A study of the effects of bowel preparation on CEA levels in patients undergoing surveillance colonoscopy.

Mechanical bowel preparation has been postulated to be another cause of "false rise' of serum carcinoembryonic antigen (CEA) levels. Furthermore, it was shown that high-risk patients for colorectal cancer had a greater rise in serum CEA after bowel preparation. To verify these findings, a prospective study of 24 consecutive patients in our surgical endoscopic unit on the effect of mechanical bowel preparation of serum CEA level as carried out from January to March 1994. Blood samples were taken before and after bowel preparation for patients undergoing surveillance colonoscopy for various reasons. Our study did not show any relationship between serum CEA levels and bowel preparation. No rise of serum CEA was found even in high-risk patients after bowel preparation.