our gi unit does " on demand" endoscopy and it seems to work really well for most patients and saves them a clinic visit. these patients have to be relativly healthy and most of them are screening colonoscopies. ther is a form, an H and P that needs to be completed on arrival and the doctor must do a full assessment. if you check the johns hopkins website and look under the department of gastroenterology, there is a nice form as well as their reccomendations for open access endoscopy. it looks like a good reference tool.