Choledochal cyst

　　The etiology of choledochal cyst is not yet clear, and there are currently three theories.

　　1. The theory of congenital anomalies

　　Some scholars believe that during the period of embryo development, the primitive bile duct cells proliferate into a cord-like entity, and then gradually become hollowed out and connected. If some part of the epithelial cells overproliferate, excessive hollowing out will occur during the hollowing out and recanalization, forming an expansion.

　　Some scholars believe that the formation of bile duct dilatation requires the joint participation of both congenital and acquired factors. During the embryonic period, bile duct epithelial cells overproliferate and form excessive vacuoles, causing the bile duct wall to develop weakly, which is a congenital factor. Added to this are acquired factors, such as bile duct terminal obstruction secondary to pancreatitis or ampulla inflammation, and the subsequent increase in bile duct pressure, which ultimately leads to the formation of bile duct dilatation.

　　2, Pancreatico-biliary duct convergence abnormality theory

　　Some scholars believe that due to the failure of the bile duct and the main pancreatic duct to separate normally during the embryonic period, the junction between the two is far from the ampulla of Vater, forming an abnormally long common bile and pancreatic duct. Moreover, the junction angle between the main pancreatic duct and the bile duct is nearly perpendicular, so the anastomosis site of the pancreatico-biliary duct is not at the duodenal papilla but locally outside the duodenum. There is no sphincter, thus losing the sphincter function, causing mutual reflux of pancreatic juice and bile. When the pancreatic juice is secreted in excess and the pressure increases, it causes the bile duct to dilate. Recent retrograde cholangiopancreatography has confirmed that up to 90-100% of cases have pancreatico-biliary convergence, and it has been found that the content of amylase in the dilated bile ducts is increased. In animal experiments, it has been observed that after the pancreatic juice enters the bile duct, the activity of amylase, trypsin, and elastase is enhanced, which may be the main cause of bile duct injury.

　　3, Viral infection theory

　　Some scholars believe that bile duct dilatation is the result of inflammatory infection in the liver and gallbladder system. After viral infection, the liver undergoes giant cell transformation, bile duct epithelium damage, leading to luminal obstruction (biliary atresia) or weakened bile duct wall (bile duct dilatation), but the number of supporters for this theory has decreased.

　　The bile duct obstruction or even blockage caused by the cystic dilatation at the lesion site and the relatively narrow distal bile duct, which leads to poor bile drainage, is the root cause of complications in bile duct dilatation. The main complications include recurrent ascending cholangitis, biliary cirrhosis, bile duct perforation or rupture, recurrent pancreatitis, stone formation, and wall canceration, etc.

　　The first symptoms of most common bile duct dilatations occur between 1 to 3 years of age, but the final diagnosis is often delayed much later. The cystic type accounts for nearly 1/4 of cases within 1 year of age, with the main clinical symptoms being abdominal mass, while the fusiform type often occurs after 1 year of age, with abdominal pain and jaundice as the main symptoms.

　　Abdominal mass, abdominal pain, and jaundice are considered the classic triad symptoms of bile duct dilatation. The abdominal mass is located in the upper right abdomen, below the costal margin, and the large ones can occupy the entire right abdomen. The mass is smooth, spherical, and may have a distinct cystic elasticity. When the cyst is filled with bile, it may present a solid sensation, resembling a tumor. However, there are often changes in size, with the mass increasing in size during infection, pain, and jaundice episodes, and slightly shrinking after symptoms alleviate.

　　Small bile duct cysts, due to their deep location, are not easily palpable. Abdominal pain occurs in the upper middle abdomen or the upper right abdomen, with varying nature and severity of pain, sometimes presenting as persistent distension pain, and sometimes as colicky pain. The patient often assumes a flexed knee prone position and refuses to eat to alleviate symptoms.

　　腹痛发作提示胆道出口梗阻，共通管内压上升，胰液胆汁可以相互逆流，引起胆管炎或胰腺炎的症状，因而临床上常伴发热，有时也有恶心呕吐。

　　症状发作时常伴有血、尿淀粉酶值的增高。黄疸多为间歇性，常是幼儿的主要症状，黄疸的深度与胆道梗阻的程度有直接关系。轻者临床上可无黄疸，但随感染、疼痛出现以后，则可暂时出现黄疸，粪色变淡或灰白，尿色较深。以上症状均为间歇性。由于胆管远端出口不通畅，胰胆逆流可致临床症发作。当胆汁能顺利排流时，症状即减轻或消失。间隔发作时间长短不一，有些发作频繁，有些长期无症状。

　　典型的三联症状，以往曾认为是胆管扩张症的必有症状，实则不然。在早期病例较少同时出现三大症状。由于获早期诊断者日众，发现梭状扩张者增多，有三联症者尚不足10％.多数病例仅有一种或两种症状。据各家报道在60～70％病例腹部可扪及肿块，60～90％病例有黄疸，虽然黄疸很明显是梗阻性的，但事实上许多病人被诊断为肝炎，经反复发作始被确诊。腹痛也缺少典型的表现，因此易误诊为其它腹部情况。肝内、外多发性胆管扩张，一般出现症状较晚，直至肝内囊肿感染时才出现症状。

　　胆总管扩张症是先天性疾病，所以在妊娠期间就应该做好产前检查，降低得病几率。症状发作期的治疗，采取禁食2～3天，以减少胆汁和胰液的分泌，缓解胆管内压力。应用解痉剂以缓解疼痛，抗生素3～5天以预防和控制感染，以及相应的对症治疗，常能达到缓解症状的目的。鉴于其频繁的发作和各种并发症，宜及时进行手术治疗。

　　胆管扩张症为较常见的先天性胆道畸形，以往认为是一种局限于胆总管的病变，因此称为先天性胆总管囊肿。本病可做以下检查：

　　1、生物化学检查血、尿淀粉酶的测定

　　在腹痛发作时应视为常规检查，有助于诊断，可提示胆管扩张症有伴发胰腺炎的可能。或提示有胰胆管异常合流，返流入胆管的高浓度胰淀粉酶经毛细胆管直接进入血液而致高胰淀粉酶血症。同时测定总胆红质、5′核甙酸酶、碱性磷酸酶、转氨酶等值均升高，在缓解期都恢复正常。在长期病程者则有肝细胞损害，在无症状病例检验方面则正常。

　　2、B型超声

　　B型超声显像具有直视、追踪及动态观察等优点。如胆道梗阻而扩张时，能正确地查出液性内容的所在和范围，胆管扩张的程度和长度，其诊断正确率可达94％以上。应作为常规检查的诊断方法。

　　3. Percutaneous Liver Biliary Ductography (PTC)

　　PTC is easy to be successful in cases of biliary duct dilatation, can clearly show the intrahepatic bile ducts and their directions, and clearly determine whether there is bile duct dilatation and the extent of dilatation. It can differentiate the cause or obstruction site in cases of jaundice, and can observe the pathological changes of the bile duct wall and its interior, differentiate the cause of obstruction according to the characteristics of the image.

　　4. Endoscopy

　　Retrograde Cholangiopancreatography (ERCP) can inject contrast agent directly into the bile duct and pancreatic duct through the papilla opening with the help of duodenoscopy, determine the extent of bile duct dilatation and the site of obstruction, and can also show the length and abnormal conditions of the common channel between the pancreatic and bile ducts.

　　5. Gastrointestinal Barium Meal Examination

　　For those with large cystic dilatation, it can show the duodenum shifting to the left anterior position, the duodenal frame expanding and presenting a crescent-shaped indentation. Its diagnostic value has been replaced by ultrasound examination.

　　6. Intraoperative Cholangiography

　　During surgery, the contrast agent is directly injected into the bile duct, which can display the entire image of the intrahepatic and extrahepatic bile duct systems and the pancreatic duct, understand the range of intrahepatic bile duct dilatation, the reflux condition of the pancreatic duct, and help to select the surgical method and postoperative management.

　　Among the above various examination methods, ultrasound examination and biochemical tests are generally performed first in clinical practice, such as palpation of abdominal masses, the diagnosis can be established. If the lump cannot be palpated clinically, and the ultrasound examination suggests a diagnosis, then ERCP examination is required. If limited by equipment and age, then PTC examination is performed, and other examination methods are supplemented as necessary.

　　Patients with choledochal dilatation should pay attention to nutrition and avoid spicy and刺激性 food. During the acute phase of symptoms, treatment should include fasting for 2 to 3 days to reduce the secretion of bile and pancreatic juices, and relieve the pressure within the bile duct.

　　The conventional method of Western medicine for the treatment of choledochal dilatation is mainly to prevent and treat choledochitis, long-term use of broad-spectrum antibiotics, but the therapeutic effect is generally not satisfactory. Due to the extensive nature of the lesions, surgical treatment is often unsuccessful, such as when the lesions are limited to one lobe, liver lobectomy can be performed, but according to reports, less than 1/3 of the cases can be resected. The long-term prognosis is extremely poor.