ABSTRACT
Carcino-embryonic antigen [CEA] is probably the foremost oncofetal antigen known. CEA was first thought to be a specific indicator for the presence of colorectal carcinoma, but it was found elevated in many benign conditions and other many causes. Of the study was to assess the effect of bowel preparation on CEA levels in patients undergoing colonoscopy or barium enema. The study included forty patients divided into two groups undergoing bowel preparation for colonoscopy and barium enema for different indications, excluding those with cancer colon and inflammatory bowel disease. CEA was measured before and after bowel preparation but before colonoscopy or radiology using ELISA technique. The cases were presented with bleeding pre rectum, diarrhoea, constipation and chronic abdominal pain. The mean level of CEA in patients prepared for colonoscopy was 4.8 +/- 5.20 ng/dl and was 6.6 +/- 6.28 ng/dl before and after preparation respectively, while in patients prepared for barium enema, the mean of CEA was 3.15 +/- 4.04 ng/dl and 11.62 +/- 10.10 ng/dl before and after preparation respectively. There was an increase in the level of CEA after bowel preparation in both groups, with more significant rise in patients prepared for barium enema group. The rise of CEA after bowel preparation is one of false positive causes of rise in serum CEA