My guess is anyone who had a colonoscopy would have the word somewhere in their progress note, so you could search --> Notes and Encounters --> Any Field (contains).
I think it would be easier to do this in advance, say via tracked data or maybe easier to use the Chart ID (Misc. Field 1) and enter colonoscopy and save. Then any time you wanted to pull up patients with a past colonoscopy, you would simply search on that.
Probably a bunch of ways.
