I've had two due to a family history of nasty things growing there with both sets of grandparents. The procedure itself isn't anything to worry about but the stuff they give you to drink to clean yourself out is unbearable. Even worse than McDonalds coffee. To make it palatable take some blackcurrant cordial into hospital with you. Not Ribena, get some of that really strong concentrated stuff that Aldi do. They may give you the option of having the 2 or 4 jug mix. Go for the 2 jug mix to get it over and done with in half the time. And keep your runners on, you'll be good for the 4 minute mile!