Thanks for these corrections. Yes, I should have said "fast". And indeed for my recent colonoscopy, I was given laxative, not an enema, it's a sachet of powder that you dissolve in a litre of water; you then have to gulp that down as well as drinking lots of water. Years ago I had a sigmoidoscopy, and then they did give me an enema. That's the only time I've had an enema, and I didn't know what to expect. It was very rapid, and rather dramatic.