Anatomic variations of the colon detected on abdominal CT scans

Abstract

PURPOSE: The frequency of anatomic variations of the colon detected on abdominal CT scans was examined. MATERIALS AND METHODS: 296 consequtive abdominal tomography were evaluated prospectively for the presence of retrorenal colon, retrogastric (pancreaticogastric interposition or retrosplenic) colon, high positioned colon, interposition of the colon between the psoas muscle and the kidney and hepatodiaphragmatic interposition (anterior or posterior). RESULTS: We observed 2 retrogastric colon [1 pancreaticogastric (0.3%), 1 retrosplenic (0.3%)], 7 retrorenal colon (1.2%) being bilateral in two cases, 2 interposition of colon between the psoas muscle and the kidney (0.7%), 1 posterior (0.3%) and 6 anterolateral hepatodiaphragmatic interposition (2.1%) and 12 high positioned cecum (4.2%) (in 4 of them cecum was totally subhepatic in location). Terminal ileum was lying in Morrison's pouch and anterior to renal hilus in two of the cases with subhepatic cecum. CONCLUSION: Anatomic variations of the colon probably result due to mild embryologic abnormalities of bowel rotation and fixation, short transvers mesocolon, intraperitoneal ascending or descending colon, increased intraperitoneal pressure or decreased retroperitoneal fat. Pancreaticogastric interposition occurs in approximately 0.2%, partial retrorenal colon in 9-10%, complete retrorenal colon 1%, interposition between psoas muscle and kidney in 0.7-1.7%, anterolateral hepatodiaphragmatic interposition in 1.3-3% of individuals. When located in lesser sac it simulates several pathologies of this area. On intravenous urography images it may cause mass effect. In percutaneous interventions and surgical procedures colon may be perforated. For these reasons tomography images should be evaluated for the presence of these anatomic variations.