I've never had a CT scan of my intestines but I have had many colonoscopies over the years. The main advantage that I can think that a colonoscopy would have over a CT scan is that a biopsy could be taken. So really it depends on why you need the investigation doing. If it's for ?Ulcerative colitis then a biopsy would confirm whether you have UC or Crohns disease, which is quite an important diference. Just to warn you though a CT scan won't hurt & a colonoscopy is extremely painful - get plenty of pain relief on board before the procedure!!! Best of luck.