Biliary tract infections occur when bacteria infect the bile ducts, which are tubes that carry bile from the liver to the gallbladder and small intestine. These infections can result from blockages, such as gallstones, or conditions that affect bile flow. Symptoms may include fever, chills, abdominal pain, and jaundice. Diagnosis typically involves blood tests, imaging studies like ultrasound or CT scans, and sometimes a cholangiogram to visualize the bile ducts. Treatment usually includes antibiotics to fight the infection and may require procedures to remove blockages or drain infected bile.