Preoperative Biliary Drainage (PBD) to reduce yellowing has been a hot issue and controversial issue in the study of HC diagnosis and treatment. One of the controversies is whether PBD should be performed: proponents believe that since most patients require hepatectomy, reducing preoperative bilirubin improves liver tolerance and helps reduce postoperative complications; opponents believe that PBD itself requires bile duct placement and increases the incidence of postoperative infectious complications. Secondly, there are many PBD methods, including nasobiliary drainage, PTBD, and ENBD endoprosthesis, so which method should be used to reduce yellowing? Third, if PBD is required, what should be the limit of total bilirubin (TB)? Nimura1, Kawasaki2, and Seyama3 advocate routine PBD by PTBD and surgery after at least 4 weeks to reduce TB to less than 2 mg/dL; to minimize postoperative complications, preoperative portal vein embolization (PVE) is also advocated for patients with >60% of expected hepatic resection. Thrombosus (PVE), resulting in 43-48% postoperative complications and even excellent results of zero mortality. Neuhaus4 and Gerherds5 advocate PBD with an ENBD endoprosthesis approach and believe that TB should be reduced to less than 5 mg/dL, both with postoperative complication rates of 56% and 65%, respectively. Gerherds yet believes that abdominal abscess complications may be related to the placement of the endoprosthesis; Blumgart6 at Sloan-Kettering Memorial Cancer Center (MSKCC), USA, does not advocate PBD and advocates that patients should be treated surgically within one week after admission, with a postoperative complication rate of 65%. A more eclectic view is held by Academician Wong7, who does not support routine yellow reduction, but certain patients, such as those with episodes of cholangitis, or poor general condition, should undergo PBD. Due to the varying criteria for postoperative complications, it is not possible to compare the effects of PBD with or without PBD regarding the above mentioned studies. In a group of 58 HC resected patients in our center, 31 patients underwent PBD, resulting in a complication rate of 58.1% in the PBD group and 51.9% in the group without PBD, with no significant difference between the two groups, and no significant difference in the incidence of individual complications (e.g., abdominal infection, sepsis, wound infection, etc.), infectious complications between the two groups, and multifactorial analysis showed whether PBD and the level of TB ( 10 mg/dL, 20 mg/dL) did not affect the incidence of postoperative complications.8 Thus, the role of PBD needs to be further investigated, and we are conducting a relevant multicenter RCT study to obtain a more definitive conclusion. Povoski9 confirmed a positive correlation between PBD and positive intraoperative bile culture bacterial rate, with increased postoperative complication rates, infectious complications, operative mortality, and wound infection in the reduced yellow group, and they concluded that PBD is an important factor in the proliferation of bile bacteria and affects postoperative prognosis.8 Of the 225 cases of hilar cholangiocarcinoma in Jarnagin10 who were Ro resectors, 8 (10%) died due to postoperative complications, six of which died from infectious complications, while five had biliary stents placed prior to surgery. Hochwald11 et al. examined 34 patients with biliary drainage followed by surgical treatment for infection and found a significantly lower rate of bile bacterial positivity in the PTBD group compared to the ERBD group (65% vs. 100%,P=0.035). In addition, Hemming12 et al. noted that ERBD can cause severe inflammation of the hepatic hilum, making surgical manipulation difficult. In our clinical practice, we have also experienced that inflammation and edema of the hilar tissues are obvious during surgery after endostent drainage for bile duct cancer, which increases 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, a management that usually does not involve the surgeon. The current data, it can be concluded that PTBD external drainage is the preferred mode of PBD. In fact, the success rate of PTBD placement in our center is close to 100%, and the low incidence of complications such as PBD-related cholangitis and abdominal implantation suggests that this is a safer technique. Imaging diagnosis and evaluation After the diagnosis of HC, imaging examination should focus on the following issues: the extent of tumor invasion of the bile duct; whether there is invasion of the portal vein; whether there is evidence of liver lobe invasion and/or liver lobe atrophy; whether there is lymph node invasion and distant metastasis. Based on the understanding of the above issues, a decision can be made whether the patient can be operated and the initial surgical plan can be determined. Commonly used clinical tools include ultrasound (US), CT, magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP), cholangiography, and in some patients, delayed imaging of the abdominal aorta or superior mesenteric artery. In hilar cholangiocarcinoma, the tumor is usually small, or the tumor grows along the bile duct wall. Experienced ultrasound physicians can make a clear diagnosis and determine whether there is portal vein invasion, and it has been reported that the specificity and sensitivity of ultrasound diagnosis can reach 99% and 93%.6 MRCP is considered one of the most promising noninvasive imaging examinations, which can clearly show the intrahepatic and extrahepatic biliary tree, clarify the level of bile duct obstruction Blumgart6 believes that the combination of ultrasound and MRCP results can determine the surgical plan for hilar cholangiocarcinoma without the need for invasive PTC or ERCP cholangiography. However, both ultrasound and MRCP judgments require the participation of imaging physicians with some experience, and under the conditions of our country, the disciplines are more fragmented, which reduces the accuracy of preoperative diagnosis of hilar cholangiocarcinoma. Our center proposes the PTC-CT examination method, using 64-row CT to perform PTC-CT, injecting contrast agent through PTCD bile duct placement, combined with CT angiography, which has good visualization of the biliary system and can show the bile ducts of grade 1-4, and the three-dimensional image can assist in judging the extent of bile duct invasion, and can determine most cases of hepatic artery and portal vein invasion. portal vein invasion cases, and this method is helpful to assist clinicians in selecting surgery and deciding on surgical methods.13 Although numerous tests are available, the preoperative imaging diagnosis of HC is still unsatisfactory, and we are not always able to accurately determine preoperatively whether a particular HC patient is suitable for surgery and what kind of surgery to perform. Our center’s experience is to value the results of ultrasound examinations (performed by experienced ultrasound physicians) and to combine them with PTC-CT, PTC or MRCP either to obtain images of the biliary tree for judgment; and to advocate the participation of imaging specialists in the analysis of preoperative imaging results to assist in the development of surgical plans. The Bismuth staging proposed by Bismuth and Corlette in 1975 and modified in 1988 is the commonly used clinical staging method for HC. This staging is helpful for selecting the surgical procedure, but this staging is only valuable for the localization of tumor invasion of the bile duct, and cannot reflect the relationship between the tumor and other surrounding structures, let alone serve as a standard for disease stage. In 1998, Burke of MSKCC proposed the Proposed T-staging system, which was revised in 2001.10 This staging system takes into account portal vein invasion and liver atrophy, two factors related to surgical resection, and has been reported in the literature to be closely related to the radical resection rate, margin negativity, and prognosis of HC.10, 14 The Center has used the modified Proposed T-staging system to determine the extent of tumor invasion. Our center analyzed 127 patients with HC using modified recommended T-staging criteria and found that T-staging was closely related to radical resection rate and cut margin, but its relationship with prognosis was not observed due to the low follow-up rate.15 This staging is helpful for the diagnosis and treatment of HC, but further improvement is needed because it does not include factors such as lymph node invasion, hepatic artery invasion, and distant metastasis. In 2002, the UICC/AJCC proposed the sixth version of TNM staging for HC. Compared with the fifth edition of TNM staging, the sixth edition has the following improvements: T3 in T factor is subdivided into T3 and T4, distant and proximal tumor invasion of surrounding organs is distinguished and vascular invasion factor is added; N factor N1 and N2 are combined into N1, i.e. as long as there is local lymph node metastasis, it is N1 and no longer sub-stage.16 An analytical study of 106 cases of HC comparing the fifth and sixth editions16 suggested that the portal vein invasion factor should not be overemphasized and that the lymph node invasion factor should be mentioned as equally important is still imperfect. Nevertheless, with the inclusion of vascular invasion, the sixth edition of UICC/AJCC TNM staging is more reasonable and in line with clinical needs. Expanded radical resection At present, it is clear that surgical resection is the only possible hope to achieve a cure for HC, and therefore a positive attitude should be taken to strive for the best outcome. The results were better with zero mortality and a 5-year survival rate of 40%, and their histological margin negativity rate was 63.8% (37/59). In contrast, Lillemoe at Hopkins University School of Medicine 17109 HCs were resected and 36 (37%) had residual tumor with a negative histologic margin rate of 26% and a 5-year survival rate of 11%. 87.1%, 24.2%, and 6%, respectively, indicating that negative cut margins significantly affect prognosis. Therefore, in terms of surgery, the aim of extended radical resection should be to increase the rate of histologically negative margins and thus improve postoperative survival, otherwise it is a blind “extended” resection. In Bismuth type III or IV cases, HC resection with additional hepatectomy is the first choice, while local resection is not advisable when radical surgery is proposed. It is generally believed that caudal lobectomy (S1) can improve the rate of radical resection, and many Japanese authors recommend routine resection of S1 for cholangiocarcinoma; however, it has also been reported that caudal lobectomy should be added only for central type HC involving the left hepatic duct or caudal bile duct, but not for those involving mainly the right hepatic duct without hilar invasion.18 HC mainly invades the lymphatic duct and nerve sheath, with 74% and 69% of the invasion of both, respectively. Therefore, radical resection must be accompanied by “pulsation” of the hepatoduodenal ligament to remove all lymphatic and nerve tissue. If the lymph nodes surrounding the pancreas are involved and difficult to remove, an extended radical surgery including HPD should be considered. However, any extended surgery is inappropriate when the intraoperative judgment is that radical treatment cannot be achieved. To prevent hepatic failure after an expanded surgery, especially after an expanded right hepatectomy, it is generally considered necessary to require preoperative yellowness reduction therapy and portal vein embolization (PVE) of the proposed resected side of the liver. There have been many reports suggesting that PVE should be performed after yellow reduction therapy to TB <5mg/dl, and if the hepatic resection volume exceeds 60%, then PVE should be performed and the TB should be reduced to <2mg/dl after 2 weeks before surgery.1-3 V. Liver transplantation A Spanish study22 showed that the survival rates of 36 cases of hilar cholangiocarcinoma after liver transplantation were 82%, 53%, and 32% at 1, 3, and 5 years, respectively. Of the 36 cases, 22 were surgically unresectable, and the authors concluded that liver transplantation was effective compared to palliative treatment with a 5-year survival rate of 0. The data from Mayo Clinic23 showed that in 38 patients with preoperative neoadjuvant radiotherapy/chemotherapy followed by liver transplantation for stage I, II or surgically unresectable hilar cholangiocarcinoma, the 1-, 3- and 5-year survival rates were 92%, 82% and 82%, respectively, compared with 82%, 48% and 21% for 26 cases with surgical resection during the same period. Moreover, the tumor recurrence rate after liver transplantation was lower than that of tumor resected patients (13% vs. 27%, P=0.022). The findings suggest that liver transplantation for hilar cholangiocarcinoma is feasible in a select group of cases. In a German group of studies24 showing 32 patients with HC undergoing liver transplantation, 4 patients survived more than 5 years (12.5%), whereas in 151 patients with radical resected HC during the same period, 28 survived more than 5 years (18.5%), and the authors concluded that surgical resection helped to improve survival and quality of life compared with liver transplantation. The present data show that liver transplantation is feasible for the treatment of hilar cholangiocarcinoma, but it cannot be used as a standard treatment measure yet, and its status and role in the treatment of HC need further study. VI. management of vascular invasion Whether the portal vein is invaded and whether the invaded portal vein is resected is one of the important factors affecting the prognosis. ebabta reported 52 consecutive cases of hepatectomy plus portal vein resection for moderately advanced hilar cholangiocarcinoma (22), and the results showed that the operative mortality rate in the portal vein resection group was similar to that in the non-portal vein resection group (108 cases) (9.6% vs. 9.3%). The prognosis of the portal vein invasion group was significantly lower than that of the non-portal vein invasion group (5-year survival rate 9.9% vs. 36.8%, p<0.0001); portal vein bulk metastasis was an independent prognostic factor. In addition, it was found that < span="">tumor cells were very close to the outer portal vein, often < 1 mm, with fibrotic nodal tissue in between, suggesting a high likelihood of positive margins if not combined with portal vein resection< span="">. The Ebabta study showed that hepatic resection combined with portal vein resection can result in long-term survival for certain intermediate to advanced hilar cholangiocarcinoma, and if The authors concluded that their results provide a good basis for the UICC/AJCC 6th edition TNM staging. 23 patients in another group of studies by Neuhaus4 underwent portal vein reconstruction, and multifactorial analysis showed that the combination of portal vein reconstruction was the only independent predictor of postoperative prognosis. The presence or absence of microscopic invasion of the portal vein did not affect survival in Ebata’s study (median survival 16.6 months in the microscopic invasion group and 19.4 months in the microscopic non-invasion group, p=0.1506), so it is possible that the prognosis of HC may be affected differently by gross or microscopic invasion of the portal vein, and further study of the difference is needed. The portal vein can be reconstructed by repair, patching, reanastomosis of the severed end, and external iliac vein grafting.1 Care should be taken during surgery: the time to block the portal vein should not be too long, and should be completed in about 15 min; the anastomosis should not be in tension, and if direct anastomosis is not possible, the saphenous vein or external iliac vein should be cut before cutting the portal vein for use, and in general, resection of the portal vein longer than 75 px may require a Vascular transplantation. The resection and reconstruction of the hepatic artery is less frequently reported, but in China, it has been reported that resection of the hepatic artery does not have serious consequences25 and is therefore considered feasible. However, reconstruction after resection of both the intrinsic hepatic artery and the right hepatic artery has been reported abroad.12 It is undoubtedly dangerous to perform hemihepatectomy with resection of the contralateral hepatic artery in jaundiced patients, with only portal vein supply to the remaining liver, and there are no studies to prove that jaundiced patients with impaired liver function and normal hepatic artery anatomy can avoid liver failure as long as they have portal vein supply. Therefore, we believe that the hepatic artery on the side of the remaining liver should be ensured to be unobstructed during HC hemihepatectomy and reconstructed if severed to effectively prevent postoperative liver ischemia resulting in liver failure or bile-intestinal anastomosis ischemia, and any random removal of the contralateral hepatic artery should not be advocated.