Patients should closely follow their physician’s advice about all the preparatory measures necessary before an endoscopy. Patients usually are asked to stop eating for several hours prior to or the night before the procedure, because food that is present may obstruct the physician’s view of the digestive tract and potentially cause the patient to vomit during the procedure. Patients may also be advised to change their medication routine. For example, taking aspirin just prior to an upper endoscopy could cause false readings on some tests.

Patients scheduled to have an endoscopy of the lower gastrointestinal tract usually have to take laxatives and may be asked to undergo an enema prior to the procedure to ensure that the colon is empty of stool. They also are asked to avoid solid food for several days prior to the procedure.