Toxic megacolon (TM) (also known as toxic dilation) can be a serious complication of inflammatory bowel disease (IBD) and occurs more often with ulcerative colitis (UC) than Crohn's disease (CD). TM is rare and occurs in less than 5% of cases of severe IBD. TM occurs when the colon becomes severely distended, or inflated, and subsequently loses sufficient blood flow, resulting in ischemic or dying tissue. Treating IBD flare-ups before they become severe may help in preventing TM.
Causes of Toxic Megacolon
TM can be spontaneous in people with particularly severe IBD. In some cases, it can result from the overuse of certain drugs, including narcotics; drugs used for pain relief, anticholinergics; drugs used for depression, anxiety and nervousness; and antidiarrheals, such as loperamide. For this reason, it is usually recommended that people with UC do not take over-the-counter antidiarrheal medications without consent from, and close supervision by, a gastroenterologist.Symptoms
Presentations of toxic megacolon include:- Abdominal pain and tenderness
- Distended abdomen
- Rapid heart rate
- Decreased blood pressure
- Leukocytosis (high white blood cell count)
- Evidence of colonic distension on abdominal x-ray
- High fever (40° C [104° F])
- Dehydration
People with TM often appear quite ill and have a history of several days of diarrhea and abdominal pain.
Treatment
Early treatment is important in TM to avoid life-threatening complications, such as shock, colon perforation (a tear in the colon wall), peritonitis (infection in the abdomen) and septicemia (infection in the blood). Left untreated, the colon may rupture, a condition that is fatal in 30% of cases. When treated effectively in the early stages, TM has a fatality rate of less than 4%.The bowel must be decompressed, which is usually accomplished by passing a tube from outside the body in to the colon. If the patient is dehydrated or in shock, IV therapy may be used to replace electrolytes and fluids. Since a rupture may cause a serious infection, antibiotics may be given. Corticosteroids can help suppress the inflammation in the colon.
In severe cases that do not respond to treatment, an emergency partial or total colectomy may be necessary. In a total colectomy, also called a proctocolectomy, the colon is removed. A protocolectomy may be preferred in people with UC, as a j-pouch can then be created during a second surgery, after the recovery from TM. The j-pouch procedure will obviate the need for a permanent ileostomy. Since a proctocolectomy is also a surgical treatment for severe UC, the UC will not recur after surgery. It is not recommended for cases of CD, as the CD may recur in the ileal pouch.
In most cases, once the TM has been effectively treated, the prognosis is very good.
Sources:
A.D.A.M. "Toxic Megacolon." A.D.A.M., Inc 2004. 30 Jul 2009.
Cleveland M. "Toxic Megacolon." Discovery Health 9 Oct 2006. 13 Oct 2008.
