Impact of reducing duodenobiliary reflux on biliary stent patency: an in vitro evaluation and a prospective randomized clinical trial that used a biliary stent with an antireflux valve

Enteral extended biliary stents versus conventional plastic biliary stents for the treatment of extrahepatic malignant biliary obstruction: a single-center prospective randomized controlled study

BACKGROUND AND AIMS

The main limitation of plastic stents is the relatively short stent patency due to occlusion. We designed enteral extended biliary stents with lengths of 26 cm (EEBS-26 cm) and 30 cm (EEBS-30 cm) to prolong stent patency. This study aimed to compare patency among EEBS-26 cm, EEBS-30 cm, and conventional plastic biliary stent (CPBS).

METHODS

A single-center prospective randomized controlled study was conducted. Eligible patients were randomized into the EEBS-26 cm, EEBS-30 cm, and CPBS groups, respectively. All patients were followed up every 3 months until stent occlusion, patient death, or at 12-month follow-up. The primary outcome was stent patency. The secondary outcomes included stent occlusion rate, patient survival, mortality, the rate of technical success, and adverse events.

RESULTS

Totally 117 patients were randomized into the three groups. There were no significant differences among the three groups in technical success rate, hospital stay, mortality, patient survival, and adverse events (P = 1.000, 0.553, 0.965, 0.302, and 0.427, respectively). Median stent patency durations in the EEBS-26 cm, EEBS-30 cm, and CPBS groups were 156.0 (95% CI 81.6-230.4) days, 81.0 (95% CI 67.9-94.1) days, and 68.0 (95% CI 20.0-116.0) days, respectively (P = 0.002). The EEBS-26 cm group had longer stent patency compared with the CPBS (P = 0.007) and EEBS-30 cm (P < 0.001) groups. The EEBS-26 cm group had lower stent occlusion rates compared with the other groups at 6 months (48.1% vs. 90.5% vs. 82.8%, P = 0.001) and 9 months (75.0% vs. 100.0% vs. 92.9%, P = 0.022).

CONCLUSION

EEBS-26 cm has prolonged stent patency and is safe and effective for the alleviation of unresectable extrahepatic malignant biliary obstruction.

Safety and Efficacy of a Large-Bore Biliary Metallic Stent for Malignant Biliary Obstruction

Self-expandable metallic stents (SEMSs) are typically inserted in patients with unresectable malignant biliary obstruction. However, SEMSs are susceptible to occlusion. To overcome this issue, we developed a large-bore, dumbbell-shaped, fully covered SEMS (FCSEMS-L) and compared its efficacy and safety with those of a conventional FCSEMS (FCSEMS-C) in patients with malignant biliary obstruction. Methods: Patients with unresectable distal malignant biliary obstruction were retrospectively enrolled between January 2011 and February 2021. All patients underwent endoscopic insertion of FCSEMSs. Recurrent biliary obstruction (RBO), patient survival time, complications, and prognosis were analyzed. Results: RBO occurred in 31 patients (35.6%) who received an FCSEMS-L, and in 34 (45.9%) who received an FCSEMS-C. Stent occlusion occurred in 19 patients (21.8%) who received an FCSEMS-L, and in 22 (29.7%) who received an FCSEMS-C. Stent migration occurred in 12 patients (13.8%) with an FCSEMS-L and 12 (16.2%) with an FCSEMS-C. The median time to RBO (TRBO) was 301 days with an FCSEMS-L and 203 days with an FCSEMS-C. The median survival time was 479 days with an FCSEMS-L and 523 days with an FCSEMS-C. The TRBO and patient survival time did not significantly differ between the two groups. Conclusions: There were no significant differences in efficacy and complication rates between the fully covered large bore SEMSs and conventional fully covered SEMSs.

Design and Optimization of a New Anti-reflux Biliary Stent With Retractable Bionic Valve Based on Fluid-Structure Interaction Analysis

Duodenal biliary reflux has been a challenging common problem which could cause dreadful complications after biliary stent implantation. A novel anti-reflux biliary stent with a retractable bionic valve was proposed according to the concertina motion characteristics of annelids. A 2D equivalent fluid-structure interaction (FSI) model based on the axial section was established to analyze and evaluate the mechanical performances of the anti-reflux biliary stent. Based on this model, four key parameters (initial shear modulus of material, thickness, pitch, and width) were selected to investigate the influence of design parameters on anti-reflux performance via an orthogonal design to optimize the stent. The results of FSI analysis showed that the retrograde closure ratio of the retractable valve primarily depended on initial shear modulus of material (p < 0.05) but not mainly depended on the thickness, pitch, and width of the valve (p > 0.05). The optimal structure of the valve was finally proposed with a high retrograde closing ratio of 95.89%. The finite element model revealed that the optimized anti-reflux stent possessed improved radial mechanical performance and nearly equal flexibility compared with the ordinary stent without a valve. Both the FSI model and experimental measurement indicated that the newly designed stent had superior anti-reflux performance, effectively preventing the duodenobiliary reflux while enabling the bile to pass smoothly. In addition, the developed 2D equivalent FSI model provides tremendous significance for resolving the fluid-structure coupled problem of evolution solid with large deformation and markedly shortens the calculation time.

Possible reasons for the regrettable results of patency of an inside stent in endoscopic transpapillary biliary stenting

Endoscopic biliary decompression is a minimally invasive procedure for cholestasis since the first endoscopic retrograde cholangiopancreatography-guided biliary stenting performed by Soehendra and Reynders-Frederix. Among the endoscopic biliary decompression, endoscopic transpapillary biliary stenting (EBS), is a mainstream choice and presently has two methods of placement: stenting above the sphincter of Oddi (SO) (suprapapillary) and stenting across the SO (transpapillary). Stent patency is the most important concern for patients, endoscopists and physicians because it can affect both the life prognosis and treatment schedule of patients. Biliary stent occlusion can occur because of several factors. Among them, direct food impaction, biofilm formation, and sludge formation play important roles and are presumed to be theoretically overcome by EBS above the SO. Thus, EBS above the SO is expected to result in a longer patency than EBS across the SO. In the literature, there have been six comparative studies on EBS for distal biliary obstruction in which the stent was placed above or across the SO, including two randomized controlled trials (RCTs) with negative results of stenting above the SO. With respect to EBS for hilar biliary obstruction, there have been no RCTs, whereas four retrospective comparative studies with negative results and four retrospective comparative studies showing positive results of stenting above the SO have been reported. In this review, we focused on EBS above and across the SO, and summarized the positive and negative results of the two types of stenting to promote effective clinical practice and to provide a basis for future studies.

Verification of Duodenobiliary Reflux With SPECT/CT Imaging

ABSTRACT

Duodenobiliary reflux is believed to be 1 of the causes of recurrent bacterial cholangitis. We reported a 65-year-old woman with intermittent epigastric pain for 20 years. She was diagnosed with cholelithiasis in the past, and she still had recurrent abdominal pain after the stone was removed. The patient was suspected of having duodenobiliary reflux and received duodenobiliary reflux imaging. After oral administration of 700 mL water containing 5 mCi 99mTc-DTPA, SPECT/CT images of the abdomen were acquired. Abnormal radioactivity was seen in the common bile duct, indicating the presence of duodenobiliary reflux.

Endoscopic Double Stenting for the Management of Combined Malignant Biliary and Duodenal Obstruction

Periampullary cancers are often diagnosed at advanced stages and can cause both biliary and duodenal obstruction. As these two obstructions reduce patients’ performance status and quality of life, appropriate management of the disease is important. Combined malignant biliary and duodenal obstruction is classified according to the location and timing of the duodenal obstruction, which also affect treatment options. Traditionally, surgical bypass (gastrojejunostomy and hepaticojejunostomy) has been performed for the treatment of unresectable periampullary cancer. However, it has recently been substituted by less invasive endoscopic procedures due to its high morbidity and mortality. Thus, endoscopic double stenting (transpapillary stenting and enteral stenting) has become the current standard of care. Limitations of transpapillary stenting include its technical difficulty and the risk of duodenal-biliary reflux. Recently, endoscopic ultrasound-guided procedures have emerged as a novel platform and have been increasingly utilized in the management of biliary and duodenal obstruction. As the prognosis of periampullary cancer has improved due to recent advances in chemotherapy, treatment strategies for biliary and duodenal obstruction are becoming more important. In this article, we review the treatment strategies for combined malignant biliary and duodenal obstruction based on the latest evidence.

New anti-reflux plastic stent to reduce the risk of stent-related cholangitis in the treatment of biliary strictures

BACKGROUND

There is little data available on the role of new anti-reflux plastic stents (ARPSs).

AIM

To compare the use of ARPSs with that of traditional plastic stents (TPSs) for patients with biliary strictures.

METHODS

Consecutive patients with biliary strictures who underwent first endoscopic biliary stenting between February 2016 and May 2019 were included. The onset of stent-related cholangitis, stent patency, clinical success, and other adverse events were evaluated.

RESULTS

Sixty-seven patients in the ARPS group and 66 patients in the TPS group were included in the final analyses. Fewer patients experienced stent-related cholangitis in the ARPS group than that in the TPS group (8 patients vs 18 patients; P = 0.030). The median time till the onset of first stent-related cholangitis was later in the ARPS group than that in the TPS group (128.5 d vs 76 d; P = 0.039). The cumulative median stent patency in the ARPS group was 185 d, which was significantly longer than that in the TPS group (133 d; P = 0.001). The clinical success rates and other adverse events did not significantly differ between both groups.

CONCLUSION

Placement of new ARPS might be a safe and effective optional therapeutic strategy to reduce the risk of stent-related cholangitis and prolong stent patency.

Antireflux metal stent for biliary obstruction: Any benefits?

Endoscopic retrograde cholangiopancreatography with stent placement has been utilized as standard palliative management of distal malignant biliary obstruction (MBO). Compared to plastic stents, metal stents can provide longer-term relief of symptoms. When a large-bore metal stent is placed across the ampulla, patients are predisposed to the risk of cholangitis or stent dysfunction due to reflux of duodenal contents. To mitigate the risk of adverse events associated with the duodenobiliary reflux, efforts have been directed to development of antireflux metal stents (ARMSs). The antireflux property has been introduced through adding of an antireflux valve to the duodenal stent end. Evidence from clinical studies indicates that ARMSs may not only reduce the risk of ascending cholangitis during follow-up but also prolong stent patency time. However, the results of clinical studies testing ARMSs are inconsistent owing to heterogeneous designs of antireflux valves and stent bodies. Metal stents are increasingly indicated for benign biliary strictures and MBO in the setting of neoadjuvant chemotherapy, and therefore, research is warranted to evaluate ARMSs for those indications. Given that endoscopic ultrasound (EUS)-guided transmural biliary drainage has gained popularity, the optimal timing of placing an ARMS in relation to EUS-guided and percutaneous drainage should be investigated. Development and evaluation of ARMSs require an integrative approach utilizing phantom and animal models, measurements of stent mechanical properties, and in vivo functional study after stent placement. In this review article, we summarize updated evidence on ARMSs for MBO and discuss issues that should be addressed in future studies.

3D Printed Model of Extrahepatic Biliary Ducts for Biliary Stent Testing

Several inflammatory conditions of the bile ducts cause strictures that prevent the drainage of bile into the gastrointestinal tract. Non-pharmacological treatments to re-establish bile flow include plastic or self-expanding metal stents (SEMs) that are inserted in the bile ducts during endoscopic retrograde cholangiopancreatography (ERCP) procedures. The focus of this study was to 3D print an anatomically accurate model of the extrahepatic bile ducts (EHBDs) with tissue-like mechanical properties to improve in vitro testing of stent prototypes. Following generation of an EHBD model via computer aided design (CAD), we tested the ability of Formlabs SLA 3D printers to precisely print the model with polymers selected based on the desired mechanical properties. We found the printers were reliable in printing the dimensionally accurate EHBD model with candidate polymers. Next, we evaluated the mechanical properties of Formlabs Elastic (FE), Flexible (FF), and Durable (FD) resins pre- and post-exposure to water, saline, or bile acid solution at 37 °C for up to one week. FE possessed the most bile duct-like mechanical properties based on its elastic moduli, percent elongations at break, and changes in mass under all liquid exposure conditions. EHBD models printed in FE sustained no functional damage during biliary stent deployment or when tube connectors were inserted, and provided a high level of visualization of deployed stents. These results demonstrate that our 3D printed EHBD model facilitates more realistic pre-clinical in vitro testing of biliary stent prototypes.

Design and evaluation of a novel anti-reflux biliary stent with cone spiral valve

Endoscopic placement of biliary stent is a well-established palliative treatment for biliary obstruction. However, duodenobiliary reflux after stent placement has been a common problem which may lead to dreadful complications. This paper designed a novel anti-reflux biliary stent with a cone spiral valve. Fluid-Structure Interaction (FSI) simulations were established to evaluate the efficiency of the anti-reflux stent comparing with a clinically applied standard stent. According to the stress distribution of the valve, the fatigue performance in the stress concentration area was analyzed. The results show that when the antegrade flow through the valve, the cone spiral valve could stretch and open to realize adequate drainage under the normal physiological pressure of biliary tract; When the duodenal reflux through the valve, the valve would be compressed and close with a result of nearly zero at the outlet flow rate. Furthermore, the anti-reflux stent achieved improved radial mechanical performance with 2.7 times higher radial stiffness than standard stent. Finite element analysis (FEA) also indicates that compared with the standard stent, the addition of the anti-reflux valve had little negative effect on flexibility of the stent. Fatigue analysis results showed that the valve was reliable. This research provides the new stent with a cone spiral valve and proves that it is technically feasible and effective for preventing the duodenobiliary reflux while ensuring the antegrade bile flow without compromising the other biomechanical performances.

Metallic Stent Mesh Coated with Silver Nanoparticles Suppresses Stent-Induced Tissue Hyperplasia and Biliary Sludge in the Rabbit Extrahepatic Bile Duct

Recent therapeutic strategies to suppress restenosis after biliary stent placement are insufficient. Here, we demonstrate the usefulness of a self-expandable metal stent (SEMS), a stent mesh coated with silver nanoparticles (AgNPs), for suppression of both stent-induced tissue hyperplasia and biliary sludge formation in the rabbit bile duct. The AgNP-coated SEMSs were prepared using a simple bio-inspired surface modification process. Then, the prepared SEMSs were successfully placed in 22 of 24 rabbits. Sludge formation in the AgNP-coated SEMS groups was significantly decreased compared to the control group on gross findings. Cholangiographic and histologic examinations demonstrated significantly decreased tissue hyperplasia in the AgNP-coated SEMS groups compared with the control group (p < 0.05 for all). There were no differences between the AgNP-coated SEMS groups (p > 0.05 for all). However, in the group coated with the greatest concentration of AgNPs (Group D), submucosal fibrosis was thicker than in the other AgNP-coated groups (p < 0.05 for all). The AgNP-coated metallic stent mesh significantly suppressed stent-induced tissue hyperplasia and biliary sludge formation in the rabbit bile duct. Taken together, the AgNP coating strategy developed in this study could be widely utilized in non-vascular medical devices for anti-bacterial and anti-inflammatory responses.

[Mechanisms and prevention of biliary stent occlusion]

One of significant achievements of modern endoscopy is development of retrograde biliary stenting for obstructive jaundice. This method ensured widespread application of endoscopic decompression in the treatment of patients with malignant biliary obstruction as preparation before radical surgery and final palliative care. Endoscopic retrograde transpapillary stenting firmly took its place together with antegrade and percutaneous stenting. There are certain advantages of this technique including minimally invasiveness and favorable quality of life. However, this approach is associated with some drawbacks associated with stent occlusion and difficult correction of this complication. The maximum diameter of the plastic stent (PS) is determined by the width of the working channel of the duodenoscope. In this regard, self-expandable metal stents (SEMS) were developed to increase the diameter of bile drainage channel. SEMS are associated with prolonged function. However, there is another problem. It is a germination of SEMS followed by impossible removal of the stent for its subsequent replacement. A further step in development of endoscopic biliary stents was the use of special SEMS coating to exclude tumor or granulation ingrowth. The problem of biliary stent occlusion remains relevant despite some improvement of stenting results. Mechanisms of occlusion of biliary stents and prevention of these events are discussed in this review.

New antireflux plastic stent for patients with distal malignant biliary obstruction

BACKGROUND

Endoscopic biliary stenting is a well-established palliative treatment for patients with unresectable distal malignant biliary obstruction (MBO). However, the main problem with stent placement is the relatively short duration of stent patency. Although self-expanding metal stents (SEMSs) have a longer patency period than plastic stents (PSs), the higher costs limit the wide use of SEMSs. A PS with an antireflux valve is an attractive idea to prolong stent patency, but no ideal design for an antireflux PS (ARPS) has been proposed. We developed a new ARPS with a “duckbilled” valve attached to the duodenal end of the stent.

AIM

To compare the patency of ARPSs with that of traditional PSs (TPSs) in patients with unresectable distal MBO.

METHODS

We conducted a single-center, prospective, randomized, controlled, double-blind study. This study was conducted at the West China Hospital of Sichuan University. Consecutive patients with extrahepatic MBO were enrolled prospectively. Eligible patients were randomly assigned to receive either an ARPS or a TPS. Patients were followed by clinic visits or telephone interviews every 1-2 mo until stent exchange, death, or the final study follow-up in October 2018. The primary outcome was the duration of stent patency. Secondary outcomes included the rate of technical success, the rate of clinical success, adverse events, and patient survival.

RESULTS

Between February 2016 and December 2017, 38 patients were randomly assigned to two groups, with 19 patients in each group, to receive ARPSs or TPSs. Stent insertion was technically successful in all patients. There were no significant differences between the two groups in the rates of clinical success or the rates of early or late adverse events (P = 0.660, 1.000, and 1.000, respectively). The median duration of stent patency in the ARPS group was 285 d [interquartile range (IQR), 170], which was significantly longer than that in the TPS group (median, 130 d; IQR, 90, P = 0.005). No significant difference in patient survival was noted between the two groups (P = 0.900).

CONCLUSION

The new ARPS is safe and effective for the palliation of unresectable distal MBO, and has a significantly longer stent patency than a TPS.

Suspended over length biliary stents versus conventional plastic biliary stents for the treatment of biliary stricture: A retrospective single-center study

To compare patency between suspended over length biliary stents (SOBSs; made from nasobiliary tube) and conventional plastic biliary stents (CPBSs).We retrospectively analyzed 61 patients with extrahepatic biliary stricture who underwent SOBS placement (intrahepatic bile duct) and 74 patients who underwent CPBS placement. Stent patency and complications were compared.The SOBS group was slightly older and contained more females than the CPBS group but other baseline characteristics were similar. Malignant biliary obstruction accounted for 57.4% (SOBS group) and 45.9% (CPBS group) of cases. Technical success rate, hospital stay and post-procedure complications were similar between groups. Median patency in the CPBS and SOBS group was 116 (2-360) days and 175 (3-480) days, respectively (P <.001). The SOBS group had lower stent occlusion rates than the CPBS group at 3 months (9.8% vs 36.5%), 4 months (22.0% vs 55.4%), 5 months (35.6% vs 67.6%), and 6 months (39.3% vs 77.0%) (all P <.01). In Cox regression analysis, stent type (SOBS vs CPBS) was the only factor associated with patency (hazard ratio [HR]: 3.449; 95% CI: 1.973-6.028; P <.001).SOBS may have better medium-term patency than CPBS for benign/malignant biliary stricture.

Evaluation of valve function in antireflux biliary metal stents

Background

To overcome duodenobiliary reflux induced by biliary stents, antireflux valve (ARV) biliary stents have been developed and showed improvement in stent patency. However, negative study results have also been reported because stent patency may be decreased by the malfunction of ARV itself. Given such mixed results, the true efficacy of ARV remains unknown and the mechanism of its dysfunction needs to be clearly elucidated. The aim of this study was to investigate the exact mechanism of ARV dysfunction using in vitro phantom models.

Methods

Two experimental models were designed to evaluate two important environmental factors suspected to cause ARV malfunction, i.e. bile flow and pH. Three types of ARV metal stents from different companies were used for the experiments: a funnel type ARV, a windsock type ARV, and a wine glass-shaped ARV. Ten stents of each type were tested (five stents in the bile flow phantom model, and another five stents in the duodenal pH environmental model). To determine ARV malfunction, ARV-induced flow resistance was measured using a custom-made testing device. All stents from the two models were removed every 2 weeks for 12 weeks after stent insertion and were evaluated on morphological and functional changes of the ARV.

Results

Only ARV of wine glass-shaped ARV was morphologically changed due to silicone bond detachment in the bile flow model. All types of ARV were morphologically changed in the pH model. The morphological changes of ARV influenced the flow resistance. The antegrade pressure gradients were increased over time in the pH model (p < 0.05).

Conclusions

Morphological change of the ARVs may induce dysfunction of ARV metal stents, which is mainly due to duodenal pH environment. In the future, development of new ARV that is not affected by duodenal environmental factors can be expected to improve stent patency.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0878-8) contains supplementary material, which is available to authorized users.

Bare-metal stents across the Vater's ampulla is a safe method for patients with lower bile duct obstruction

This study explored the effect of the implant position of stents across the Vater's ampulla on treatment outcomes in patients with lower bile duct obstruction.In the retrospective study, 41 patients with malignant obstruction of the lower bile duct and obstructive jaundice received percutaneous transhepatic biliary placement of bare-metal stents. Basic demographic data on patients, such as sex, age, and primary diseases, and follow-up data, including postoperative complications and jaundice-free survival, were recorded. The follow-up data on patients with an involved ampulla, patients with an uninvolved ampulla, patients with a stent across the ampulla, and patients with a stent at a site other than the ampulla were compared. Furthermore, prognostic factors for jaundice- free survival were investigated using Cox proportional hazards regression analysis.Among the 41 patients, 38 patients experienced subsiding of jaundice, whereas 3 cases had unsuccessful stent patency. Whether or not the ampulla was involved did not influence the incidence rates of postoperative complications and the jaundice-free survival time. Notably, when stents were placed across the ampulla, the jaundice-free survival time was significantly longer than when stents were placed at sites other than across the ampulla (P < .05). Furthermore, placement of the stent across the ampulla or at other sites was an independent prognostic factor (hazard ratio = 0.154, 95% confidence interval 0.042-0.560, P = .005) for jaundice-free survival of patients.The current study revealed that the implant position of a stent across the ampulla resulted in maintenance of stent patency and prolongation of the jaundice-free survival time.

Bile Flow Phantom Model and Animal Bile Duct Dilation Model for Evaluating Biliary Plastic Stents with Advanced Hydrophilic Coating

Background/Aims

The efforts to improve biliary plastic stents (PSs) for decreasing biofilm formation and overcome short patency time have been continued. The aim of this study is to evaluate the effect of advanced hydrophilic coating for patency and biodurability of PS.

Methods

Using an in vitro bile flow phantom model, we compared patency between prototype PS with hydrophilic coating (PS+HC) and prototype PS without hydrophilic coating (PS−HC). We performed an analysis of the degree of luminal narrowing by microscopic examination. Using an in vivo swine bile duct dilation model made by endoscopic papillary closure and stent insertion, we evaluated biodurability of hydrophilic coating.

Results

In the phantom model, PS+HC showed less biofilm formation and luminal narrowing than PS−HC at 8 weeks (p<0.05). A total of 31 stents were inserted into the dilated bile duct of seven swine models, and 24 stents were successfully retrieved 8 weeks later. There was no statistical difference of stent patency between the polyethylene PS+HC and the polyurethane PS+HC. The biodurability of hydrophilic coating was sustained up to 8 weeks, when assessing the coating layer by scanning electron microscopy examination.

Conclusions

Advanced hydrophilic coating technology may extend the patency of PS compared to uncoated PS.

The Stent Patency and Migration Rate of Different Shaped Plastic Stents in Bile Flow Phantom Model and In Vivo Animal Bile Duct Dilation Model

BACKGROUND/AIM

In research and development of biliary plastic stents (PS), continuous efforts have been made to overcome short patency time and high rate of migration. The aim of this study was to evaluate the patency and migration rate of different PS shapes for a given period of time.

METHODS

Using an in vitro bile phantom model, we compared the patency among different shapes of PS (three straight PS, four double-pigtail PS, and a new screw-shaped PS). We performed an analysis of the degree of luminal narrowing by light microscopic examination. Using an in vivo swine model, we compared the patency and migration rate among the three different types of PS.

RESULTS

Eight weeks after the bile exposure in the bile flow phantom model, 80 PS were retrieved and analyzed. The straight PS showed less biofilm formation and luminal narrowing than other types of PS (p < 0.05). Forty-nine PS were inserted into the dilated bile ducts of 10 swine models, and 39 PS were successfully retrieved 8 weeks later. The stent migration occurred less frequently in the double-pigtail PS and the screw-shaped PS than it did in the straight PS (11.1, 10, and 27.3%, respectively). However, there was no statistical difference in stent patency among the different shapes.

CONCLUSIONS

Stent patency may not be significantly different depending on the shape of PS for 8 weeks. The screw-shaped PS showed similar patency and migration rate to the double-pigtail PS. These results may help guiding future PS development and clinical decisions.

Time Sequence Evaluation of Biliary Stent Occlusion by Dissection Analysis of Retrieved Stents

BACKGROUND AND AIMS

Multiple factors can affect the occlusion of plastic stents. Previous data demonstrate that side holes may induce more biofilm formation probably via microturbulence and bile flow disturbances that could lead to occlusion. These results, however, have not been replicated in subsequent clinical studies with different methods. The objective of this study is to evaluate the physical characteristics of plastic stent occlusion over time.

METHODS

This is a plastic stent sequential analysis study. Biliary stents removed via ERCP from February 24, 2015, to June 2, 2015, were included. One hundred and forty-eight retrieved straight-type plastic stents were longitudinally cut by a custom-made cutting device. These dissected stents were then evaluated in detail with regard to the location of stent occlusion and the stent patency period. Location of stent occlusive debris was the primary outcome in this study.

RESULTS

Biofilm formations and occlusions by debris were sequentially but separately tallied. Biofilm formations were initially seen around the side hole areas within 30 days and spread to the entire stent by 60 days. Then, occlusion process by debris was mainly initiated by 80 days and progressed to full occlusion by median of 90 days. Although some occlusions were also observed around the side hole areas within 30 days, affected areas were more widely observed after biofilm formation.

CONCLUSIONS

This study is the first to attempt to describe the distribution of stent occlusions over time. These observations may help guide future stent development.

Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention

Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, we will discuss basic mechanisms of plastic stent occlusion, along with a systematic summary of previous efforts and related studies to improve stent patency and potential new techniques to overcome existing limitations.

A prospective, randomized study of the patency period of the plastic antireflux biliary stent: an interim analysis

BACKGROUND

There is as yet no ideal design of a plastic biliary stent with the longest patency period.

OBJECTIVE

To study the safety and effective patency period of a new plastic antireflux biliary stent in the clinical setting.

DESIGN

We conducted a prospective, randomized trial to compare the patency of 2 similar plastic biliary stents, one of which has an antiduodenobiliary reflux property.

SETTING

The study was conducted at 2 separate tertiary centers in 2 countries.

PATIENTS

Patients with inoperable distal malignant biliary obstruction were recruited.

INTERVENTIONS

One of the 2 types of plastic stents under study was randomly chosen and inserted in the common bile duct of the study subjects. The subjects were followed until the end of study or occlusion occurrence.

MAIN OUTCOME MEASUREMENTS

Our primary endpoint was the time to stent occlusion in days, with stent-related adverse events and all-cause mortality the secondary endpoints.

RESULTS

A total of 16 subjects were recruited for the study; 7 were allocated to group A (ordinary Tannenbaum stent) and 9 to group B (antireflux biliary stent). Five of 7 subjects (71%) in group B had stent occlusion within 8 days, and the primary end point was reached in all 7 subjects within 30 days, whereas the primary endpoint was not reached within 30 days in any of the subjects in group A. Our data showed a significantly shorter stent patency period in group B compared with group A (P < .003).

LIMITATIONS

Small sample size.

CONCLUSION

Routine use of antireflux plastic biliary stents in the palliative management of malignant biliary obstructions cannot be recommended at present. (Clinical trial registration number: NCT01142921.).

An Update to Hepatobiliary Stents

Endoscopic stent placement is a common primary management therapy for benign and malignant biliary strictures. However, continuous use of stents is limited by occlusion and migration. Stent technology has evolved significantly over the past two decades to reduce these problems. The purpose of this article is to review current guidelines in managing malignant and benign biliary obstructions, current endoscopic techniques for stent placement, and emerging stent technology. What began as a simple plastic stent technology has evolved significantly to include uncovered, partially covered, and fully covered self-expanding metal stents (SEMS) as well as magnetic, bioabsorbable, drug-eluting, and antireflux stents.(1).

Novel biliary self-expanding metal stents: indications and applications

Endoscopic insertion of a self-expanding metal stent (SEMS) through a malignant common bile duct stricture is the first line of palliation for malignant jaundice. Patency of these stents remains a major concern. SEMS dysfunction can result from tumor ingrowth, overgrowth and/or clogging. Initial SEMS modifications involved covering the central part of the stent in order to reduce ingrowth and ultimately increase patency. Fully covered stents became available shortly after reports of their use in human patients. The potential removability and radial strength of SEMS have led to evaluation of their use in new indications including benign biliary strictures, post sphincterotomy bleeding and perforation. Other aspects of development include the addition of features such as anti-reflux valves, drug elution and spontaneous biodegradability. These aspects and their clinical implications are reviewed and discussed.

Managing malignant biliary obstruction in pancreas cancer: choosing the appropriate strategy

Most patients with pancreatic cancer develop malignant biliary obstruction. Treatment of obstruction is generally indicated to relieve symptoms and improve morbidity and mortality. First-line therapy consists of endoscopic biliary stent placement. Recent data comparing plastic stents to self-expanding metallic stents (SEMS) has shown improved patency with SEMS. The decision of whether to treat obstruction and the means for doing so depends on the clinical scenario. For patients with resectable disease, preoperative biliary decompression is only indicated when surgery will be delayed or complications of jaundice exist. For patients with locally advanced disease, self-expanding metal stents are superior to plastic stents for long-term patency. For patients with advanced disease, the choice of metallic or plastic stent depends on life expectancy. When endoscopic stent placement fails, percutaneous or surgical treatments are appropriate. Endoscopic therapy or surgical approach can be used to treat concomitant duodenal and biliary obstruction.

Novel antireflux covered metal stent for recurrent occlusion of biliary metal stents: a pilot study

BACKGROUND

Feasibility of antireflux metal stent (ARMS), designed to prevent duodenobiliary reflux, was reported in patients with distal malignant biliary obstruction. In this prospective pilot study, we aimed to evaluate a newly designed ARMS as a reintervention for self-expandable metallic stent (SEMS) occlusion believed to be caused by duodenobiliary reflux.

PATIENTS AND METHODS

Patients with non-resectable distal malignant biliary obstruction were included in whom a prior SEMS was occluded as a result of sludge or food impaction between March 2010 and January 2012 at two Japanese tertiary referral centers. The occluded SEMS were endoscopically removed, if possible, and subsequently replaced by a newly designed ARMS. We evaluated the technical success rate and complications of ARMS and compared the time to occlusion of ARMS with that of prior SEMS.

RESULTS

A total of 13 patients were included. ARMS was successfully placed in all patients in a single procedure. No procedure-related complications were identified. ARMS occlusion occurred in two patients (15%), the causes of which were sludge in one patient and unknown in the other. ARMS migration occurred in four patients (31%). ARMS patency time was significantly longer than that of prior SEMS (median, not available vs 58 days; P = 0.039).

CONCLUSIONS

This newly designed ARMS is a technically feasible, safe, and effective reintervention for SEMS occlusion as a result of sludge or food impaction. An anti-migration mechanism to improve the outcomes of ARMS should be considered.

Functional self-expandable metal stents in biliary obstruction

Biliary stents are widely used not only for palliative treatment of malignant biliary obstruction but also for benign biliary diseases. Each plastic stent or self-expandable metal stent (SEMS) has its own advantages, and a proper stent should be selected carefully for individual condition. To compensate and overcome several drawbacks of SEMS, functional self-expandable metal stent (FSEMS) has been developed with much progress so far. This article looks into the outcomes and defects of each stent type for benign biliary stricture and describes newly introduced FSEMSs according to their functional categories.

Future developments in biliary stenting

Biliary stenting has evolved dramatically over the past 30 years. Advancements in stent design have led to prolonged patency and improved efficacy. However, biliary stenting is still affected by occlusion, migration, anatomical difficulties, and the need for repeat procedures. Multiple novel plastic biliary stent designs have recently been introduced with the primary goals of reduced migration and improved ease of placement. Self-expandable bioabsorbable stents are currently being investigated in animal models. Although not US Food and Drug Administration approved for benign disease, fully covered self-expandable metal stents are increasingly being used in a variety of benign biliary conditions. In malignant disease, developments are being made to improve ease of placement and stent patency for both hilar and distal biliary strictures. The purpose of this review is to describe recent developments and future directions of biliary stenting.

Radiotherapy prolongs biliary metal stent patency in malignant pancreatobiliary obstructions

Background/Aims

Biliary stenting is the most effective decompressive method for treating malignant biliary obstructive jaundice. Although the main cause of stent occlusion is tumor growth, few studies have investigated whether stent patency is affected by the combination of cancer-treatment modalities. The aim of this study was to evaluate the effects of local radiotherapy on metal-stent patency in patients with malignant biliary obstruction.

Methods

Patients who underwent self-expandable biliary metallic stenting for malignant biliary obstruction from 1999 to 2007 were included. Forty patients received chemotherapy and radiation therapy (radiation group, RG), and 31 patients received only chemotherapy (nonradiation group, NRG).

Results

The cumulative median stent patency was significantly longer in the RG than in the NRG (17.7 months; 95% confidence interval [CI], 1.8 to 33.6 months vs 8.7 months; 95% CI, 4.9 to 12.5 months; p=0.025). Stent occlusion caused by tumor growth or stent migration occurred in two (5%) and three (7.5%) cases in the RG and in six (19.3%) and two (6.5%) cases in the NRG, respectively.

Conclusions

The patency of biliary metal stents in pancreatobiliary cancer patients who receive chemoradiation therapy is significantly longer than that in patients who do not receive radiotherapy, which suggests that local cancer control significantly affects stent patency.

Clinical advantages of a metal stent with an S-shaped anti-reflux valve in malignant biliary obstruction

BACKGROUND AND AIM

Transpapillary stent insertion is the standard treatment for palliating malignant biliary obstruction. However, luminal occlusion often occurs due to sludge formation, tumor ingrowth, or tumor overgrowth. Currently, influx of duodenal contents by duodenobiliary reflux is considered a mechanism of stent obstruction. The aim of the present study was to evaluate the efficacy and safety of a metal stent with an anti-reflux valve in distal malignant biliary obstruction.

METHODS

Thirty-two patients diagnosed with unresectable malignant biliary obstruction were enrolled. This trial was conducted at two tertiary hospitals in Korea from June 2009 to June 2011. An uncovered metal stent (M.I.Tech) with an S-type anti-reflux valve was placed.

RESULTS

A total of 32 patients were enrolled. The technical success rate of stent insertion was 100%. The median duration of stent patency was 14.4 months. Stent occlusion occurred in 11 cases, which was caused by sludge formation in six cases, tumor ingrowth in four cases, and migration of the stent membrane in one case. During the follow-up period, there were no episodes of ascending cholangitis, acute pancreatitis, or bleeding.

CONCLUSIONS

The new metal stent with an S-shaped anti-reflux valve demonstrated a relatively long duration of stent patency. This was attributable to reductions in duodenobiliary reflux by the anti-reflux valve. Also, the stent with an S-shaped anti-reflux valve is technically feasible and very safe. However, further prospective, randomized comparison studies of stents with anti-reflux valves and conventional stents are needed to evaluate the duration of stent patency.

Pancreatic and biliary stents

Biliary and pancreatic stents are used in a variety of benign and malignant conditions including strictures and leaks and in the prevention of post-ERCP pancreatitis.Both plastic and metal stents are safe, effective, and easy to use. SEMSs have traditionally been used for inoperable malignant disease. Covered SEMSs are now being evaluated for use in benign disease. Increasing the duration of patency of both plastic and metal stents remains an important area for future research.

New antireflux self-expandable metal stent for malignant lower biliary obstruction: in vitro and in vivo preliminary study

AIM

Antireflux plastic biliary stents prevent duodenal biliary reflux and improve the stent patency rate. However, the efficacy of the antireflux valve in a self-expandable metal stent (SEMS) for a malignant biliary obstruction has not been well established. We evaluated the efficacy of a SEMS with an antireflux valve using in vitro flow studies and determined the impact of reducing duodenobiliary reflux on the stent patency rate.

METHODS

In vitro testing was conducted using a bile perfusion system to evaluate the antegrade and retrograde flow resistance, and to determine the ideal shape for the valve. Then, a prospective case series in humans was conducted with an adequately designed SEMS with an antireflux valve.

RESULTS

During the study period, five patients with an unresectable non-hilar malignant biliary obstruction underwent insertion of a SEMS with an antireflux valve. Placement of the SEMS with antireflux valve was successful on the first attempt in all patients, and no procedure-related complications occurred. Follow up was obtained in all cases. Serum bilirubin level did not decrease to the normal range within 1 month in four patients. Stent occlusions occurred in all four patients as a result of valve malfunctions due to sludge impaction or a clog. Therefore, the study was terminated early due to unexpected results.

CONCLUSION

SEMS with an antireflux valve was ineffective in patients with non-hilar malignant biliary obstruction due to limitations on current stent technology.

Endoscopic management of benign biliary strictures

Endoscopic retrograde cholangiopancreatography (ERCP) is the first-line management in most situations when a benign biliary stricture is suspected. Although management principles are similar in all subgroups, the anticipated response rates, need for ancillary medical and endoscopic approaches, and use of less proven strategies vary between differing causes. Exclusion of malignancy should always be a focus of management. Newer endoscopic techniques such as endoscopic ultrasound, cholangioscopy, confocal endomicroscopy, and metal biliary stenting are increasingly complementing traditional ERCP techniques in achieving long-term sustained stricture resolution. Surgery remains a definitive management alternative when a prolonged trial of endoscopic therapy does not achieve treatment goals.

Endoscopic retrograde cholangiopancreatography for distal malignant biliary stricture

Endoscopic biliary stent placement is widely accepted as palliation for malignant biliary obstruction or as a treatment of benign biliary stricture. Although various biliary stent designs have become available since self-expandable metallic stents were introduced, no single ideal stent has been developed. An ideal stent should be patent until death, or surgery, in patients with resectable malignant biliary obstruction. Fewer complications, maneuverability, cost-effectiveness, and removability are also important factors. Alternatively, should we develop a novel method for biliary drainage other than biliary stenting via endoscopic retrograde cholangiopancreatography? This article reviews the current status of biliary stenting for malignant biliary obstructions.

Endoscopic biliary stenting for irretrievable common bile duct stones: Indications, advantages, disadvantages, and follow-up results

BACKGROUND

The advantages of endoscopic retrograde cholangiopancreatography (ERCP) over open surgery have made it the predominant method of treating patients with choledocholithiasis. After sphincterotomy, however, 10%-15% of common bile duct (CBD) stones cannot be removed with a basket or balloon. Methods for managing "irretrievable stones" include surgery; mechanical, intraductal shock wave, and extracorporeal shock wave lithotripsy; chemical dissolution; and biliary stenting. Endoscopic biliary stent insertion, which is frequently used in specific situations, has both advantages and disadvantages. To maximize the advantages and minimize the complications of biliary endoprosthesis, it is important to recognize its proper indications and to apply the technique in proper situations.

DATA SOURCES

We reviewed all publications cited in Pubmed and published through July 2011 on biliary endoprosthesis in patients with irretrievable CBD stones. We analyzed the indications, advantages, disadvantages, and long-term follow-up results of this technique.

RESULTS

Despite the occurrence of related complications, such as cholangitis, endoscopic placement of an endoprosthesis may reduce stone size, allowing later clearance of unextractable stones. Permanent biliary stenting may be a definitive treatment in selected elderly patients who are poor candidates for surgery.

CONCLUSION

Endoscopic biliary stenting remains a simple and safe method for patients with stones difficult to manage by conventional endoscopic methods and those patients unfit for surgery or at high surgical risks.

Duodenal invasion is a risk factor for the early dysfunction of biliary metal stents in unresectable pancreatic cancer

BACKGROUND

Although the placement of self-expandable metal stents (SEMSs) has been widely accepted as palliation for distal malignant biliary obstruction, the risk factors for their early dysfunction remain unclear.

OBJECTIVE

To identify risk factors for early (<3 months) SEMS dysfunction in unresectable pancreatic cancer.

DESIGN

A multicenter retrospective study.

SETTING

Five tertiary referral centers.

PATIENTS

Patients were included who underwent first-time SEMS placement for distal malignant biliary obstruction caused by pancreatic cancer between April 1994 and August 2010.

MAIN OUTCOME MEASUREMENTS

Rates and causes of early dysfunction were evaluated, and risk factors were analyzed.

RESULTS

In all, 317 eligible patients were identified. Covered SEMSs were placed in 82% of patients. Duodenal invasion was observed endoscopically in 37%. The median time to dysfunction was 170 days. The rates of all and early SEMS dysfunction were 55% and 31%, respectively. The major causes of SEMS dysfunction were food impaction and nonocclusion cholangitis (21% each) in early dysfunction and sludge (29%) in nonearly dysfunction. The rate of early dysfunction was 42% with duodenal invasion and 24% without duodenal invasion (P = .001). Early dysfunction caused by food impaction was more frequent in patients with duodenal invasion (10% and 4%, P = .053). Duodenal invasion was a risk factor (odds ratio 2.35; 95% CI, 1.43-3.90; P = .001) in a multiple logistic regression model.

LIMITATIONS

A retrospective design.

CONCLUSIONS

Duodenal invasion is a risk factor for early SEMS dysfunction in patients with pancreatic cancer.

Sphincter of Oddi manometry by choledochoscope in patients with duodenobiliary reflux

BACKGROUND AND AIM

  Previous research has confirmed that duodenobiliary reflux exists in patients with choledocholithiasis. The objective of this study was to investigate whether the motor activity of the sphincter of Oddi (SO) has an effect on duodenobiliary reflux.

METHODS

  A total of 51 patients orally ingested 1mL water containing technetium-99m diethylenetriaminepentaacetatic acid, and a 2-h bile collection was obtained from the T tube. Technetium counts in the collected bile were performed using an RM905 radioactivity meter. The patients were divided into two groups: reflux group (duodenobiliary reflux positive) and control group (duodenobiliary reflux negative). Next, 33 cases were randomly selected and double blinded to receive SO manometry by choledochoscope.

RESULTS

  Of the 51 total cases, 16 bile samples exhibited radioactivity. The average SO basal pressure and contraction pressure values were 7.2±3.9mmHg and 53.5±24.5mmHg, respectively, in the reflux group, and 14.7±11.0mmHg and 117.2±65.6mmHg, respectively, in the control group. The choledochus pressure values were 5.1±1.6mmHg and 11.5±7.4mmHg in the reflux group and the control group, respectively. The differences between the groups were statistically significant; however, the SO contraction frequency, SO contraction duration, and duodenum pressure values were not significantly different between the groups.

CONCLUSION

  The decreases in the SO basal pressure and SO contraction pressure, and the decrease in choledochus pressure, might play a role in duodenobiliary reflux.

Endoscopic stenting for palliation of malignant biliary obstruction

Malignant biliary obstruction results in jaundice, often with symptoms that decrease the quality of life. Biliary stent placement has largely supplanted surgical bypass for palliation of malignant biliary obstruction. Traditional rigid plastic stents are commonly used, inexpensive and easily removed, although with limited duration of stent patency. Self-expandable metal stents (SEMS) attain larger luminal diameters and provide longer patency than traditional rigid plastic stents in patients with distal bile duct obstruction. SEMS are composed of a variety of metals and can be uncoated, partially covered, or fully covered. Data do not support a prolongation of patency with covered SEMS for distal obstruction, although they have the potential for removability. The data to support SEMS for palliation of hilar biliary obstruction are not as convincing and reintervention for stent occlusion can be difficult. In this article, the design and performance of expandable metal stents for treatment of malignant biliary obstruction will be reviewed.

New method of covered wallstents for distal malignant biliary obstruction to reduce early stent-related complications based on characteristics

AIM

We previously reported a low occlusion rate with covered Wallstents for malignant biliary obstruction, but stent-related complications other than occlusion posed a problem. A modified covered Wallstent insertion method based on stent characteristics was evaluated to reduce stent-related complications.

METHODS

A total of 138 patients with distal malignant biliary obstruction received covered Wallstent placement. From October 2001 to October 2003, 69 patients received covered Wallstent placement (Group 1). Thereafter, we modified our stent insertion method and 69 patients received stent placement using this modified method from November 2003 to January 2007 (Group 2). The modified insertion method consists of endoscopic sphincterotomy carried out in patients without pancreatic duct invasion and longer stent placement with the center of the stent located in the center of the biliary stricture to prevent pancreatitis, kinking of the bile duct, and stent dislocation. A comparative analysis was carried out using prospectively collected data in these two cohorts.

RESULTS

Tumor ingrowth was not observed, and stent occlusion rate was 18.8% in Group 1 and 23.2% in Group 2. The overall rates of stent-related complications did not differ (39.1% in Group 1 and 30.4% in Group 2), but stent-related complications within 3months decreased from 22 episodes in Group 1 to 13 episodes in Group 2. Median event-free survival was prolonged by modified stent insertion method (125days in Group 1 and 268days in Group 2, P=0.020), although cumulative survival and stent patency were not significantly different.

CONCLUSIONS

Our modified method of covered Wallstent placement showed improved event-free survival.

A novel antireflux metal stent for the palliation of biliary malignancies: a pilot feasibility study (with video)

BACKGROUND

Antireflux stents that prevent duodenal biliary reflux may improve biliary drainage and prolong stent patency. However, the use of antireflux metal stents (ARMSs) in the human biliary system has not been reported.

OBJECTIVE

To evaluate the safety and efficacy of ARMSs for the palliation of unresectable distal biliary malignancies.

DESIGN AND SETTING

A retrospective case series in a tertiary referral center.

PATIENTS

From August 2007 to April 2009, a total of 23 patients with unresectable nonhilar malignant biliary obstruction.

INTERVENTION

Endoscopic placement of an ARMS.

MAIN OUTCOME MEASUREMENTS

Technical success and early complications with follow-up of stent patency and patient survival.

RESULTS

Placement of an ARMS was successful on the first attempt in all patients. There were no procedure-related complications. Follow-up was obtained in 22 cases. Serum bilirubin level returned to normal within 1 month of stenting in 20 patients. Six stent malfunctions occurred as a result of tumor ingrowth (1 patient), tumor overgrowth (2 patients), and stent migration (3 patients). The remaining patients were free of biliary symptoms until death or final follow-up. The median duration of stent patency of ARMSs was 14 months, with cumulative patency rates at 3, 6, and 12 months of 95%, 74%, and 56%, respectively. The median survival of the patients was 7.9 months (range, 1-14 months).

LIMITATIONS

Small number of patients in single endoscopy center.

CONCLUSIONS

Endoscopic insertion of an ARMS is technically feasible, safe, and effective in patients with distal malignant biliary obstruction. The impact of ARMSs in prolonging stent patency and life expectancy deserves further randomized evaluation.

Reflux of duodenal contents and cholangitis in patients undergoing self-expanding metal stent placement

BACKGROUND

It has been reported that the occurrence of acute cholangitis is common, especially when the self-expanding metal stent (SEMS) is placed across the main duodenal papilla.

OBJECTIVE

To determine the incidence of duodenobiliary reflux and acute cholangitis after placement of SEMSs across the main duodenal papilla.

DESIGN

A prospective study.

SETTING

A tertiary-care teaching hospital.

PATIENTS

One hundred consecutive patients with malignant bile-duct obstruction.

INTERVENTIONS

A barium meal examination was performed 21 days after placement of SEMSs. Reflux of barium was monitored by using fluoroscopy. The patients were also monitored for the occurrence of fever. Serum bilirubin, alanine aminotransferase, alkaline phosphatase, and total and differential leukocyte counts were evaluated before and after the barium study.

MAIN OUTCOME MEASUREMENTS

The occurrence of duodenobiliary reflux and acute cholangitis.

RESULTS

Two patients developed acute cholangitis because of the failure of the function of the SEMS, and they died during the first week. Severe reflux of barium was evident in all the patients. However, none of them developed features of acute cholangitis because of reflux. After a mean (SD) follow-up of 6.4 +/- 1 months, 6 patients developed acute cholangitis because of blockage of the SEMS from ingrowth of tumor or collection of debris at the lower end of the SEMS.

LIMITATIONS

Unblinded study.

CONCLUSIONS

After placement of SEMSs across the main duodenal papilla, reflux of duodenal contents is a universal phenomenon. Acute cholangitis was observed only in cases with blockage of the SEMS from tumor ingrowth or debris.

Removal of a large stone growing around and encasing a plastic biliary stent: respect the ductal axis

Plastic biliary stents are commonly used during Endoscopic Retrograde Cholangio-Pancreatography (ERCP). The main indication for biliary stenting is benign or malignant obstruction. Plastic stents, among others, can be used as an escape route in patients with large common bile duct stones, or in cases of acute cholangitis with or without sphincterotomy to provide drainage until definitive treatment. Stent occlusion is the main disadvantage, limiting their patency to around 3 months, after which replacement is recommended. We present a case of a large, close to 2cm, stone developing around and encasing the proximal end of a plastic biliary stent. The stent/stone complex was successfully removed en bloc. The stent was placed in the common bile duct without sphincterotomy, and remained in situ for 2 years. The presented case highlights the importance of definitive treatment for common bile duct stones, the need to respect the ductal axis especially when dealing with large stones and the significance of biliary sphincterotomy during endoscopic interventions in the bile duct.

Endoscopic management of biliary malignancies

The current status of endoscopic diagnosis and treatment of biliary malignancies is discussed. Three ways are now available to approach the bile duct endoscopically. Endoscopic diagnostic modalities are quite useful for the assessment of local changes because of their high spatial resolution and ability in tissue and bile acquisition for histologic, cytologic, and molecular biologic evaluations. Endoscopic biliary drainage is less invasive and beneficial for patients with obstructive jaundice compared with surgical or percutaneous transhepatic drainage. Continuous evolution should expand its indications.

Metal or plastic stent for malignant biliary obstruction: what's got the most bang for your buck?

Malignant biliary obstruction is most commonly managed by the endoscopist. Various plastic and metal stents are currently available. It is important to be aware of the pros and cons of each. The identifying factors that determine the prognosis for the patient might also help determine which type of stent to place. This month's article by Moss et al., is a meta-analysis of seven randomized controlled trials analyzing the cost-effectiveness of plastic and metal stents. This meta-analysis helps guide the endoscopist in deciding what type of stent would be most beneficial and cost effective for their patients.