|Classification and external resources|
Micrograph of pseudomembranous colitis, a cause of toxic megacolon. H&E stain.
Toxic megacolon (megacolon toxicum) is an acute form of colonic distension. It is characterized by a very dilated colon (megacolon), accompanied by abdominal distension (bloating), and sometimes fever, abdominal pain, or shock.
Toxic megacolon is usually a complication of inflammatory bowel disease, such as ulcerative colitis and, more rarely, Crohn's disease, and of some infections of the colon, including Clostridium difficile infections, which have led to pseudomembranous colitis. Other forms of megacolon exist and can be congenital (present since birth, such as Hirschsprung's disease). Also, it can be caused by Entamoeba histolytica.
Signs and symptoms
- Abdominal pain
- Abdominal bloating
- Abdominal tenderness
- Tachycardia (rapid heart rate)
There may be signs of septic shock. A physical examination reveals abdominal tenderness and possible loss of bowel sounds. An abdominal radiography shows colonic dilation. White blood cell count is usually elevated. Severe sepsis may present with hypothermia or leukopenia.
The objective of treatment is to decompress the bowel and to prevent swallowed air from further distending the bowel. If decompression is not achieved or the patient does not improve within 24 hours, a colectomy (surgical removal of all or part of the colon) is indicated. Fluid and electrolyte replacement help to prevent dehydration and shock. Use of corticosteroids may be indicated to suppress the inflammatory reaction in the colon if megacolon has resulted from active inflammatory bowel disease. Antibiotics may be given to prevent sepsis.
If the condition does not improve, the risk of death is significant. In case of poor response to conservative therapy, a colectomy is usually required. This may involve all or part of the colon being removed, with the resulting option of anastomosis or ileostomy. Ileostomy carries far less risk of infection and postoperative complications because the risk of deterioration of sutures within the intestinal tract (as a result of anastomosis) is not present. The risk of death and shock has been reported to be lower in children, but most children required colectomy in one case-control study.
- Perforation of the colon
Emergency action may be required if severe abdominal pain develops, particularly if it is accompanied by fever, rapid heart rate, tenderness when the abdomen is pressed, bloody diarrhea, frequent diarrhea, or painful bowel movements.
Colonoscopy is contraindicated, as it may rupture the dilated colon resulting in peritonitis and septic shock.
- "Toxic megacolon" at Dorland's Medical Dictionary
- Autenrieth DM, Baumgart DC (August 2011). "Toxic Megacolon". Inflammatory Bowel Diseases. doi:10.1002/ibd.21847.
- Benchimol EI, Turner D, Mann EH, et al. (June 2008). "Toxic megacolon in children with inflammatory bowel disease: clinical and radiographic characteristics". Am. J. Gastroenterol. 103 (6): 1524–31. doi:10.1111/j.1572-0241.2008.01807.x. PMID 18510624.
- Panos MZ, Wood MJ, Asquith P (December 1993). "Toxic megacolon: the knee-elbow position relieves bowel distension". Gut 34 (12): 1726–7. doi:10.1136/gut.34.12.1726. PMC 1374472. PMID 8282262.
- Toxic megacolon. National Institutes of Health. Used as the public domain source for this article. Update on 1/26/2004 by: Sreeni Jonnalagadda, M.D., Interventional and Pancreatobiliary Endoscopy, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.