Bile duct obstruction, which is usually present in acute<unk> , is generally due to gallstones. 10–30% of cases, however, are due to other causes such as benign stricturing (narrowing of the bile duct without an underlying tumor), postoperative damage or an altered structure of the bile ducts such as narrowing at the site of an anastomosis (surgical connection), various tumors (cancer of the bile duct, gallbladder cancer, cancer of the ampulla of Vater, pancreatic cancer, cancer of the duodenum), anaerobic organisms such as Clostridium and Bacteroides (especially in the elderly and those who have undergone previous surgery of the biliary system). Parasites which may infect the liver and bile ducts may cause<unk> ; these include the roundworm Ascaris lumbricoides and the liver flukes Clonorchis sinensis, Opisthorchis viverrini and Opisthorchis felineus. In people with AIDS, a large number of opportunistic organisms has been known to cause AIDS cholangiopathy, but the risk has rapidly diminished since the introduction of effective AIDS treatment.<unk>  may also complicate medical procedures involving the bile duct, especially ERCP. To prevent this, it is recommended that those undergoing ERCP for any indication receive prophylactic (preventative) antibiotics. The presence of a permanent biliary stent (e.g. in pancreatic cancer) slightly increases the risk of<unk> , but stents of this type are often needed to keep the bile duct patent under outside pressure.
Ascending cholangitis
HELLP syndrome
Primary biliary cholangitis
Biliary pseudolithiasis
Gallstone ileus
Cholangitis 
Pancreatic abscess
Recurrent pyogenic cholangitis