Malignant biliary obstruction can arise from intrahepatic, extrahepatic, and hilar locations from either primary or metastatic disease. Biliary-enteric surgical bypass has been surpassed in the last 20 years by endoscopic balloon dilation and stenting. The goal of stenting for biliary decompression is to palliate obstructive symptoms; it has not been shown that survival is affected by stenting alone. Novel endoscopic therapies, including photodynamic therapy and radiofrequency ablation, have been evaluated and show promise. Both therapies seem to be safe and effective in the treatment of malignant bile duct strictures but are in need of prospective studies of longer duration.
Key points
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Endoscopic stenting is the decompressive procedure of choice for unresectable malignant bile duct obstruction.
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The choice of stent (plastic versus metal, covered versus uncovered) is influenced by stricture location, expected patient survival, potential need for removability, and cost.
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For malignant hilar obstruction, a goal of stent placement resulting in more than 50% of liver volume drained should be achieved whenever possible, which frequently requires bilateral stent placement.
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Photodynamic therapy and radiofrequency ablation are promising endoscopic therapies for the treatment of malignant bile duct strictures.
Introduction
Many disease processes, arising from primary or metastatic disease in intrahepatic, extrahepatic, or hilar locations, can lead to malignant biliary strictures ( Table 1 ). Until the 1980s, biliary-enteric surgical bypass was the treatment of choice for people with malignant pancreaticobiliary disease. However, in the last 20 years, endoscopic decompression, primarily through stent placement, has emerged as a therapeutic option offering lower overall cost, shorter hospitalization, and lower morbidity when compared with surgical intervention. The goal of intervention is to relieve biliary obstruction that develops in 70% to 90% of patients with unresectable disease. Obstruction can ultimately lead to jaundice, pruritus, secondary biliary cirrhosis, cholangitis, coagulopathy, and weight loss through malabsorption. Biliary decompression palliates these symptoms and improves quality of life but has not been shown to affect survival.
| Location | Lesion |
|---|---|
| Intrahepatic bile ducts |
|
| Extrahepatic bile duct |
|
| Hilar region |
|
Introduction
Many disease processes, arising from primary or metastatic disease in intrahepatic, extrahepatic, or hilar locations, can lead to malignant biliary strictures ( Table 1 ). Until the 1980s, biliary-enteric surgical bypass was the treatment of choice for people with malignant pancreaticobiliary disease. However, in the last 20 years, endoscopic decompression, primarily through stent placement, has emerged as a therapeutic option offering lower overall cost, shorter hospitalization, and lower morbidity when compared with surgical intervention. The goal of intervention is to relieve biliary obstruction that develops in 70% to 90% of patients with unresectable disease. Obstruction can ultimately lead to jaundice, pruritus, secondary biliary cirrhosis, cholangitis, coagulopathy, and weight loss through malabsorption. Biliary decompression palliates these symptoms and improves quality of life but has not been shown to affect survival.
| Location | Lesion |
|---|---|
| Intrahepatic bile ducts |
|
| Extrahepatic bile duct |
|
| Hilar region |
|
Biliary stenting
With the push for less invasive and more cost-efficient measures in medicine, a variety of stents are now available for use in malignant pancreaticobiliary disease. The choice seems relatively simple: plastic or metal? What seems simple from the surface can be layered with details, ultimately making one product more favorable than another for your patients. A preprocedural checklist should include lesion resectability, goals of care, life expectancy, location of the lesion, length of the lesion, covered versus uncovered, cost, and ultimately the physician’s comfort with the product ( Box 1 ). Once this is all considered, the procedure can finally begin.
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Lesion resectability and goals of care
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Life expectancy given stage of disease and comorbidities
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Location and length of the lesion
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Plastic versus self-expanding metal stents
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Covered versus uncovered
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Cost comparisons
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Physician comfort level with the procedure
Plastic Stents
Plastic stents have been used since the 1980s and are made from materials including Teflon, polyurethane, and polyethylene. Diameters range from 7.0F to 11.5F and lengths extend from 5 to 18 cm. Options include straight stents with flaps at each end, a single-pigtail stent, or double-pigtailed stent for anchoring purposes ( Fig. 1 ). Insertion is via a push catheter over a guidewire. Plastic stents are very effective and are inexpensive when compared with their metallic counterparts; however, the short duration of stent patency, approximately 3 months, is a drawback. Stent occlusion can develop in the setting of sludge, tumor overgrowth, tissue debris, or bacterial colonization, requiring repeat endoscopic retrograde cholangiopancreatographies (ERCP) every 3 months, or more frequently for stent occlusion, through the remainder of the patients’ life.
Metal Stents
Self-expanding metal stents (SEMS) are configured into a cylinder by interwoven wires and are deployed from a preconstrained position within a delivery catheter, in a through-the-scope manner ( Fig. 2 ). These stents offer a larger diameter (6–8–10 mm sizes), which leads to an extended duration of stent patency (approximately 6 to 12 months). SEMS are more expensive than plastic and may not be removable because of tumor and tissue ingrowth. They can be made from 3 separate materials: stainless steel, nitinol (nickel and titanium combination), or Platinol (platinum core with nitinol encasement). Nitinol has been traditionally used, but there is a lack of evidence that any one material is superior to the others.
Stents are uncovered, partially covered, or fully covered. The covering consists of a silicone, polycaprolactone, polyether polyurethane, polyurethane, or expanded polytetrafluoroethylene fluorinated ethylene propylene lining. After deployment, the stent expands into both the tumor and normal biliary epithelium through radial pressure in the following 24 to 48 hours.
Covered Versus Uncovered and Future Developments
There have been multiple studies comparing the patency of covered versus uncovered stents used in distal pancreaticobiliary malignancy ( Table 2 ). The potential benefit of covered SEMS is removability, along with a theoretical longer patency rate. Studies have displayed reduced tumor ingrowth, but patency rates remained on par with uncovered SEMS because of tumor overgrowth, debris, sludge, and food impaction. Potential disadvantages of fully covered stents include higher rates of stent migration, inability to use them at the hilum, and higher cost.
| Author | Covered SEMS Patency | Uncovered SEMS Patency | Significance |
|---|---|---|---|
| Yoon et al, 2006 | Mean of 398 d | Mean of 319 d | P = .578 |
| Park et al, 2006 | Mean of 148.9 d | Mean of 143.5 d | P = .531 |
| Telford et al, 2010 | Median of 357 d a | Median of 711 d | P = .530 |
| Kullman et al, 2010 | 154 d (Day when 25% of stents occluded) | 199 d (Day when 25% of stents occluded) | P = .348 |
| Saleem et al, 2011 | Weighted mean difference of + 60.56 d | Weighted mean difference of −60.56 d | P = .001 |
Uncovered SEMS are recommended in patients with intact gallbladders or hilar lesions to prevent cystic duct or major hepatic duct occlusion from the covered lining. Multiple studies have also demonstrated low rates of migration of uncovered SEMS in malignant biliary obstruction ; however, the disadvantages include tumor ingrowth and limited removability. The future of stent development is in the direction of drug-eluding stents incorporating chemotherapeutic agents, radioactive stents, and biodegradable stents.
Indications and Efficacy Introduction
Endoscopic biliary stenting is the therapeutic modality of choice to decompress the biliary system in pancreaticobiliary malignancies. Two variables should be considered before the procedure: the indication for decompression and the efficacy of the intervention. After these are considered and a plan is made, the intervention can be relatively straightforward.
Preoperative Decompression
The need for preoperative biliary decompression, however, is controversial. Placing a short, distal metal or plastic stent does not affect the surgeon’s ability to perform a future pancreatoduodenectomy; however, the benefit of preoperative biliary drainage with regard to postoperative outcomes has been questioned. Proceeding directly to surgery limits the number of interventions, potentially reducing costs and procedure-related complications. A recent multicenter randomized controlled trial included 202 patients with resectable pancreatic cancer. The patients were either taken to surgery within 1 week of diagnosis or had preoperative biliary drainage for 4 to 6 weeks followed by surgery. Significantly more serious complications were found in the biliary drainage group compared with those in the surgery alone group (74% vs 39%), although mortality rates were not significantly different. This study was criticized for a 25% ERCP failure rate in addition to the use of plastic stents. However, previous retrospective studies have failed to show significantly different length of stay, infectious complications, readmission rates, and 30- and 90-day mortality rates between preoperative biliary decompression and surgery alone.
Preoperative biliary decompression may improve symptoms, prevent complications of cholestasis, especially if there is a delay in surgical resection, and allow time for neoadjuvant chemotherapy in patients with locally advanced malignancy. In a recent retrospective study, 55 patients with resectable or borderline resectable pancreatic cancer were followed after receiving SEMS and neoadjuvant chemotherapy. Stent placement relieved obstruction in all of the patients, and the median time for chemotherapy was 104 days. The presence of the short biliary stent did not interfere with surgery in the 27 patients who underwent pancreatoduodenectomy. The extent of liver dysfunction has also been suggested to be a major contributing factor to postoperative morbidity and mortality in regard to jaundice, secondary biliary cirrhosis, weight loss, and hypoalbuminemia, which can develop rapidly with unrelieved obstruction.
Unknown Resectability
Unknown resectability leads to a significant clinical dilemma. A recent decision analysis evaluated several approaches in patients with unknown resectability and concluded that short-length SEMS is the preferred initial cost-minimizing strategy in patients with a distal common bile duct (CBD) stricture caused by suspected malignancy who are undergoing ERCP before definitive cancer staging. The authors prefer short (4 cm), covered SEMS, especially if a histologic diagnosis has not been confirmed. For those patients with more proximal biliary strictures, plastic stents should generally be placed if a definitive diagnosis or staging has not been obtained or completed.
Distal: Plastic Versus Metal
Stenting in the case of unresectable malignancy for palliation is straightforward and is typically the initial endoscopic treatment, which only varies in terms of the lesion’s location. Placing plastic stents is both effective and cost-effective and maintains the ability to remove or exchange the stent. However, the patency of plastic stents is typically 3 months because they eventually develop occlusion from sludge, bacterial colonization, or bacterial biofilm and require replacement. Metal stents now help alleviate these issues with a prolonged duration of patency (median of 9 months) because of their increased diameter, but metal stents come with higher costs and may not be removable. A large meta-analysis evaluated the outcomes of surgical bypass, endoscopically placed metal stents, and endoscopically placed plastic stents in patients with obstruction distal to the hilum. This study included almost 2500 patients from 24 separate studies. The results showed that SEMS produced similar outcomes to plastic stents in regard to decompression success but with improved patency rates, and the study concluded that SEMS are the treatment of choice in patients with unresectable distal malignant biliary obstruction.
Numerous other randomized controlled trials have also compared plastic stents with SEMS and confirm longer patency, decreased hospitalization, decreased endoscopic procedures, and reduced overall cost in the SEMS group ( Table 3 ). SEMS should be standard of care in patients with unresectable distal pancreaticobiliary malignancy with life expectancy of more than 3–6 months.
| Author | Plastic Stents | SEMS | Significance |
|---|---|---|---|
| Knyrim et al, 1993 | 43% Stent failure rate | 22% Stent failure rate | P = .0035 |
| Prat et al, 1998 | 3.2 mo (Median time for dysfunction) | 4.8 mo (Median time for dysfunction) | Not reported |
| Kaassis et al, 2003 | 5 mo (Median first obstruction) | Median not reached | P = .007 |
Distal: Covered Versus Uncovered
Several trials compared stent patency rates of covered and uncovered SEMS in distal malignant biliary disease; a significant difference has not been shown (see Table 2 ). The findings of a subsequent meta-analysis, however, contradicted these studies, showing that covered SEMS have prolonged stent patency (weighted mean difference + 60.56 days) and prolonged survival (weighted mean difference + 68.76 days) compared with the uncovered SEMS. There was a trend toward increased stent migration, tumor overgrowth, and sludge formation with covered SEMS. The choice of covered versus uncovered SEMS should be made on an individual basis in patients with distal malignant biliary obstruction depending on whether a tissue diagnosis has been obtained. If a tissue diagnosis has confirmed malignancy, then an uncovered stent is chosen. If no histologic diagnosis has been determined, a fully covered stent is appropriate to permit future removal if, as in certain cases, such as autoimmune pancreatitis and lymphoma, the obstruction may be resolved medically.
Hilar: Plastic Versus Metal Stents
Lesions in the hilum can be more technically challenging but should be stented, if technically feasible. Hilar obstruction can be treated with plastic stents or uncovered SEMS as to not occlude drainage from the contralateral biliary system. In both retrospective and randomized controlled trials, SEMS outperformed plastic endoprosthesis with higher rates of successful drainage, prolonged survival, prolonged patency, and lower rates of adverse outcomes, including cholangitis, stent migration, perforation, or the need for unplanned ERCP/percutaneous transhepatic cholangiography ( Table 4 ).
| Author | Plastic Stent | SEMS | |
|---|---|---|---|
| Perdue et al, 2008 | 32% Complications at day 30 a 39% Stent-related adverse outcome rate | 9% Complications at day 30 a 12% Stent-related adverse outcome rate | P = .027 P = .017 |
| Wagner et al, 1993 | 50% Long-term stent failure rate Reinterventions for stent-related complications 2.4 ± 2.6 per pt | 18.2% Long-term stent failure rate Reinterventions for stent-related complications 0.4 ± 0.5 per pt | NS NR |
| Sangchan et al, 2012 | 46.3% Successful drainage Median survival 49 d | 70.4% Successful drainage Median survival 126 d | P = .011 P = .02 |
a Including occlusion, migration, perforation, and/or new cholangitis.
Unilateral Versus Bilateral Drainage
The adequacy of unilateral or bilateral drainage continues to be debated in the setting of hilar lesions with therapy directed at palliation of obstructive symptoms. To relieve jaundice, approximately 25% to 30% of the liver needs to be drained ; however, unilateral drainage may incompletely relieve jaundice and increase the risk for cholangitis. Previous studies have shown variable outcomes in regard to successful decompression, stent patency, and complication rates. In a recent 2-center retrospective study, cross-sectional imaging was used in 107 patients with hilar tumors to estimate liver volume drained by ERCP stenting. Patients were divided into groups according to the liver volume successfully drained: less than 30%, 30% to 50%, and greater than 50%. The investigators found that the main factor associated with effective drainage (defined as a decrease in serum bilirubin by 50% at day 30) was stents draining a volume greater than 50%, which frequently required bilateral stents. This group also displayed a longer median survival (119 vs 59 days, P = .005). Conversely, intubating an atrophic sector (<30%) was not helpful and increased the risk of cholangitis. The authors, therefore, consider high-quality cross-sectional imaging to be critical before endoscopic decompression of malignant hilar obstruction. Attempts should be made to maximize biliary drainage. If only unilateral drainage is possible, the dominant biliary system should be sought, based on preceding imaging studies. Draining more than 50% of the liver volume should be targeted, which may be achieved with unilateral or bilateral stenting ( Fig. 3 ). The authors minimize contrast injection during the procedure, using only the minimum needed for effective stent placement. Care is taken to avoid injecting, intubating, or stenting atrophic (<30% of volume) segments. Stricture dilation using graded dilators (4F–7F, 5F–10F) and/or balloon dilation is performed to allow the large stents (SEMS or 10F plastic) and bilateral drainage if possible. When attempting bilateral drainage, the authors prefer placing a wire in each segment before deployment. If this is not successful, wire placement through the interstices of the stent followed by dilation can be attempted ( Fig. 4 ). Finally, when attempting SEMS placement across hilar strictures, the type of SEMS chosen may be important because some are quite stiff and may be difficult to advance across tight and angulated strictures. The authors’ preference is the 8-mm diameter uncovered Wallflex stent (Boston Scientific, Natick, Massachusetts), either unilaterally or bilaterally, across hilar strictures.
Related posts:
Endoscopic Advances in Biliary Disease
Pre-ERCP Imaging of the Bile Duct and Gallbladder
Endoscopic Evaluation of Bile Duct Strictures
Endoscopic Management of Benign Bile Duct Strictures
Endoscopic Ultrasonographic Access and Drainage of the Common Bile Duct
Endoscopic Management of Acute Cholecystitis
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