & How It Works

The digestive system is made up of the gastrointestinal (GI) tract—also called the digestive tract—and the liver, pancreas, and the gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus.

Related Research

Last Reviewed August 2019

This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.

NIDDK would like to thank:
Samantha Hendren, M.D., M.P.H., University of Michigan, and Joseph Levy, M.D., New York University School of Medicine