Intrahepatic choledocholithiasis refers to the formation of stones in the bile ducts anywhere above the confluence of the left and right hepatic ducts. In the past two decades, due to the increasing understanding of the pathophysiology of intrahepatic bile duct stones, and especially the extensive use of modern hepatobiliary techniques, the efficacy of intrahepatic bile duct stones has been greatly improved.
Intrahepatic bile duct stones are mostly brown stones rich in bilirubin calcium salts, soft and friable in texture. Studies have shown that even in patients with intrahepatic bile duct stones with only one side involved, there is a significant impairment of biliary flow dynamics throughout the liver. Impaired biliary flow dynamics can lead to the development of bacterial biliary disease. Bacterial glucuronidase and phosphatase in the bile hydrolyze conjugated soluble glucuronide bilirubin and lecithin into unconjugated bilirubin calcium salts and fatty acid calcium soaps, and calcium salts are continuously deposited to form stones. Long-term chronic inflammatory irritation eventually leads to atrophic changes in the liver parenchyma and, if the entire liver is involved, to biliary cirrhosis and portal hypertension. Chronic inflammatory irritation can also induce the occurrence of bile duct cancer, and the percentage of patients with intrahepatic bile duct stones combined with bile duct cancer can be as high as 10% or more. Long-term chronic inflammation also often leads to narrowing of the corresponding bile ducts, which further contributes to stone formation by affecting bile flow.
The most clinically significant anatomical-pathological feature of intrahepatic bile duct stones is the regional distribution of stones strictly along the diseased bile duct tree in the liver. This feature makes hepatic resection an important part of the treatment of intrahepatic bile duct stones. Hepatic resection removes not only the stone and the stenosis that caused it, but also the liver parenchyma that has been destroyed by chronic inflammation and the possible presence of bile duct cancer. Hepatic resection is the most effective treatment for intrahepatic bile duct stones because it eliminates the entire causal event occurring in the liver.
The indications for hepatic resection of intrahepatic choledocholithiasis include two aspects.
1. Significant atrophy of the involved liver segment or lobe;
2, multiple bile duct strictures in the involved liver segment or lobe, and obvious dilatation of the surrounding bile ducts, which are difficult to deal with, especially when the lesion is located in the left hemisphere or left outer lobe. Based on its anatomic-pathological characteristics, the basic strategy for hepatic resection treatment of intrahepatic bile duct stones is to perform regular hepatic resection according to Couinaud functional segmentation.
Unlike hepatic resection for primary liver cancer and other liver tumors, hepatic resection for intrahepatic bile duct stones has significant characteristics.
The liver to be resected often has obvious atrophy, and there is a clear demarcation between the atrophied liver and the adjacent normal liver segments or lobes;
2, The proximal opening of the bile duct in the affected liver segment or lobe is often narrowed, and hepatic resection requires complete removal of the diseased bile duct;
3. When the lesion is located in the right hepatic half, lobe atrophy and secondary compensatory hyperplasia of the left hepatic half (atrophy-proliferative complex) will cause the liver to rotate along the longitudinal axis of the body, causing displacement of the hepatic portal structures and making surgery difficult;
4, Intrahepatic bile duct variability, improper treatment may also easily cause residual stones or damage to the bile ducts of adjacent liver segments or lobes;
5. The resected specimens should be carefully examined and undergo rapid pathology, and radical surgery should be performed if necessary.
Therefore, for the treatment of intrahepatic bile duct stones, accurate and comprehensive hepatic bile duct imaging data is indispensable, whether from the consideration of treatment effect or from the consideration of surgical safety. Special attention should be paid to the variation of the right anterior or right posterior lobe bile ducts. The right anterior or right posterior lobe bile ducts may merge into the left hepatic duct, or they may merge into the common hepatic duct to form the so-called “secondary hepatic portal”. There are also two major variations in the anatomy of the left hepatobiliary duct: one is that segments II and III of the left outer lobe converge behind the angle of the left branch of the portal vein and then merge with segment IV of the left inner lobe to form the left hepatic duct; the other is that segment IV first converges with segment III and then with segment II to form the left hepatic duct. All of these variants should be paid special attention during the localization and diagnosis of intrahepatic bile duct stones and hepatectomy [IU5].
Currently, advanced diagnostic imaging methods are available to enable us to obtain clear and comprehensive hepatobiliary imaging data preoperatively. High-quality CT or MRI is indispensable for the qualitative and localized diagnosis of intrahepatic bile duct stones, and MRCP can provide complete biliary images. Therefore, most patients with intrahepatic bile duct stones do not require invasive cholangiography preoperatively. the greatest advantage of MRCP is that it is noninvasive and it is an image of the bile ducts in a physiological state, free from stone obstruction. its disadvantage is that the image quality is much inferior to direct imaging and its resolution is limited. Therefore, surgery for intrahepatic bile duct stones must be performed under the guidance of direct cholangiography and/or cholangioscopy. The recommended practice is to perform intraoperative cholangiography first and compare it with preoperative images, followed by procedures such as hepatectomy and finally re-imaging to confirm the presence of residual stones. It should be noted that the posteriorly oriented right posterior lobe bile ducts overlap with the right anterior lobe bile ducts in the orthogonal cholangiogram and are difficult to distinguish. In addition, bile ducts filled with stones may be missed in cholangiography. Therefore, when interpreting cholangiography images, each bile duct should be carefully examined to confirm and, if necessary, a full cholangioscopic examination should be performed. Clinically, intrahepatic bile duct stones are most commonly found in the left hemisphere or left outer lobe. In the case of a “secondary hilar” variant, the opening of the variant bile duct may be very low and must not be missed.
It should be clear that hepatic resection is only one method of the comprehensive treatment system for intrahepatic bile duct stones, and it is meaningless to talk about hepatic resection without the specific clinical status. Whether it is the mastering of the indications for hepatic resection or the selection of the specific operation, it should be combined with the actual situation of the patient, and based on the five basic principles of removing the lesion, removing the stone, correcting the stricture, clearing the bile flow and preventing the recurrence, combined with the intrahepatic bile duct stone extraction and stricture repair and shaping, the patient should be treated systematically and standardized in order to achieve satisfactory treatment results.
At present, there is no unified classification method for intrahepatic bile duct stones internationally, which to some extent affects the standardization of intrahepatic bile duct stone treatment and makes it difficult to compare the clinical data of different treatment centers in a comprehensive manner. The Japanese Hepatolithiasis Research Group classified intrahepatic bile duct stones into intrahepatic type (TypeI) and intra- and extrahepatic type (Type
IE), and further classified intrahepatic bile duct stones into Type R (stones in the right hepatic half), Type L (stones in the left hepatic half), Type LR (stones in both the left and right hepatic halves), and Type C (stones in the caudal lobe) according to the distribution of stones within the liver. This typing method is mainly based on the distribution of stones in the liver, which is relatively simple, but has little significance in guiding clinical treatment.
In order to better standardize and guide the clinical treatment of intrahepatic bile duct stones, the Biliary Surgery Group of the Chinese Society of Surgery proposed the “Clinicopathological classification of intrahepatic bile duct stones” based on the clinical data of more than 1000 cases of intrahepatic bile duct stones [8]. Based on the distribution of stones in the liver and the degree of liver lesions caused, intrahepatic bile duct stones were classified into three types, and on this basis, the corresponding clinical treatment guidelines were proposed.
Type I: i.e., limited type, the stones are confined to a certain hepatic or subhepatic bile duct, the affected liver and bile duct lesions are mild, and the clinical manifestations are mostly stationary.
Type II: Regional type, the stones are distributed regionally along the intrahepatic bile ducts, filling one or several hepatic segments, often combined with stenosis of the hepatic ducts and atrophy of the affected hepatic segments, the clinical presentation may be obstructive or cholangitis type.
Type III: Diffuse type, with stones spread in the bile ducts of both hepatic lobes, and subdivided into three subtypes according to the parenchymal lesions of the liver.
Type IIIa: diffuse type without regional destruction, stones are widely distributed in the intrahepatic bile ducts without significant parenchymal atrophy and fibrosis.
Type IIIb: Diffuse type with regional destruction, with stones widely distributed in the intrahepatic bile ducts and associated with segmental atrophy and fibrosis of the liver parenchyma, usually combined with severe stenosis of the atrophic liver segment draining the bile ducts.
Type IIIc: and diffuse type with biliary hepatic steatosis, stones are widely distributed in the intrahepatic bile ducts and associated with hepatic steatosis and portal hypertension. It is usually associated with severe stenosis of the right and left hepatic ducts or bile ducts below the confluence.
The above typing method is proposed on the basis of the integrated clinicopathological changes of intrahepatic bile duct stones, which is a more perfect typing method so far and has obvious guiding significance for the clinical treatment of intrahepatic bile duct stones. According to our data, most of the intrahepatic bile duct stones seen in clinical practice are type II, IIIa and IIIb. The management of type II bile duct stones is relatively simple and is a clear indication for hepatic resection, while the clinical management of type IIIa and IIIb intrahepatic bile duct stones requires a comprehensive analysis based on the presence of hepatic parenchymal atrophy, the degree and location of bile duct stenosis, the distribution of stones and the extrahepatic bile duct, and a highly individualized treatment plan. The treatment plan is highly individualized. Patients with type III intrahepatic bile duct stones often have a combination of stenosis at the opening or confluence of the right and left hepatic ducts or significant impairment of biliary flow dynamics. Therefore, hilar cholangioplasty and/or hepaticoenteric anastomosis is the basic treatment for type III intrahepatic bile duct stones. The need for hepatic segmental resection depends on the presence of disfigured atrophy of the liver parenchyma and the presence of uncorrectable strictures.
In conclusion, the clinical treatment strategy for intrahepatic choledocholithiasis is basically mature, and hepatic resection, as one of the methods in the comprehensive treatment system, needs to be applied in combination with other methods. Hepatic resection for intrahepatic bile duct stones has its own characteristics, and individualized treatment under the guidance of accurate and comprehensive imaging is the basic strategy to ensure the efficacy of intrahepatic bile duct stones.