 After informed consent was obtained, the patient was brought to the endoscopy suite.  She was placed in the left lateral position and was given IV Demerol and Versed for sedation.  When adequate level of sedation was achieved, a digital rectal exam was performed, which demonstrated no masses and no hemorrhoids.  The colonoscope was inserted into the rectum and air was insufflated.  The scope was coursed through the rectum and sigmoid colon, descending colon, transverse colon, ascending colon to the level of the cecum.  There were no polyps, masses, diverticuli, or areas of inflammation.  The scope was then slowly withdrawn carefully examining all walls.  Air was aspirated.  Once in the rectum, the scope was retroflexed.  There was no evidence of perianal disease.  No source of the anemia was identified.