What causes constipation? - Explained 9 & 10

Problems with the Colon and Rectum

Intestinal obstruction, scar tissue—also called adhesions—diverticulosis, tumors, colorectal stricture, Hirschsprung disease, or cancer can compress, squeeze, or narrow the intestine and rectum and cause constipation.

Problems with Intestinal Function

The two types of constipation are idiopathic constipation and functional constipation. Irritable bowel syndrome (IBS) with predominant symptoms of constipation is categorized separately.

Idiopathic—of unknown origin—constipation does not respond to standard treatment.

Functional constipation means that the bowel is healthy but not working properly. Functional constipation is often the result of poor dietary habits and lifestyle. It occurs in both children and adults and is most common in women. Colonic inertia, delayed transit, and pelvic floor dysfunction are three types of functional constipation. Colonic inertia and delayed transit are caused by a decrease in muscle activity in the colon. These syndromes may affect the entire colon or may be confined to the lower, or sigmoid, colon.

Pelvic floor dysfunction is caused by a weakness of the muscles in the pelvis surrounding the anus and rectum. However, because this group of muscles is voluntarily controlled to some extent, biofeedback training is somewhat successful in retraining the muscles to function normally and improving the ability to have a bowel movement.

Functional constipation that stems from problems in the structure of the anus and rectum is known as anorectal dysfunction, or anismus. These abnormalities result in an inability to relax the rectal and anal muscles that allow stool to exit.

People with IBS having predominantly constipation also have pain and bloating as part of their symptoms.