How do you decide which patients get antibiotics before their endoscopic procedures and which do not? Perhaps you consider the patient's risk factors and the procedure she's about to undergo. Or perhaps you've developed your own protocols. Whatever you do, the scientific evidence backing it is probably pretty slim - controlled studies on the effectiveness of prophylactic antibiotics are rare. To strengthen your footing, I set out to find the most recent indications for administrating antibiotics to endoscopy patients. I pored over journals, committee recommendations, statistics, verdicts and testimony from gastroenterologists from over the past two decades. Here's what I found out.