ERCP with cholangioscopy is becoming a widespread technique to treat complicated choledocholithiasis, document CBD clearance after stone extraction and to assess biliary duct strictures. During the procedure, a large amount of water is used to irrigate the common bile duct in order to improve visualization. This can result in CBD distension and may increase the possibility of bacterial translocation and subsequent bacteremia or septicemia. According to the ASGE guidelines, antibiotic prophylaxis prior to ERCP is indicated when biliary duct obstruction is suspected prior to ERCP procedures . There are no current guidelines addressing antibiotics prophylaxis prior to ERCP with cholangioscopy. The investigators recent ACG funded prospective trial examining the risk of bacteremia in ERCP with cholangioscopy have shown the presence of bacteremia in 8.8% of patients undergoing ERCP with cholangioscopy, thus prompting the use of prophylactic antibiotics in patients undergoing these procedures. However the study was not powered to examine factors associated with increased bacteremia and infectious complications. In spite of the use of pre-procedural antibiotics in some of the published series, infectious complications such as cholangitis and sepsis were still reported after the procedure. In the landmark study by Chen et al, in which 297 patients prospectively underwent single-operator cholangioscopy in 15 referral centers across the US and Europe, nine patients developed cholangitis. Antibiotics administration prior to the procedures was left to the standard of practice at each participating institution and was not reported in this study. In a retrospective study by Kalaitzakis et al, nine out of 179 patients who underwent cholangioscopy for CBD stricture or treatment of CBD stones developed cholangitis. Cholangitis was fatal in one case and required prolonged hospitalization in the other case. All patients in this study had antibiotics prophylaxis prior to the procedure. Manta et al had one case of cholangitis in their series of 52 patients who underwent cholangioscopy for CBD stricture. Two patients out of 87 patients had cholangitis in the study by Osania et al., which prospectively included patients who underwent cholangioscopy for CBD stricture. The cholangitis rate in the previously mentioned studies ranged from 2% to 5%. This high rate of post procedure cholangitis in spite of the use of pre-procedural antibiotics suggest that post procedure antibiotics are of value in subsets of patients who will undergo ERCP with cholangioscopy. In the investigators preliminary data, bacteremia rate was significantly higher in patients with CBD strictures who had cholangioscopy with biopsies. It is possible that strictures could lead to colonization of biliary epithelium with bacteria. Obtaining biopsies may cause disruption of the endothelial barrier allowing bacterial translocation. In addition, cholangitis was seen in one patient in the investigators cohort who underwent laser lithotripsy for large stone. Choledocholithiasis is another source of bacterial colonization which could increase the risk of cholangitis after ERCP and cholangioscopy. The investigators protocol objective is to examine the factors that are potentially associated with increased frequency of bacteremia and subsequent infectious complication after ERCP with cholangioscopy in a setting of uniform pre-procedure antibiotics. The investigators hypothesize that biopsy of CBD strictures and Laser Lithotripsy are risk factors for increased rate of bacteremia and infectious complications after ERCP with cholangioscopy.