Before introducing the new concept of “fourth portal”, let us first review the process of the formation of the concepts of the first, second and third portals of the liver, which were first described by Glisson in his Anatomy of the Liver in 1654, and then by Wu Mengchao on behalf of his research group, who presented their “five lobes and four segments” theory of liver anatomy in the Seventh National Surgical Symposium in 1960. In 1960, Wu Mengchao, on behalf of his research group, reported their “five lobes and four segments” theory of liver anatomy at the Seventh National Surgical Conference, laying the foundation of liver anatomy for the people of China, and the rapid development of hepatic surgery ensued. The liver is a very special organ in the human body, which undertakes a series of important functions such as detoxification, metabolism, immune defense and bile secretion. Most of the blood returning from the stomach, spleen and intestines needs to be metabolized and detoxified by the liver before entering the heart. This special structure results in the fact that the blood flow into the liver and the blood flow out of the liver are not in the same “portal”. The portal through which blood enters the liver is called the hepatic hilum, or figuratively, the “first hilar”. The first portal contains important structures such as the hepatic artery, portal vein, bile ducts, lymphatic vessels and nerves. The blood supply to the liver comes from the portal vein and the hepatic artery. The return veins of the liver are not located in the “first portal”, and the main vessels involved in the blood flow out of the liver (left, middle, and right hepatic veins) are collectively referred to as the “second portal”. If both the “first portal” and the “second portal” are effectively controlled during surgery, the surgical risk is greatly reduced. Surgery can be performed safely on most parts of the liver. The concept of “first and second portals” is a major step forward in liver surgery. The exchange of surgical experiences among hepatobiliary surgeons became very intuitive and easy. However, there were difficulties with the hepatic caudate lobectomy procedure. The caudate lobe of the liver is adjacent to the inferior vena cava, the largest blood vessel in the body. The blood returning from the caudate lobe of the liver does not go through the “second hepatic portal” to the heart, but is mostly injected directly into the inferior vena cava through some small venous branches (i.e., the short hepatic veins). If these short hepatic branches directly injected into the vena cava are not properly handled during resection of the caudate lobe, hemorrhage may occur. Surgical procedures such as caudate lobectomy have brought increasing attention to the “short hepatic veins”, which scholars collectively refer to as the “third hepatic portal”, and the introduction of this concept marks the beginning of clinicians’ understanding of the venous outflow tract of the liver. This concept signifies that clinicians have a more comprehensive understanding of the venous outflow tracts of the liver, and caudate lobectomy has therefore gained great development. In recent years, we have found that in the operation involving caudate lobectomy (e.g. radical hepatectomy for cholangiocarcinoma, caudate lobectomy for hepatocellular carcinoma, etc.), before the portal vein enters the liver, there are many small branches from the left and right branches of the portal vein and the bifurcation part of the portal vein, which directly nourish the neighboring hepatic tissues, and the range of nourishment involves the hepatic segments II, IV, V, VI, VII, and caudate lobes, and the diameters of these blood vessels are different in size, with the thickest being about 4 mm and the thinnest being about 4 mm. The diameter of these vessels varies in size, with the thickest being about 4 mm and the thinnest about 1 mm, and these vessels can be torn off by slight pulling during surgery. We call them “short portal veins”. If we do not have sufficient knowledge of these veins during the operation, the operation may result in accidental bleeding, which may make the operation difficult. By pre-dissecting the “short portal vein” before liver resection, we significantly reduced intraoperative bleeding, shortened postoperative hospitalization days, and reduced the incidence of postoperative complications and the total amount of intraoperative and postoperative blood transfusion in patients compared with the control group. The related paper was published in Hepatobiliary & Pancreatic Diseases International, a surgical journal. In order to further understand the distribution characteristics of the short portal veins, we carried out anatomical studies of cadaveric livers, recorded and analyzed the vascular course, starting and stopping points of the short portal veins, and for the first time, proposed to collectively refer to the short portal veins as the “fourth porta hepatis”. The related thesis has been published in Surgical and Radiologic Anatomy, an international anatomical journal. In the past, “the first, second and third hepatic valves” were used to refer to the specific anatomical locations of the liver, which is both graphic and vivid. Surgeons can avoid the use of awkward vocabulary when communicating, making it easier to express and understand, and greatly facilitating the advancement of hepatobiliary surgery. The development of anatomical concepts reflects the progress of contemporary surgical techniques! It is believed that the concept of the “fourth portal” will improve the anatomical foundation of the hepatic blood supply and inflow channels, which will be more conducive to drawing the attention of hepatobiliary surgeons to the anatomical characteristics of the “short portal vein”, and will also help to further improve the safety of hepatic surgery. It will also help to further improve the safety of liver surgery. Anatomical concepts and surgical techniques complement each other and promote each other’s development.