If gallstones form in the biliary system they can cause blockage of the bile ducts, which normally drain bile from the gallbladder and liver. Occasionally the gallstones can also block the flow of digestive enzymes from the pancreas because both the bile ducts and pancreas ducts drain through the same small opening (called the Ampulla of Vater) which is held tight by a small circular muscle (called the Sphincter of Oddi). [See Figure 1 below]. This results in inflammation of the pancreas and is known as gallstone pancreatitis. Blockage of the bile ducts may cause symptoms such as abdominal pain, nausea and vomiting. If the bile duct remains blocked bile is unable to drain properly, jaundice (yellow discoloration of the eyes and skin) can develop and an infection known as cholangitis may also occur.