Today, we will talk about the causes of jaundice, including intrahepatic and extrahepatic obstruction. Among them, bacterial infection, tumor, immune, drug, viral infection, etc. may be the cause. The first thing I want to do is to talk about junior high school geography. Remember the map of China that says, “A rooster sings the world white”? Remember that countless tributaries converge to form the Mother River across the east and west? If the liver is our rooster map, and our biliary system, let’s consider her as the great mother river. She consists of a trickle of water that eventually converges into a sea. After a short stop at the gallbladder, it plunges into the intestine, which stretches for miles and miles. For example, if there is a tumor in the pancreas or duodenum near the bile duct “entrance” (don’t panic, benign or malignant), the river will widen in the upstream area, and the abdominal ultrasound will indicate dilated bile ducts inside and outside the liver and enlarged gallbladder. This is extrahepatic obstruction. If there is a blockage of a very thin tributary in the liver, then the ultrasound will not see anything. Sometimes MRI analysis is needed, and sometimes even a small amount of liver tissue needs to be carefully removed with a fine needle and looked at under a microscope, which is known as a “liver puncture” or “liver biopsy”. The cause may be inflammatory edema of any segment of the bile duct, or compression. For example, diffuse hepatocellular inflammatory edema, where each hepatocyte becomes fat and compresses the tiny bile duct tributaries next to it; various viral hepatitis, drug-related hepatitis, autoimmune hepatitis, alcoholic hepatitis, etc. can all have hepatocellular edema and compress the tiny bile ducts. For example, if some kind of bacteria infects the biliary system, just like cyanobacteria pollute the river, the bile duct cells will also be edematous and damaged because of the infection; often the patient will have a fever oh. Another example is that one day your immune cells suddenly go crazy and don’t recognize their own bile duct cells, and they go on a rampage, similar to a gangster show, ending in inflammation and necrosis of the bile duct system and jaundice. The original name of the disease is “primary biliary cirrhosis”, but now I think it is too scary, people early detection and early treatment, where the cirrhosis of the liver? So now the name is changed to “primary biliary cholangitis”! In addition, IgG4-related cholangitis and primary sclerosing cholangitis caused by abnormal function of the autoimmune system also belong to this type of jaundice. It’s not fair to you that new and unfamiliar names are popping up all over the place! Let the medical professionals think about it.