Ascending colon compression by psoas muscle hypertrophy.

Extrinsic compression of the ascending colon was observed on the barium enema of a professional athlete. Ultrasound examination demonstrated psoas muscle enlargement as the cause of this abnormal radiographic finding. The effect of psoas muscle hypertrophy should be considered when extrinsic compression of the colon is observed on the barium enema of muscular individuals. Ultrasound is useful to differentiate anatomic variant from pathological conditions which may deviate the ureters and/or the ascending colon.