Plastic biliary stent occlusion: factors involved and possible preventive approaches

Biliary stent insertion after stone clearance in patients awaiting cholecystectomy: Systematic review and meta-analysis

Background and study aims

Laparoscopic cholecystectomy is the standard treatment for patients with cholecystitis or gallbladder stones after common bile duct (CBD) clearance. According to the sequential strategy, cholecystectomy should be performed within 2 weeks after CDB clearance with endoscopic retrograde cholangiopancreatography (ERCP). However, in real-life experience, the average waiting time is 60 to 180 days. We aimed to evaluate the clinical rationale for prophylactic stent placement in CBD to prevent recurrent biliary events.

Patients and methods

This systematic review and meta-analysis was performed following a protocol designed a priori (PROSPERO: CRD42024564804; July 13, 2024). All published studies involving patients who had undergone ERCP for CBDs and who were awaiting cholecystectomy were included.

Results

At the end of the revision process, four full texts including 755 patients were included in the meta-analysis. The odds ratio (OR) for symptom recurrence in patients awaiting cholecystectomy was 0.74 (95% confidence interval [CI] 0.30-1.79; I 2 67%). The pooled OR for adverse event occurrence was 0.74 (95% CI 0.45-1.24) in the stent group. The post-ERCP pancreatitis and cholangitis risk were 0.76 (95% CI 0.25-2.34) and 0.92 (95% CI 0.31-2.67), respectively.

Conclusions

This meta-analysis showed no benefit for stent insertion after bile duct clearance in patients scheduled for delayed cholecystectomy. Further randomized controlled trials with bigger cohorts are needed to assess any benefit for this procedure, which in the meantime, cannot be recommended.

Intraductal ablation therapy for malignant biliary obstruction

BACKGROUND

Malignant biliary obstruction is usually attributed to the enlargement of tumors within or adjacent to the biliary tract, leading to blockage or compression of the bile ducts. Common causes include pancreatic head cancer, bile duct cancer, gallbladder cancer, liver cancer, and metastatic diseases. Most cases have an insidious onset, lack effective early screening methods, and 70% of patients cannot undergo surgical resection, with a 5-year survival rate of about 30%. Therefore, relieving biliary tree obstruction is crucial. Biliary stents often mitigate the obstruction but can be hindered by tumor progression, endothelial hyperplasia, and bile sludge. As a result, new treatment approaches are constantly being explored to improve outcomes for patients with malignant biliary obstruction.

CURRENT SITUATION

One promising technique that has emerged in recent years is radiofrequency ablation (RFA). This innovative method utilizes high-frequency radio waves to generate heat and selectively target tumor cells through localized heating while preserving surrounding healthy tissue. RFA aims to slow tumor growth and enhance biliary stent durability. Studies on endoscopic RFA for malignant biliary obstruction are encouraging. Integrating it with palliative care may better manage symptoms and extend patient quality of life.

CONCLUSION

In conclusion, while malignant biliary obstruction remains a complex medical challenge with limited treatment options available for some patients, ongoing research into innovative techniques like radiofrequency ablation offers hope for better outcomes in the future. It is crucial for healthcare professionals to stay informed about these advancements and continue exploring new ways to enhance patient care in this difficult clinical scenario.

Biofunctional coatings and drug-coated stents for restenosis therapy

Palliative therapy utilizing interventional stents, such as vascular stents, biliary stents, esophageal stents, and other stents, has been a prevalent clinical strategy for treating duct narrowing and partial blockage. However, stent restenosis after implantation usually significantly compromises therapeutic efficacy and patient safety. Clinically, vascular stent restenosis is primarily attributed to endothelial hyperplasia and coagulation, while the risk of biliary stent occlusion is heightened by bacterial adhesion and bile sludge accumulation. Similarly, granulation tissue hyperplasia leads to tracheal stent restenosis. To address these issues, surface modifications of stents are extensively adopted as effective strategies to reduce the probability of restenosis and extend their functional lifespan. Applying coatings is one of the technical routes involving a complex selection of materials, drug loading capacities, release rates, and other factors. This paper provides an extensive overview of state of the art drug-coated stents, addressing both challenges and future prospects in this domain. We aim to contribute positively to the ongoing development and potential clinical applications of drug-coated stents in interventional therapy.

A microsystem for in vivo wireless monitoring of plastic biliary stents using magnetoelastic sensors

With an interest in monitoring the patency of stents that are used to treat strictures in the bile duct, this paper reports the investigation of a wireless sensing system to interrogate a microsensor integrated into the stent. The microsensor is comprised of a 28-μm-thick magnetoelastic foil with 8.25-mm length and 1-mm width. Magnetic biasing is provided by permanent magnets attached to the foil. These elements are incorporated into a customized 3D polymeric package. The system electromagnetically excites the magnetoelastic resonant sensor and measures the resulting signal. Through shifts in resonant frequency and quality factor, the sensor is intended to provide an early indication of sludge accumulation in the stent. This work focuses on challenges associated with sensor miniaturization and placement, wireless range, drive signal feedthrough, and clinical use. A swine specimen in vivo experiment is described. Following endoscopic implantation of the sensor enabled plastic stent into the bile duct, at a range of approximately 17 cm, the signal-to-noise ratio of ~106 was observed with an interrogation time of 336 s. These are the first reported signals from a passive wireless magnetoelastic sensor implanted in a live animal.

Forgotten Biliary Plastic Stents: Complications, Management, and Clinical Outcomes

Background and Objectives: Endoscopic biliary plastic stenting is a safe and effective temporary therapeutic modality used in various benign biliary disorders. Long-term indwelling stents for more than one year without retrieval are termed "forgotten biliary stents". In clinical practice, the forgotten stents are underestimated and the majority of data were obtained from case reports. The aim of this study was to determine the forgotten-biliary-plastic-stent-related complications, their management, and the patients' clinical outcomes. Materials and Methods: This retrospective study was performed at three hospitals during the period from January 2021 to December 2023. In total, 577 patients with biliary plastic stents-inserted for a variety of benign biliary conditions-were included. They were divided into two groups, as follows: group 1 included 527 patients who had biliary stents removed within 3 months, and group 2 included 50 patients with biliary stents retrieved after one year of their deployment. The stent-related complications (e.g., acute cholangitis, stent clogging, distal stent migration, new common bile duct (CBD) stone formation, and proximal stent migration) and the endoscopic management success rate were evaluated. Results: Irretrievable CBD stones were the main indication for biliary plastic stenting in both groups. The stent-related complications, number of endoscopic sessions, and hospital admissions were significantly higher in the patients with forgotten biliary stents than those with stent removal within 3 months. All the study patients were successfully managed endoscopically with uneventful outcomes. Conclusions: Based on this retrospective study, non-adherence to the endoscopists' instructions is the main reason for retained biliary stents for more than one year. The patients with forgotten stents had significantly higher complication rates, a higher number of endoscopic sessions, and a higher number of hospital admissions than those with stents that were retrieved in the scheduled time. All patients were managed endoscopically with a technical success rate of 100%, and with no complication-related mortality.

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Penetration of duodenal wall by proximal end of biliary straight plastic stent in a patient with ampullary carcinoma

A 70-year-old woman presented to our hospital with abdominal discomfort. Gastrointestinal endoscopy revealed an ampullary tumor, while a biopsy revealed a pathological diagnosis of adenocarcinoma. No distant metastases were observed and neoadjuvant chemotherapy and surgical resection were planned. Shortly thereafter, she developed obstructive jaundice due to the ampullary carcinoma. The patient underwent endoscopic retrograde cholangiopancreatography, during which a straight plastic stent was placed in the bile duct. The patient was discharged without complications. Neoadjuvant chemotherapy was initiated. Two months later, she was readmitted for surgery while asymptomatic. Endoscopic retrograde cholangiopancreatography was scheduled to replace the stent with a nasobiliary drainage tube for the surgery. Endoscopic imaging revealed that the proximal end of the stent had penetrated the duodenum on the oral side of the ampullary carcinoma. The distal end of the stent was grasped with forceps and the stent was successfully removed. A catheter was inserted into the bile duct orifice and cholangiography was performed, which revealed that the distal bile duct and the duodenum had formed a fistula. A guidewire was placed in the bile duct via the papilla and a nasobiliary drainage tube was placed. After endoscopic retrograde cholangiopancreatography, the patient exhibited smooth progress without issue. Pancreaticoduodenectomy was performed on the fourth day after the nasobiliary drainage tube placement, and the patient's postoperative course was uneventful. The proximal end of a biliary stent penetrating the duodenal wall is an infrequent phenomenon. This case report highlights a rare but noteworthy adverse event associated with straight biliary plastic stent placement.

Pilot study on cultural and metagenomic analysis of bile and biliary stentslead to unveiling the key players in stent occlusion

Endoscopic Retrograde Cholangio-Pancreatography (ERCP) with biliary stenting is a minimally invasive medical procedure employed to address both malignant and benign obstructions within the biliary tract. Benign biliary strictures (BBSs), typically arising from surgical interventions such as liver transplants and cholecystectomy, as well as chronic inflammatory conditions, present a common clinical challenge. The current gold standard for treating BBSs involves the periodic insertion of plastic stents at intervals of 3-4 months, spanning a course of approximately one year. Unfortunately, stent occlusion emerges as a prevalent issue within this treatment paradigm, leading to the recurrence of symptoms and necessitating repeated ERCPs. In response to this clinical concern, we initiated a pilot study, delving into the microbial composition present in bile and on the inner surfaces of plastic stents. This investigation encompassed 22 patients afflicted by BBSs who had previously undergone ERCP with plastic stent placement. Our preliminary findings offered promising insights into the microbial culprits behind stent occlusion, with Enterobacter and Lactobacillus spp. standing out as prominent bacterial species known for their biofilm-forming tendencies on stent surfaces. These revelations hold promise for potential interventions, including targeted antimicrobial therapies aimed at curtailing bacterial growth on stents and the development of advanced stent materials boasting anti-biofilm properties.

The application of impantable sensors in the musculoskeletal system: a review

As the population ages and the incidence of traumatic events rises, there is a growing trend toward the implantation of devices to replace damaged or degenerated tissues in the body. In orthopedic applications, some implants are equipped with sensors to measure internal data and monitor the status of the implant. In recent years, several multi-functional implants have been developed that the clinician can externally control using a smart device. Experts anticipate that these versatile implants could pave the way for the next-generation of technological advancements. This paper provides an introduction to implantable sensors and is structured into three parts. The first section categorizes existing implantable sensors based on their working principles and provides detailed illustrations with examples. The second section introduces the most common materials used in implantable sensors, divided into rigid and flexible materials according to their properties. The third section is the focal point of this article, with implantable orthopedic sensors being classified as joint, spine, or fracture, based on different practical scenarios. The aim of this review is to introduce various implantable orthopedic sensors, compare their different characteristics, and outline the future direction of their development and application.

Endoluminal radiofrequency ablation in patients with malignant biliary obstruction: a randomised trial

BACKGROUND

Endoluminal radiofrequency ablation (RFA) has been promoted as palliative treatment for patients with cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC) in order to improve biliary drainage and eventually prolong survival. No high level evidence is, however, available on this technique.

DESIGN

In this randomised controlled study, we compared endoluminal RFA plus stenting with stenting alone (control group) in patients with malignant biliary obstruction; metal stents were primarily placed. Primary outcome was overall survival; secondary outcomes were stent patency, quality of life and adverse events. In a superiority design, survival was assumed to be doubled by RFA as compared with 6.4 months in the control group (n=280).

RESULTS

A total of 161 patients (male:female 90:71, mean age 71±9 years) were randomised before recruitment was terminated for futility after an interim analysis. Eighty-five patients had CCA (73 hilar, 12 distal) and 76 had pancreatic cancer. There was no difference in survival in both subgroups: for patients with CCA, median survival was 10.5 months (95% CI 6.7 to 18.3) in the RFA group vs 10.6 months (95% CI 9.0 to 24.8), p=0.58)) in the control group. In the subgroup with pancreatic cancer, median survival was 6.4 months (95% CI 4.3 to 9.7) for the RFA vs 7.7 months (95% CI 5.6 to 11.3), p=0.73) for the control group. No benefit was seen in the RFA group with regard to stent patency (at 12 months 40% vs 36% in CCA and 66% vs 65% in PDAC), and quality of life was unchanged by either treatment and comparable between the groups. Adverse events occurred in seven patients in each groups.

CONCLUSION

A combination of endoluminal RFA and stenting was not superior to stenting alone in prolonging survival or improving stent patency in patients with malignant biliary obstruction.

TRIAL REGISTRATION NUMBER

NCT03166436.

Role of Biliary Stent in Recurrence of Biliary Stones and Complications After Stone Clearance in Patients Awaiting Cholecystectomy: A Randomized Trial

INTRODUCTION

The role of prophylactic biliary stenting after clearance of choledocholithiasis in patients awaiting cholecystectomy for concomitant cholelithiasis is controversial. We planned a randomized controlled trial to study the effect of prophylactic biliary stenting after achieving biliary clearance in reducing recurrence of choledocholithiasis and biliary complications in patients awaiting cholecystectomy.

METHODS

Patients with concomitant cholelithiasis and choledocholithiasis were included, and those who had evidence of clearance of choledocholithaisis (documented on occlusion cholangiogram during endoscopic retrograde cholangiography [ERC]) were randomized to prophylactic biliary stenting or no stenting. Choledocholithaisis recurrence rate (primary outcome), biliary complications and need for repeat/emergency ERC (secondary outcomes) were compared till 3 months after clearance.

RESULTS

Between September 2021 and July 2022, 70 patients were randomized into group A, stenting (n = 35), and group B, no stenting (n = 35). Sixty-six patients were included in the final analysis. Baseline characteristics were comparable between the 2 groups. Ten (15.2%) patients had recurrence of choledocholithiasis, and it was comparable between the 2 groups (7/34 [20.6%] and 3/34 [9.4%], P = 0.306). Five patients (2 cholecystitis and 3 post-ERC pancreatitis) from the stent group while none from the no stent group developed complications, and this difference was statistically significant ( P = 0.024). None of the patients in both the groups needed emergency ERC during the follow-up.

DISCUSSION

This randomized trial shows a higher complication rate with prophylactic stenting, while there is no benefit in preventing choledocholithiasis recurrence in patients waiting for cholecystectomy after biliary clearance (CTRI registration number: CTRI/2021/09/036538).

The perfect biliary plastic stent: the search goes on

The introduction of biliary plastic stents has been a landmark achievement in the field of endoscopic retrograde cholangiopancreatography, ensuring minimally invasive and highly effective relief of the obstructed biliary system. Attempts to improve the patency and avoid complications after biliary plastic stenting have led to several innovations, but complications due to stent occlusion are still frequent. Because these complications are clinically relevant, and may guide stent choice and patient management, efforts have been made to elucidate the causes of and ways to prevent occlusion of indwelling stents. In this narrative review we focus on biliary plastic stents and discuss the mechanisms of stent occlusion, existing evidence on salient outcomes, as well as options to overcome existing limitations and prolong plastic stent patency.

Effectiveness of a new approach to minimally invasive surgery in palliative treatment of patients with distal malignant biliary obstruction

BACKGROUND

Palliative endoscopic biliary drainage is the primary treatment option for the management of patients with jaundice which results from distal malignant biliary obstruction (DMBO). In this group of patients, decompression of the bile duct (BD) allows for pain reduction, symptom relief, chemotherapy administration, improved quality of life, and increased survival rate. To reduce the unfavorable effects of BD decompression, minimally invasive surgical techniques require continuous improvement.

AIM

To develop a technique for internal-external biliary-jejunal drainage (IEBJD) and assess its effectiveness in comparison to other minimally invasive procedures in the palliative treatment of patients with DMBO.

METHODS

A retrospective analysis of prospectively collected data was performed, which included 134 patients with DMBO who underwent palliative BD decompression. Biliary-jejunal drainage was developed to divert bile from the BD directly into the initial loops of the small intestine to prevent duodeno-biliary reflux. IEBJD was carried out using percutaneous transhepatic access. Percutaneous transhepatic biliary drainage (PTBD), endoscopic retrograde biliary stenting (ERBS), and internal-external transpapillary biliary drainage (IETBD) were used for the treatment of study patients. Endpoints of the study were the clinical success of the procedure, the frequency and nature of complications, and the cumulative survival rate.

RESULTS

There were no significant differences in the frequency of minor complications between the study groups. Significant complications occurred in 5 (17.2%) patients in the IEBJD group, in 16 (64.0%) in the ERBS group, in 9 (47.4%) in the IETBD group, and in 12 (17.4%) in the PTBD group. Cholangitis was the most common severe complication. In the IEBJD group, the course of cholangitis was characterized by a delayed onset and shorter duration as compared to other study groups. The cumulative survival rate of patients who underwent IEBJD was 2.6 times higher in comparison to those of the PTBD and IETBD groups and 20% higher in comparison to that of the ERBS group.

CONCLUSION

IEBJD has advantages over other minimally invasive BD decompression techniques and can be recommended for the palliative treatment of patients with DMBO.

Influence of bacteriobilia on postoperative complications in patients with periampullary tumors

BACKGROUND

Periampullary tumours (PAT) may cause obstruction of distal choledochus. The bile stasis is a risk factor for microbial colonisation of bile (bacteriobilia), cholangitis, hepatic insufficiency and coagulopathy. PAT obstruction can be managed surgically or non-operatively - by inserting a biliary drain or stent (BDS). Although BDS allows for adequate bile drainage, liver function restitution and coagulopathy, increased bacteriobilia has been reported and this is associated with an increased incidence of postoperative complications.

METHODS

A monocentric, prospective, comparative study including 100 patients operated with PAT. The effects of bacteriobilia and the presence of a drain in the biliary tract on the development of postoperative complications were evaluated.

RESULTS

Positive microbial findings in bile were found in 67% of patients. It was 98% in the biliary drain group vs. 36% in non-drained patients (p = 0.0001). In 68% 2 or more different bacterial strains were simultaneously present (p = 0.0001). Patients with a positive microbial finding in bile had more frequent incidence of infectious complications 40.2% (27) vs. 9.1% (3); p = 0.0011. The most frequent infectious complication was wound infection 29.8% (20) vs. 3.03% (1); p = 0.0014. Similarly, a higher incidence of postoperative infectious complications occurred in patients with BDS - 36% (18) vs. 24% (12); p = 0.2752.

CONCLUSION

The presence of a drain or stent in the biliary tract significantly increases the microbial colonisation of bile. It is associated with a significant increase in infectious complications, especially infections in the wound.

Risk factors for post-endoscopic retrograde cholangiopancreatography cholangitis in patients with hepatic alveolar echinococcosis-an observational study

BACKGROUND

Hepatic alveolar echinococcosis (HAE) is considered to be one of the most deadly chronic parasitic diseases in the world. We have shown that the incidence of cholangitis in patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) was increased significantly. On this finding, we carried out, a preliminary study on the risk factors for cholangitis after ERCP.

AIMS

To retrospectively detect the risk factors for post-ERCP cholangitis in patients with biliary tract affected by HAE.

METHODS

The study included data from 51 cases of AE who had undergone therapeutic ERCP between January 2015 and December 2019. Demographic and treatment data were extracted from the medical records, and the association between potential risk factors and the development of post-ERCP cholangitis was evaluated using a collected database.

RESULTS

There were five cases of mild cholangitis after ERCP (Tokyo criteria), and no moderate or severe cholangitis occurred. The incidence rate of cholangitis after ERCP was 9.8%. Univariate analysis showed hilar bile duct stenosis (p = .016), endoscopic retrograde biliary drainage (p = .007), a stent diameter ≥8.5 Fr (p = .000) and single stent implantation (p = .010) were risk factors for post -ERCP cholangitis. All cases of cholangitis improved under conservative treatment.

CONCLUSION

Patients with hilar bile duct compression or endoscopic retrograde biliary drainage appeared to be more likely to develop post-ERCP cholangitis. The number and diameter of biliary stents may influence post-ERCP cholangitis. Sample size and clinical heterogeneity are two insurmountable difficulties, and a larger sample size needs to be collected to verify the risk factors for screening. KEY MESSAGESMany studies reported the post-ERCP complications in patients with hepatic alveolar echinococcosis and found that the incidence of post-ERCP cholangitis was significantly high. Therefore, we conducted a preliminary study on the risk factors of postoperative cholangitis in patients who underwent ERCP.The incidence rate of cholangitis after ERCP was 9.8%. We found that hilar bile duct stenosis, and endoscopic retrograde biliary drainage, were risk factors for cholangitis, and stent diameter and the number of stent implantation may influence the incidence rate of cholangitis after ERCP.Sample size and clinical heterogeneity are two insurmountable difficulties, and a larger sample size needs to be collected to verify the risk factors of screening.

A Case of a Mass of the Pancreatic Head Presenting as Mixed Hemorrhagic and Septic Shock

Acute cholangitis is a biliary tract infection secondary to the obstruction, which causes biliary stasis and bacterial overgrowth. Typically, it presents with the Charcot triad of right upper quadrant abdominal pain, jaundice, and fever. Most acute cholangitis cases are secondary to choledocholithiasis. There are rare cases resulting from pancreatic neoplasm. We report the case of a 43-year-old Caucasian male who was found unresponsive at home with hypotension, anemia, and severe jaundice. Initial imaging studies were notable for a periampullary mass lesion causing intrahepatic biliary ductal dilation. Endoscopic retrograde cholangiopancreatography (ERCP) revealed an actively oozing periampullary fungating mass. In this case, acute cholangitis and hemorrhagic shock secondary to bleeding periampullary lesions are atypical. This case presents an effective treatment plan for this condition.

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.

Recent developments in antibacterial or antibiofilm compound coating for biliary stents

Cholestasis of the indwelling biliary stents usually leads to stone recurrence after endoscopic retrograde cholangio pancreatoraphy (ERCP). Biliary stents, including metallic and none-degradable plastic stents are widely used in clinical settings due to their many excellent properties. However, conventional biliary stents still suffer from poor antibacterial activity and anti-bile-adhesion, which lead to injured, local fibroblasts proliferating. Currently, various coatings for biliary stents have been prepared to meet the clinical demands. In this review, we start by summarizing and discussing classifications of biliary stents and antibacterial/antibiofilm mechanism. Then, the latest advances about developing antibacterial and antibiofilm coatings for improving the properties of biliary stents are reviewed and discussed in detail. Lastly, we list several possible directions for future development of biliary stents coatings and biliary stent, such as anti-bile-adhesion coating, multifunctional coating, drug-eluting biodegradable biliary stents and 3D printed biliary stents.

Distal Biliary Stent Migration in Patients with Irretrievable Bile Duct Stones: Long-Term Comparison Between Straight and Double-Pigtail Stents

BACKGROUND

Prolonged biliary stenting may be considered in high-risk patients with irretrievable bile duct stones (IBDS). Distal stent migration (DSM) is a known complication, although data beyond the recommended interval of temporary stenting (3-6 months) are lacking. We compared the long-term incidence of DSM between straight and double-pigtail stents in patients with IBDS.

METHODS

Consecutive patients with IBDS undergoing plastic biliary stenting (1/2009-12/2019) were retrospectively reviewed. DSM was confirmed on follow-up examination when the stent was no longer present at the papillary orifice nor fluoroscopically visible in the bile duct. Kaplan-Meier and Cox regression analyses were used to determine estimates and predictors of DSM.

RESULTS

Overall, 618 biliary stenting procedures (410 patients) were included: 289 with a straight stent (group A) and 329 with a double-pigtail (group B). By Kaplan-Meier analysis, the DSM rates were 8.4 and 14.6% at 6 months, 21.4 and 27.7% at 12 months, 27 and 43.5% at 18 months, and 37.2 and 60.4% at 24 months, for groups A and B, respectively (p = 0.004). Double-pigtail stents were at higher risk for DSM (HR = 7.38, p = 0.04), whereas an inverse correlation was noted with age (HR = 0.97, p = 0.0001). Considering only temporary stenting procedures (≤ 6 months; n = 297), the probability of DSM was not significantly different between the two groups (p = 0.07).

CONCLUSIONS

In a setting of prolonged stenting for IBDS, the probability of DSM appears to be higher when a double-pigtail stent is used and in younger patients. A relative anti-migratory advantage of double-pigtail over straight stents appears negligible in this study.

Implants with Sensing Capabilities

Because of the aging human population and increased numbers of surgical procedures being performed, there is a growing number of biomedical devices being implanted each year. Although the benefits of implants are significant, there are risks to having foreign materials in the body that may lead to complications that may remain undetectable until a time at which the damage done becomes irreversible. To address this challenge, advances in implantable sensors may enable early detection of even minor changes in the implants or the surrounding tissues and provide early cues for intervention. Therefore, integrating sensors with implants will enable real-time monitoring and lead to improvements in implant function. Sensor integration has been mostly applied to cardiovascular, neural, and orthopedic implants, and advances in combined implant-sensor devices have been significant, yet there are needs still to be addressed. Sensor-integrating implants are still in their infancy; however, some have already made it to the clinic. With an interdisciplinary approach, these sensor-integrating devices will become more efficient, providing clear paths to clinical translation in the future.

Construction of ultrasmooth PTFE membrane for preventing bacterial adhesion and cholestasis

Bacterial adhesion and bile sludge accumulation can increase the risk of complications such as stent restenosis after biliary stent implantation. Compared with active and passive antimicrobial surfaces, a significant advantage of slippery liquid-infused porous surfaces (SLIPSs) is their recoverable anti-adhesive properties. According to the mechanism of SLIPSs and the application environments of the biliary system, a polytetrafluoroethylene (PTFE) electrospun fibrous membrane-impregnated silicone-oil system was developed to construct an ultrasmooth surface. Experimental results indicated that a PTFE SLIPS with 350 cSt of silicone oil had an extremely small roll angle (< 5°) and a high slip rate (4.8 ± 0.1 mm/s) and maintained excellent sliding stability after 7 d of immersion in model bile system. Thus, it can inhibit the adhesion of proteins, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and bile sludge. Moreover, when human fibroblasts were cultured on the PTFE SLIPS, it exhibited good cytocompatibility. Therefore, the proposed ultrasmooth PTFE membranes provide a promising alternative for biliary system to prevent bacterial adhesion and bile sludge accumulation.

Environmental, Microbiological, and Immunological Features of Bacterial Biofilms Associated with Implanted Medical Devices

The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings, and it has been the subject of many studies in the past few years, with most of them focused on prosthetic joint infections. We review here recent works on biofilm formation and microbial colonization on a large variety of indwelling devices, ranging from heart valves and pacemakers to urological and breast implants and from biliary stents and endoscopic tubes to contact lenses and neurosurgical implants. We focus on bacterial abundance and distribution across different devices and body sites and on the role of environmental features, such as the presence of fluid flow and properties of the implant surface, as well as on the interplay between bacterial colonization and the response of the human immune system.

Stentolith in Bile Duct: A Neglected Entity-Case Report with Review of Literature

Stentolith is a forgotten stent that acts as a nidus for stone formation leading to a stone-stent complex. Once the planned procedure is completed, these stents should be removed within 4 to 6 weeks, but if they are required for a longer period, then they should be replaced every 3 to 6 months. Devastating complications may ensue —such as cholangitis, biliary stricture, or secondary biliary cirrhosis. Management primarily comprises surgical intervention with common bile duct exploration or endoscopic clearance. The majority of patients eventually develop symptoms that lead to their diagnosis and subsequent management. This article, however, details the case of a silent stentolith and how it may have led to disastrous complications if surgical intervention was not done promptly.

Emerging Trends in Biliary Stents: A Materials and Manufacturing Perspective

Biliary stent technology has come a long way since its inception. There have been significant advancements in materials used, designs, and deployment strategies. Options have expanded from thermoplastic and metallic...

Migration of biliary stent into the gallbladder: A surprising intraoperative finding

Post-endoscopic retrograde cholangiopancreatography stenting is a well-established treatment for benign as well as malignant biliary obstruction. The most frequently encountered complication is stent clogging. Stent migration (proximal or distal), on the other hand, is not very common. Proximal migration of a choledochal endoprosthesis into the gallbladder has not yet been reported in the literature.

Biliary stents are forgotten more frequently in elderly patients

Background/aim

Plastic biliary stents that remain in situ for more than 12 months, called forgotten biliary stents (FBSs), can cause complications such as cholangitis, stent migration, stent occlusion, and perforation.

Materials and methods

The medical records of patients who underwent ERCP procedures from December 2016 to December 2020 were analysed retrospectively. Data on patient characteristics, indications for ERCP and stenting, stent types, stenting duration, complications, and causes of FBSs were obtained from the hospital’s database.

Results

A total of 48 cases with FBSs were analysed. The mean age (SD) of the patients was 71.23 years (±12.165), the male-to-female ratio was 23/25 (0.92), and the mean stenting duration was 27.12 months (range: 12–84 months). The most common indication for biliary stenting was irretrievable choledochal stones (40/48). Stone formation (79%) and proximal stent migration (26.4%) were the most frequent complications. The patients in the FBS group were significantly older than those from whom stents were removed in a timely manner (71.23 vs. 62.43 years, p < 0.001). Endoscopic treatment was possible in all cases; surgery was not required in any case. The most common cause of FBSs cited by patients was not having been informed about the need for long-term management of their stents (n = 14, 29.2%)

Conclusion

FBSs are potentially problematic particularly in elderly patients. Communication with the patient to remind them of the need for stent management is important for preventing FBSs.

Fully covered metal biliary stents: A review of the literature

Fully covered self-expandable metal stents (FCSEMS) represent the latest advancement of metal biliary stents used to endoscopically treat a variety of obstructive biliary pathology. A large stent diameter and synthetic covering over the tubular mesh prolong stent patency and reduce risk for tissue hyperplasia and tumor ingrowth. Additionally, FCSEMS can be easily removed. All these features address issues faced by plastic and uncovered metal stents. The purpose of this paper is to comprehensively review the application of FCSEMS in benign and malignant biliary strictures, biliary leak, and post-sphincterotomy bleeding.

Serum Metabolomic and Lipoprotein Profiling of Pancreatic Ductal Adenocarcinoma Patients of African Ancestry

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a characteristic dysregulated metabolism. Abnormal clinicopathological features linked to defective metabolic and inflammatory response pathways can induce PDAC development and progression. In this study, we investigated the metabolites and lipoproteins profiles of PDAC patients of African ancestry. Nuclear Magnetic Resonance (NMR) spectroscopy was conducted on serum obtained from consenting individuals (34 PDAC, 6 Chronic Pancreatitis, and 6 healthy participants). Seventy-five signals were quantified from each NMR spectrum. The Liposcale test was used for lipoprotein characterization. Spearman's correlation and Kapan Meier tests were conducted for correlation and survival analyses, respectively. In our patient cohort, the results demonstrated that levels of metabolites involved in the glycolytic pathway increased with the tumour stage. Raised ethanol and 3-hydroxybutyrate were independently correlated with a shorter patient survival time, irrespective of tumour stage. Furthermore, increased levels of bilirubin resulted in an abnormal lipoprotein profile in PDAC patients. Additionally, we observed that the levels of a panel of metabolites (such as glucose and lactate) and lipoproteins correlated with those of inflammatory markers. Taken together, the metabolic phenotype can help distinguish PDAC severity and be used to predict patient survival and inform treatment intervention.

Biosafety of a novel covered self-expandable metal stent coated with poly(2-methoxyethyl acrylate) in vivo

Covered self-expandable metal stents (CSEMS) are often used for palliative endoscopic biliary drainage; however, the unobstructed period is limited because of sludge occlusion. The present study aimed to evaluate the biosafety of a novel poly(2-methoxyethyl acrylate)-coated CSEMS (PMEA-CSEMS) for sludge resistance and examine its biosafety in vivo. Using endoscopic retrograde cholangiopancreatography, we placed the PMEA-CSEMS into six normal porcine bile ducts and conventional CSEMS into three normal porcine bile ducts. We performed serological examination and undecalcified histological analysis at 1, 3, and 6 months during follow-up. In the bile ducts with PMEA-CSEMS or conventional CSEMS, we observed no increase in liver enzyme or inflammatory marker levels in the serological investigations and mild fibrosis but no inflammatory response in the histopathological analyses. Thus, we demonstrated the biosafety of PMEA-CSEMS in vivo.

Development of biliary stent applying the antibacterial activity of silver: A literature review

BACKGROUND

Endoscopic transpapillary stenting is commonly performed in patients with obstructive jaundice caused by a biliary stricture. Although the plastic stent (PS) is widely used for biliary drainage because of the low-cost and easy procedure, patency is short after placement in the bile duct because of the small diameter. Dysfunction of PS is primarily caused by biliary sludge that forms as a result of bacterial adhesion and subsequent biofilm formation on the inner surface of the stent. It is well known that silver ions have excellent antibacterial activity against a wide range of microorganisms.

OBJECTIVE

This review provides an overview and perspective of the significance of silver-coated biliary stents.

METHODS

We collected literature regarding silver-coated biliary stents, reviewed the current research/development status and discussed their possible usefulness.

RESULTS

To date, several in vivo/vitro studies evaluated the patency of silver-blended or silver-coated biliary stents. These studies suggested that the silver coating on a PS was likely to prolong the patency period.

CONCLUSION

The development of biliary stents using silver is expected to prolong stent patency and prevent frequent stent replacement.

The Exploration of a Novel Biodegradable Drug-Eluting Biliary Stent: Preliminary Work

PURPOSE

To explore the degradation, drug release, and mechanical properties of drug-incorporated films made of different ratios of poly(lactic-co-glycolic acid) (PLGA) and different amounts of paclitaxel (PTX), which may serve as the material platform for the manufacturing of biodegradable drug-eluting biliary stents.

MATERIALS AND METHODS

PLGA of different lactic acid/glycolic acid ratios (50/50, 70/30, and 80/20) and 0%, 10, 20, and 30% weight by weight (w/w) PTX was mixed to make PLGA films, which were then cut into small pieces for further testing. Films were immersed in phosphate-buffered saline (pH 7.4) for a maximum of 11 weeks. Samples were taken randomly at Day 2, 4, 6, 8, 10, 12, 14, and weekly thereafter until Week 11 to test tensile strength, weight loss, pH value of the soaking solution, and drug release. The morphology of films was observed using scanning electron microscope (SEM).

RESULTS

At Week 10 of degradation, PLGA 80/20 still withstood a tensile strength of 9.7 newton (N), while PLGA 50/50 and 70/30 cracked spontaneously since Day 4. At Week 11, weight loss of PLGA 50/50, 70/30, and 80/20 was 95.15, 82.32, and 16.17%, respectively; and the lowest pH value of soaking solution was 1.87, 1.95, and 6.58, respectively. Drug release of 10, 20, and 30% PTX groups was 3.52-4.48%, 1.90-2.26%, and 1.44-2.06%, respectively. SEM proved smooth films before degradation; however, after the tensile strength was lost, cracks could be seen.

CONCLUSION

The degradation rate of PLGA can be controlled by altering lactic acid/glycolic acid ratio. Overall, PLGA 50/50 and 70/30 degrade significantly faster than 80/20. PLGA can serve as an effective drug carrier for PTX while being the stent strut, and PTX can be slowly released as PLGA degrades.

Application of Damage Control Tactics and Transpapillary Biliary Decompression for Organ-Preserving Surgical Management of Liver Injury in Combat Patient

The combat penetrating gunshot injury is frequently associated with damage to the liver. Bile leak and external biliary fistula (EBF) are common complications. Biliary decompression is commonly applied for the management of EBF. Also, little is known about the features of combat trauma and its management in ongoing hybrid warfare in East Ukraine. A 23-year-old male was diagnosed with thoracoabdominal penetrating gunshot wound (GSW) by a high-energy multiple metal projectile. Damage control tactics were applied at all four levels of military medical care. Biliary decompression was achieved by endoscopic retrograde cholangiopancreatography (ERCP), endoscopic sphincterotomy (EST) and the placement of biliary stents. Occlusion of the stent was treated by stent replacement, and scheduled ERCP was performed. Partial EBF was diagnosed from the main wound defect of the liver and closed without surgical interventions on the 34th day after the injury. A combination of operative and nonoperative techniques for the management of the combat GSW to the liver is effective along with the application of damage control tactics. A scheduled ERCP application is an effective approach for the management of EBF, and liver resection could be avoided. A successful biliary decompression was achieved by the transpapillary intervention with the installation of stents. Stent occlusion could be diagnosed in the early post-traumatic period, which is effectively managed by scheduled ERCP as well as stent replacement with a large diameter as close as possible to the place of bile leak.

A Novel Design of Tri-Layer Membrane with Controlled Delivery of Paclitaxel and Anti-Biofilm Effect for Biliary Stent Applications

Here, we developed a novel biliary stent coating material that is composed of tri-layer membrane with dual function of sustained release of paclitaxel (PTX) anticancer drug and antibacterial effect. The advantages of using electrospinning technique were considered for the even distribution of PTX and controlled release profile from the nanofiber mat. Furthermore, film cast method was utilized to fabricate AgNPs-immobilized PU film to direct the release towards the tumor site and suppress the biofilm formation. The in vitro antibacterial test conducted against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria species showed excellent antibacterial effect. The in vitro drug release study confirmed the sustained release of PTX from the tri-layer membrane and the release profile fitted first order with correlation coefficient of R² = 0.98. Furthermore, the release mechanism was studied using Korsmeyer–Peppas model, revealing that the release mechanism follows Fickian diffusion. Based on the results, this novel tri-layer membrane shows curative potential in clinical development.

A fully covered self-expandable metallic stent coated with poly (2-methoxyethyl acrylate) and its derivative: In vitro evaluation of early-stage biliary sludge formation inhibition

The adhesion and deformation behavior of proteins at the inner surface of fully covered, self-expandable metallic stents coated with biocompatible polymers, poly(2-methoxyethyl acrylate) (PMEA) and poly(3-methoxypropyl acrylate) (PMC3A), were analyzed. Model bile solution, proteins, and bacteria were used to unravel the inhibitory ability of the polymer coatings. Adsorbance of proteins and adherence of bacteria were both strongly inhibited by the polymer coatings. Circulation tests were performed under clinical conditions using human bile from patients. Adsorption/deformation of proteins and early-stage sludge formation were inhibited on stent surfaces coated with PMEA derivatives. The present study revealed that early-stage biliary sludge formation on PMEA- and PMC3A-coated stents was suppressed due to the strong resistance of the polymers to protein adsorption/deformation, brought about by intermediate water in hydrated polymer coatings, which is not present in conventional coating materials, such as silicone and polyurethane.

[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.

Implementation of a simplified self-releasing biliary stent in choledocholithiasis: Experience in 150 cases

INTRODUCTION

Our aim was to introduce a simple way of making a self-releasing biliary stent for laparoscopic common biliary duct exploration.

METHODS

To make a self-releasing biliary stent, an absorbable thread was sutured to a J-shape polyurethane biliary stent. After the evacuation of the calculi, a guide wire was placed into the duodenum antegradely, facilitating the insertion of the biliary stent. The pigtail of the stent was left in the duodenum. The choledochotomy was then sutured, with the absorbable thread left outside the bile duct.

RESULTS

This study consisted of 150 patients with choledocholithiasis. The mean operating time was 126 ± 36 minutes. The postoperative hospital stay was 6.5 ± 3.6 days. In 149 cases, the biliary stents were released and discharged out of the body with feces. The inside body time of the rapid-releasing stent was 13.6 ± 2.6 days, and it was 28.0 ± 4.6 days for the slow-releasing stent. One stent was removed by endoscopy. Transient hyperamylasemia occurred in 32 patients (21.3%) without clinical onset of pancreatitis. Bile leakage occurred in three patients (2.0%), all of whom recovered after treatment. Residual lithiasis was found in one patient (0.7%) and was retracted by endoscopy 30 days after the first procedure. No infection or dislocation of the stent was found.

CONCLUSION

For laparoscopic common biliary duct exploration for choledocholithiasis, this method provides an alternative way to make a simple and safe self-releasing stent. It enables the endoscopic retraction of biliary stents to be avoided.

Antibacterial activity of iron oxide, iron nitride, and tobramycin conjugated nanoparticles against Pseudomonas aeruginosa biofilms

BACKGROUND

Novel methods are necessary to reduce morbidity and mortality of patients suffering from infections with Pseudomonas aeruginosa. Being the most common infectious species of the Pseudomonas genus, P. aeruginosa is the primary Gram-negative etiology responsible for nosocomial infections. Due to the ubiquity and high adaptability of this species, an effective universal treatment method for P. aeruginosa infection still eludes investigators, despite the extensive research in this area.

RESULTS

We report bacterial inhibition by iron-oxide (nominally magnetite) nanoparticles (NPs) alone, having a mean hydrodynamic diameter of ~ 16 nm, as well as alginate-capped iron-oxide NPs. Alginate capping increased the average hydrodynamic diameter to ~ 230 nm. We also investigated alginate-capped iron-oxide NP-drug conjugates, with a practically unchanged hydrodynamic diameter of ~ 232 nm. Susceptibility and minimum inhibitory concentration (MIC) of the NPs, NP-tobramycin conjugates, and tobramycin alone were determined in the PAO1 bacterial colonies. Investigations into susceptibility using the disk diffusion method were done after 3 days of biofilm growth and after 60 days of growth. MIC of all compounds of interest was determined after 60-days of growth, to ensure thorough establishment of biofilm colonies.

CONCLUSIONS

Positive inhibition is reported for uncapped and alginate-capped iron-oxide NPs, and the corresponding MICs are presented. We report zero susceptibility to iron-oxide NPs capped with polyethylene glycol, suggesting that the capping agent plays a major role in enabling bactericidal ability in of the nanocomposite. Our findings suggest that the alginate-coated nanocomposites investigated in this study have the potential to overcome the bacterial biofilm barrier. Magnetic field application increases the action, likely via enhanced diffusion of the iron-oxide NPs and NP-drug conjugates through mucin and alginate barriers, which are characteristic of cystic-fibrosis respiratory infections. We demonstrate that iron-oxide NPs coated with alginate, as well as alginate-coated magnetite-tobramycin conjugates inhibit P. aeruginosa growth and biofilm formation in established colonies. We have also determined that susceptibility to tobramycin decreases for longer culture times. However, susceptibility to the iron-oxide NP compounds did not demonstrate any comparable decrease with increasing culture time. These findings imply that iron-oxide NPs are promising lower-cost alternatives to silver NPs in antibacterial coatings, solutions, and drugs, as well as other applications in which microbial abolition or infestation prevention is sought.

Biomaterials in Gastroenterology: A Critical Overview

In spite of the large diversity of diagnostic and interventional devices associated with gastrointestinal endoscopic procedures, there is little information on the impact of the biomaterials (metals, polymers) contained in these devices upon body tissues and, indirectly, upon the treatment outcomes. Other biomaterials for gastroenterology, such as adhesives and certain hemostatic agents, have been investigated to a greater extent, but the information is fragmentary. Much of this situation is due to the paucity of details disclosed by the manufacturers of the devices. Moreover, for most of the applications in the gastrointestinal (GI) tract, there are no studies available on the biocompatibility of the device materials when in intimate contact with mucosae and other components of the GI tract. We have summarized the current situation with a focus on aspects of biomaterials and biocompatibility related to the device materials and other agents, with an emphasis on the GI endoscopic procedures. Procedures and devices used for the control of bleeding, for polypectomy, in bariatrics, and for stenting are discussed, particularly dwelling upon the biomaterial-related features of each application. There are indications that research is progressing steadily in this field, and the establishment of the subdiscipline of "gastroenterologic biomaterials" is not merely a remote projection. Upon the completion of this article, the gastroenterologist should be able to understand the nature of biomaterials and to achieve a suitable and beneficial perception of their significance in gastroenterology. Likewise, the biomaterialist should become aware of the specific tasks that the biomaterials must fulfil when placed within the GI tract, and regard such applications as both a challenge and an incentive for progressing the research in this field.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

Drug-eluting fully covered self-expanding metal stent for dissolution of bile duct stones in vitro

BACKGROUND

The treatment of difficult common bile duct stones (CBDS) remains a big challenge around the world. Biliary stenting is a widely accepted rescue method in patients with failed stone extraction under endoscopic retrograde cholangiopancreatography. Fully covered self-expanding metal stent (FCSEMS) has gained increasing attention in the management of difficult CBDS.

AIM

To manufacture a drug-eluting FCSEMS, which can achieve controlled release of stone-dissolving agents and speed up the dissolution of CBDS.

METHODS

Customized covered nitinol stents were adopted. Sodium cholate (SC) and disodium ethylene diamine tetraacetic acid (EDTA disodium, EDTA for short) were used as stone-dissolving agents. Three different types of drug-eluting stents were manufactured by dip coating (Stent I), coaxial electrospinning (Stent II), and dip coating combined with electrospinning (Stent III), respectively. The drug-release behavior and stone-dissolving efficacy of these stents were evaluated in vitro to sort out the best manufacturing method. And the selected stone-dissolving stents were further put into porcine CBD to evaluate their biosecurity.

RESULTS

Stent I and Stent II had obvious burst release of drugs in the first 5 d while Stent III presented controlled and sustainable drug release for 30 d. In still buffer, the final stone mass-loss rate of each group was 5.19% ± 0.69% for naked FCSEMS, 20.37% ± 2.13% for Stent I, 24.57% ± 1.45% for Stent II, and 33.72% ± 0.67% for Stent III. In flowing bile, the final stone mass-loss rate of each group was 5.87% ± 0.25% for naked FCSEMS, 6.36% ± 0.48% for Stent I, 6.38% ± 0.37% for Stent II, and 8.15% ± 0.27% for Stent III. Stent III caused the most stone mass-loss no matter in still buffer or in flowing bile, which was significantly higher than those of other groups (P < 0.05). In vivo, Stent III made no difference from naked FCSEMS in serological analysis (P > 0.05) and histopathological examination (P > 0.05).

CONCLUSION

The novel SC and EDTA-eluting FCSEMS is efficient in diminishing CBDS in vitro. When conventional endoscopic techniques fail to remove difficult CBDS, SC and EDTA-eluting FCSEMS implantation may be considered a promising alternative.

Impact of infected stent removal on recurrent cholangitis with time-to-event analysis

BACKGROUND

The optimal approach at treating infected biliary stents at the time of cholangitis remains unknown. This study aims to compare the efficacy of stent exchange versus stent sweeping/stent-in-stent approaches at treating cholangitis.

METHODS

The study was a retrospective cohort study. Patients with biliary stents and cholangitis were included. Outcomes were rate of recurrent cholangitis and time to recurrent cholangitis in those whose stents were left in place (stent sweeping and stent-in-stent) compared to those whose stents were removed (stent exchange). Primary analysis included patients with metal biliary stents only. Secondary analysis included those with metal and plastic biliary stents.

RESULTS

A total of 182 patients (age 64 ± 12;89 F) with a metal biliary stent(s) at index cholangitis were included. Of these, 40 (22%) had stents removed, i.e., stent exchange. The remaining 142 (78%) did not have stent removal (97 with stent-in-stent and 45 with stent sweeping). Recurrent cholangitis occurred in 22.5% and 42.3% in the stent removal and non-removal groups, respectively (p = 0.02). Stent removal remained a negative predictor of recurrent cholangitis after controlling for age, sex, history of diabetes, and chemotherapy (OR 0.39, p = 0.03). Median time from index cholangitis to recurrent cholangitis was shorter for patients whose stents were not removed compared to those whose stents were removed (182 vs 450 days, p = 0.011). On Cox regression model, stent removal remained a negative predictor of recurrent cholangitis after controlling for age, sex, history of diabetes, and chemotherapy (HR 0.41, p = 0.01). The findings persisted in the secondary analysis including both metal and plastic biliary stents (303 patients).

CONCLUSION

Biliary stent removal with stent exchange at the time of cholangitis appears to be more effective at preventing recurrent cholangitis than leaving an infected stent in the biliary system.

Encapsulation Approaches for In-Stent Wireless Magnetoelastic Sensors

Wireless magnetoelastic sensors offer significant potential for measuring the accumulation of biomass within stents - enabling early detection prior to stent occlusion - but the encapsulation of these sensors remains a critical challenge. The encapsulation must allow the sensors to navigate the curvature and accommodate the contact forces imparted during and after the implantation procedure, while also leaving the sensor open to mechanical interaction with the biomass during the extended period of deployment. This paper is focused on the encapsulation of ribbon-like magnetoelastic sensors (12.5 mm x 1 mm x 60 μm) within plastic biliary stents (inner diameter of 2.54 mm). The compromise between two polymer-based package designs - one mechanically flexible (Type F) and one mechanically stiff (Type S) - is evaluated. The primary advantage of the Type F package is the flexibility during the delivery process while that of the Type S package is in maintaining a strong signal even when the stent is in a curved bile duct. The maximum thicknesses of the Type F and S packages are 0.53 mm and 0.74 mm, respectively. Mechanical tests show that both types protect the sensors from forces imparted by a standard introducer, and allow the encapsulated sensors to accommodate bending with a radius of curvature as small as 3 cm. The Type F package has also been tested in situ, in the bile duct of a porcine carcass. The signal is measurable with a wireless range of 10 cm, at a resonant frequency of 159 kHz and a quality factor of 397.

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.

Quantification of major constituents of biofilms in occluded pancreatic stents

PURPOSE

Biofilms comprise bacterial populations enclosed in a matrix that attaches to surfaces such as medical stents. We characterized the biofilm components in occluding pancreatic stents and investigated potential factors for the formation of the biofilms.

METHODOLOGY

The clinical details of 24 patients (M : F, 15 : 9) undergoing pancreatic stent retrieval were noted and the retrieved stents were processed for the quantification of biofilm proteins and polysaccharides and the molecular identification of bacteria.

RESULTS

The patients' ages ranged from 16 to 62 years. The underlying indications for stent insertion were bile duct stone prophylaxis against post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (n=7; 29.1 %) and pancreatic ductal leaks (n=17; 70.9 %). The retrieved stent sizes were 5 Fr (n=5; 20.8 %) and 7 Fr (n=19; 79.2 %), with a mean insertion duration of 103 days. The polybacteria detected by PCR in 95.8 % of the stents were Pseudomonas (n=8), Staphylococcus (n=8), Serratia (n=5), Aeromonas (n=4), Proteus (n=4), Klebsiella (n=4), Escherichia coli (n=4), Enterococcus (n=4), Streptococcus (n=4), Citrobacter (n=3), Bacillus (n=2), Enterobacter (n=1), Vibrio (n=1) and Clostridium (n=1). Several other organisms were identified by sequencing. The mean protein concentration was 0.585±0.29 mg ml^-1 and the mean polysaccharide concentration was 0.054±0.03 mg ml^-1. No significant differences were observed in the quantity of proteins and polysaccharides (P=0.933) for various factors, namely gender, presence of cholangitis, indications for stenting, stent sizes and duration of indwelling stents. Age was found to be a significant (P=0.013) factor for protein deposition for those aged >50 years.

CONCLUSION

The majority of the pancreatic stents grew polymicro-organisms, and those from patients aged >50 years showed significant deposition of protein, which is a key element in biofilm formation. Understanding the constituents of the biofilms in pancreatic stents could be very useful in developing future strategies for the prevention of biofilm formation.

Endoscopic Ultrasound-Guided Choledochoduodenostomy Using a Lumen-Apposing Metal Stent in Pancreatic Head Neoplasm-Associated Biliary Obstruction

Endoscopic ultrasound (EUS)-guided transluminal drainage of obstructed bile duct with conventional metal and plastic stents has been in practice for several years, but this modality carries its own potential complications and obstacles. Nevertheless, the novel Hot AXIOS stent (Boston Scientific Corp., Marlborough, MA) has been shown to overcome some of those factors, which justifies its application in a variety of clinical indications, such as EUS-guided choledochoduodenostomy (EUS-CDS) for biliary drainage after failed endoscopic retrograde cholangiopancreatography. We present a case of EUS-CDS with an electrocautery enhanced lumen-apposing stent for biliary drainage.

Acute cholangitis - an update

Acute cholangitis is bacterial infection of the extra-hepatic biliary system. As it is caused by gallstones blocking the common bile duct in most of the cases, its prevalence is greater in ethnicities with high prevalence of gallstones. Biliary obstruction of any cause is the main predisposing factor. Diagnosis is established by the presence of clinical features, laboratory results and imaging studies. The treatment modalities include administration of intravenous fluid, antibiotics, and drainage of the bile duct. The outcome is good if the treatment is started early, otherwise it could be grave.

Characterization of biofilms in biliary stents and potential factors involved in occlusion

AIM

To quantify the components in biofilms and analyze the predisposing factors involved in occlusion of biliary stents.

METHODS

In a prospective study conducted from April 2011 to March 2014 at a tertiary care hospital, all consecutive patients who required endoscopic biliary stent exchange/removal were included. Etiology of the biliary disease was diagnosed by imaging, cytology and on follow-up. Clinical details of patients with biliary stent retrieval were noted. All extracted stents were collected in sterile containers and immediately processed for quantification of biofilm proteins and polysaccharides. Molecular identification of commonly known and unknown bacteria was performed by polymerase chain reaction and density gradient gel electrophoresis methods.

RESULTS

Eighty one patients (41 males) with age range of 20-86 years were studied. The underlying causes for stent insertion were bile duct stones (n = 46; 56.8%) benign stricture (n = 29; 35.8%) and malignancy (n = 6; 7.4%) with cholangitis in 50 (61.7%) patients. The retrieved stent sizes were 7 Fr (n = 62; 76.5%) and 10 Fr (n = 19; 23.5%) with 65 days median insertion duration. Polybacterial consortia were detected in 90.1% of the stents. The most common bacteria identified by polymerase chain reaction alone and/or sequencing were Pseudomonas (n = 38), Citrobacter (n = 23), Klebsiella (n = 22), Staphylococcus (n = 20), Serratia (n = 16), Escherichia coli (n = 14), Streptococcus (n = 13), Enterococcus (n = 13), Aeromonas (n = 12), Proteus (n = 10) and Enterobacter (n = 9). Protein concentration according to gender (0.547 ± 0.242 mg/mL vs 0.458 ± 0.259 mg/mL; P = 0.115) as well as age > 60 years and < 60 years (0.468 ± 0.295 mg/mL vs 0.386 ± 0.238 mg/mL; P = 0.205) was non-significant. However, polysaccharide concentration was significant both according to gender (0.052 ± 0.021 mg/mL vs 0.049 ± 0.016 mg/mL; P < 0.0001) and age (0.051 ± 0.026 mg/mL vs 0.038 ± 0.016 mg/mL; P < 0.011). Protein concentration in the biofilm was significantly higher (0.555 ± 0.225 mg/mL vs 0.419 ± 0.276 mg/mL; P = 0.018) in patients with cholangitis, lower (0.356 ± 0.252 mg/mL vs 0.541 ± 0.238 mg/mL; P = 0.005) in the 10 Fr group than the 7 Fr group, and significantly higher (0.609 ± 0.240 mg/mL vs 0.476 ± 0.251 mg/mL; P = 0.060) in stents of ≥ 6 mo of indwelling time. However presence/absence of cholangitis, size of stent, indication of stent insertion and indwelling time did not affect the quantity of polysaccharide concentration.

CONCLUSION

Plastic stents retrieved from patients with biliary tract disease showed polymicrobial organisms with higher protein content among patients with cholangitis and those with smaller diameter stents. Longer indwelling duration had more biofilm formation.