Lecture : Introduction Tokyo guidelines, the guidelines for the management of acute cholecystitis, were revised for the second time in 2018 (Tokyo Guidelines 2018: TG18). TG18 included a section on safe steps of laparoscopic cholecystectomy (LC) to avoid bile duct injury (BDI). On the other hand, this year, guidelines on safe surgical procedures to prevent BDI in LC were published (Brunt LM, Surgical Endoscopy, 2020). This guideline was gathered by experts from five surgical societies, including SAGES, AHPBA, IHPBA, SSAT, and EAES. This guideline was called as “BDI guidelines” in this presentation. BDI incidence, medical costs, and prognosis The BDI caused significantly higher medical costs and a significantly higher rate of mortality rates. The BDI incidence was 0.5% in a study from the United States. As a result of the Japanese society of endoscopic surgery survey, BDI occurred in 130 to 160 patients each year, and the BDI incidence was reported to be 0.4 to 0.6%. According to Japan, Korea, Taiwan collaborated a questionnaire survey, the total number of respondents who experienced BDI or near-misses was over 70% and the ratio increased as experience accumulated, reaching over 80% among surgeons who had performed LC over 1,000 cases in their entire career. Basic procedure and prevention of misidentification TG18 and BDI guidelines recommended the creation of a critical view of safety (CVS). CVS consists of three important factors. At the Calot’s triangle, there are only two vessels: the cystic duct and the cystic artery. Then, at least one-third of the adipose tissues at the lower part of the gallbladder bed is completely removed. TG18 proposed the six safe steps for creating CVS to avoid BDI. Against “Difficult gallbladder” When gallstones are impacted in the gallbladder neck for a long time, the normal gallbladder layers are destroyed. Scarring change may occur at the gallbladder neck. Therefore, exposing the appropriate layer becomes difficult, making the dissection extremely difficult. BDI may occur in patients with severe fibrosis and scarring due to inflammation at the Calot’s triangle; therefore, TG18 proposed the use of bailout procedures. Bailout procedures included open conversion, subtotal cholecystectomy, and fundus-first technique. According to a systematic review and meta-analysis, although postoperative bile leak more commonly occurs after laparoscopic subtotal cholecystectomy, compared with open conversion, the BDI incidence, postoperative complications, reoperation, and mortality rate were all lower. Optimal timing of LC TG18 conducted a systematic review and meta-analysis regarding the timing of surgery, BDI occurrence, and operation time, showing that these variables did not significantly differ between the early and delayed surgery group. Therefore, TG18 recommended early LC for AC regardless of the exact time that passed since onset. The BDI guidelines recommended the use of TG18 severity classification and management according to severity grades. And, early LC within 72 hours was recommended especially for patients with mild AC. Education and coaching for trainee BDI guidelines recommended CVS education and coaching during LC. However, trainees are sometimes experiencing difficulties performing LC for AC because of massive intraoperative bleeding and severe inflammation. We introduced some modifications of instruction for performing LC by the trainee. I will present our modification of these procedures. Conclusion I sincerely hope that the bile duct injury will be eliminated by this knowledge and procedures.