Antireflux metal stent for biliary obstruction: Any benefits?

Biliary stents for active materials and surface modification: Recent advances and future perspectives

Demand for biliary stents has expanded with the increasing incidence of biliary disease. The implantation of plastic or self-expandable metal stents can be an effective treatment for biliary strictures. However, these stents are nondegradable and prone to restenosis. Surgical removal or replacement of the nondegradable stents is necessary in cases of disease resolution or restenosis. To overcome these shortcomings, improvements were made to the materials and surfaces used for the stents. First, this paper reviews the advantages and limitations of nondegradable stents. Second, emphasis is placed on biodegradable polymer and biodegradable metal stents, along with functional coatings. This also encompasses tissue engineering & 3D-printed stents were highlighted. Finally, the future perspectives of biliary stents, including pro-epithelialization coatings, multifunctional coated stents, biodegradable shape memory stents, and 4D bioprinting, were discussed.

Impact of the suprapapillary method on patency in distal malignant biliary obstruction: a multicenter randomized controlled trial

BACKGROUND AND AIMS

Placement of a self-expandable metal stent (SEMS) across the duodenal major papilla carries a risk of duodenobiliary reflux (DBR). The suprapapillary method of stent placement may reduce DBR and improve stent patency compared with the transpapillary method. This study compared the clinical outcomes between the suprapapillary and transpapillary methods for distal malignant biliary obstruction (DMBO).

METHODS

Between January 2021 and January 2023, consecutive patients with DMBO from 6 centers in South Korea were randomly assigned to either the suprapapillary arm or transpapillary method arm in a 1:1 ratio. The primary outcome was the duration of stent patency, and secondary outcomes were the cause of stent dysfunction, adverse events, and overall survival rate.

RESULTS

Eighty-four patients were equally assigned to each group. The most common cause of DMBO was pancreatic cancer (50, 59.5%), followed by bile duct (20, 23.8%), gallbladder (11, 13.1%), and other cancers (3, 3.6%). Stent patency was significantly longer in the suprapapillary group (median, 369 days [interquartile range, 289-497] vs 154 days [interquartile range, 78-361]; P < .01). Development of DBR was significantly lower in the suprapapillary group (9.4% vs 40.8%, P < .01). Adverse events and overall survival rate were not significantly different between the 2 groups.

CONCLUSIONS

The placement of SEMSs using the suprapapillary method resulted in a significantly longer duration of stent patency. It is advisable to place the SEMS using the suprapapillary method in DMBO. Further studies with a larger number of patients are required to validate the benefits of the suprapapillary method. (Clinical trial registration number: KCT0005572.).

Therapeutic biliary stents: applications and opportunities

INTRODUCTION

Biliary stents are used to optimize ductal patency and enable bile flow in the management of obstruction or injury related to biliary tract tumors, strictures, stones, or leaks. Although direct therapeutic applications of biliary stents are less well developed, stents can be used to deliver drugs, radioisotopes, and photodynamic therapy.

AREAS COVERED

This report provides an in-depth overview of the clinical indications, and therapeutic utility of biliary stents. Unique considerations for the design of biliary stents are described. The properties and functionalities of materials used for stents such as metal alloys, plastic polymers, or biodegradable materials are described, and opportunities for design of future stents are outlined. Current and potential applications of stents for therapeutic applications for biliary tract diseases are described.

EXPERT OPINION

Therapeutic biliary stents could be used to minimize inflammation, prevent stricture formation, reduce infections, or provide localized anti-cancer therapy for biliary tract cancers. Stents could be transformed into therapeutic platforms using advanced materials, 3D printing, nanotechnology, and artificial intelligence. Whilst clinical study and validation will be required for adoption, future advances in stent design and materials are expected to expand the use of therapeutic biliary stents for the treatment of biliary tract disorders.

Percutaneous insertion of long-covered biliary stents in patients with malignant duodenobiliary stricture

OBJECTIVE

To investigate the technical feasibility, safety, and efficacy of a long-covered biliary stent in patients with malignant duodenobiliary stricture.

METHODS

This retrospective study enrolled 57 consecutive patients (34 men, 23 women; mean age, 64 years; range, 32-85 years) who presented with malignant duodenobiliary stricture between February 2019 and November 2020. All patients were treated with a long (18 or 23 cm)-covered biliary stent.

RESULTS

The biliary stent deployment was technically successful in all 57 patients. The overall adverse event rate was 17.5% (10 of 57 patients). Successful internal drainage was achieved in 55 (96.5%) of 57 patients. The median patient survival and stent patency times were 99 days (95% confidence interval [CI], 58-140 days) and 73 days (95% CI, 60-86 days), respectively. Fourteen (25.5%) of the fifty-five patients presented with biliary stent dysfunction due to sludge (n = 11), tumor overgrowth (n = 1), collapse of the long biliary stent by a subsequently inserted additional duodenal stent (n = 1), or rapidly progressed duodenal cancer (n = 1). A univariate Cox proportional hazards model did not reveal any independent predictor of biliary stent patency.

CONCLUSIONS

Percutaneous insertion of a subsequent biliary stent was technically feasible after duodenal stent insertion. Percutaneous insertion of a long-covered biliary stent was safe and effective in patients with malignant duodenobiliary stricture.

CLINICAL RELEVANCE STATEMENT

In patients with malignant duodenobiliary stricture, percutaneous insertion of a long-covered biliary stent was safe and effective regardless of duodenal stent placement.

KEY POINTS

• Percutaneous insertion of long-covered biliary stents in patients with malignant duodenobiliary stricture is a safe and effective procedure. • Biliary stent deployment was technically successful in all 57 patients and successful internal drainage was achieved in 55 (96.5%) of 57 patients. • The median patient survival and stent patency times were 99 days and 73 days, respectively, after placement of a long-covered biliary stent in patients with duodenobiliary stricture.

Biliary drainage in malignant biliary obstruction: an umbrella review of randomized controlled trials

Background

There are still many controversies about biliary drainage in MBO, and we aimed to summarize and evaluate the evidence associated with biliary drainage.

Methods

We conducted an umbrella review of SRoMAs based on RCTs. Through July 28, 2022, Embase, PubMed, WOS, and Cochrane Database were searched. Two reviewers independently screened the studies, extracted the data, and appraised the methodological quality of the included studies. GRADE was used to evaluate the quality of the evidence.

Results

36 SRoMAs were identified. After excluding 24 overlapping studies, 12 SRoMAs, including 76 RCTs, and 124 clinical outcomes for biliary drainage in MBO were included. Of the 124 pieces of evidence evaluated, 13 were rated "High" quality, 38 were rated "Moderate", and the rest were rated "Low" or "Very low". For patients with MBO, 125I seeds+stent can reduce the risk of stent occlusion, RFA+stent can improve the prognosis; compared with PC, SEMS can increase the risk of tumor ingrowth and reduce the occurrence of sludge formation, and the incidence of tumor ingrowth in C-SEMS/PC-SEMS was significantly lower than that in U-SEMS. There was no difference in the success rate of drainage between EUS-BD and ERCP-BD, but the use of EUS-BD can reduce the incidence of stent dysfunction. For patients with obstructive jaundice, PBD does not affect postoperative mortality compared to direct surgery. The use of MS in patients with periampullary cancer during PBD can reduce the risk of re-intervention and stent occlusion compared to PC. In addition, we included four RCTs that showed that when performing EUS-BD on MBO, hepaticogastrostomy has higher technical success rates than choledochoduodenostomy. Patients who received Bilateral-ENBD had a lower additional drainage rate than those who received Unilateral-ENBD.

Conclusions

Our study summarizes a large amount of evidence related to biliary drainage, which helps to reduce the uncertainty in the selection of biliary drainage strategies for MBO patients under different circumstances.

Efficacy and complications of inoperable malignant distal biliary obstruction treatment by metallic stents: fully covered or uncovered?

Obstructive jaundice caused by malignant distal biliary obstruction is a common clinical symptom in patients with inoperable biliary-pancreatic cancer. Endoscopic retrograde cholangiopancreatography (ERCP)-guided stent implantation is an effective treatment for obstructive jaundice. Internal stent drainage is more physiologic and associated with a better quality of life than external stent drainage methods such as percutaneous transhepatic gallbladder drainage or percutaneous transhepatic cholangiodrainage. Self-expanding metallic stents, which may be covered and uncovered, are commonly used. However, some uncertainties remain regarding the selection of metallic stents, including drainage patency time, clinical effect, stent migration, and post-operative complications such as pancreatitis, bleeding, and cholecystitis. This review aims to summarize the current progress and controversies surrounding the use of covered or uncovered metallic stents in inoperable common biliary obstruction via ERCP.

Increased risk of biliary infection after biliary stent placement in users of proton pump inhibitors

OBJECTIVES

Proton pump inhibitors (PPIs) are widely prescribed medications for gastric acid-induced diseases. Despite the effectiveness of PPIs, recent evidence suggested an increased risk of various bacterial infections in PPI users. The current study was conducted to evaluate the risk of biliary infection after endoscopic biliary stent placement in regular users of PPIs.

METHODS

Consecutive patients with a native papilla who underwent endoscopic retrograde cholangiopancreatography and stent placement for biliary stricture between January 2010 and August 2019 were included in this retrospective study. The cumulative incidences of biliary infection were compared between regular and non-regular PPI users.

RESULTS

During the study period, 270 regular PPI users and 146 non-regular PPI users were included in the analyses. Age, gender, and indication of endoscopic retrograde cholangiopancreatography were not different between the two groups. The incidences of biliary infection were 43% in regular PPI users and 36% in non-regular PPI users but the time to biliary infection was significantly shorter in regular PPI users than in non-regular users (28 vs. 87 days, p = 0.01). The cumulative incidence of biliary infection was significantly higher in regular PPI users compared with non-regular users (p = 0.008). The multivariable Cox regression analysis also showed a significantly higher hazard ratio of biliary infection in regular PPI users (1.62 [95% confidence interval 1.16-2.26; p = 0.005]).

CONCLUSIONS

Regular PPI use was associated with a higher risk of biliary infection after endoscopic biliary drainage. Inappropriate PPI use should be avoided.

Suprapapillary Biliary Stents Have Longer Patency Times than Transpapillary Stents-A Systematic Review and Meta-Analysis

BACKGROUND AND STUDY AIMS

Endoscopic biliary stent placement is a minimally invasive intervention for patients with biliary strictures. Stent patency and function time are crucial factors. Suprapapillary versus transpapillary stent positioning may contribute to stent function time, so a meta-analysis was performed in this comparison.

METHODS

A comprehensive literature search was conducted in the CENTRAL, Embase, and MEDLINE databases to find data on suprapapillary stent placement compared to the transpapillary method via endoscopic retrograde cholangiopancreatography in cases of biliary stenosis of any etiology and any stent type until December 2020. We carried out a meta-analysis focusing on the following outcomes: stent patency, stent migration, rate of cholangitis and pancreatitis, and other reported complications.

RESULTS

Three prospective and ten retrospective studies involving 1028 patients were included. Suprapapillary stent placement appeared to be superior to transpapillary stent positioning in patency (weighted mean difference = 50.23 days, 95% CI: 8.56, 91.98; p = 0.0.018). In a subgroup analysis of malignant indications, suprapapillary positioning showed a lower rate of cholangitis (OR: 0.34, 95% CI: 0.13, 0.93; p = 0.036). Another subgroup analysis investigating metal stents in a suprapapillary position resulted in a lower rate of pancreatitis (OR: 0.16, 95% CI: 0.03, 0.95; p = 0.043) compared to transpapillary stent placement. There was no difference in stent migration rates between the two groups (OR: 0.67, 95% CI: 0.17, 2.72; p = 0.577).

CONCLUSIONS

Based on our results, suprapapillary biliary stenting has longer stent patency. Moreover, the stent migration rate did not differ between the suprapapillary and transpapillary groups.

Comparative efficacy and safety of local palliative therapeutics for unresectable malignant biliary obstruction: a Bayesian network meta-analysis

BACKGROUND

Both radiofrequency ablation (RFA), photodynamic therapy (PDT), and biliary stent alone are common local palliative therapies for unresectable malignant biliary obstruction (MBO), but the best modality is uncertain.

RESEARCH DESIGN AND METHODS

Embase, Cochrane Library, PubMed, and Web of Science were systematically searched up to 30 January 2022, for eligible studies that compared either two or all modalities in unresectable MBO.

RESULTS

Thirty-three studies with 2974 patients were included in this study. The PDT+Stent and RFA+Stent groups had better overall survival and longer mean survival time than Stent alone (all P < 0.05). Moreover, patients with RFA+Stent demonstrated better mean duration of stent patency (MD: 2.0, 95%CI,1.1 to 2.8, P < 0.05) than Stent alone. The three modalities had similar postoperative mild bleeding, cholangitis, and pancreatitis (all P ≥ 0.05). According to network ranking, PDT+Stent was most likely to provide better survival, RFA+Stent was most likely to maintain stent patency.

CONCLUSIONS

RFA or PDT plus biliary stent is effective and safe local palliative therapy for unresectable MBO, but the current studies cannot absolutely determine which modality is the best. We should offer patients the most appropriate treatment according to the advantage of each therapy and the patient's performance status.

Risk factors for biliary stent infections in malignant biliary obstruction secondary to unresectable malignancies

BACKGROUND

Palliative biliary drainage in patients with unresectable malignant biliary obstruction (MBO) frequently leads to biliary stent infection (BI), which could impact medical care. The aim of this study was to assess the risk factors for BI occurrence in patients after stenting procedure and the impact of BI on patient survival.

METHODS

All consecutive patients hospitalized from 2014 to 2018 for MBO and biliary stenting were retrospectively included. Demographic, clinical, and microbiological characteristics of each BI episode during a 1-year follow-up were described. Documented BI was defined as the association of BI episode and confirmed blood stream infection (BSI). Univariate and multivariate analyses were performed to evaluate risk factors for the first BI occurrence.

RESULTS

Among 180 patients, 56% were men (mean age of 69±12), and 54% have pancreatic cancer, 16% biliary cancer, 2% hepatic cancer, and 28% lymph node or metastatic compression; metallic stent was placed in 92%. A total of 113 BI episodes occurred in 74 patients, 55% of the first episodes occurring within 3 months after stenting. BI was documented in 56% of the episodes. Enterobacteriaceae were the most frequent pathogens found, while no yeasts were documented. Mortality rate in patients with BI was 64%. Multivariate analysis showed a significant difference in BI occurrence for two criteria: WHO score 3-4 (OR=8.79 [1.79-42.89]; p=0.007) and transpapillary stenting location (OR=3.72 [1.33-10.44]; p=0.013).

CONCLUSION

Since transpapillary stenting is a risk factor for BI, preserving the papilla as much as possible is a priority so as to avoid BI.

Local palliative therapies for unresectable malignant biliary obstruction: radiofrequency ablation combined with stent or biliary stent alone? An updated meta-analysis of nineteen trials

BACKGROUND

Recently, there has been a burgeoning interest in radiofrequency ablation combined with stent (RFA + Stent) for unresectable malignant biliary obstruction (MBO). This study aimed to perform a meta-analysis to evaluate the efficacy and safety of RFA + Stent compared with biliary stent alone.

METHODS

We searched PubMed, Cochrane Library, Embase, and Web of Science databases from their inception dates to June 20, 2021, for studies that compared RFA + Stent and stent alone for unresectable MBO. The main outcomes were survival, patency, and adverse effects. All meta-analyses were calculated using the random-effects model.

RESULTS

A total of 19 studies involving 1946 patients were included in this study. Compared with stent alone, RFA + Stent was significantly associated with better overall survival (HR 0.55; 95% CI 0.48, 0.63; P < 0.00001), longer mean survival time (SMD 2.20; 95% CI 1.17, 3.22; P < 0.0001), longer mean stent patency time (SMD 1.37; 95% CI 0.47, 2.26; P = 0.003), higher stent patency at 6 months (OR 2.82; 95% CI 1.54, 5.18; P = 0.0008). The two interventions had similar incidence of postoperative abdominal pain (OR 1.29; 95% CI 0.94, 1.78; P = 0.11), mild bleeding (OR 1.28; 95% CI 0.65, 2.54; P = 0.48), cholangitis (OR 1.09; 95% CI 0.76, 1.55; P = 0.65), pancreatitis (OR 1.39; 95% CI 0.82, 2.38; P = 0.22). Furthermore, the serum bilirubin levels and stricture diameter after operations were significantly alleviated than before operations, but the degree of alleviation between the two groups were not significantly different (all P > 0.05).

CONCLUSION

Although the alleviation of serum bilirubin and stricture diameter did not differ between the two interventions, RFA + Stent can significantly improve the survival and stent patency with comparable procedure-related adverse events than stent alone. Thus, RFA + Stent should be recommended as an attractive alternative to biliary stent alone for patients with unresectable MBO.

Prevention of pancreatitis after stent implantation for distal malignant biliary strictures: systematic review and meta-analysis

INTRODUCTION

Biliary stent placement remains a palliative treatment for patients with unresectable distal malignant biliary strictures (DMBS). The incidence of post-ERCP-pancreatitis (PEP) significantly increases in patients receiving fully covered self-expandable metal stents (FCSEMS) who undergo endoscopic retrograde cholangiopancreatography (ERCP).

AREAS COVERED

This review provides an overview of prevention of PEP after stent implantation for DMBSs. The following operational variables were evaluated: (1) stent type (plastic or metal stent); (2) stent location (above or across the sphincter of Oddi); (3) prophylactic pancreatic duct stent placement; (4) endoscopic sphincterotomy (EST). PubMed, EMBASE, and Cochrane database were searched to identify eligible studies up to October 2021. The odds ratio (OR) with 95% confidence intervals (CI) were pooled using fixed- or random- effects models.

EXPERT OPINION

1. PEP occurs more frequently in DMBS patients with self-expandable metal stents (SEMS) compared to that plastic stent (PS). 2. The PEP incidence is higher in covered stents than that in uncovered self-expandable metal stents (USEMS), but not significantly. 3. PEP incidence increases in patients receiving transpapillary FCSEMS placement, particularly when there is an absence of pancreatic duct dilation, and prophylactic pancreatic stenting is recommended for these patients. 4. Limited studies with small sample indicate that there is no significant difference in PEP incidence between transpapillary and suprapapillary stents placement for DMBS. 5. Limited studies indicate that EST does not significantly affect the incidence of pancreatitis in DMBS patients.

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.

Updated evidence on the clinical impact of endoscopic radiofrequency ablation in the treatment of malignant biliary obstruction

Endoscopic biliary radiofrequency ablation (RFA) was recently developed as a novel adjunctive procedure and a promising therapeutic option in patients with malignant biliary obstruction (MBO). RFA can achieve local tumor control, resulting in improved biliary stent patency and a potential survival benefit. However, the efficacy of biliary RFA remains controversial, and previous studies have shown conflicting results. At present, extrahepatic cholangiocarcinoma is considered the condition most effectively treated by biliary RFA, but there is limited research even on this point. Further, limitations of RFA associated with the devices used during the procedure are an important subject of discussion. In addition to further well-designed clinical trials, development of innovative devices is warranted to investigate and conclusively establish the usefulness of biliary RFA. In this review we summarize the updated evidence regarding the use of endoscopic biliary RFA for MBO and discuss issues that should be addressed in future studies.

Risk Factors of Duodenobiliary Reflux-Related Dysfunction of Covered Biliary Metal Stents after Treatment of Duodenal Stricture in Patients with Malignant Biliary and Duodenal Obstruction

Duodenal obstruction is often accompanied with unresectable malignant distal biliary obstruction in patients who have undergone biliary self-expandable metal stent (SEMS) placement. Duodenobiliary reflux (DBR) is a major cause of recurrent biliary obstruction (RBO) after covered biliary SEMS placement. We analyzed the risk factors for DBR-related SEMS dysfunction following treatment for malignant duodenal obstruction. Sixty-one patients with covered SEMS who underwent treatment for duodenal obstruction were included. We excluded patients with tumor-related stent dysfunction (n = 6) or metal stent migration (n = 1). Fifty-four patients who underwent covered biliary SEMS placement followed by duodenal metal stenting or surgical gastrojejunostomy were included. Eleven patients had DBR-related biliary SEMS dysfunction after treatment of duodenal obstruction. There was no difference between the duodenal metal stenting group and the surgical gastrojejunostomy group. Duodenal obstruction below the papilla of Vater and a score of ≤2 on the Gastric Outlet Obstruction Scoring System after treatment for duodenal obstruction were associated with DBR-related covered biliary SEMS dysfunction. Thus, creating a reliable route for ensuring good oral intake and avoiding DBR in patients with duodenal obstruction below the papilla of Vater are both important factors in preventing DBR-related covered biliary SEMS dysfunction.

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.

A Prospective Multicenter Study of "Inside Stents" for Biliary Stricture: Multicenter Evolving Inside Stent Registry (MEISteR)

Background: Endoscopic biliary stent placement is the standard of care for biliary strictures, but stents across the papilla are prone to duodenobiliary reflux, which can cause stent occlusion. Preliminary studies of “inside stents” placed above the papilla showed encouraging outcomes, but prospective data with a large cohort were not reported. Methods: This was a prospective multicenter registry of commercially available inside stents for benign and malignant biliary strictures. Primary endpoint was recurrent biliary obstruction (RBO). Secondary endpoints were technical success of stent placement and removal, adverse events, and stricture resolution. Results: A total of 209 inside stents were placed in 132 (51 benign and 81 malignant) cases with biliary strictures in 10 Japanese centers. During the follow-up period of 8.4 months, RBO was observed in 19% of benign strictures. The RBO rate was 49% in malignant strictures, with the median time to RBO of 4.7 months. Technical success rates of stent placement and removal were both 100%. The adverse event rate was 8%. Conclusion: This prospective multicenter study demonstrated that inside stents above the papilla were feasible in malignant and benign biliary strictures, but a randomized controlled trial is warranted to confirm its superiority to conventional stents across the papilla.