What is Megacolon?

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  • Written By: J.M. Willhite
  • Edited By: Heather Bailey
  • Last Modified Date: 17 March 2019
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Megacolon is a medical condition characterized by the dilation of the colon, which may be congenital or triggered by the presence of infection or an intestinal obstruction. Regardless of the cause, all presentations of this condition often induce similar symptoms. Treatment is dependent on the underlying cause and often involves the administration of intravenous fluids to prevent dehydration and corrective surgery to restore proper functionality to the colon.

Toxic megacolon is considered to be a life-threatening complication associated with the existence of an underlying intestinal condition. The presence of inflammation and infection contribute to the toxicity of the condition that causes the large intestine to dilate. Symptomatic individuals may experience a variety of symptoms that can include abdominal discomfort, tenderness, and distention. Additional signs of toxicity may include elevated heart rate, fever and nausea, and, in extreme cases, shock.

Congenital megacolon is an intestinal blockage due to impaired muscle movement within the bowel. Due to missing nerves within the bowel, intestinal contents accumulate, causing abdominal distention and bowel dysfunction. Often diagnosed in infancy, this condition causes newborns to develop constipation, abdominal distention, and vomiting. Additional symptoms may include the absence of a first stool (merconium), jaundice, and watery diarrhea.


A primary intestinal obstruction may occur in either the small or large intestine and may present as an acute or chronic condition. Frequently diagnosed in children and the elderly, this form of colonic dilation is idiopathic in nature, meaning there is no known cause in the absence of inflammation or infection. Individuals with chronic conditions, such as cerebral palsy or other neurological disorders, or those who are bedridden usually possess an increased risk for developing this condition. Those who become symptomatic with non-toxic forms of colon dilation may experience abdominal discomfort, nausea, and vomiting.

Diagnostic tests used to confirm the presence of colon dilation vary. In the presence of abdominal distention, a physical examination and palpation of the affected area may be performed. Any abnormalities discovered during a preliminary examination will usually prompt additional testing. If toxic megacolon is suspected, additional testing may include the administration of an abdominal X-ray and blood tests to evaluate electrolyte levels and detect the presence of any markers indicative of infection.

Infants suspected of having congenital megacolon may be given a barium enema and abdominal X-ray to confirm the presence of intestinal dysfunction. A rectal examination may determine the presence of impaired rectal muscle tone, which can contribute to symptom manifestation. In some cases, an anal manometry may also be performed to evaluate rectal pressure.

If an intestinal obstruction is suspected, a barium test may be conducted to confirm the presence and location of the blockage. Prior to testing, an individual is given barium, either orally or as an injection, which is then tracked with the use of X-ray to evaluate the condition and functionality of the upper GI tract and related organs, including the intestines. An esophageal manometry may be performed to evaluate the condition of the esophagus and intestinal function may be assessed with an intestinal radionuclide scan.

Treatment for the toxic condition is multi-faceted in approach. To reverse the effects of the condition, intravenous fluids may be administered to prevent dehydration and, if the colon has become perforated, a partial or complete excision of the colon, known as a colectomy, may be performed. In order to prevent the spread of infection, which can lead to sepsis, antibiotics may also be administered. Due to a significant risk for death, prompt and appropriate treatment for colonic dilation is essential. Complications associated with this condition may include shock, sepsis, and colon perforation.

Congenital megacolon often necessitates the removal of the abdominal portion of the colon and the rectum. The remaining colonic tissue is utilized to function in place of the excised portion. Prior to surgery, the bowel is decompressed to alleviate pressure and allow for easier manipulation of the organ. The procedure is often conducted during two separate surgeries, and both may be completed before the child is a year old. Complications associated with this corrective surgery can include short bowel syndrome, intestinal inflammation, and intestinal perforation.

Non-toxic, colonic dilation may also be treated with medication and surgery. A colonoscopy may be used to alleviate accumulated air and intravenous fluids may be administered to prevent dehydration that may result from excessive nausea and vomiting. Additional treatment for this potentially, recurrent condition may include the use of nasogastric suction, which involves the positioning of a nasogastric (NG) tube to decompress the bowel, and an implementation of dietary changes. Individuals with this condition generally demonstrate improvement within days of treatment. Complications may include diarrhea, unintentional weight loss, and mineral and vitamin deficiencies.


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Post 2

@Lostnfound -- Wow. I had no idea cats could get megacolon! I've had cats all my life, and none of them have ever had that problem, thank goodness.

Post 1

Pets -- especially cats -- can also get megacolon, which can be very serious. In cats, it usually causes constipation, and pet owners will need to be vigilant about making sure their pets are having regular bowel movements. The pet will often need to be on a special diet and if overweight, will need to lose weight, since obesity may be a contributing factor in pets.

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