Narrow ish tube down your throat slightly thicker one up back stairs as t'were... they go through a long and complex cleaning, and chemical sterilisation process between each patient,,, How you are positioned will vary but you will have a member of the nursing team holding you in position and supporting you two years of 5 endoscopy lists a week as a nurse plus two cystoscopy (up into the bladder,,,) the only problems we had were due to people being too drowsy after the sedation and needing to sleep it off... one list a week was very different and far more complex but only one problem with that that was resolved with injections to stop an allergic reaction,,, they will be available just in case but normally go out of date without ever being used