Pseudothickening of Colonic Wall

Axial and coronal-reformatted CT images of a 58-year-old woman show apparent circumferential wall thickening of the sigmoid colon (arrows) with a smooth transition into the more proximal colon. No pericolonic fat stranding is seen. Colonoscopy was performed but showed no colonic pathology.  Subsequent follow-up CT was also normal.  

Facts:

• When distended, normal colonic wall should be less than 3 mm or even imperceptible
• Fecal contents, fluid or colonic redundancy make true wall measurement difficult or impossible

Pseudothickening of Colonic Wall

• Could be mistaken for true pathology such as annular neoplasm or inflammatory stenosis
• Pseudothickening should be mild. Its margin should gradually return to full distention
• Normal pericolonic fat

References:

Mang T et al. Pitfalls in multi-detector row CT colonography: a systematic approach.. Radiographics 2007;27:431.

Macari M, Balthazar EJ. CT of bowel wall thickening significance and pitfalls of interpretation. AJR 2001;176:1105.