What is an Enlarged Colon?

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  • Originally Written By: Lucinda Reynolds
  • Revised By: C. Mitchell
  • Edited By: C. Wilborn
  • Last Modified Date: 18 September 2018
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An enlarged colon is a medical condition that happens when a person’s colon becomes stretched or widened, which makes it very difficult for it to process and expel waste. Within the medical community this condition is sometimes also called “megacolon.” It can be either temporary or long-term, and is usually treated with a series of lifestyle and diet changes. In more serious cases anti-inflammatory medications and even surgery may be required, but a lot of this depends on the specifics of the problem and how long it’s been going on.

Colon Basics

The colon is part of the large intestine, and plays a very important role in digestion. Its primary function is to absorb water and salts from food leaving the stomach, and it stores waste until it can be expelled from the body. There are four main parts of this organ: the ascending colon, the descending colon, the transverse colon, and the sigmoid colon. Enlargement can happen in any of these places, but tends to be most common in the descending and transverse portions.


The specific definition of a megacolon tends to vary somewhat depending on the patient, but in general it’s diagnosed whenever any portion of the intestine has a diameter that is at least 25% larger than the standard “normal.” Sometimes this sort of distortion is temporary and may go away on its own, but in other chronic cases it is more or less permanent, or recurs with some frequency.

Main Causes of Enlargement

A number of different things can be at the root of this condition, but the most common tend to be intense constipation, likely due to diet changes; and specific digestive disorders like Crohn’s disease. Crohn’s disease is a chronic inflammatory bowel problem that that affects the thickness of the intestinal wall and the overall efficacy of digestion.

Enlargement can also be caused by long term use of some narcotics, which can dilate blood vessels and damage intestinal tissues. It can be a side effect of certain medications, too. Infections and injury can also be causes, as can certain genetic disorders. Colon cancer can also cause enlargement depending on the nature of the cancerous growths and their placement.

Symptoms and Problems

Extraordinary constipation is usually one of the first signs of a megacolon. A number of different things can cause constipation, but when enlargement is to blame the blockage is usually persistent, which is to say it lasts for days if not weeks, and it is usually also accompanied by intense abdominal pain and cramping. If nerve damage to the inside of the colon happens, it can sometimes impair the peristaltic movement of the colon, too, which is the muscular movement that pushes waste matter through the intestine. Fecal matter can continue to accumulate in the bowel in these cases, and will become hard and very difficult to evacuate.

Infection is also a big concern, particularly if an enlarged colon is left untreated for any period of time. An infected enlargement is often known as a toxic megacolon, and this can become a serious medical condition. Infection can cause waste to build up and can spread fecal matter and other bacteria to other parts of the digestive system and larger body.


In most cases the only way to diagnose this condition is through physical exam. Palpitating or feeling the abdomen can allow a healthcare professional to identify any areas of swelling of tension, and feeling inside the rectum can bring any tissue problems to light. Medical examiners who suspect enlargement after these preliminary steps will often order abdominal X-rays or scans both to confirm the diagnosis and to pinpoint the exact location of the enlargement. In some cases an anorectal manometry is sometimes used, too; this test involves inflating a balloon inside the rectum to test the nerve function.

Treatment Options

The treatment for this condition depends on what is causing the dilatation. If the megacolon is caused by an inflammatory condition or disease, then treating that cause may be enough to reduce the size of the colon back to normal. Sometimes lifestyle changes, particularly where diet is concerned, may be all that is required. Experts usually recommend adding more fiber and drinking more water. In cases where megacolon is a recurrent issue, it is critical that the patient follows the orders of his or her healthcare provider to avoid flare-ups. It’s often the case that enlargements get worse every time they happen. Anti-inflammatory medications may also be prescribed.

There are some cases in which surgery may be necessary to fix the colon, though this normally only happens when other treatments and medications have failed. Surgeons are often able to remove the part of the bowel that is enlarged and either replace it with a graft from another portion of the intestine or simply reattach it, shortening the colon slightly. This doesn’t usually guarantee that no other portion of the intestine can become enlarged, but it usually dramatically reduces the risk.


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