The constitution of bile—bile salts and immunoglobulin secreted by the epithelium of the bile duct also has a protective role. Bacterial contamination alone in absence of obstruction does not usually result in cholangitis. However increased pressure within the biliary system (above 20 cmH2O) resulting from obstruction in the bile duct widens spaces between the cells lining the duct, bringing bacterially contaminated bile in contact with the blood stream. It also adversely affects the function of Kupffer cells, which are specialized macrophage cells that assist in preventing bacteria from entering the biliary system. Finally, increased biliary pressure decreases production of IgA immunoglobulins in the bile. This results in bacteremia (bacteria in the blood stream) and gives rise to the systemic inflammatory response syndrome (SIRS) comprising fever (often with rigors), tachycardia, increased respiratory rate and increased white blood cell count; SIRS in the presence of suspected or confirmed infection is called sepsis. Biliary obstruction itself disadvantages the immune system and impairs its capability to fight infection, by impairing the function of certain immune system cells (neutrophil granulocytes) and modifying the levels of immune hormones (cytokines).In ascending cholangitis, it is assumed that organisms migrate backwards up the bile duct as a result of partial obstruction and decreased function of the sphincter of Oddi. Other theories about the origin of the bacteria, such as through the portal vein or transmigration from the colon, are considered less likely.
Removable plastic stents are used in uncomplicated gallstone disease, while permanent self-expanding metal stents with a longer lifespan are used if the obstruction is due to pressure from a tumor such as pancreatic cancer. A nasobiliary drain may be left behind; this is a plastic tube that passes from the bile duct through the stomach and the nose and allows continuous drainage of bile into a receptible. It is similar to a nasogastric tube, but passes into the common bile duct directly, and allows for serial x-ray cholangiograms to be done to identify the improvement of the obstruction. The decision on which of the aforementioned treatments to apply is generally based on the severity of the obstruction, findings on other imaging studies, and whether the patient has improved with antibiotic treatment. Certain treatments may be unsafe if blood clotting is impaired, as the risk of bleeding (especially from sphincterotomy) is increased in the use of medication such as clopidogrel (which inhibits platelet aggregation) or if the prothrombin time is significantly prolonged. For a prolonged prothrombin time, vitamin K or fresh frozen plasma may be administered to reduce bleeding risk. Percutaneous biliary drainage
In cases where a person is too ill to tolerate endoscopy or when a retrograde endoscopic approach fails to access the obstruction, a percutaneous transhepatic cholangiogram (PTC) may be performed to evaluate the biliary system for placement of a percutaneous biliary drain (PBD).