Lower gastrointestinal bleeding with negative or inconclusive radiographic studies: the role of colonoscopy.

The records of more than 1,000 patients who underwent colonoscopy were reviewed. The study group consisted of 55 of these 1,000 patients who had persistent unexplained bleeding per rectum and negative radiographic examinations. Colonoscopy was helpful in defining the site of bleeding in approximately 50 per cent of the patients studied.