a picture of the biliary tree.
                                                            
                                                     
                        
                                                
                        
                        
                            a safeguard for the patient since it helps to confirm that the surgeon has properly identified the anatomy and also the lack of any ductal injury
                                                            
                                                     
                        
                                                
                        
                        
                            a test where dye is introduced into the biliary system and outlines the system so that the anatomy is more readily identified