Duct stones are a common digestive system disease. Depending on the origin of the stones, they can be divided into primary duct stones and secondary duct stones. Primary duct stones refer to stones formed inside the bile duct, mainly composed of pigment stones or mixed stones. Secondary duct stones refer to stones that originate in the gallbladder and then pass into the common bile duct, mainly composed of cholesterol stones. The classic clinical symptoms include paroxysmal upper abdominal pain, chills, fever, and jaundice, known as Charcot’s triad. If the bile duct infection is severe and complicated by acute obstructive suppurative cholangitis, the condition can develop rapidly, and signs of septic shock may occur. Without timely treatment, the patient may die within a short period of time due to circulatory failure. Historically, the approach to treating duct stones was cholecystojejunostomy or laparoscopic common bile duct exploration, but due to the high incidence of surgical complications, slow wound healing, and the development of endoscopic techniques, ERCPs and corresponding minimally invasive techniques have become a preferred treatment for duct stones.

What is ERCP?

Endoscopic retrograde cholangiopancreatography (ERCP) is a diagnostic and therapeutic technique that involves injecting a contrast agent into the bile duct through the ampulla of Vater under endoscopic guidance. On this basis, sphincterotomy can be performed, the duct stones can be removed, and internal drainage procedures such as internal and external biliary drainage under endoscopic guidance can be performed to relieve obstruction, prevent infection, and resolve obstructive jaundice. ERCP has become the current gold standard for diagnosing pancreatobiliary diseases.

Diagnostic and therapeutic value of ERCP

When clinical symptoms of duct stones occur, abdominal ultrasound is generally used as the first-line diagnostic modality. However, abdominal ultrasound can miss duct stones in the middle and lower segments of the bile duct due to interference from abdominal gases, fats, lymph nodes with calcification around the porta hepatis, and postoperative scar tissue outside the bile duct. The diagnostic accuracy rate for duct stones confirmed by abdominal ultrasound is only about 50%. CT is superior to ultrasound in diagnosing duct stones, with a diagnostic accuracy rate of approximately 80%, but CT cannot accurately display pathological changes in the biliary system or the number, size, and distribution of stones. In contrast, ERCP devices provide clear visualization of the ampulla of Vater and the entire biliary tree, enabling accurate determination of the size, number, location, and pathological changes of intrahepatic and extrahepatic bile duct stones. Therefore, ERCP is the most important examination for the preoperative diagnosis of duct stones. However, because the procedure is complicated and the patient experiences pain, non-invasive imaging techniques such as magnetic resonance cholangiopancreatography (MRCP) that do not need a contrast agent can also display the biliary and pancreatic duct systems and the internal stones in the bile duct.

Secondary duct stones are generally small in size and quantity, and can easily become impacted in the lower segment, gallbladder or papillary region of the bile duct. Therefore, ERCPs and endoscopic sphincterotomy (EST) can be performed, after which stone removal through a stone retrieval basket or balloon catheter drag approach may be used. In general, this can completely remove all stones, and complications such as bleeding, perforation, and infection are low, with significant advantages. If the stones are large, with a diameter greater than 1 cm, and are difficult to remove after ERCP and EST, then lithotripsy can be used first, followed by stone retrieval through a stone retrieval basket or balloon catheter. It may be necessary to perform multiple stone removal procedures to completely remove all stones. Due to the high degree of difficulty, this approach increases the risk of surgery and the incidence of complications.

ERCP treatment as a new technique for the diagnosis and treatment of duct stones, compared with traditional surgical approaches, has the advantages of being minimally invasive, with low pain, rapid efficacy, fewer complications and shorter hospital stays. Therefore, it is especially suitable for elderly patients, the weak, or those who have undergone biliary tract surgery, and has been widely accepted and welcomed by patients. Thus, it has become the preferred treatment method for duct stone patients.