Toxic megacolon

Case contributed by Craig Hacking
Diagnosis certain


Acute colitis of uncertain etiology. Worsening abdominal pain and distension.

Patient Data

Age: 45 years
Gender: Female

Increase in gaseous distension of the distal transverse colon, now measuring up to 80 mm in diameter (2 days ago was 60 mm). The transverse colon and sigmoid colon are both featureless consistent with severe colitis. There is fecal loading in the right side of colon. No evidence of free gas or pneumatosis intestinalis. The appearance is concerning for toxic megacolon.


Fecal material, particularly in sigmoid and rectum, is fluid-like. Mild hyperemia and wall thickening is noted involving proximal sigmoid colon, descending colon to the splenic flexure. Distal transverse colon is featureless and dilated to 72 mm. Mid transverse colon is mildly thick walled with mild hyperemia. Hepatic flexure, ascending colon, cecum within normal limits. No evidence of large or small bowel obstruction. Small bowel within normal limits.

The liver is enlarged spanning 21.4 cm but otherwise normal. Numerous small calculi are noted in the gallbladder without features of cholecystitis. Spleen at the upper limits of normal, 11.8 cm. Adrenal glands and kidneys are within normal limits. Prominent renal pelvis and mild calyceal dilatation is in keeping with hydronephrosis, the ureters can be traced into the bladder, no focal bladder lesions. Gas within the bladder is due to recent catheterization.

No lymphadenopathy.

No suspicious bony lesions. Fusion of the right sacroiliac joint while the left sacroiliac joint demonstrates sclerosis and minor erosions at the inferior aspect.

Right subsegmental lower lobe atelectasis. Small non-circumferential pericardial effusion, no anterior pericardial effusion.


Colitis with some features suggesting inflammatory bowel disease as a possible cause given sacroiliac joint changes.

Case Discussion

The patient was subsequently diagnosed with ulcerative colitis (verbal communication with the treating gastroenterologist).

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