You will receive accurate preparation instructions the day before the examination. An empty stomach allows for the best and safest examination, so you should have nothing to eat or drink, including water, for approximately ten hours before the examination. Your doctor will tell you when to start fasting. Tell your doctor in advance about any medications you take; you might need to adjust your usual dose for the examination. Tell your doctor of the presence of a pacemaker, previous abdominal surgery, swallowing problem or previous history of obstructions in the bowel.