Congenital bile duct dilatation

　　There are many theories about the etiology, and there is no definitive conclusion yet. Most believe it is a congenital disease. Some also believe that acquired factors are involved in its formation. The main theories include three:

　　1. The theory of congenital anomalies suggests that during the period of embryonic development, the primitive bile duct cells proliferate into a cord-like entity, which then gradually becomes hollow and permeable. If some part of the epithelial cells overproliferate, then during the process of hollowing and permeating, it overhollows and forms an expansion. Some scholars believe that the formation of bile duct dilatation requires the joint participation of congenital and acquired factors. The overproliferation of bile duct epithelial cells and the overhollow formation during the embryonic period, which cause the wall of the bile duct to be underdeveloped, are congenital factors. Added to these are the acquired factors in later life, such as the terminal obstruction of the common bile duct due to pancreatitis or ampulla inflammation, and the subsequent increase in intraductal pressure, which ultimately leads to the formation of bile duct dilatation.

　　2. The theory of combined pancreaticobiliary ductal drainage suggests that due to the failure of the common bile duct and the main pancreatic duct to separate normally during embryonic development, the junction of the two is located far from the ampulla of Vater, forming a common pancreaticobiliary channel that is too long, and the junction angle between the main pancreatic duct and the common bile duct is nearly perpendicular. Therefore, the site of the pancreaticobiliary anastomosis is not at the duodenal papilla, but outside the duodenal wall, where there is no sphincter present, thus losing the sphincter function and causing mutual reflux of pancreatic juice and bile. When the secretion of pancreatic juice is excessive and the pressure increases, it causes the bile duct to dilate. In recent years, retrograde pancreaticobiliary造影 has confirmed that the combined flow of pancreaticobiliary ducts reaches 90-100%, and it has been found that the content of amylase in the dilated bile ducts is increased, which is a fact. 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. Virus infection theory believes that biliary atresia, neonatal hepatitis, and bile duct dilatation are caused by a single cause, which is the result of inflammatory infection of the liver and biliary system. After viral infection, the liver undergoes giant cell transformation, bile duct epithelium is damaged, leading to luminal obstruction (biliary atresia) or wall weakness (bile duct dilatation). However, the number of supporters for this theory has decreased.

　　Once diagnosed, this disease should be treated surgically as soon as possible. Delaying treatment not only increases the child's suffering but also increases the chance of complications. The malformation of cystic dilatation in the lesion and the relative stenosis of the distal bile duct lead to poor bile drainage and even obstruction, which is the root cause of complications.

　　The main ones are:

　　1. Recurrent ascending cholangitis

　　2. Biliary cirrhosis

　　3. Biliary duct perforation or rupture

　　4. Recurrent pancreatitis

　　5. Stone formation and wall canceration

　　The diagnosis of this disease can be considered based on the three main symptoms that appear intermittently since childhood, namely, abdominal pain, abdominal mass, and jaundice. If symptoms recur, the possibility of diagnosis is greatly increased. Cystic-type cases are mainly characterized by abdominal mass, with an earlier onset of disease, and diagnosis can be made by palpation combined with ultrasound examination. Striated-type cases are mainly characterized by abdominal pain symptoms, and in addition to ultrasound examination, ERCP or PTC examination is also required for correct diagnosis. Jaundice symptoms are not significantly different between the two types and can occur in both. The first symptom in most cases occurs between 1 to 3 years of age, but the final diagnosis is often delayed. Cystic-type cases account for about 1/4 of cases within 1 year of age, with the main clinical symptom being abdominal mass, while the striated type often occurs after 1 year of age, with abdominal pain and jaundice as the main symptoms.

　　1. Abdominal mass, abdominal pain, and jaundice are considered the classic triad of symptoms of this disease. The abdominal mass is located in the upper right quadrant, below the costal margin, and can occupy the entire right abdomen in large cases. The mass is smooth and spherical, and may have a marked cystic elasticity. When the cyst is filled with bile, it can present a solid-like sensation, resembling a tumor. However, there is often a change in size, with the mass increasing during episodes of infection, pain, and jaundice, and slightly shrinking after symptoms are relieved. 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 quadrant, with varying nature and intensity of pain, sometimes presenting as persistent distension, and sometimes as colicky pain. Patients often adopt a flexed knee prone position and refuse to eat to alleviate symptoms. The onset of abdominal pain suggests biliary duct obstruction, with increased pressure in the common bile duct, and reciprocal reflux of pancreatic juice and bile, which can cause symptoms of cholangitis or pancreatitis. Therefore, fever is often accompanied by clinical symptoms, and nausea and vomiting may also occur. Elevated blood and urine amylase levels are often present during episodes. Jaundice is usually intermittent and is often the main symptom in infants, with the depth of jaundice directly related to the degree of biliary obstruction. In mild cases, jaundice may not be present clinically, but it can temporarily appear after infection and pain, with the feces becoming pale or grayish and the urine darker. All these symptoms are intermittent. Due to the obstruction of the distal biliary duct outlet, reciprocal reflux of bile and pancreas can lead to clinical symptoms. When bile can flow smoothly, symptoms are alleviated or disappear. The interval between episodes varies, with some frequent and some asymptomatic for a long time.

　　2. The typical triad symptoms, which were previously considered as inevitable symptoms of the disease, are not necessarily so. In early cases, the three major symptoms were less likely to appear simultaneously. In recent years, with the increase in early diagnosis, the number of fusiform dilatations has increased, and the proportion of patients with the triad symptoms is still less than 10%. Most cases have only one or two symptoms. According to various reports, about 60-70% of cases can be palpated in the abdomen, and 60-90% of cases have jaundice. Although jaundice is obviously obstructive, in fact, many patients are diagnosed with hepatitis and are not diagnosed until after repeated attacks. Abdominal pain also lacks typical manifestations, making it easy to misdiagnose as other abdominal conditions. Multiple bile duct dilatations both inside and outside the liver generally appear late, and symptoms only appear when intraparenchymal cysts become infected.

　　3. Caroli disease: In 1958, Caroli first described cases of multiple cystic dilatation of intraparenchymal bile ducts, therefore congenital intraparenchymal bile duct dilatation is also known as Caroli disease, which belongs to congenital liver cystic fibrous lesions, believed to be an autosomal recessive inheritance, more common in males, mainly seen in children and young adults. Early reported cases did not accompany liver fibrosis and portal hypertension, but in later reports, 2/3 of the cases were accompanied by congenital liver fibrosis, and they were often accompanied by various renal lesions, such as polycystic kidneys, and late cases may develop liver cirrhosis and portal hypertension. According to Sherlock's classification, it is divided into four categories: congenital liver fibrosis, congenital intraparenchymal bile duct dilatation, congenital common bile duct dilatation, and congenital liver cysts, collectively known as liver and biliary fibrous cystic disease. One or more lesions may coexist in the biliary system. This disease is characterized by bile duct inflammation and calculi caused by bile duct dilatation and bile stasis within the liver, but due to the atypical clinical symptoms, it can occur at any age, with recurrent right upper quadrant abdominal pain, fever, and jaundice. During the attack, the liver is significantly enlarged, and after the infection is controlled, the liver often shrinks rapidly with the improvement of symptoms. Liver function damage is not proportional to clinical symptoms. In the early stage of the disease, it is often misdiagnosed as cholecystitis or liver abscess. If there are other fibrous cystic lesions such as congenital liver fibrosis or extrahepatic bile duct dilatation, the symptoms are more complex, and symptoms such as liver cirrhosis, extrahepatic biliary obstruction, and urinary tract infection may occur. Diagnosis is often difficult, and it often requires surgical intervention to confirm the diagnosis. In recent years, with the application of diagnostic methods such as ultrasound imaging and various bile duct造影 techniques, correct diagnosis of intraparenchymal lesions can be obtained, so the number of reported cases has also increased, but secondary bile duct dilatation caused by other reasons is often included, which leads to confusion in the concept of Caroli disease.

　　1. Relief measures:Treatment during the acute attack of symptoms should adopt fasting for 2 to 3 days to reduce the secretion of bile and pancreatic juice, alleviate the pressure in the bile duct. Use antispasmodics to relieve pain, antibiotics for 3 to 5 days to prevent and control infection, and corresponding symptomatic treatment, which can often achieve the purpose of alleviating symptoms. In view of its frequent attacks and various complications, timely surgical treatment should be performed.

　　2. Preoperative preparation:The surgical preparation performed is a general preoperative preparation.

　　1. Biochemical examination, determination of blood and urine amylase levels, should be regarded as routine examination during the onset of abdominal pain, which is helpful for diagnosis.

　　2. Type B ultrasound imaging.

　　3. Percutaneous liver puncture cholangiography (PTC).

　　4. Endoscopic retrograde cholangiopancreatography (ERCP).

　　5. Gastrointestinal barium meal examination.

　　6. Intraoperative bile duct造影.

　　Among the various examination methods, ultrasound examination and biochemical tests are generally performed first in clinical practice. If an abdominal mass is palpated clinically, the diagnosis can be established. If a mass is not palpated clinically, but an ultrasound examination suggests a diagnosis, then ERCP examination is required. If limited by equipment and age, PTC examination is performed, and other examination methods are supplemented if necessary.

　　1. Diet and health care for congenital bile duct cyst: various fat-soluble vitamins (A, D, K, etc.) should be supplemented to maintain good nutritional status.

　　2. Natural vitamin A exists only in animal foods such as: animal liver, eggs, cream, and cod liver oil; the carotenoids contained in plants can be converted into vitamin A in the liver.

　　3. Cholesterol in the human body can be converted into vitamin D. Foods rich in vitamin D include fish, fish eggs, liver, egg yolks, cream, butter, cheese, meat, milk, fruits, nuts, vegetables, and grains.

　　4. There are many foods rich in vitamin K. However, the best sources include dark green vegetables and cabbage, spinach, coriander, beetroot, cauliflower, and kale. In addition, specific vegetable oils such as soybean oil, rapeseed oil, cottonseed oil, and olive oil also contain vitamin K.

　　Surgical treatment:

      1. The external drainage technique is applied to individual severe cases, such as severe obstructive jaundice with liver cirrhosis, severe biliary tract infection, spontaneous bile duct perforation, and secondary treatment after the condition improves.

　　Cyst-enteric internal drainage surgery between cysts and intestines, such as cystojejunal anastomosis, due to a large number of complications, such as recurrent cholangitis, anastomotic stricture, stone formation, etc., later turned to cystojejunal Roux-en-Y anastomosis, and various anti-reflux operations were designed on the intestinal loop, but there is still the problem of pancreatico-biliary convergence, so postoperative symptoms of cholangitis or pancreatitis still occur, and even reoperation may be required, and there have been frequent reports of postoperative wall canceration. Therefore, it is currently rarely used.

　　The resection of bile duct expansion and bile duct reconstruction surgery in recent years is advocated to have a radical effect, which includes the resection of the bile duct expansion site and bile duct reconstruction to achieve the purpose of pancreatico-biliary diversion. Physiological bile duct reconstruction surgery can be adopted, placing the jejunum between the hepatic duct and duodenum, or adding a anti-reflux valve, or using Roux-en-Y hepaticojejunal anastomosis, hepaticojejunal anastomosis, etc. All these methods can achieve good results. The most important thing is that the anastomosis must be large enough to ensure adequate bile drainage.

　　The treatment of intrahepatic bile duct dilation, secondary to extrahepatic bile duct dilation, has a cylindrical-shaped dilation, which often returns to normal after surgery. If it is cystic dilation, it is a mixed type. After extrahepatic bile duct drainage, regardless of the size of the anastomosis, there is still intrahepatic bile stasis, infection, and the formation of stones or cancer. Therefore, for those with limited cystic dilation in the liver, most people advocate for partial and resectional surgery.

　　The treatment of Caroli's disease: The main method is to prevent and treat cholangitis, and long-term application of broad-spectrum antibiotics, but the therapeutic effect is generally not satisfactory. Due to the extensive nature of the lesions, surgical treatment often fails. If the lesions are limited to one lobe, lobectomy can be performed, but according to reports, less than 1/3 of cases can be resected. The long-term prognosis is extremely poor.

　　After the radical operation for bile duct expansion, even though the purpose of pancreatic juice and bile diversion has been achieved, some cases still frequently present with clinical manifestations such as abdominal pain, increased amylase in blood, cholangitis, or pancreatitis. This is related to intrahepatic bile duct expansion and morphological abnormalities of the pancreatic duct. Symptoms can be relieved after fasting, anti-inflammatory, antispasmodic, and cholagogue treatment. With the passage of time, the interval between attacks gradually extends. Long-term follow-up shows satisfactory results in 80% of cases.