Technical tips and issues of biliary stenting, focusing on malignant hilar obstruction

Endoscopic management of malignant biliary obstructions

Malignant biliary obstruction (MBO), both distal and hilar, represents an ensemble of different clinical conditions frequently encountered in everyday practice. Given the frequent unresectability of the disease at presentation and the increasing indications for neoadjuvant chemotherapy, endoscopic biliary drainage is generally required during the course of the disease. With the widespread use of interventional endoscopic ultrasound (EUS) and the introduction of dedicated devices, EUS-guided biliary drainage has rapidly gained acceptance, together with transpapillary endoscopic biliary drainage and the percutaneous approach. This comprehensive review describes the current role of endoscopy for distal and hilar MBO supported by evidence, with a focus on the current hot topics in this field.

Development of novel biliary metal stent with coil-spring structure and its application in vivo swine biliary stricture model

Background

As of date, endoscopic biliary stenting with plastic stent (PS) and self-expandable metal stent (SEMS) have been widely used for the palliation of biliary tract strictures. However, these two stents have several limitations regarding the management of biliary strictures caused by intrahepatic and hilar cholangiocarcinoma. PS has short patency and also risks bile duct injury and bowel perforation. SEMS is difficult to revise when occluded by tumor overgrowth. To compensate for such shortcomings, we developed a novel biliary metal stent with coil-spring structure. The aim of this study was to investigate the feasibility and efficacy of the novel stent in a swine model.

Methods

The biliary stricture model was prepared in six mini-pigs using endobiliary radiofrequency ablation. Conventional PS (n=2) and novel stents (n=4) were deployed endoscopically. Technical success was defined as successful stent placement and clinical success was defined as >50% reduction of serum bilirubin level. Adverse events, stent migration, and endoscopic removability for one month after stenting were also assessed.

Results

The biliary stricture was successfully created in all animals. The technical success rate was 100 %, and the clinical success rate was 50% in the PS group and 75% in the novel stent group. In the novel stent group, the median pre- and post-treatment serum bilirubin levels were 3.94 and 0.3 mg/dL. Stent migration occurred in two pigs and two stents were removed by endoscopy. There was no stent-related mortality.

Conclusions

The newly designed biliary metal stent was feasible and effective in a swine biliary stricture model. Further studies are needed to verify the usefulness of the novel stent in the management of biliary strictures.

Role of ERCP in Malignant Hilar Biliary Obstruction

Malignant hilar biliary obstruction (MHO), an aggressive perihilar biliary obstruction caused by cholangiocarcinoma, gallbladder cancer, or other metastatic malignancies, has a poor prognosis. Surgical resection is the only curative treatment method for biliary malignancies. However, most of the patients with MHO cannot undergo surgeries on presentation because of an advanced inoperable state or a poor performance state due to old age or comorbid diseases. Therefore, palliative biliary drainage is mandatory to improve symptomatic jaundice and quality of life. Among drainage methods, endoscopic biliary drainage is the current standard for the palliation of unresectable advanced MHO. The development of stents and various accessories and advances in endoscopic techniques including endoscopic ultrasonography have facilitated primary endoscopic intervention in difficult high-grade hilar strictures. However, some issues are still under debate, such as palliation methods, appropriate stents, the number of stents, deployment methods, and additional local ablation therapies. Therefore, this review presents currently optimal endoscopic palliation methods for advanced MHO based on the reported literature.

Endoscopic Bilateral Stent-in-Stent Versus Stent-by-Stent Deployment in Advanced Malignant Hilar Obstruction: A Meta-Analysis and Systematic Review

BACKGROUND AND AIM

There is no clear data to compare the effectiveness and safety of bilateral stent-in-stent (SIS) or stent-by-stent (SBS) deployment for advanced malignant hilar obstruction (MHO). This meta-analysis was done to investigate clinical outcomes of these deployment methods.

METHODS

We did a literature search to identify studies that reported the clinical outcomes of bilateral metal stents in patients with advanced MHO. Weighed pooled rates (WPR) along with 95% confidence interval (95% CI) were calculated in order to compare outcomes including technical and clinical success, adverse events, and stent occlusion between the two groups. We conducted a meta-analysis using a random-effects model.

RESULTS

Five comparative studies with 250 patients, and 20 single-arm studies for the SIS or SBS method were eligible for the meta-analysis and systematic review. The bilateral SIS deployment had a significantly higher technical success rate than did SBS deployment (OR 6.43; 95% CI 1.08-38.09). There was no difference in the clinical success (OR 1.23; 95% CI 0.45-3.38), overall adverse events rates (OR 0.42; 95% CI 0.15-1.18), or overall occlusion rate (OR 1.55; 95% CI 0.89-2.70). As a single-armed group, WPR of technical success of the SIS and SBS groups was 96.4% and 89.6%, respectively. Clinical success was 97.5% and 98.3%. Overall, adverse events were 35.9% and 22.6%. Occlusion rates were 27.7% and 37.7%.

CONCLUSIONS

Although there was a lack of quality data and heterogeneity, bilateral SIS deployment had a higher technical feasibility than did the SBS method in patients with advanced MHO, without differences in terms of clinical success, adverse events, or occlusion rates.

Editors' Choice of Noteworthy Clinical Endoscopy Publications in the First Decade

This is a special review to celebrate the 10th anniversary of Clinical Endoscopy. Each deputy editor has selected articles from one's subspecialty that are significant in terms of the number of downloads, citations, and clinical importance. The articles included original articles, review articles, systematic reviews, and meta-analyses.

[A Recent Update on Endoscopic Drainage of Advanced Malignant Hilar Obstruction]

Malignant hilar obstruction (MHO) is considered an aggressive perihilar obstruction caused by cholangiocarcinoma, gallbladder cancer, or metastatic malignancies and has a poor prognosis. Although surgical resection is the only curative treatment method, the majority of patients with MHO do not undergo surgery due to an advanced inoperable state at presentation. Currently, effective biliary drainage provides the necessary palliation for symptomatic improvement. Among the drainage methods, percutaneous access may be preferred, especially for advanced MHO because of the technical difficulty involved with other techniques. Recently, primary endoscopic palliation using plastic or metal stents has been shown to have higher technical feasibility and clinical success without increasing adverse events even in patients with high-degree MHO. The development of various accessories, endoscopic ultrasonography, and advances in techniques have facilitated primary endoscopic intervention. However, some aspects continue to be debated such as the palliation methods, appropriate stents, the number of stents, the deployment methods, and additional local ablation therapies. Therefore, this review discusses the current optimal endoscopic treatment methods for advanced MHO based on reported literature.

A preliminary single-center investigation of percutaneous biliary stenting in malignant hilar biliary obstruction: what impacts the clinical success and the long-term outcomes?

PURPOSE

The purpose of this study is to investigate the influencing factors that may impact the clinical success, jaundice-free time, and overall survival in patients of malignant hilar biliary obstruction (MHBO) treated with a self-expanding metallic stent (SEMS).

MATERIALS AND METHODS

Patients diagnosed with MHBO and treated with SEMS through percutaneous access from 1 Jul. 2013 to 1 Jul. 2018 were enrolled in this monocentric study. Demographic information, disease baseline measurements, and interventional strategies were collected and examined. Bilirubin was measured 1-3 days before and 3-7 days after stenting using the unit of "μmol/L." The bilirubin reduction ratio was compared between different study groups, which were separated by specific characteristics. Univariate and multivariate analyses were performed to evaluate each characteristic's impact on jaundice-free time (JF) and overall survival time (OS). Statistical analyses were conducted using SPSS 14.0, p < 0.05 indicated significance.

RESULTS

Eighty patients were enrolled. Direct bilirubin (DB) and indirect bilirubin (IB) both significantly decreased after stenting (U = 1575.0, p < 0.001; U = 1541.0, p < 0.001). The DB reduction ratio of the "nearby lymph metastases" group was significantly higher (U = 566.0, p = 0.037). The IB reduction ratio in the "single stent" group was significantly higher (U = 554.0, p = 0.018). Sixty-six cases reached jaundice recurrence, the median JF was 6 months, and the 95% confidence interval was 4.411 ~ 7.589 months. Fifty-eight cases ended in death, the median OS was 7 months, and the 95% confidence interval was 5.759 ~ 8.241 months. "Nearby lymph metastases" and "distant metastases" independently impacted OS (OR = 2.344, p = 0.013; OR = 3.239, p = 0.042). "IB reduction ratio" independently impacted both JF and OS (OR = 0.422, p = 0.021; OR = 0.315, p = 0.001).

CONCLUSION

The goal of treatment in patients with MHBO is to recover liver function. However, the overall survival is greatly impacted by the presence of metastases. Managing to obtain adequate liver function recovery may improve the long-term outcomes in affected patients.

The risk of acute cholangitis after endoscopic stenting for malignant hilar strictures: A large comprehensive study

BACKGROUND AND AIM

Endoscopic stenting for unresectable malignant hilar biliary strictures (MHBS) remains challenging. Post-endoscopic retrograde cholangiopancreatography cholangitis (PEC) can be the most common and fatal adverse event. In the present study, we aimed to systematically evaluate the incidence, severity, risk factors, and consequences of PEC after endoscopic procedures for advanced MHBS.

METHODS

Of 924 patients, we identified 502 patients with MHBS (Bismuth types II to IV) who underwent endoscopic stenting as the primary therapy at two centers over 16 years. PEC and its severity were verified according to the current Tokyo guidelines.

RESULTS

A total of 108 patients (21.5%) experienced acute PEC. Mild, moderate, and severe cholangitis were encountered in 51 (10.1%), 42 (8.4%), and 15 (3.0%) patients, respectively. Multivariate analyses showed that metal stenting (verse plastic stenting) (OR 0.328, 95% CI 0.200-0.535, P < 0.001) and Bismuth classification (IV vs III/II) (OR 2.499, 95% CI 1.150-5.430) were independent predictors for PEC and the moderate/severe type. Patients with PEC had significantly lower clinical success rates (86.3% vs 41.7%, P < 0.001), a higher rate of early death (6.5% vs 0.5%, P < 0.001), a shorter median stent patency (4.9 vs 6.4 months, P < 0.001), and shorter overall survival (2.6 vs 5.2 months, P < 0.001) compared with the noncholangitis group.

CONCLUSIONS

After endoscopic stenting for advanced MHBS, cholangitis may occur in as many as 21.5% of patients, which may be associated with a poor prognosis. The risk is high in patients with Bismuth type IV and may be reduced by using metal stents.

Biliary stenting for hilar malignant biliary obstruction

Although endoscopic intervention is the mainstay for palliation of malignant biliary obstruction, a percutaneous approach has been preferred, particularly in patients with advanced high-grade hilar malignant biliary obstruction, because of the technical difficulty and risk of complications. However, recently, primary endoscopic palliation using plastic or metal stents has had higher technical and clinical success with fewer adverse events than the percutaneous approach. Endoscopic interventions are being done more and more frequently because of advances in metal stents, accessories, and techniques. However, several concerns, such as optimal stent type, number, and deployment method, remain to be resolved. Therefore, we reviewed the literature in order to identify the optimal biliary stenting strategy for patients with hilar malignant biliary obstruction, focusing on stent type (plastic vs metal), number (unilateral [single] vs bilateral [multiple]), and deployment method (stent-in-stent vs stent-by-stent).

A 17 years retrospective study on multiple metal stents for complex malignant hilar biliary strictures: Survival, stents patency and outcomes of re-interventions for occluded metal stents

BACKGROUND

Endoscopic placement of SEMSs for malignant hilar biliary strictures (MHBS) is well-established palliative treatment for inoperable patients. Objectives of this study were evaluation of survival and stents patency after placement of multiple SEMS for palliation of complex MHBS.

METHODS

Retrospective review of patients with MHBS that underwent ERCP with insertion of multiple SEMSs for palliation. Survival-associated factors and stents patency were analyzed by Cox multivariate analysis.

RESULTS

Between January 1998 and January 2015, 740 patients with nonoperable MHBS that underwent ERCP were identified and only 18.2% of these received multiple SEMSs. Complications were observed in 7.5% of the patients with no procedure-related mortality. Palliative therapies (chemotherapy, external beam radiotherapy and high dose rate brachytherapy) were done in some patients, and outcomes were evaluated. Overall mean survival of the 134 patients was 323 days. Of these, 59% did not had stents malfunction while 41% patients had episodes of SEMSs malfunction and mean survival after re-interventions was 502.9 days. Survival was not influenced by type of tumor, sex or age.

CONCLUSIONS

Endoscopic multiple SEMSs placement is safe and effective in patients with complex MHBS. Survival is independent from the type and complexity of MHBS while is prolonged in patients undergoing HDR brachytherapy. Prompt recognition of SEMSs malfunction is fundamental for survival.

Prospective comparison of endoscopic bilateral stent-in-stent versus stent-by-stent deployment for inoperable advanced malignant hilar biliary stricture

BACKGROUND AND AIMS

Although the efficacy of palliative bilateral biliary drainage using self-expandable metal stents has been demonstrated, it is unclear which bilateral method is optimal for advanced malignant hilar biliary strictures (MHSs). This pilot study compared bilateral stent-in-stent (SIS) with stent-by-stent (SBS) deployment for advanced MHSs.

METHODS

Patients with inoperable high-grade MHSs were enrolled in this prospective randomized multicenter study. The primary outcome was the rate of adverse events, whereas secondary outcomes were technical and clinical success, reintervention, therapeutic outcomes, stent patency, and survival duration.

RESULTS

This study randomized 69 of 74 pathologically diagnosed patients to the SIS (n = 34) or SBS (n = 35) groups. The total adverse event rate after stent deployment did not differ between the 2 groups (23.5% in the SIS group vs 28.6% in the SBS group, P = .633). The primary technical success rate was 100% (34/34) and 91.4% (32/35) in the SIS and SBS groups, respectively (P = .081). The clinical success rate was 94.1% (32/34) and 90.6% (29/32), respectively (P = .668). The stent patency rate at 3 months was 85.3% in the SIS group and 65.7% in the SBS group (P = .059). At 6 months, the stent patency rate was 47.1% and 31.4%, respectively (P = .184). The median cumulative stent patency and survival probability did not differ between the 2 groups.

CONCLUSIONS

Efficacy of bilateral SIS and SBS deployment may be similar in terms of total adverse events, technical and clinical success, stent patency, and survival. The stent patency rates at 3 and 6 months was higher in the SIS group without statistical difference. (Clinical trial registration number: NCT01141088.).

Bilateral versus unilateral placement of metal stents for inoperable high-grade malignant hilar biliary strictures: a multicenter, prospective, randomized study (with video)

BACKGROUND AND AIMS

The efficacy of palliative biliary drainage by using bilateral or unilateral self-expandable metal stents (SEMSs) for a malignant hilar biliary stricture (MHS) remains controversial. This prospective, randomized, multicenter study investigated whether bilateral drainage by using SEMSs is superior to unilateral drainage in patients with inoperable MHSs.

METHODS

Patients with inoperable high-grade MHSs who underwent palliative endoscopic insertion of bilateral or unilateral SEMSs were enrolled. The main outcome measurements were the rate of primary reintervention for malfunction after successful placement of SEMSs, stent patency, technical and clinical success rates, adverse events, and survival duration.

RESULTS

A total of 133 pathology-diagnosed patients were randomized to the bilateral group (n = 67) or the unilateral group (n = 66). The primary technical success rates were 95.5% (64/67) and 100% (66/66) in the bilateral and unilateral groups, respectively (P = .244). The clinical success rates were 95.3% (61/64) and 84.9% (56/66), respectively (P = .047). The primary reintervention rates based on the per-protocol analysis were 42.6% (26/61) in the bilateral group and 60.3% (38/63) in the unilateral group (P = .049). The median cumulative stent patency duration was 252 days in the bilateral group and 139 days in the unilateral group. The risk of stent patency failure was significantly higher in the unilateral group (log-rank test; P < .01). In a multivariate Cox proportional hazard model to assess stent patency, bilateral SEMS placement was a favorable factor (adjusted hazard ratio 0.30, 95% confidence interval, 0.172-0.521; P < .001). Survival probability and late adverse events were not different between the 2 groups.

CONCLUSIONS

Unilateral and bilateral drainage strategies by using SEMSs had similar technical success rates, but bilateral drainage resulted in fewer reinterventions and more durable stent patency in patients with inoperable high-grade MHSs. (Clinical trial registration number: NCT02166970.).

Serial insertion of bilateral uncovered metal stents for malignant hilar obstruction using an 8 Fr biliary system: a case series of 17 consecutive patients

Controversy exists over the need for unilateral versus bilateral stent placement in patients with malignant obstruction at the biliary hilum. Placement of bilateral uncovered self-expanding metal stent (UCSEMS) at this location is technically challenging, and generally associated with lower rates of procedural success. Serial insertion of side-by-side UCSEMS may be especially difficult when simultaneous deployment is not possible using larger stent delivery catheters. In this single-center, retrospective case series of all patients who underwent bilateral placement of uncovered Wallflex(TM) biliary stents between July 2008 and July 2014, we evaluate the feasibility, technical success, and safety of patients undergoing serial insertion of bilateral UCSEMS using the 8 Fr Wallflex(TM) biliary system for malignant hilar obstruction. A total of 17 patients were included. Primary cholangiocarcinoma, Bismuth IV, was the most common diagnosis. Mean procedure time was 54.4 minutes. Overall procedural technical success was achieved in 17/17 patients. Stricture dilation was necessary prior to Wallflex(TM) insertion in 8/17 patients (47.1%). Transpapillary extension of two stents was performed in all patients. There were no cases of stent deployment malfunction, or inability to insert or deploy the 2(nd) stent. Nine of 17 patients (52.9%) required inpatient hospitalization following ERCP; the most common indications were abdominal pain and need for IV antibiotics. There was one case of ERCP-related cholangitis otherwise; there were no other major complications. Bilateral, serial insertion of UCSEMS using the 8 Fr Wallflex(TM) biliary system in malignant hilar obstruction is feasible with an excellent technical success profile. Using this device for side-by-side deployment of UCSEMS appears to be safe in the majority of patients.

Endoscopic management of hilar biliary strictures

Hilar biliary strictures are caused by various benign and malignant conditions. It is difficult to differentiate benign and malignant strictures. Postcholecystectomy benign biliary strictures are frequently encountered. Endoscopic management of these strictures is challenging. An endoscopic method has been advocated that involves placement of increasing number of stents at regular intervals to resolve the stricture. Malignant hilar strictures are mostly unresectable at the time of diagnosis and only palliation is possible.Endoscopic palliation is preferred over surgery or radiological intervention. Magnetic resonance cholangiopancreaticography is quite important in the management of these strictures. Metal stents are superior to plastic stents. The opinion is divided over the issue of unilateral or bilateral stenting.Minimal contrast or no contrast technique has been advocated during endoscopic retrograde cholangiopancreatography of these patients. The role of intraluminal brachytherapy, intraductal ablation devices, photodynamic therapy, and endoscopic ultrasound still remains to be defined.

Technical tips and troubleshooting of endoscopic biliary drainage for unresectable malignant hilar biliary obstruction

Unresectable malignant hilar biliary obstruction (MHBO) occurs in various diseases, such as cholangiocarcinoma, gallbladder carcinoma, hepatocellular carcinoma, pancreatic cancer, and lymph node metastasis of the hilum of the liver. The majority of patients with advanced MHBO are not candidates for surgical resection because of the tumor location in the hepatic hilum and adjacent areas, advanced tumor stage, or comorbidities. Therefore, these patients often have a poor prognosis in terms of survival and quality of life. Most of these patients will require non-surgical, palliative biliary drainage. To date, various biliary drainage techniques for unresectable MHBO (UMHBO) have been reported. Of these techniques, endoscopic biliary drainage is currently considered to be the most safe and minimally invasive procedure. However, endoscopic biliary drainage for UMHBO is still not standardized regarding the optimal stent, drainage area, stenting method, and reintervention technique. Recently, towards standardization of this technique for UMHBO, clinical research and trials including randomized controlled trials have been performed. In this article, we reviewed the most important issues regarding endoscopic biliary drainage for UMHBO, focusing on prospective studies. We also described in detail the techniques and future perspectives of endoscopic biliary drainage in patients with UMHBO.

Endoscopic prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is not an uncommon adverse event but may be an avoidable complication. Although pancreatitis of severe grade is reported in 0.1%-0.5% of ERCP patients, a serious clinical course may be lethal. For prevention of severe PEP, patient risk stratification, appropriate selection of patients using noninvasive diagnostic imaging methods such as magnetic resonance cholangiopancreatography or endoscopic ultrasonography (EUS), and avoidance of unnecessary invasive procedures, are important measures to be taken before any procedure. Pharmacological prevention is also commonly attempted but is usually ineffective. No ideal agent has not yet been found and the available data conflict. Currently, rectal non-steroidal anti-inflammatory drugs are used to prevent PEP in high-risk patients, but additional studies using larger numbers of subjects are necessary to confirm any prophylactic effect. In this review, we focus on endoscopic procedures seeking to prevent or decrease the severity of PEP. Among various cannulation methods, wire-guided cannulation, precut fistulotomy, and transpancreatic septostomy are reviewed. Prophylactic pancreatic stent placement, which is the best-known prophylactic method, is reviewed with reference to the ideal stent type, adequate duration of stent placement, and stent-related complications. Finally, we comment on other treatment alternatives, and make the point that further advances in EUS-guided techniques may afford useful PEP prophylaxis.

Bilateral metallic stenting in malignant hilar obstruction

Endoscopic palliative biliary drainage is considered as a gold standard treatment in advanced or inoperable hilar cholangiocarcinoma. Also, metal stents are preferred over plastic stents in patients with >3 months life expectancy. However, the endoscopic intervention of advanced hilar obstruction is often more challenging and complex than that of distal malignant biliary obstructions. In this literature review, we describe the issues commonly encountered during endoscopic unilateral (single) versus bilateral (multiple) biliary stenting for malignant hilar obstruction. Also, we provide technical guidance to improve the technical success rates and patient outcomes, focusing on bilateral metallic stenting techniques such as stent-in-stent or side-by-side deployment.

Biliary stenting for cholangiocarcinoma: An update

Cholangiocarcinoma (bile duct cancer) is the most common malignant tumor of the biliary tree. This devastating malignancy presents late, and is notoriously difficult to diagnose, thus resulting a high mortality. The majority of cholangiocarcinoma patients present with an unresectable disease, and survive less than 12 mo following diagnosis. Biliary stent placement is an effective palliative therapy for malignant biliary obstruction, which can significantly improve the quality of life, and extend the survival time of patients. Different biliary stent placement methods would closely affect the prognosis of patients. The purpose of this article is to review the treatment efficacy, insertion paths and types of biliary stents. This paper also covers emerging biliary stents including drug stents, and biliary stent combination local therapy.

Hepato-biliary-enteric stent drainage as palliative treatment for proximal malignant obstructive jaundice

The proximal malignant obstructive jaundice remains one of the most challenging problems for hepato-biliary surgeons. Particularly when the findings preclude surgical resection at exploration, the next decision seems hard to make. A novel palliative treatment called "hepato-biliary-enteric stent drainage" was designed for these proximal malignant obstructive jaundice patients. Hepato-biliary-enteric stent drainage was performed with silicone tube whose diameter was determined according to the degree of dilated biliary ducts, and the proximal end of the tube was placed to intrahepatic ducts as far as possible, the distal end was placed across the duodenal papilla. Between February 2011 and August 2012, 23 patients with the proximal malignant obstructive jaundice of unresectable tumors at exploration received hepato-biliary-enteric stent drainage. Patient's liver function results, symptoms, complications, and survival time were documented. The bilirubin levels of all 23 patients had a considerable and persistent decrease after operation and remained low or normal before death except for four cases of recurrent jaundice (two resulted from migration of tube and other two resulted from hepatocellular carcinoma extensively involving liver parenchyma). After effective drainage, clinical symptoms of cholangitis such as fever or pain were markedly relieved. No procedure-related bleeding, bile leakage, pancreatitis were observed. The median survival time was 212 days, half-year and 1-year survival rate were 56.5 and 21.7%, respectively. Hepato-biliary-enteric stent drainage with less expense, less complications, and easy operation may be an ideal option for patients with unresectable malignancy in the hilar region at exploration.

Highlights of the 48th seminar of korean society of gastrointestinal endoscopy

This special May issue of Clinical Endoscopy discusses the tutorial contents dealing with either the diagnostic or therapeutic gastrointestinal (GI) endoscopy that contain very fundamental and essential points in this filed. The seminar of Korean Society of Gastrointestinal Endoscopy (KSGE) had positioned as one of prime educational seminars covering the very beginner to advanced experts of GI endoscopy. Besides of four rooms allocated for each lecture, two additional rooms were open for either live demonstration or hands-on course, covering totally 20 sessions including one special lecture. Among these prestigious lectures, 12 lectures were selected for the current review articles in this special issue of Clinical Endoscopy journal. Basic course for beginner to advanced tips to expert were all covered in this seminar. This introductory review prepared by four associated editors of Clinical Endoscopy contained core contents divided into four sessions-upper gut, lower gut, pancreaticobiliary, and specialized topic session part-to enhance understandings not covered by enlisted review articles in this issue.