Methylene blue-aided cholangioscopy unravels the endoscopic features of ischemic-type biliary lesions after liver transplantation

Epineural Methylene Blue Injection May Aid Localization of Digital Nerves in Dupuytren's Surgery

Background

In Dupuytren's surgery, limited fasciectomy is still the gold-standard treatment. A relatively high risk of iatrogenic nerve injury has been observed especially when the spiral cords of the Dupuytren's tissue pull digital nerves away from their normal anatomical location. Intraoperative neural marking could facilitate locating the potentially displaced nerves. Hence, surgery could be undertaken more quickly with a lower risk of iatrogenic nerve injury.

Objectives

We hypothesize that digital nerves may be stained with methylene blue (MB) in vivo providing a visual aid to distinguish them from Dupuytren's tissue. We aim to (a) test an in vivo nerve staining technique using MB in a rat sciatic nerve model and to (b) assess the safety of epineural MB injection.

Methods

Three experiments were performed: first, the effects of (a) sham surgery, (b) epineural needle insertion, and (c) 40 μL epineural saline injection were tested in the rat sciatic nerve. Second, we determined the (a) histoanatomical localization of the epineurally injected 40 µL 1 m/m% MB stock solution and (b) we tested which saline dilution (i.e., 1:40, 1:80, and 1:160) of the stock solution does provide optimal blue color upon 40 µL epineural injection. Third, the functional and morphological effect of 40 µL 1:80 diluted MB injection was compared with that of saline, injected into the contralateral sciatic nerve. The functional effects were tested by assessing the pain threshold by using a dynamic plantar esthesiometer (DPA) and by examination of the animal's gate and paw posture. Sciatic nerves were subjected to histological examination and morphometry to test structural damage.

Results

Neither epineural needle insertion nor saline injection caused any functional or morphological changes. Histological examination revealed that the MB stained the epineural compartment. Epineural injection of 40 μL 1:80 diluted MB into the sciatic nerve stained an 18.18-mm segment of the nerve distal to the puncture point. DPA revealed unchanged pain threshold values on the plantar surface of the limbs. Normal gait and foot posture suggested normal motor functions in all groups. No histological changes were seen in the stained nerves, and the nerve fiber density remained unchanged.

Conclusion

We demonstrated that in vivo nerve staining with MB is a suitable method to mark nerves without causing detectable negative effect to the stained nerve. Human trials are required to prove the efficacy of the technique in Dupuytren's disease.

Novel biomarkers and endoscopic techniques for diagnosing pancreaticobiliary malignancy

The UK incidence of pancreatic ductal adenocarcinoma is 9 per 100,000 population, and biliary tract cancer occurs at a rate of 1–2 per 100,000. The incidence of both cancers is increasing annually and these tumours continue to be diagnosed late and at an advanced stage, limiting options for curative treatment. Population-based screening programmes do not exist for these cancers, and diagnosis currently is dependent on symptom recognition, but often symptoms are not present until the disease is advanced. Recently, a number of promising blood and urine biomarkers have been described for pancreaticobiliary malignancy and are summarised in this review. Novel endoscopic techniques such as single-operator cholangioscopy and confocal endomicroscopy have been used in some centres to enhance standard endoscopic diagnostic techniques and are also evaluated in this review.

Post-transplant cholangiopathy: Classification, pathogenesis, and preventive strategies

Biliary complications are the most frequent cause of morbidity, re-transplantation, and even mortality after liver transplantation. In general, biliary leakage and anastomotic and non-anastomotic biliary strictures (NAS) can be recognized. There is no consensus on the exact definition of NAS and different names and criteria have been used in literature. We propose to use the term post-transplant cholangiopathy for the spectrum of abnormalities of large donor bile ducts, that includes NAS, but also intraductal casts and intrahepatic biloma formation, in the presence of a patent hepatic artery. Combinations of these manifestations of cholangiopathy are not infrequently found in the same liver and ischemia-reperfusion injury is generally considered the common underlying mechanism. Other factors that contribute to post-transplant cholangiopathy are biliary injury due to bile salt toxicity and immune-mediated injury. This review provides an overview of the various types of post-transplant cholangiopathy, the presumed pathogenesis, clinical implications, and preventive strategies.

Advances in endoscopic management of biliary complications after living donor liver transplantation: Comprehensive review of the literature

Apart from noticeable improvements in surgical techniques and immunosuppressive agents, biliary complications remain the major causes of morbidity and mortality after living donor liver transplantation (LDLT). Bile leakage and stricture are the predominant complications. The reported incidence of biliary complications is 15%-40%, and these are known to occur more frequently in living donors than in deceased donors. Despite the absence of a confirmed therapeutic algorithm, many approaches have been used for treatment, including surgical, endoscopic, and percutaneous transhepatic techniques. In recent years, nonsurgical approaches have largely replaced reoperation. Among these, the endoscopic approach is currently the preferred initial treatment for patients who undergo duct-to-duct biliary reconstruction. Previously, endoscopic management was achieved most optimally through balloon dilatation and single or multiple stents placement. Recently, there have been significant developments in endoscopic devices, such as novel biliary stents, as well as advances in endoscopic technologies, including deep enteroscopy, the rendezvous technique, magnetic compression anastomosis, and direct cholangioscopy. These developments have resulted in almost all patients being managed by the endoscopic approach. Multiple recent publications suggest superior long-term results, with overall success rates ranging from 58% to 75%. This article summarizes the advances in endoscopic management of patients with biliary complications after LDLT.

Endoscopic management of post-liver transplant biliary complications

Biliary complications are being increasingly encountered in post liver transplant patients because of increased volume of transplants and longer survival of these recipients. Overall management of these complications may be challenging, but with advances in endoscopic techniques, majority of such patients are being dealt with by endoscopists rather than the surgeons. Our review article discusses the recent advances in endoscopic tools and techniques that have proved endoscopic retrograde cholangiography with various interventions, like sphincterotomy, bile duct dilatation, and stent placement, to be the mainstay for management of most of these complications. We also discuss the management dilemmas in patients with surgically altered anatomy, where accessing the bile duct is challenging, and the recent strides towards making this prospect a reality.

Current status of peroral cholangioscopy in biliary tract diseases

Peroral cholangioscopy (POC) is an important tool for the management of a selected group of biliary diseases. Because of its direct visualization, POC allows targeted diagnostic and therapeutic procedures. POC can be performed using a dedicated cholangioscope that is advanced through the accessory channel of a duodenoscope or via the insertion of a small-diameter endoscope directly into the bile duct. POC was first described in the 1970s, but the use of earlier generation devices was substantially limited by the cumbersome equipment setup and high repair costs. For nearly ten years, several technical improvements, including the single-operator system, high-quality images, the development of dedicated accessories and the increased size of the working channel, have led to increased diagnostic accuracy, thus assisting in the differentiation of benign and malignant intraductal lesions, targeting biopsies and the precise delineation of intraductal tumor spread before surgery. Furthermore, lithotripsy of difficult bile duct stones, ablative therapies for biliary malignancies and direct biliary drainage can be performed under POC control. Recent developments of new types of conventional POCs allow feasible, safe and effective procedures at reasonable costs. In the current review, we provide an updated overview of POC, focusing our attention on the main current clinical applications and on areas for future research.

Novel endoscopic approaches in the diagnosis and management of biliary strictures

Indeterminate bilary strictures present the clinician with a wide differential diagnosis. Histological confirmation is usually required for treatment, but tissue acquisition remains challenging. Novel developments in endoscopic technology, such as single operator cholangioscopy and confocal endomicroscopy, have led to improvements in diagnostic accuracy in recent years. In patients with non-resectable malignant biliary obstruction, effective biliary decompression improves symptoms and enables patients to undergo palliative therapies. Improvements in endoscopic techniques, biliary stents and the development of local ablative techniques have led to further improvements in stent patency and survival in these patients. In this article, we review emerging diagnostic and therapeutic techniques for the endoscopic management of indeterminate biliary strictures.

Prospective evaluation of single-operator peroral cholangioscopy in liver transplant recipients requiring an evaluation of the biliary tract

In this descriptive study, we examined the role of single-operator cholangioscopy (SOC) in the evaluation of biliary complications after liver transplantation (LT). We prospectively included adult recipients of deceased donor LT who were referred for endoscopic retrograde cholangiopancreatography between June 2009 and July 2011. All patients underwent SOC with biopsy of the biliary anastomosis. Sixteen patients were included: 12 with biliary anastomotic strictures (ASs), 2 with common bile duct stones, 1 with a bile leak, and 1 with sphincter of Oddi dysfunction. Patients with ASs displayed 1 of 2 patterns: (A) mild erythema (n = 9) or (B) edema, ulceration, and sloughing (n = 3). Those without ASs displayed a pale mucosa with mild edema at the anastomosis. Patients with ASs and pattern B required a longer period of stenting than patients with pattern A (457 versus 167 days, P = 0.02). In addition, patients with pattern A had a better response and better resolution of their strictures with endoscopic therapy than those with pattern B (66% versus 33%, P = 0.13). Histological examinations of ASs showed nonspecific intraepithelial inflammation in patients with patterns A and B. Biopsy samples from patients without ASs showed normal columnar epithelial bile duct cells. The total cholangioscopy time for all procedures was 26.8 ± 10.1 minutes. In conclusion, SOC in LT recipients is feasible and allows adequate visualization and tissue sampling of ASs and bile ducts. Two distinct visual patterns that are easily identified with SOC may help to predict the outcomes of endoscopic therapy in patients with biliary complications after LT.

Effects of autologous bone marrow mononuclear cells implantation on cholangiocytes apoptosis in model of intrahepatic ischemic type biliary lesion in rabbits

AIM

To investigate the effects of autologous bone marrow mononuclear cells (BM-MNCs) implantation on regulation of cholangiocyte apoptosis in a model of intrahepatic ischemic type biliary lesion (ITBL) in rabbits.

MATERIALS AND METHODS

Thirty Japanese white rabbits were divided randomly into 3 groups (10 per group) including controls (group A), ITBL model (group B), and BM-MNCs implantation groups (group C). All rabbits underwent the same surgical procedure to prepare the liver for graft removal during transplantation. Subsequently, no additional vascular intervention was performed in group A. In group B, the hepatic artery and common bile duct were clamped with microvascular clips for 2 hours, where after the clips were removed to recover the blood supply. Group C received, BM-MNCs (10(8) cells per rabbit) injected through the hepatic artery after removing the clips. The animals were killed 4 weeks after operation. The survival rate, histopathologic examination, cholangiocyte apoptosis with terminal uridine nick-end labeling (TUNEL) staining and expressions of Bcl-2 and Bax proteins were examined using immunohistochemical staining.

RESULTS

Group A animals showed a survival of 100%; the rates in groups B and C were both 90%. Histopathologic examination revealed normal intrahepatic cholangiocytes in group A, obviously damaged ones in group B, and alleviated damage in group C. TUNEL staining indicated apoptosis of cholangiocytes in group B was more serious than that in group A or group C. Immunohistochemical staining demonstrated significantly decreased Bcl-2 expression in group B compared with that in group A; Bcl-2 expression in group C returned to the level of group A. Simultaneously, the Bax expression presented adverse results; the ratios of Bcl-2/Bax were ranked as group A > group C > group B.

CONCLUSION

Implantation of autologous BM-MNCs significantly reduced apoptosis of intrahepatic cholangiocytes and prevented or abated intrahepatic ITBL.

Prospective evaluation of the clinical utility of ERCP-guided cholangiopancreatoscopy with a new direct visualization system

BACKGROUND

Older systems for cholangiopancreatoscopy have demonstrated improved diagnostic and therapeutic abilities over standard ERCP but have shown limited feasibility. The SpyGlass Direct Visualization System addresses many of the shortcomings of the older platforms, but its potential advantages have not been rigorously evaluated.

OBJECTIVE

To prospectively evaluate the feasibility, clinical efficacy, and safety of the SpyGlass system.

DESIGN

Prospective cohort study.

SETTING

Tertiary care center.

PATIENTS

All patients undergoing cholangiopancreatoscopy at our institution.

INTERVENTIONS

Cholangiopancreatoscopy with the SpyGlass system.

MAIN OUTCOME MEASUREMENTS

Procedure success, defined as complete stone clearance for stone cases. For nonstone-related lesions, success was defined when all 3 of the following were met: (1) advancement of the SpyScope to the desired target, (2) adequate visualization, and (3) successful applications of all necessary diagnostic and/or therapeutic maneuvers.

RESULTS

Overall, SpyGlass was successful in 70 of 75 patients (93.3%). In patients with biliary stones, complete stone clearance was achieved in 24 of 26 patients (92.3%). Cholangioscopy for nonstone-related indications was successful in 43 of 44 patients (97.7%). Pancreatoscopy was attempted in 5 patients and was successful in 3 (60%). The mean total procedure time (standard ERCP plus SpyGlass) was 64.3 minutes, the total SpyGlass time was 27.5 minutes, the mean SpyGlass visualization time was 14.2 minutes, the mean SpyBite sampling time was 12.1 minutes, the mean Spy therapy time was 8.4 minutes, and the mean set-up time was 5 minutes. There were 4 adverse events (4.8%).

LIMITATIONS

Single-center experience, no comparison group, potential for selection bias.

CONCLUSIONS

ERCP-guided cholangiopancreatoscopy with the SpyGlass system is technically feasible and can be successfully and safely performed in the vast majority of patients. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00861198.).

Per-oral cholangioscopy

Direct endoscopic views of bile duct have been described in literature since the 1970s. Since then rapid strides have been made with the advent of technologically advanced systems with better image quality and maneuverability. The single operator semi-disposable per-oral cholangioscope and other novel methods such as the cholangioscopy access balloon are likely to revolutionize this field. Even though cholangioscopy is currently used primarily for characterization of indeterminate strictures and management of large bile duct stones, the diagnostic and therapeutic indications are likely to expand in future. The following is an overview of the currently available per-oral cholangioscopy equipments, indications for use and future directions.

Establishment of a rat model of extrahepatic biliary ischemic stenosis

AIM: To develop a rat model of extrahepatic biliary ischemic stenosis.

METHODS: Forty-eight Sprague-Dawley rats were divided randomly and equally into four groups: rats undergoing sham operation and those subjected to clamping of the common bile duct with a clip for 60, 120, or 180 min. After scheduled clamping, the clip was removed to recover blood supply. The animals were killed 4 and 8 wk after operation. The survival, liver function, and histopathological changes were observed in rats of each group.

RESULTS: The survival rate was 100% in rats undergoing sham operation and those undergoing clamping for 60 or 120min, and 75% in those undergoing clamping for 180 min. At week 4, the body weight of rats undergoing clamping for 60, 120 or 180 min was lower than that of rats undergoing sham operation (240.4 g ± 11.5 g, 212.7 g ± 13.6 g, 200.6 g ± 11.8 g vs 260.6 g ± 15.7 g, all P < 0.05). Liver function parameters were higher in rats undergoing clamping for 60, 120 or 180 min than in those undergoing sham operation (ALT: 55.3 IU/L ± 5.3 IU/L, 215.6 IU/L ± 26.8 IU/L, 245.5 IU/L ± 38.5 IU/L vs 45.5 IU/L ± 3.9 IU/L, all P < 0.05; AST: 161.3 IU/L ± 15.9 IU/L, 645.3 IU/L ± 50.5 IU/L, 698.8 IU/L ± 46.7 IU/L vs 140.3 IU/L ± 6.1 IU/L, all P < 0.05; TILB: 8.5 μmol/L ± 1.2 μmol/L, 72.6 μmol/L ± 11.0 μmol/L, 78.7 μmol/L ± 12.2 μmol/L vs 6.1 μmol/L ± 1.2 μmol/L, all P < 0.05; ALP: 202.4 IU/L ± 20.7 IU/L, 815.4 IU/L ± 68.1 IU/L, 902.9 IU/L ± 96.6 IU/L vs 158.5 IU/L ± 23.6 IU/L, all P < 0.05; GGT: 10.6 IU/L ± 2.7 IU/L, 52.3 IU/L ± 8.6 IU/L, 57.4 IU/L ± 11.3 IU/L vs 7.6 IU/L ± 1.4 IU/L, all P < 0.05). Histopathological examination showed that biliary stenosis was not apparent and wall fibrosis was milder in rats undergoing sham operation and those undergoing clamping for 60 min, while severe biliary stenosis and wall fibrosis were observed in those undergoing clamping for 120 or 180 min. At week 8, these lesions could not regress spontaneously.

CONCLUSION: An animal model of extrahepatic biliary ischemic stenosis is successfully established with the clamping method in rats, which provides a useful tool for basic and clinical research of the etiology, development and prophylaxis of extrahepatic biliary ischemic stenosis after liver transplantation.

Gauze pledgetting versus endoscopic-guided aerosolized spray for nasal anesthesia before transnasal EGD: a prospective, randomized study

BACKGROUND

Methods and efficacy of nasal anesthesia before ultrathin transnasal EGD (UT-EGD) are crucial for patient tolerance.

OBJECTIVE

To compare patient tolerance, safety, and adverse events between cotton-tipped applicator primed gauze pledgetting (CTGP) and endoscopic-guided aerosolized spray (EGAS) methods of nasal anesthesia.

DESIGN

We performed a prospective, randomized-controlled trial to compare procedural discomforts, optical quality, total procedure time, and adverse events between the CTGP and EGAS methods.

SETTING

A large, tertiary referral hospital in Taiwan.

PATIENTS

A total of 240 consecutive patients with epigastric discomfort were included in the study.

INTERVENTION

The author performed all standardized nasal anesthesia and UT-EGD using a 5.9-mm diameter transnasal endoscope.

MAIN OUTCOME MEASUREMENTS

Technical success, patient tolerability profiles, optical quality, total procedure time, and adverse events.

RESULTS

There was no statistical difference in insertion failure rates between the 2 methods (CTGP 0% vs EGAS 5%, P = .07). When compared with the EGAS method, CTGP reduced pain during insertions through the inferior nasal meatus (3.4 +/- 0.5 vs 3.2 +/- 0.4, P = .006), middle nasal meatus (4.0 +/- 0.7 vs 3.4 +/- 0.5, P = .002), and upper esophageal sphincter (2.9 +/- 0.7 vs 2.6 +/- 0.8, P = .005). CTGP elicited less unpleasant taste, fewer gagging episodes, and less throat pain after examination. Both methods had similar safe hemodynamic profiles, low epistaxis rates (0% vs 2%, P = .46), and comparable visual capacity and procedure time. Although similar proportions of patients in both groups would like to receive the same procedure the next time, CTGP had a higher overall tolerance.

CONCLUSION

Compared with the EGAS method, CTGP achieved a better tolerability profile and elicited less bad taste, fewer gagging episodes, and less throat pain after UT-EGD in Taiwanese patients.

Cholangioscopy for special applications: primary sclerosing cholangitis, liver transplant, and selective duct access

Cholangioscopy is gaining renewed interest and gradually expanded use as a result of recent technical improvements in endoscopes and accessories, coupled with shortcomings in the accuracy of currently available techniques for biliary sampling and diagnosis. Challenging clinical dilemmas that may benefit from its application include early diagnosis of cholangiocarcinoma in the setting of primary sclerosing cholangitis, early identification of biliary infection or ischemia following orthotopic liver transplantation, and selective duct access with wires and other devices during therapeutic endoscopic retrograde cholangiopancreatography. Preliminary data suggest that cholangioscopy has significant utility in assessment and management of primary sclerosing cholangitis. Applications in posttransplant patients and for selective duct access remain minimally defined and used.

Endoscopic management of biliary strictures after liver transplantation

Bile duct strictures remain a major source of morbidity after orthotopic liver transplantation (OLT). Biliary strictures are classified as anastomotic or non-anastomotic strictures according to location and are defined by distinct clinical behaviors. Anastomotic strictures are localized and short. The outcome of endoscopic treatment for anastomotic strictures is excellent. Non-anastomotic strictures often result from ischemic and immunological events, occur earlier and are usually multiple and longer. They are characterized by a far less favorable response to endoscopic management, higher recurrence rates, graft loss and need for retransplantation. Living donor OLT patients present a unique set of challenges arising from technical factors, and stricture risk for both recipients and donors. Endoscopic treatment of living donor OLT patients is less promising. Current endoscopic strategies for biliary strictures after OLT include repeated balloon dilations and placement of multiple side-by-side plastic stents. Lifelong surveillance is required in all types of strictures. Despite improvements in incidence and long term outcomes with endoscopic management, and a reduced need for surgical treatment, the impact of strictures on patients after OLT is significant. Future considerations include new endoscopic technologies and improved stents, which could potentially allow for a decreased number of interventions, increased intervals before retreatment, and decreased reliance on percutaneous and surgical modalities. This review focuses on the role of endoscopy in biliary strictures, one of the most common biliary complications after OLT.

Management of pancreaticobiliary disease using a new intra-ductal endoscope: The Texas experience

AIM: To evaluate a new single-operator mini-endoscope, Spyglass^®, for its performance, feasibility and safety in the management of pancreaticobiliary disease.

METHODS: In a multicenter retrospective analysis of patients undergoing intraductal endoscopy, we evaluated 128 patients (71 men, mean age 57.6 years). Indications were therapeutic (TX) in 72 (56%) and diagnostic (DX) in 56 (44%).

RESULTS: Peroral endoscopy was performed in 121 and percutaneous in seven. TX indications included CBD stones in 41, PD stones in six, and biliary strictures in 25. DX indications included abnormal LFT’s in 15, abnormal imaging in 38 and cholangiocarcinoma staging in three. Visualization of the stone(s) was considered good in 31, fair in six, and poor in four. Advancement of the electrohydraulic lithotripsy probe was not possible in three patients and proper targeting of the lesion was partial in four patients. A holmium laser was used successfully in three patients. Ductal clearance was achieved in 37 patients after one procedure and in four patients after two procedures. Diagnosis of biliary strictures was modified in 20/29 and confirmed to be malignant in 10/23. Of the modified patients, no diagnosis was available in 17. Spyglass^® demonstrated malignancy in 8/17 and non-malignancy in nine. Suspected pathology by imaging studies and abnormal LFT’s was modified in 43/63 (66%). Staging of cholangiocarcinoma demonstrated multicentric cholangiocarcinoma in 2/3. There was no morbidity associated with the use of Spyglass^®.

CONCLUSION: Spyglass Spyscope^® is a first generation, single operator miniature endoscope that can evaluate and treat various biliary and pancreatic tract diseases.

Establishment of an animal model of ischemic type intrahepatic biliary lesion in rabbits

AIM: To explore a method to establish an animal model of ischemic type intrahepatic biliary lesion in rabbits.

METHODS: Forty Japanese white rabbits of clean grade were divided randomly into four groups (10 rabbits per group) including sham operation (SO) group, and artery-bile obstruction (ABO)-1 h group, ABO-2 h group and ABO-3 h group. All the rabbits in this study underwent the same initial surgical procedure in which the liver was prepared as for graft removal during liver transplantation. Subsequently in the SO group, no additional vascular intervention was performed, while in groups ABO-1 h, ABO-2 h and ABO-3 h, the animals underwent combined clamping of the hepatic artery and common bile duct with microvascular clips for 1, 2 and 3 h, respectively. After the scheduled occlusion time, the clip was removed to recover blood supply. The animals were killed 4 wk after operation. The survival rate, liver function, cholangiography and histopathological manifestation of the rabbits in each group were observed.

RESULTS: The survival rate was 100% in groups SO, ABO-1 h and ABO-2 h, while it was 60% in group ABO-3 h. At each observation time, the change degree of the indexes of liver function was proportional to the clamping time (ABO-3 h > ABO-2 h > ABO-1 h > SO, P < 0.05). Cholangiographical and histopathologic manifestations both showed that intrahepatic biliary lesion aggravated proportionally with the increase of the clamping time.

CONCLUSION: An animal model of ischemic type intrahepatic biliary lesion in rabbits is successfully established, which may provide a reliable technique for basic and clinical research into the etiology, development and prophylaxis of ischemic type intrahepatic biliary lesion after liver transplantation.

Intraductal biliary and pancreatic endoscopy: An expanding scope of possibility

Intraductal endoscopy describes the use of an endoscope to directly visualize the biliary and pancreatic ducts. For many years, technological challenges have made performing these procedures difficult. The “mother-baby” system and other various miniscopes have been developed, but routine use has been hampered due to complex setup, scope fragility and the time consuming, technically demanding nature of the procedure. Recently, the SpyGlass peroral cholangiopancreatoscopy system has shown early success at providing diagnostic information and therapeutic options. The clinical utility of intraductal endoscopy is broad. It allows better differentiation between benign and malignant processes by allowing direct visualization and targeted sampling of tissue. Therapeutic interventions, such as electrohydraulic lithotripsy (EHL), laser lithotripsy, photodynamic therapy, and argon plasma coagulation (APC), may also be performed as part of intraductal endoscopy. Intraductal endoscopy significantly increases the diagnostic and therapeutic yield of standard endoscopic retrograde cholangiography (ERCP), and as technology progresses, it is likely that its utilization will only increase. In this review of intraductal endoscopy, we describe in detail the various endoscopic platforms and their diagnostic and clinical applications.