Bile leak and bile duct stricture caused by accidental injury to the bile duct can occur with any surgical operation involving the bile duct. The current leading cause of bile duct injury is laparoscopic cholecystectomy (LC). Although LC has been shown to be superior to open cholecystectomy for shorter hospital stays, lower rates of systemic complications, faster recovery, and better cosmetic results, the risk of bile duct injury during LC is 2 to 6 times higher compared to open cholecystectomy. Currently, there is no significant change in the incidence of biliary injury, even though some authors have reported a trend toward a decrease. The overall incidence is estimated to be between 0.25% and 0.74% for severe bile duct injury, and between 0.1% and 1.7% for minor bile duct injury.Bergman et al. classified postoperative bile duct injury as follows: type A: bile duct leak or bile leak from the vagus bile duct (minor injury); type B: bold duct leak with or without coexisting bile duct stricture (severe injury); type C: bile duct stricture without bile leak (severe injury); Type D: complete transection of the bile duct (severe injury). I. Clinical features and diagnosis The three main clinical features of biliary tract injury include: (1) biliary fistula; (2) biliary peritonitis; and (3) obstructive jaundice with or without acute cholangitis. Different combinations of these clinical features can be present. Most importantly, although some clinical manifestations such as simple jaundice or well-drained biliary fistula do not require any emergency management, the presence of infection must be considered an indication for close observation and early treatment of sepsis. When postoperative symptoms appear late, due to slow progression, there may be no overt jaundice or a typical non-jaundiced cholestasis with or without pruritus of the skin, as well as recurrent episodes of acute cholangitis. Suspected biliary tract injury is not always easy to diagnose definitively. When mild symptoms such as vague abdominal pain, bloating, low-grade fever, and nausea present in the early post-LC period, some possible complication should be suspected. The initial extraction of bile from the abdominal cavity with few or no specific symptoms should also be investigated as soon as possible to finalize the diagnosis and further develop the best treatment plan for each specific patient. In order to develop a treatment plan, direct cholangiography is most important to obtain a precise anatomical localization and to classify the injury. In cases of suspected biliary tract injury, the ERCP technique is not significantly different from the conventional examination. However, special attention should be paid to the contrast injection, aiming to be slow and careful in order to accurately visualize the injury. Large injections of contrast into the bile duct should be avoided. Small injections and early filling radiographs are also important to show small residual CBD stones. Percutaneous hepatic percutaneous cholangiography (PTC) and/or MRCP may be used as alternatives in patients who have failed ERCP or failed intrahepatic bile duct visualization due to proximal bile duct injury. II. Treatment In recent years, ERCP has played a crucial role in the management of postoperative biliary complications. The following two main and typical clinical manifestations can be treated with the aid of ERCP: (1) biliary intra-abdominal or external fistula; (2) obstructive syndrome with cholestasis, cholangitis and/or jaundice. Diagnostic ERCP is indicated to identify clinically suspected biliary injury and should obtain as much imaging information as possible. In addition to type D injuries with complete bile duct transection requiring surgery, therapeutic ERCP is increasingly being used as first-line treatment for those postoperative biliary complications that are effective for endoscopic treatment. Endoscopic treatment of type A injuries The vast majority of bile leaks due to minor injuries originate from the stump of the bile duct. A small number of bile leaks can also originate from severed Luschka ducts (small peripheral bile ducts connecting the intrahepatic biliary system to the gallbladder), small subsegments of bile ducts that travel through the bed of the gallbladder, and vagal branches of segments and subsegments that converge into the CBD at the proximal end of the cystic duct. In principle, the treatment of these biliary leaks is not different from leaks originating from the stump of the cystic duct. Elimination of the pressure gradient on both sides of the papilla can be achieved by endoscopic sphincterotomy (ES) alone, ES and stenting or nasobiliary drainage (NBD) implantation, stenting alone without prior ES or NBD implantation. All approaches appear to be equally effective and usually close the bile leak within a week of treatment. The choice of endoscopic treatment remains controversial. If CBD stones are present, ES and lithotripsy are the most logical, with or without combined stenting or NBD implantation. However, each option is subject to certain limitations: ES can be combined with intrinsic near-term or potential long-term complications; stenting requires secondary access to remove the stent and can also result in blockage or displacement; NBD requires prolonged hospitalization, patient discomfort, and occasional dislodgement. Postoperative bile leaks due to minor injuries (type A) are usually effective for endoscopic treatment and have a high success rate. All methods appear to be equally effective in closing biliary leaks within a few days. 2. Endoscopic treatment of type B injuries In severe injuries, the bile leak originates from either a CBD or an injury to one of the large branches of the intrahepatic bile ducts that form the main confluence (type B). In both cases, ES alone is not sufficient to close the fistula. It is preferable to implant at least one large-diameter plastic stent (10-11.5 Fr) and maintain it for a long time to adequately divert the leaking bile from the injury site. The second purpose of stent implantation is to prevent strictures from occurring at the site of damage to the bile duct wall. For this purpose, the stent should be left in place for several months to ensure a firm healing process. In the event of stenosis at the site of injury, the implanted stent makes it easier to perform subsequent endoscopic manipulations to dilate the stenosis. The success rate of treatment in this case is 71% to 79%. Bile duct stenting has also been successfully used to reestablish continuity of damaged biliary branches at the level of the main confluence of the bile duct and bile leaks originating from the vagus bile duct. In severe bile duct injuries with biliary leaks, the main therapeutic objective is also to close the fistula and transform an acute problem into a stable state. In any case, the high effectiveness of endoscopic treatment in this condition has led to its recognition as a first-line treatment. 3. endoscopic treatment of type C injuries (biliary strictures) In the pre-laparoscopic era, the treatment of postoperative biliary strictures was traditionally a surgical procedure. the role of ERCP was limited to diagnosis and, in particular, to determining the level and extent of the injury. With the increasing use of ERCP in the evaluation and treatment of acute complications of LC, therapeutic ERCP has been widely used for the treatment of both near and distant postoperative biliary strictures. Endoscopic therapy is today used as a first-line non-surgical treatment alternative to surgery, and endoscopic therapy does not exclude the option of surgery as a remedial treatment after failed endoscopic therapy. Endoscopic treatment of postoperative bile duct strictures is based on two steps: transmigration of the stricture; and dilatation of the stricture. (1) Transgressing the stricture The morphological requirement that allows transgressing the stricture is the continuity of the CBD. In most cases, especially when symptoms persist for a long time after surgery and the stenosis is incomplete after endoscopic cannulation into the CBD, crossing the stenosis becomes the first step in performing dilatation therapy. This operation is often more difficult in postoperative stenoses than in neoplastic stenoses, because even stenoses that are usually short are often asymmetrical. In addition, fibrosis makes the stenosis slender and tight. It is often necessary to apply a thin hydrophilic guidewire with a straight or J-shaped tip (0.021 or 0.018 inch); these maneuvers require patience, skill, and optimal radiographic surveillance. Changing the patient’s position helps to determine the correct path for following the guidewire radiographically. Pulling the inflated extraction balloon below the stricture helps to straighten the bile duct and adjust the axial direction of the guidewire. Once the stricture is passed, the hydrophilic guidewire should be replaced with a stiffer and more stable guidewire for the following dilation treatment. (2) Stenosis dilation The purpose of stenosis dilation is twofold: first, to recanalize the bile duct to restore normal bile flow, and second, to ensure effective dilation to avoid restenosis in the long term. In the initial phase of endoscopic treatment, only the first aim can be pursued; even if it is very effective in the short term, it is obvious that dilation alone is difficult to maintain good results in the long term follow up. Nowadays, balloon dilation is mainly used for the initial treatment with the implantation of one or more plastic stents to achieve continuous supportive dilation. The role of stent implantation is to maintain long-term patency of the stenosis while the scar is shaped and cured (months to years depending on the treatment protocol). Usually two 10 Fr stents are implanted and replaced every three months to avoid cholangitis due to stent occlusion, and the stents are left in place for 1 year. The long-term outcome of endoscopic treatment was compared with surgical treatment in a retrospective study of ten years (1981-1990) of multidisciplinary experience reported by the Amsterdam group. Overall, 35 cases underwent surgical procedures (all Roux-en-Y bile duct jejunostomy) and 66 cases underwent endoscopic treatment. Patient characteristics, type of initial injury, and level of obstruction did not differ significantly between the two groups. After a mean follow-up of 50 and 42 months for surgical and endoscopic treatment, respectively, 83% of cases in both groups showed excellent (asymptomatic patients with normal or stable laboratory parameters) or good (simple cholangitis attacks) results. This important study also shows that endoscopic treatment can be considered at least as effective as surgery in terms of long-term outcome and that endoscopic treatment has a great advantage in that it does not preclude further surgical treatment when needed.The treatment protocol used in the group of cases reported by Costamagna et al [21] (55 cases) consisted of the largest possible number of stents (10 Fr is ideal) determined by the tension of the stricture and the internal diameter of the CBD. The treatment protocol used in a group of cases (55) reported by Costamagna et al. Treatment was continued until the morphological stenosis on cholangiography had completely disappeared. 40% of the cases required initial balloon dilation, which was almost always applied during the first treatment. Three patients underwent a combined application of percutaneous puncture and endoscopic treatment. The average number of stents placed was 1.7 (1 to 4) at the first treatment and 3.2 (1 to 6) at the end of treatment. Loss of stenosis could be observed by NBD cholangiography 24 to 48 hours after stent removal. early complications (3 cholangitis, 1 pancreatitis) occurred in 4 (9%) cases, and stent occlusion requiring early replacement occurred in 8 patients (18%). The average duration of treatment was 12.1±5.3 months (2-24 months). Follow-up should be every 3 months for the first year and every 6 months after one year, including clinical manifestations, laboratory parameters and ultrasound of the liver. Forty-two of the initial 55 patients completed a mean follow-up of 49 months after the end of treatment and were considered acceptable for evaluation. 10 cases were excluded, 5 of them because of complete transection of the CBD and the other 5 were treated with self-expanding metal stents (SEMS). Another 3 cases were not included for different reasons. 2 cases died during the follow-up for unrelated reasons. In the remaining 40 patients, there was no recurrence of symptoms due to recurrent biliary strictures, and the treatment success rate was 89%. Figures 2a to d show the endoscopic treatment of severe common bile duct stenosis after multiple biliary procedures. Recently, the use of fully coated retrievable self-expanding metal stents for the treatment of benign biliary strictures has been reported with good results, but there is a lack of data from controlled studies with large samples. Based on published data, endoscopic treatment with combined stenting is at least as effective as surgery for severe injury or stricture of the bile duct. Figures 3a to c show the endoscopic treatment of severe stenosis of the lower bile duct. The advantages of endoscopic treatment are simplicity, reproducibility, and minimally invasive. Therefore, endoscopic treatment should be considered in the treatment strategy for most patients with severe bile duct injury in hospitals where it is available. For most of them, endoscopic treatment may be the only treatment needed. Complications Complications can occur during the initial treatment phase or at the time of stenting. Complications related to ES (acute pancreatitis, retroperitoneal perforation and hemorrhage) occur during the initial treatment phase and are usually performed to access the bile duct. The ES-related complications of this condition do not differ in incidence, severity and management after the occurrence of complications from other more common conditions, such as the treatment of CBD stones. Complications during stent implantation are mainly due to stent dysfunction such as blockage, displacement, dislodgement, and impaction. Acute cholangitis is the typical clinical presentation after the onset of stent dysfunction. This condition is usually mild and self-limiting, but still requires immediate endoscopic management, i.e., reimplantation of the stent to re-establish proper bile drainage. A typical complication of long-term stenting is the formation of bile sludge and stones over the stricture. This condition can cause cholangitis, but can also be completely asymptomatic. To avoid early reocclusion before implantation of a new stent, it is essential to remove all stones and bile sludge by applying a mesh basket or airbag. To avoid stone formation, stent replacement every three months should not be prolonged. Therefore, patient compliance is essential in the management of postoperative biliary strictures, and patients should be informed of the potential dangers of not following a planned treatment regimen on time.