The mechanisms involved in development of toxic megacolon are not entirely clear, although chemical mediators such as nitric oxide and interleukins are thought to play a pivotal role in its pathogenesis 5.
The colon (typically transverse colon) becomes dilated to at least 6 cm (usually greater). There is additional loss of haustral markings, with pseudopolyps often extending into the lumen. Thumbprinting from mucosal oedema may be present. There may be signs of pneumoperitoneum if dilatation has progressed to cause perforation.
- barium studies and colonoscopy should be avoided, due to the risk of perforation
- 1. Thoeni RF, Cello JP. CT imaging of colitis. Radiology. 2006;240 (3): 623-38. Radiology (full text) - doi:10.1148/radiol.2403050818 - Pubmed citation
- 2. Norland CC, Kirsner JB. Toxic dilatation of colon (toxic megacolon): etiology, treatment and prognosis in 42 patients. Medicine (Baltimore). 1969;48 (3): 229-50. Pubmed citation
- 3. Imbriaco M, Balthazar EJ. Toxic megacolon: role of CT in evaluation and detection of complications. Clin Imaging. 2001;25 (5): 349-54. Pubmed citation
- 4. Moulin V, Dellon P, Laurent O et-al. Toxic megacolon in patients with severe acute colitis: computed tomographic features. Clin Imaging. 2011;35 (6): 431-6. doi:10.1016/j.clinimag.2011.01.012 - Pubmed citation
- 5. Gan SI, Beck PL. A new look at toxic megacolon: an update and review of incidence, etiology, pathogenesis, and management. Am. J. Gastroenterol. 2003;98 (11): 2363-71. doi:10.1111/j.1572-0241.2003.07696.x - Pubmed citation