WEO NEWSLETTER AND CONTENTS

Abstract

Digestive EndoscopyVolume 24, Issue 1 p. 65-70 Free Access WEO NEWSLETTER AND CONTENTS First published: 27 December 2011 https://doi.org/10.1111/j.1443-1661.2011.01201.xCitations: 3AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Welcome Welcome the WEO newsletter which from today on will be co-published in Digestive Endoscopy. The World Endoscopy Organization (WEO) is a world federation of national digestive endoscopy societies. Member societies are normally affiliated to and represented by one of three geographical zones: Asian-Pacific (APSDE), European/Mediterranean (ESGE) and Inter-American (SIED). We are pleased to announce that WEO has formed an official affiliation with the Journal Digestive Endoscopy. Additionally to excerpts of the monthly WEO e-newsletter WEO will publish abstracts from major meetings and position statements via Digestive Endoscopy. Videos recorded during live teaching seminars at the WEO Centers of Excellence will be linked to this website as well as being available on http://www.worldendo.org. We are very pleased to have this close bond of cooperation and look forward to an exciting collaboration. Editor The Executive Committee of WEO is pleased to announce that Professor John Baillie, currently a member of the Gastroenterology Group at Wake Forest Baptist Medical Center in WINSTON-SALEM, N. C., will assume the Editorship of the WEO Newsletter. Dr. Baillie who hails from Scotland, has considerable experience in formulating interesting and informative articles in the Newsletter format and we welcome this opportunity to work with John Baillie. He trained with Drs. Vennes and Silvis in Minneapolis, Minnesota, USA and then worked with Dr. Peter Cotton at Duke University before his current position. He is about to enter community practice and as we embrace his decision to take the reins of the WEO Newsletter, we wish him well in his new venture. Successful Training in Gastrointestinal Endoscopy This book is designed for gastroenterologists in training, it is a fully practical book, containing the guidelines for all the endoscopy procedures and techniques trainees are required to learn. WEO fully endorses Successful Training in Gastrointestinal Endoscopy and wishes to recommend it to endoscopists in training as well as experienced gastroenterologists as a comprehensive, easy to use reference book. A DVD is included, featuring video clips that demonstrate the endoscopic procedures step by step and highlight common problems in teaching endoscopy. For each procedure, an expert explains what needs to be learned, how best to learn it, and how to ensure that sufficient training has taken place to ensure competency. This book is ideal for preparing for certification or recertification, enabling the reader to learn from the talents of a highly skilled group of practitioners and trainers. Video link from WEO Center of Excellence in Amsterdam: Endoscopic Mucosal Resection of a large sessile polyp in the colon This month WEO highlights the Department of Gastroenterology and Hepatology at the Academic Medical Centre of the University of Amsterdam, Netherlands The AMC Amsterdam is one of the founding members of the WEO Centers of Excellence group. This video was taken during the last live course presented at the Academic Medical Center in Amsterdam under the directorship of Dr. Paul Fockens. Dr. James East from St. Marks Hospital in London is performing an endoscopic mucosal resection on a large sessile polyp. Indigo carmine dye spray is used by the direct syringe-application method to enhance the visual characteristics of the Kudo-type pit pattern. The pit pattern is typical of a tubulovillous adenoma. Dr. Ralf Kiesslich of Mainz, Germany aids in the commentary during the EMR. An injection is made in the distal most portion of the polyp using blue tinted saline. The right portion of the distal most edge of the polyp is removed first, followed by injection into the left portion. By multiple snare applications using coagulation current, Dr. East has been able to remove almost all of the polyp. A few small adenomatous remnants are destroyed with the APC in a directed application. This represents classic piecemeal polypectomy with total lesion removal. Video link: http://www.worldendo.org/weo-video-east-201109.html?kenn=weo_nl201117 iPEN: Endoscopic terminology – MST at work (the iPEN initiative) The standardization of endoscopic nomenclature is a vital element in the work to improve communication of endoscopic findings, between endoscopists, as well as to the referring physician. The Minimal Standard Terminology project was started to facilitate this process, and has recently gained momentum through the increased efforts by WEO. This is the WEO initiative for Proper Endoscopic Nomenclature (iPEN) which will encourage all endoscopists to use the same descriptive MST language to report their findings. The complete documentation of the terminology is available at the WEO website and the WEO Image atlas is being developed as a universally accessible source of high quality images. We will keep this issue in the minds of our readers by presenting endoscopic images regularly, along with the pertinent MST descriptive term, to remind endoscopists about the iPEN concept. For this, we would be delighted to have high quality images submitted to us for publishing in this series as well as inclusion into the online atlas. You send the photos, we will add the MST description. Lars Aabakken, chairman Committee of standardization and terminology Image of the month: Fig. 1 Figure 1Open in figure viewerPowerPoint Image of the month. Esophageal stromal tumor. Protruding lesion: Tumor/mass Attribute Attribute value Location Esophagus, mid third Number Single Size 1 cm Free margins N/A Paris type N/A Surface Normal Bleeding None Comments: Rounded protrusion in the mid esophagus, covered with endoscopically normal mucosa. The MST classification of tumors is only partially applicable, since the surface-based descriptors do not apply. The endoscopic description should include exact location, which is not apparent from the image alone. Moreover. Its palpatory features should be described, i.e. firm, soft, pillow-sign, etc. Further characterization would mandate EUS, likely with an FNA sampling. Submitted by Joseph Sung The Chinese University of Hong Kong Hong Kong, China Brainteaser by Bjorn Rembacken Fig. 2 and Fig. 3 are the oesophagus of a 25 year old man presenting after attempting to swallow a large piece of chicken. This had resulted in absolute dysphagia for a day following which an endoscopy was carried out. This is the mucosal views following the endoscopy. Figure 2Open in figure viewerPowerPoint Brainteaser. Figure 3Open in figure viewerPowerPoint Brainteaser. Which statement is correct? a) This mucosal appearance is common following a food bolus obstruction b) Fluconazole should now be prescribed c) Oesophageal manometry is likely to confirm the diagnosis d) Topical corticosteroids is a recognised treatment e) The finding of eosinophils within the mucosa is diagnostic. EXPLANATION 'Trachealisation’ of the oesophageal mucosa (corrugated oesophagus) is a common finding in the normal oesophagus. However, the white spots seen on these images are unusual. They are too small and numerous to be due to candida. Biopsies will confirm that the white spots are composed of eosinophilic micro-abscesses, a typical finding in eosinophilic oesophagitis. The normal oesophagus is largely devoid of eosinophils. However, a few eosinophils (<10/HPF) is a common finding in reflux oesophagitis. When you get more than 20–25 eosinophils/HPF, eosinophilic oesophagitis is the histological diagnosis. As the infiltrate can be patchy, at least 5 oesophageal biopsies should be taken and all parts of the oesophagus should be sampled. Patients (usually children) may have a history of atopy or food allergies. However, why the condition would present with dysphagia or food bolus obstruction is unknown. A range of other dyspeptic symptoms have been described but are most are likely to be the reason for requesting the gastroscopy rather than a plausible symptom due to the eosinophilic oesophagitis. Most patients are probably started on a proton pump inhibitor. If symptoms persists, topical steroid therapy has been shown to be helpful in both children and adults (J Pediatr Gastroenterol Nutr 1998; 27: 90–93, Clin Gastroenterol Hepatol 2004; 2: 568–575). Arora et al (Mayo Clin Proc 2003; 78: 830–835) treated 21 adults with 6 weeks of fluticasone 220 µg 4 puffs swallowed twice daily. All patients had complete symptomatic relief for at least 4 months. Only 3 patients had relapsed at 4 months but about half will relapse at one year Systemic steroid therapy was first reported by Liacouras (J Pediatr Gastroenterol Nutr 1998; 26:380–385) who gave 1.5 mg/kg methylprednisolone divided twice daily for 4 wk to 20 children. Thirteen out of 20 patients had a complete response and 6/20 marked clinical improvement (total 19/20 responders). As systemic steroids are associated with severe side-effects, soluble montelukast is becoming the second-line therapy of choice. THE MANAGEMENT OF BILIARY STRICTURES Bret T. Petersen, MD, FASGE Professor of Medicine, Mayo Clinic and College of Medicine, Rochester, Minnesota Biliary strictures occur as a result of multiple etiologies and with widely varied presentations. Important elements in the assessment and management of biliary strictures include: a. Stricture characterization: length, width, location, assessment of malignancy b. Endoscopic stricture access, with dilation and stent placement for unresectable malignant lesions and most benign lesions c. Medical management for specific inflammatory lesions, d. Surgical management for resectable malignant lesions and selected benign lesions Stricture characterization employs stepwise assessment of the history, laboratory studies, and imaging results. Non-invasive cross-sectional imaging is accomplished with ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), typically with magnetic resonance cholangiopancreatography (MRCP). Invasive imaging includes endoscopic ultrasonography (EUS) for diagnosis and tissue acquisition and endoscopic retrograde cholangiopancreatography (ERCP) for tissue sampling and palliative or definitive stenting. THE PATIENT HISTORY AND LABORATORY INVESTIGATION Historical features may guide both the correct diagnosis and the management strategy. Malignancy is suggested by a slow onset presentation without predisposing factors, or abrupt onset of painless jaundice, with or without abdominal discomfort. Benign strictures are suggested by biliary or right upper-quadrant surgery, chronic pancreatitis, or inflammatory bowel disease. Laboratory investigations may contribute to the diagnosis and include marked elevations in CA 19-9 or IgG-4 levels in the absence of bacterial cholangitis or overt pancreatitis. CA 19-9 levels over 1000 are often diagnostic for cancer. Levels over 400 make cancer highly likely. Lesser elevations can be seen in varied inflammatory settings but require close follow-up. Immunoglobulin G-subfraction 4 levels are strongly associated with type I autoimmune pancreatitis (AIP), being elevated in 75% of cases. Values over twice the upper limit of normal are highly specific for IgG4 associated systemic disease (ISD), which sometimes presents with cholangiopathy and biliary strictures. CONFIRMATION OR EXCLUSION OF MALIGNANCY Suspected malignant strictures with an associated mass lesion can often be confirmed with EUS-guided fine needle aspiration (FNA) and may not require cholangiography. Many clearly malignant and resectable lesions can be managed without tissue sampling. Similarly, benign strictures with an antecedent history of surgery or trauma can be managed without the risk or expense of sampling. The recent recognition of autoimmune pancreatitis (AIP) mimicking pancreatic head carcinoma has prompted greater use of pre-operative EUS/FNA when uncertainty persists after imaging and laboratory studies. Intraluminal brush cytology is about 30 to 50% sensitive and endoscopic intraductal biopsy is 50 to 70% sensitive for the presence of malignancy. Serial biopsies with bedside cytologic assessment may have greater sensitivity for malignancy. Tissue sampling employing multiple methods enhances the likelihood of making a definitive diagnosis of malignancy. Fluorescent in-situ hybridization (FISH) assessment for abnormal multiples of specific chromosomes that are diagnostic for neoplasia can enhance the yield of usual cytology by 15–20%. Pancreatography can exclude a pancreatic primary lesion or help in differentiating secondary biliary strictures due to malignancy from those due to chronic pancreatitis. Intraductal ultrasonography (IDUS) is under investigation for characterization of biliary strictures. Cholangioscopy with slender instruments passed through the duodenoscope is proving useful for characterization of indeterminate lesions, by optimal targeting of pinch biopsies. STRICTURE ACCESS Guidewire access through the stricture is necessary prior to cytology brushing, dilation, and palliative or definitive endoscopic stenting. This is usually gained with multipurpose, plastic-coated guide-wires or hydrophilic wires that are optimally flexible and slippery. For hilar lesions, MRCP should be used to map guidewire access to the optimal intrahepatic segments. When an extrahepatic stricture cannot be accessed by the ERCP route, a guidewire can be advanced via a percutaneous trans-hepatic or EUS-guided trans-mucosal route for subsequent retrograde access. This ‘combined procedure’ can enable efficient access for retrograde sampling and internal stent therapy. STRICTURE DILATION Following wire access, stricture dilation is the first step in endoscopic therapy for biliary strictures. For some strictures it is also required for cytology brushing. The tightest lesions that will only accept a 0.035” guidewire can be dilated with angioplasty balloons that are passed over 0.018” wires and expand from an outer diameter of 0.035” to 3–4mm. Rigid 4-5-6Fr dilators can be passed over 0.035” guidewires, enabling subsequent passage of standard balloon dilators. The selection of balloon diameter is based upon the size of the non-obstructed duct just distal to the stricture. Usually this calls for 4, 6, or 8 mm diameter balloons. There is a risk for rupture or tear during dilation of tight chronic strictures. Should this occur, adequate stenting for drainage is mandatory, and the addition of a nasobiliary drain may be useful along with antibiotics. Serial balloon dilation as primary therapy for benign lesions, with the placement of single 8–12Fr stents between procedures, is less successful than dilation to enable large-caliber stenting. STENT PLACEMENT Endoscopically placed stents are definitive therapy for most benign strictures and are the primary palliative measure for unresectable malignant strictures. Stent selection is based upon stricture etiology, location, ductal anatomy and an assessment of patient longevity. In general, 30% or more of a normal liver must be drained to adequately palliate obstructive jaundice. Distal lesions are easily palliated with a single stent; but proximal lesions can require two or more stents to accomplish drainage of adequate liver volume. Smaller caliber stents tend to occlude more rapidly than those with larger diameters. Typical patency durations for single stents are 6 weeks for 7Fr caliber, 8 weeks for 8.5Fr and 3–6 months for 10Fr stents. When feasible, placement of the 10Fr caliber provides the best balance between duration of patency and ease of placement and removal. Dual or multiple plastic stents may extend drainage via the crevices and irregular shape they provide, however there are no data in this regard. Self-expanding metal stents (SEMS) are typically available in 8 mm (24Fr) and 10 mm (30Fr) diameter. The smaller diameter plastic and metal stents are often used in multi-stent management of malignant hilar lesions while larger stents are employed for distal or single hilar strictures. Plastic stents can be removed and replaced when occlusion occurs but bare SEMS are permanent and cannot be removed. If these become blocked, plastic or metal stents can be placed through them. Coated SEMS resist tissue and tumor ingrowth and are usually removable when the lower end is accessible in the duodenum. In the United States SEMS of all varieties have FDA clearance for malignant lesions only, whereas some fully covered SEMS have EU marking for benign applications. MALIGNANT STRICTURES Resectable malignant strictures generally do not warrant preoperative stenting, as surgical outcomes are not improved by preoperative reduction in bilirubin levels. However stent placement is indicated for patients who require preoperative intraductal imaging and sampling, for those with bacterial cholangitis, and for those in whom surgical management is likely to be delayed beyond 1–2 weeks due to limited availability or neoadjuvant therapy. Plastic stents are most cost effective for short term use. When metal stents are placed pre-operatively, it is important to select lengths that do not encroach on the hepatic hilum and can be easily removed together with the surgical specimen. Malignant strictures that are surgically unresectable warrant the least costly drainage that will provide palliation without need for reintervention. Metal stents provide longer patency than plastic stents and are indicated for palliation in patients whose life expectancy is estimated to be several months or longer. For hilar lesions, single or bilateral bare metal stents avoid the risk of side branch occlusion. For extrahepatic lesions, there are no benefits from partially covered versus bare metal stents. Fully covered stents have not been investigated in randomized trials. Covered stents are associated with modestly higher rates of cholecystitis and possibly stent migration, but probably not pancreatitis. Plastic stenting is usually preferable for: 1) estimated longevity of less than 3–4 months; 2) some complex hilar lesions for which stent removal or alteration may be required; 3) multiple stenting of advanced hilar lesions; 4) hilar cholangiocarcinoma for which orthotopic liver transplantation after chemo/radiotherapy is being considered; 5) soft, bulky intraductal hilar lesions that are prone to early ‘ingrowth’ and occlusion of bare metal stents; 6) untreated lymphomas that will often resolve with non-surgical therapy, allowing for complete stent removal; and 7) complex hilar lesions with indolent tumors (islet cell metastasis) with longevity well beyond the patency of a permanent metal stent. INDETERMINATE STRICTURES When palliation is required in a patient with an incompletely characterized symptomatic stricture and the decision for or against surgical resection has not been resolved, plastic stent placement is generally indicated. Metal stents are labeled for malignant applications only, but preliminary series have described the utility of fully covered SEMS in benign and indeterminate lesions. BENIGN STRICTURES There are many causes of benign biliary strictures. An acute presentation after surgery or during pancreatitis suggests significant injury or stone-related obstruction, whereas sub-acute presentations suggest inflammatory processes which may resolve with time. Presentation more than three months after a possible inciting episode suggests a more fibrotic and rigid stricture which may require more aggressive or prolonged therapy. IATROGENIC/POST-OPERATIVE STRICTURES Iatrogenic strictures occur from scarring of surgical injury or surgical anastomoses. When an injury is recognized intra-operatively they should be repaired immediately. Minor injuries can occasionally be repaired over a t-tube but major injury due to surgical cautery, ligation, or transection requires proximal drainage via Roux-en-Y hepatico-jejunostomy. Post-operative strictures resulting from ligation or clipping of the bile duct present early and usually require definitive surgical management. Pre-operative characterization for severe injuries requires definition of the proximal side of the injury, often via a percutaneous approach. Ischemic injuries resulting from excessive dissection or cautery along the duct present after weeks to years, depending upon their severity. Most strictures occurring after cholecystectomy are located at or above the cystic duct take-off. In these cases, the distal duct is normal and the proximal extent depends upon the proximity of the cystic duct to the bifurcation and the severity of the injury. Endoscopic therapy for post-operative strictures using dilation and multiple stents results in 74–89% good to excellent results 3–5 years after stent removal and 80+% good to excellent results at 9–10 years. Restenoses generally occurred early (within two years), and results were best for those treated within three months of injury. Subsequently, Costamagna popularized progressive therapy with multiple 10F plastic stents, to an endpoint of complete stricture eradication. His results are at the high end of the reported outcomes. The results of therapy using partially coated SEMS are largely equivalent to plastic stenting, with relatively high complication rates related to proximal occlusion, migration, and cholecystitis. Fully coated SEMS are now being investigated for benign lesions. Percutaneous management achieves 50–60% good to excellent long-term outcomes after six months or more of percutaneous stenting and balloon dilation. This approach is limited by the small caliber of prostheses that can be left in place chronically. Surgical series have reported outcomes similar to those of endoscopy for benign strictures. A non-randomized comparison between endoscopic and surgical therapy in Amsterdam reported 83% good-to-excellent results and similar complication rates with both therapies. Complications in the surgical group were clustered early in the peri-operative period while those in the endoscopic group were experienced intermittently throughout the course of therapy. Another series reported good-to-excellent results in 87% of iatrogenic lesions and 89% of non-iatrogenic lesions. Those treated with a broad hepaticojejunostomy lapping into the left duct had excellent outcomes at four years of follow-up. ANASTOMOTIC STRICTURES Biliary complications, particularly duct leaks and strictures, occur in 10–35% of liver transplant patients. Most post-transplant strictures are at duct-to duct or biliary-enteric anastomoses. Reported success rates for endoscopic therapy of anastomotic strictures vary between 27% and 91%. This wide variation in outcomes may be due to the lack of uniform outcome criteria and the variable use of stent placement. Dilation alone yields less adequate results compared to aggressive stent therapy. Most results are equivalent to those for other benign lesions. STONE ASSOCIATED STRICTURES Choledocholithiasis can induce duct strictures and strictures can result in duct stone formation. Following stone clearance, persistent strictures and duct contamination predispose to recurrent stones. In the Mirizzi Syndrome, edema surrounding stones impacted in the cystic duct present as common hepatic duct strictures mimicking carcinoma. Management is surgical or endoscopic. CHRONIC PANCREATITIS ASSOCIATED STRICTURES Intra-pancreatic biliary strictures develop in up to 30% of patients with chronic pancreatitis. Patients with persistent obstruction and alkaline phosphatase levels >2x normal without alternate explanations should undergo a biliary drainage procedure. Surgical choledochoenterostomy is the usual procedure; however, Roux-en-Y hepaticojejunostomy may be preferable if portal hypertension is not present. Endoscopic stenting is the optimal means of palliating short-term palliation for biliary obstruction due to active pancreatic inflammation. Late stent-related complications due to occlusion are common after several months. Prolonged therapy with multiple, large plastic stents is an acceptable option in those at high risk for surgery due to portal hypertension or coagulopathy. Bare SEMS do not provide adequate long-term palliation in these patients due to their permanence and eventual occlusion. Partially-covered SEMS are usually removable and provide palliation equivalent to multiple plastic stents with fewer procedures. Fully covered SEMS will likely prove to be the optimal means of palliating these strictures in the poor operative candidate. Whether they will also yield long term benefit following removal after 9–12 months is now under investigation. PRIMARY SCLEROSING CHOLANGITIS Primary sclerosing cholangitis (PSC) is frequently complicated by symptomatic stone passage, bacterial cholangitis, or rapidly progressive jaundice – often secondary to isolated ‘dominant’ strictures at the hilum or in the extra-hepatic ducts. Fifteen to twenty percent of PSC patients develop such lesions at some time in their course, but there are no data to support endoscopic therapy for asymptomatic patients. With clinical decline ERCP is appropriate. ERCP carries greater risk in these patients, due to complications of cholangitis and the risk for wire perforation. Angled hydrophilic wires should be employed and sphincterotomy at the first procedure limits the difficulty and risk of subsequent procedures. Antibiotic coverage during and after ERCP is mandatory. As with all biliary strictures, exclusion of malignancy is the first important goal. In PSC patients, this may be extremely difficult. Most PSC strictures respond to dilation alone. Dilation is usually performed with smaller caliber balloons, as the duct caliber above and below tends to be smaller. Our practice is to dilate all accessible strictures, but stent placement is generally only appropriate for those strictures that appear extremely tight on post-dilation cholangiography. The optimal duration of stenting is poorly defined, but some reports suggest benefit from as little as 10–14 days. BILIARY STRICTURES RELATED TO IGG-4 Both autoimmune pancreatitis (AIP) and systemic IgG-4-related disease with associated sclerosing cholangitis cause biliary strictures, which may be localized to the intrapancreatic duct or dispersed throughout the biliary tree. Diagnosis is facilitated by pancreatography, CT, IgG-4 serum levels, and pancreatic or other target organ biopsies with histologic staining for IgG-4. Medical therapy with steroids and/or other immunosuppressive regimens is usually efficacious, though relapses are common. Temporary plastic stenting is indicated during onset of medical management. They can usually be removed after 4–8 weeks. SUMMARY Many benign biliary strictures can be managed with an endoscopic approach. Key steps in management include: characterization of the stricture, confident exclusion of malignancy, and stricture access followed by serial dilation and stenting procedures. SUGGESTED READING Behm B, Brock A, Clarke BW et al. Partially covered self-expandable metallic stents for benign biliary strictures due to chronic pancreatitis. Endoscopy 2009; 41: 547– 51. Bjornsson E, Lindqvist-Ottosson J, Asztely M, Olsson R. Dominant strictures in patients with primary sclerosing cholangitis. American Journal of Gastroenterology 2004; 99: 502– 8. Costamagna G, Pandolfi M, Mutignani M, Spada C, Perri V. Long-term results of endoscopic management of postoperative bile duct strictures with increasing numbers of stents. Gastrointest Endosc. 2001; 54: 162– 8. Costamagna G. Covered self-expanding metal stents in benign biliary strictures: not yet a “new paradigm but a promising alternative. Gastrointest Endosc. 2008: 67: 455– 7. Judah JR, Draganov PV. Endoscopic therapy of benign biliary strictures. World Journal of Gastroenterology 2007; 13: 3531– 9. Kaya M, Petersen BT, Angulo P, Baron T, Andrews J, Gostout CJ, Lindor KD. Balloon dilation compared to stenting of dominant strictures in primary sclerosing cholangitis. Am Journal of Gastroenterology 2001; 96: 1059– 66. Mahajan A, Ho H, Sauer B et al. Temporary placement of fully covered self-expandable metal stents in benign biliary strictures: midterm evaluation. Gastrointest Endosc. 2009: 70: 303– 9. McDonald ML, Farnell MB, Nagorney DM, et al. Benign biliary strictures: Repair and outcome with a contemporary approach. Surgery 1995; 118: 582– 91. Pasha SF, Harrison ME, Das A et al. Endoscopic treatment of anastomotic biliary strictures after deceased donor liver transplantation: outcomes after maximal stent therapy. Gastrointest Endosc. 2007; 66: 44– 51. Telford JJ, Carr-Locke DL, Baron TH et al. A randomized trial comparing uncovered and partially covered self-expandable metal stents in the palliation of distal malignant biliary obstruction. Gastrointestinal Endoscopy 2010; 72; 907– 14. Kullman E, Frozanpor F, Soderlund C et al. Covered versus uncovered self-expandable nitinol stents in the palliative treatment of malignant distal biliary obstruction: results from a randomized, multicenter study. Gastrointestinal Endoscopy 2010; 72: 915– 23. Citing Literature Volume24, Issue1January 2012Pages 65-70 FiguresReferencesRelatedInformation