Common bile duct stone (also known as choledocholithiasis) is the presence of a gallstone in the bile duct which is the tube that drains bile from the liver and gallbladder into the small intestine.
The gallbladder is a small sac that sits under the liver and stores bile after it is produced by the liver.
After a meal the gallbladder contracts and empties bile through cystic duct and bile ducts (tubes) into the small intestine to help digest fats. Gallstones are formed in the gallbladder from cholesterol and other material found in bile. A high concentration of cholesterol in bile and conditions such as pregnancy that interfere with normal gallbladder emptying promote gallstone formation.
Gallstones may be tiny or as large as a golf ball.
Occasionally a gallstone will travel out of the gallbladder and become lodged in the common bile duct. It will not pass spontaneously into the small intestine because of the sphincter muscle at the end of the common bile duct.
The obstructing stone will cause pain in the upper abdomen. If infection ensues (cholangitis) the patient will also complain of fever and severe chills.
A stone trapped in the bile duct is suspected when an ultrasound reveals gallbladder stones and blood tests reveal abnormally elevated liver enzymes. On ultrasound the bile duct may also be enlarged or swollen due to the obstruction.
The diagnosis can be confirmed by performing an MRI scan of the bile ducts (MRCP) that will demonstrate the stone in the duct.
A common bile duct stone can be removed by performing Endoscopic Retrograde Cholangiopancreatography (ERCP).
After the patient is deeply sedated, the physician passes a flexible tube (endoscope) through the mouth, esophagus and stomach and into the beginning of the small intestine called the duodenum. At this location, the bile duct drains into the intestine through a small nipple-like opening called the papilla. A plastic tube called a catheter is then passed through the scope, into the papilla and up into the bile duct. Contrast material is then injected into the ducts and images are obtained using an x-ray machine.
After the presence of a stone is confirmed a small incision is made through the sphincter muscle using a wire attached to the side of the catheter. The stone can then be pulled out of the duct into the small intestine.
Although generally safe, ERCP can cause complications such as pancreatitis, infection and intestinal perforation or bleeding.