Gnu - quite right to point that out... and that was one of the things that I found worrying... but it's obviously a calculated risk that you have to take(as with any invasive procedures). However, there was an article in a paper over here this week which highlighted a new experimental procedure (not the one mentioned by guest) which is firstly not as uncomfortable as the colonoscopy, and secondly can be carried out with a more flexible instrument which did not involve the need for a sedative/anaesthetic, and does not carry as high a level of risk.