What diseases are colonoscopies used to detect? Ive had one (last december) and it was normal. I was just wondering what diseases/problems this would exclude me from? I know i would not have colitis. And maybe not crohns unless its only in the small intestine atm. When i had the colonoscopy it came back saying i had an infection in the rectum starting with p (i cant remember the name) Does anyone know what this infection maybe called? My dr said it will just clear up in time, which i think it has b/c it caused blood in my stool prior to the colonoscopy, but have not had this since.Also i have had a celiac test which was normal, and a blood test for iron levels which was normal and a blood count (which was normal too). I had these tests 1 month ago.Does anyone know what diseases i would unlikey have b/c these tests came back normal? Or if there are any other diseases which i need other tests to detect?