Preoperative biliary drainage (PBD) prior to radical surgery for malignant obstructive jaundice to reduce jaundice and thus reduce postoperative comorbidities and mortality in patients and reduce surgical risk was considered to be the consensus until the 1980s. Starting from the late 1980s and 1990s, a series of publications on PBD in patients with malignant obstructive jaundice began to question this view both nationally and internationally. pisters et al. performed pancreaticoduodenectomy in 300 patients with malignant obstructive jaundice and preoperative yellowing reduction in 172 patients and found that the rate of postoperative wound infection increased in the yellowing reduction group, and in other complications, such as anastomotic leak, abdominal abscess infectious Jagannath et al. performed preoperative yellow reduction in 74 patients undergoing pancreaticoduodenectomy and found no difference between the two groups in terms of overall postoperative complication rate (39% vs 43%), mortality rate (4% vs 9%), and individual complication rates (sepsis, anastomotic fistula, pancreatic fistula, bleeding, and wound infection rate). Some literature [3] reported that preoperative yellowing reduction even increased complications or mortality after pancreaticoduodenectomy; Takada [4] concluded that PBD has little definite effect on improving comorbidity and mortality in pancreaticoduodenectomy; the role of PBD in resection of hilar cholangiocarcinoma is still controversial. As the obstruction site of hilar cholangiocarcinoma is in the hilum, jaundice is deeper, and radical resection often requires partial removal of the liver, which increases the complications of postoperative liver failure and mortality, and the literature reports that liver failure can occur up to 29.8% [5], which is the main feature that distinguishes it from malignant low-level biliary obstruction. The pros and cons of preoperative yellowing reduction in hilar bile duct cancer are discussed below from several aspects. I. Different experiences in Japan, Europe and the United States, and China There are several high-level centers for the diagnosis and treatment of hilar cholangiocarcinoma worldwide, located in Japan, Europe and the United States, and China, respectively. In Japan, Nimura [6] (Nagoya University) treated 177 patients with portal cholangiocarcinoma from 1999 to 2007, 142 of them were resected and 43 were combined with portal vein resection, with an in-hospital mortality rate of 9%, a comorbidity rate of 48%, and a 5-year survival rate of 43%. 30 of the 142 patients had preoperative portal vein embolization ( Portal Vein Emboliazation, PVE) and Percutaneous Transhepatic Biliary Drainage (PTBD) in 133 patients (94%), TB was reduced to less than 34 μmol/L. The authors concluded that in hilar cholangiocarcinoma, aggressive post-PBD helps to increase the rate of radical resection and improve the postoperative prognosis.Seyama (University of Tokyo) et al. performed extended resection in 58 patients with hilar cholangiocarcinoma and performed PTBD with external drainage to reduce yellowing until TB < 34 μmol/L in 39 of them with TB > 85 μmol/L, and performed preoperative (The other 8 patients did not undergo PTBD drainage because the expected hepatic resection volume exceeded 50% by PVE), achieving a better result of 42% postoperative comorbidity, 40% 5-year survival rate, and no postoperative complications of hepatic insufficiency in any of them. They concluded that preoperative yellowing reduction must be continued for more than 4 weeks to facilitate recovery of impaired liver function, and suggested that some reports of no effect of preoperative yellowing reduction were due to their yellowing reduction time shorter than Ebata performed resection with combined vascular management in 52 consecutive patients with hilar cholangiocarcinoma, 32 of whom underwent portal vein resection and reconstruction, with a postoperative mortality rate of 9.6%, and 50 patients (96.4%) underwent preoperative PTBD drainage to reduce yellowness. Jarnagin (MSKCC, Sloan-Kettering Memorial Cancer Center) in the United States admitted 225 cases of hilar cholangiocarcinoma between 1991 and 2000, 80 of which were resected routinely, 62 of which were combined with hepatectomy, with a postoperative mortality rate of 9% and 64% comorbidity, and a 5-year survival rate of 42 months after R0 resection. Eight cases (10%) belonging to Ro resectors died due to postoperative complications, six of which were due to infectious complications, while five cases had biliary stents placed before surgery, thus it is not recommended to routinely drain the bile ducts before surgery and strive for surgical treatment within one week of admission, and if drainage is needed, only one side of the intrahepatic bile duct should be drained, because postoperative infectious complications also increase when an additional drainage tube is placed. Gerherds (University of Amsterdam) in the Netherlands performed resection in 112 patients with cholangiocarcinoma of the porta hepatis, with 65% postoperative comorbidity and 18% mortality, of which 93 had intra-ERCP stent drainage to reduce yellowness, they were divided into three stages by time, and the last stage had the highest rate of postoperative abdominal abscess complications at 28%, of which 98% had preoperative intra-ERCP drainage, the authors believe that this may be related to inadequate preoperative drainage and introduction of bacteria. Neuhaus [11] (Humboldt University, Germany) performed resection in 95 patients over a decade, and preoperative ERCP internal stent drainage to reduce yellowing combined with right hepatic artery embolization in patients expected to undergo right trilobar hepatectomy from 1995 until TB was reduced to 85 μmol/L and the contralateral liver volume increased by more than 35% (27-75 d). A total of 40 hepatectomy patients were treated with preoperative yellowing reduction and drainage (35 cases of internal stent drainage, 2 cases of external PTBD drainage, and 2 cases of nasobiliary drainage), with a postoperative mortality rate of 6% and a comorbidity rate of 59%. The high bilirubin group was divided into two groups according to yellowing reduction or not, and there was no significant difference in the incidence of postoperative mortality, hepatic insufficiency, biliary leakage, and biliary tract infection complications. Huang treated 291 cases of hepatoportal bile duct cancer between 1986 and 2002 without preoperative yellowing reduction, except for patients with debilitating conditions and serum bilirubin >400 μmol/L who were not suitable for early surgery, resulting in no mortality within 30 d after surgery. In our hospital, 103 patients underwent resection from 1995 to 2005, including 76 combined hepatectomies and 42 patients with preoperative PTBD external drainage to reduce yellowing, and the postoperative mortality rate was 7.8% and the incidence of comorbidity was 33%, compared with 21.4% in the preoperative yellowing reduction group and 41% in the non-yellowing reduction group. In summary, there are still controversies regarding preoperative yellowing reduction for hilar cholangiocarcinoma: Japan mostly advocates PTBD external drainage and preoperative PVE, combining the two can maximize the radical resection rate and thus achieve a higher 5-year postoperative survival rate; for enlarged hepatectomy or radical resection with combined vascular management, preoperative yellowing reduction is beneficial to reduce the incidence of postoperative hepatic insufficiency; Europe and the United States Pre-operative yellowing reduction before ERCP internal stent drainage is mostly used, but it may cause an increase in postoperative infectious complications; pre-operative yellowing reduction must be achieved for a certain period of time, lasting at least 4 weeks, until the damaged liver function is restored in order to achieve the desired purpose. Other roles of preoperative yellowing reduction and complications Since cholangiocarcinoma in the hilar region is a new organism growing along the mucosa of bile ducts with small diameter, preoperative ultrasound and CT examination often cannot clarify the location and size of lesions, which causes difficulties in diagnosis and affects the formulation of surgical plan. Another purpose of preoperative yellowing reduction is to obtain biliary tree image by transbiliary stent ductography, so that the degree of bile duct invasion can be determined (to know whether there is invasion of bile ducts above the second level, and if the tumor invades only one bile duct, to know whether there is invasion of the contralateral bile duct and whether both bile ducts are connected, etc.), which is very meaningful for the development of treatment plan. Miyazaki made full use of preoperative imaging data, especially preoperative PTBD and percutaneous cholangioscopy, to determine the extent of tumor invasion of the bile ducts, to precisely determine the parenchyma of the resected liver, and to maximize the preservation of the liver parenchyma (Parenchyma-Preserving Hepatectomy). ERCP has limited diagnostic value because the contrast agent cannot reach above the obstruction, and even if part of the contrast agent passes through the obstruction, it is difficult to show the bile duct tree because of poor filling. Although the emergence of MRCP and spiral CT biliopancreatic duct imaging can obtain images of the biliary tree to assist diagnosis, and the literature reports that theoretically the localization diagnosis rate reaches 90-100% and the qualitative diagnosis rate is above 90%, our experience is that CT and MR have limited value in determining the extent of bile duct invasion in hilar cholangiocarcinoma, and the quality of MRCP imaging is closely related to the imaging physicians’ Jarnagin proposed the Proposed T-Stage Criteria for cholangiocarcinoma of the hilar region, which is similar to the AJCC’s T-stage Criteria. Criteria), which differed from AJCC staging in that it included tumor invasion of the bile duct as a factor in the evaluation, and found that T-stage correlated with combined hepatic resection, radical resection rate, and 5-year survival rate after surgery. Although the extent of lymph node invasion was not considered because of this staging, its appearance is an important progress in the diagnostic study of hilar bile duct cancer. In China, where the practical use of MRCP is not yet widespread and the technical results are unsatisfactory, is it possible that preoperative biliary placement angiography to obtain direct cholangiographic information can give us a better understanding of the tumor and thus improve the outcome of treatment? Seyama believes that the biggest shortcoming of preoperative PTBD placement is the occurrence of placement-related cholangitis (12/39, 30%), but he believes that cholangitis can be avoided with skilled technique and operational attention; the main causes of cholangitis are multiple imaging (42%), duct obstruction (42%), and needle tract implantation metastasis in 2 cases, and to reduce PTBD complications, it is recommended to In order to reduce PTBD complications, cholangiography is recommended to be performed one day before surgery, and it is advocated that too much pressure should not be caused during the imaging. 133 cases of PTBD in the nine years of Nimura had complications: 18 cases of cholangitis, 4, 3 and 2 cases of biliary bleeding, portal vein thrombosis and duct prolapse occurred respectively, and 4 patients had needle tract implantation metastasis, and it is believed that the main problem of preoperative PTBD drainage to reduce yellowing is that it may cause cholangitis and should be be avoided as much as possible. One study reported that the incidence of cholangitis after ERCP internal stent drainage for hilar bile duct obstruction can be as high as 53%, which is much higher than PTBD, which is caused by the operation itself and the characteristics of the biliary obstruction site for hilar bile duct cancer. III. External drainage or internal drainage? Total liver drainage or half liver drainage? Theoretically, internal drainage can reduce the pressure in the bile duct and redirect the bile to the intestine, thus alleviating the adverse effects of obstructive jaundice caused by the interruption of the “enterohepatic circulation” of bile, which should be more effective than simply draining the bile outside the body. In clinical practice, it was found that preoperative internal drainage to reduce yellowness increased the chance of postoperative infectious complications, and this impression is mostly derived from studies of preoperative ERCP internal stent drainage in pancreaticoduodenectomy patients in Europe and the United States. Jagannath et al. found a positive correlation between positive intraoperative bile culture and postoperative complication rate, total complication rate, mortality rate, infectious complication rate, and wound infection rate in the reduced yellow group. , mortality, and infectious complications; in patients with preoperative yellowing reduction, there was a positive correlation between the occurrence of complications after biliary operation and positive bile culture rate. 8 (10%) of 225 cases of hepatoportal cholangiocarcinoma belonging to Ro resectors in Jarnagin died due to postoperative complications, 6 of which died from infectious complications, while 5 cases had biliary stents placed before surgery. gerherds [ 10] found that preoperative internal drainage may increase the complication rate in the development of postoperative abdominal abscess complications. A synthesis of the current data found that the postoperative complication rate of surgery after internal drainage to reduce yellowing in Europe and the United States is mostly higher than that of the Japanese study related to external drainage to reduce yellowing. Hochwald et al. examined 34 patients with biliary drainage followed by surgical treatment for infection and found that the rate of bile bacterial positivity was significantly lower in the PTBD group than in the ERBD group (65% vs. 100%,P=0.035). In addition, Hemming et al [20] noted that ERBD can cause severe inflammation of the hepatic hilum, making surgical manipulation difficult. We have also experienced in our clinic that the inflammation and edema of the hilar tissues during surgery after endostent drainage of bile duct cancer increase the difficulty of surgery; some patients with advanced bile duct cancer have higher postoperative cholangitis after endostent drainage. Thus, it seems that the role and effect of preoperative internal drainage to reduce yellowing in hilar cholangiocarcinoma is worse than external drainage. However, so far, the approach to PBD in each unit and institution is mostly determined by the custom and experience of the unit where it is performed; in addition, some units often admit endoscopy or gastroenterology departments for preoperative hilar cholangiocarcinoma, and often perform ERCP angiography and drainage with an indwelling stent tube to reduce yellowing for diagnostic reasons. For external drainage of PTBD, is total or hemihepatic drainage (bilateral or unilateral) performed, and are as many tubes as possible placed or only the desired site is drained? Nimura’s 133 cases of preoperative PTBD (94%) had 287 tubes, with a mean of 2.1 tubes/person and a maximum of 7 tubes, and he believed that bile should be drained as much as possible, and that selective cholangiography with multiple tube placement can provide an accurate picture of the extent of tumor invasion of the bile duct, which is very beneficial for radical resection; they also They also concluded that hemihepatic drainage in cases of bilateral biliary disconnection may increase the chance of preoperative focal cholangitis. Seyama, on the other hand, does not recommend total liver drainage to avoid cholangitis because the more ducts placed, the greater the chance of obstruction, which can lead to cholangitis, and because more ducts create a greater chance of needle implantation. Kawasaki [23] held the same opinion. Animal experiments demonstrated that after 4 weeks of selective biliary drainage (right hepatic lobe bile duct) and complete biliary drainage, the ratio of right hepatic lobe to body weight was (2.2±0.4)% and (1.2±0.2)% (P<0.01), respectively, and the rate of ATP production per 100 g of body weight in the right hepatic lobe was (24.4±9.4)μmol/min and (10.9±2.0)μmol/min ( P<0.05); cytochrome p450 content per 100 g body weight in the right hepatic lobe was (31.9±14.1) nmol and (15.9±2.3) nmol, respectively (p<0.05), indicating that the function of frl after selective drainage was better than complete drainage, providing an experimental basis for selective drainage. Recently, Kamiya [25] et al. performed external drainage in patients with obstructive jaundice when bile was returned through the oral or nasoduodenal tube, which could restore the function of the intestinal barrier, and the authors suggested that this effect might be related to the phospholipids in bile that assist in intestinal mucosal repair; the authors advocated that external drainage should be used for cholangiocarcinoma of the hilar region to avoid the high risk of cholangitis caused by endoscopic placement, and whether this approach could be used as a preoperative Can this approach be applied clinically as a new method of preoperative drainage to reduce yellowing? Can this type of bile return reduce endotoxin translocation or even be beneficial in reducing postoperative complications and mortality? These questions still need further study. In conclusion and outlook: 1. Further studies are needed for preoperative reduction of yellowness in hilar cholangiocarcinoma, and a more definite conclusion can undoubtedly be drawn if a relevant randomized controlled study can be conducted in compliance with medical ethics and with a sufficient number of cases. 2. At present, whether to perform PBD before resection of hilar cholangiocarcinoma is determined by the experience and custom of each family. 3, Preoperative PTBD with yellowing reduction combined with PVE treatment is beneficial to improve the radical resection rate of hilar cholangiocarcinoma and reduce postoperative complications and mortality, and successful preoperative PVE for hilar cholangiocarcinoma has been reported in China [26], which is a research direction for hilar cholangiocarcinoma. 4. The proposed "suggested T-stage criteria" is a breakthrough in the diagnosis and treatment of hilar cholangiocarcinoma; it is still very necessary to improve the sensitivity and specificity of preoperative noninvasive examination of hilar cholangiocarcinoma and to further develop diagnostic studies such as staging.