Preparation for Upper Endoscopy

Your stomach and duodenum must be empty for the procedure to be thorough and safe, so you will not be able to eat or drink anything for at least 6 hours beforehand. Also, you must arrange for someone to take you home—you will not be allowed to drive because of the sedatives. Your physician may give you other special instructions.

Fact sheets on other diagnostic tests:
Colonoscopy ERCP Flexible Sigmoidoscopy	Liver Biopsy Lower GI Series Upper GI Series

source: http://digestive.niddk.nih.gov/ddiseases/pubs/upperendoscopy/index.htm