Toxic megacolon

Case contributed by Dr Sinéad Culleton


Recently diagnosed with Crohn disease. Admitted with severe abdominal pain and elevated inflammatory markers.

Patient Data

Age: 20 years
Gender: Female

Distended large bowel


The entire colon is distended, measuring up to 9 cm at the transverse colon and cecum with bowel wall edema and surrounding fat stranding. 

Case Discussion

The imaging features on both x-ray and CT are in keeping with toxic megacolon secondary to Crohn disease

Toxic megacolon is a combination of systemic toxicity and non-obstructive colonic dilatation. As there are many causes of colonic obstruction, the systemic toxicity together with colonic distension (usually taken as 6cm or above at the transverse colon) is considered diagnostic. Colonic distension can be pancolonic or segmental. It is a potentially fatal complication of inflammatory bowel disease or infectious colitis particularly associated with C.difficile. In patients with HIV, CMV colitis is the leading cause of toxic megacolon (1).


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Case information

rID: 40519
Published: 25th Oct 2015
Last edited: 9th Sep 2017
Inclusion in quiz mode: Included

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