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). this is often necessary in the case of a proximal stricture or a bilioenteric anastomosis (a surgical connection between the bile duct and small bowel, such as the duodenum or jejunum). once access across the stricture is obtained, balloon dilation can be performed and stones can be swept forward into the duodenum. due to potential complications of percutaneous biliary drain placement and the necessity of regular drain maintenance, a retrograde approach via ercp remains first-line therapy. cholecystectomy not all gallstones implicated in ascending cholangitis actually originate from the gallbladder, but cholecystectomy (surgical removal of the gallbladder) is generally recommended in people who have been treated for cholangitis due to gallstone disease. this is typically delayed until all symptoms have resolved and ercp or mrcp have confirmed that the bile duct is clear of gallstones. those who do not undergo cholecystectomy have an increased risk of recurrent biliary pain, jaundice, further episodes of cholangitis, and need for further ercp or cholecystostomy; the risk of death is also significantly increased. prognosis acute cholangitis carries a significant risk of death, the leading cause being irreversible shock with multiple organ failure (a possible complication of severe infections). improvements in diagnosis and treatment have led to a reduction in mortality: before 1980, the mortality rate was greater than 50%, but after 1980 it was 10–30%. patients with signs of multiple organ failure are likely to die unless they undergo early biliary drainage and treatment with systemic antibiotics. other causes of death following severe cholangitis include heart failure and pneumonia. risk factors indicating an increased risk of death include older age, female gender, a history of liver cirrhosis, biliary narrowing due to cancer, acute kidney injury and the presence of liver abscesses. complications following severe cholangitis include kidney failure, respiratory failure (inability of the respiratory system to oxygenate blood and/or eliminate carbon dioxide), abnormal heart rhythms, wound infection, pneumonia, gastrointestinal bleeding and myocardial ischemia (lack of blood flow to the heart, leading to heart attacks). epidemiology in the western world, about 15% of all people have gallstones in their gallbladder but the majority are unaware of this and have no symptoms. over ten years, 15–26% will have one or more episodes of biliary colic (abdominal pain due to the passage of gallstones through the bile duct into the digestive tract), and 2–3% will develop complications of obstruction: acute pancreatitis, cholecystitis or acute cholangitis. prevalence of gallstone disease increases with age and body mass index (a marker of obesity). however, the risk is also increased in those who lose weight rapidly (e.g. after weight loss surgery) due to alterations in the composition of the bile that makes it prone to form stones. gallstones are slightly more common in women than in men, and pregnancy increases the risk further. history dr jean-martin charcot, working at the salpêtrière hospital in paris, france, is credited with early reports of cholangitis, as well as his eponymous triad, in 1877. he referred to the condition as "hepatic fever" (fièvre hépatique). dr benedict m. reynolds, an american surgeon, reignited interest in the condition in his 1959 report with colleague dr everett l. dargan, and formulated the pentad that carries his name. it remained a condition generally treated by surgeons, with exploration of the bile duct and excision of gallstones, until the ascendancy of ercp in 1968. ercp is generally performed by internal medicine or gastroenterology specialists. in 1992 it was shown that ercp was generally safer than surgical intervention in ascending cholangitis.