Bacterial biofilm, brown pigment stone and blockage of biliary stents

Characteristics of four commonly used self-expanding biliary stents: an in vitro study

BACKGROUND

Knowledge of the characteristics of self-expanding metal stents (SEMSs) is essential during selection process to ensure the best therapeutic outcomes for patients with malignant biliary obstruction. The aim of this study was to evaluate the characteristics of four commonly used SEMSs.

METHODS

This in vitro study analyzed the radial force (RF), crush resistance (CR), axial force (AF), conformability, surface quality, foreshortening, and radiopacity of the following SEMSs: uncovered Wallflex™, EGIS single bare, Zilver 635®, and E-Luminexx™. Two samples of each SEMS type were included in this study, all having identical specifications with a diameter of 10 mm and a length of 6 cm. One sample from each type was analyzed for surface quality, followed by CR, conformability, and foreshortening. The other sample was analyzed for radiopacity, followed by RF and AF.

RESULTS

The uncovered Wallflex™ exhibited low RF, high CR, high AF, good conformability, poor surface quality, high foreshortening, and good radiopacity. The EGIS single bare demonstrated high RF, high CR, low AF, moderate conformability, good surface quality, high foreshortening, and poor radiopacity. The Zilver 635® displayed moderate RF, low CR, low AF, moderate conformability, moderate surface quality, no foreshortening, and good radiopacity. The E-Luminexx™ showed high RF, moderate CR, high AF, poor conformability, poor surface quality, no foreshortening, and good radiopacity.

CONCLUSIONS

There was considerable variation in the characteristics among the four evaluated SEMSs. These characteristics should be carefully considered during selection to ensure optimal therapeutic outcomes for patients.

RELEVANCE STATEMENT

The selection of self-expanding metal stents for treating malignant biliary obstruction requires careful consideration of various characteristics, including their radial force, crush resistance, axial force, conformability, surface quality, foreshortening, and radiopacity.

KEY POINTS

• The characteristics of self-expanding metal stents (SEMSs) can vary considerably. • Specific situations may warrant the use of SEMSs with particular characteristics over others. • Characteristics of SEMSs must be considered during selection for optimal outcomes.

Next Generation Sequencing Outperforms Cultivation-Based Methods for Detection of Bacterial Genera in Bile After Liver Transplantation

BACKGROUND AND AIMS

Bacterial cholangitis is a common complication in patients with ischemic type biliary lesions and/or anastomotic strictures after liver transplantation (LTX). Patients frequently need antibiotics and endoscopic retrograde cholangiography (ERC) to improve the bile flow. Antibiotic treatment is based on findings in standard microbiological cultivation (SMC) of bile. However, the cultivation techniques are limited to a subset of bacteria easy-to-cultivate. Therefore, the aim of our study was to evaluate the value of next generation sequencing as an additional diagnostic tool to SMC in ischemic type biliary lesions and/or anastomotic strictures.

METHODS

We sequenced the V1-V2 region of the 16S rRNA gene in 242 stored bile samples in patients after LTX and compared the results with findings of SMC. SMC was performed in n = 135 (56%) fresh bile samples in addition to NGS. SMC was part of the clinical routine in these patients.

RESULTS

NGS detected bacterial genera in bile samples more often than SMC (P = 5.42 × 10-74). SMC showed insufficient discovery of bacterial genera compared to NGS with better performance in patients receiving antibiotics prior to ERC. SMC missed many bacterial genera detected by NGS.

CONCLUSIONS

NGS was more sensitive in detecting bacteria in bile than SMC, no clinical parameters could be used to improve discovery rates in SMC and many genera were missed by SMC. Therefore, NGS should be used in a combined approach with SMC for improved diagnostics to achieve more specific and targeted antibiotic treatments.

CT imaging features of bile duct stent complications

Biliary stents have been widely used to treat both malignant and benign biliary obstruction. Biliary stenting serves as a temporary measure to maintain ductal patency and promote bile drainage. Biliary decompression can help relieve clinical symptoms of pain, obstructive jaundice, pruritis, fat malabsorption, and failure to thrive and prevent disease progression, such as secondary biliary cirrhosis and end-stage liver failure. Endoscopic placement of biliary endoprosthesis is a minimally invasive procedure well tolerated by most patients but is not without problems. Multiple early and late complications have been reported in the literature and Computed Tomography (CT) is the most used modality to assess normal positions and evaluate patients suspected of stent complications. The aim of this article is to provide a review various of biliary stent related complications, as seen on CT. Current literature on risk factors, diagnosis and management is also discussed.

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.

Magnetic Microswarm and Fluoroscopy-Guided Platform for Biofilm Eradication in Biliary Stents

Biofilm eradication from medical implants is of fundamental importance, and the treatment of biofilm-associated pathogen infections on inaccessible biliary stents remains challenging. Magnetically driven microrobots with controlled motility, accessibility to the tiny lumen, and swarm enhancement effects can physically disrupt the deleterious biostructures while not developing drug resistance. Magnetic urchin-like capsule robots (MUCRs) loaded with magnetic liquid metal droplets (MLMDs, antibacterial agents) are designed using natural sunflower pollen, and the therapeutic effect of swarming MUCR@MLMDs is explored for eradicating complex mixtures of bacterial biofilm within biliary stents collected from patients. The external magnetic field triggers the emergence of the microswarm and induces MLMDs to transform their shape into spheroids and rods with sharp edges. The inherent natural microspikes of MUCRs and the obtained sharp edges of MLMDs actively rupture the dense biological matrix and multiple species of embedded bacterial cells by exerting mechanical force, finally achieving synergistic biofilm eradication. The microswarm is precisely and rapidly deployed into the biliary stent via endoscopy in 10 min. Notably, fluoroscopy imaging is used to track and navigate the locomotion of microswarm in biliary stents in real-time. The microswarm has great potential for treating bacterial biofilm infections associated with medical implants.

Stent Selection in Preoperative Biliary Drainage for Patients With Operable Pancreatic Cancer Receiving Neoadjuvant Therapy: A Meta-Analysis and Systematic Review

With the increasing use of neoadjuvant therapy (NAT) in patients with pancreatic cancer to reduce tumor burden on prognosis, preoperative biliary drainage (PBD) is becoming increasingly necessary. The aim of this study was to summarize the latest evidence and compare the clinical efficacy of metal stents (MS) and plastic stents (PS) in patients undergoing neoadjuvant therapy for operable pancreatic cancer. Eligible studies were searched in PubMed, Embase and Cochrane Library from their inception to September 2021. In this study, RevMan 5.4 was used to perform the analyses. Two randomized controlled trials (RCTs) and six retrospective studies with 316 patients were included. All patients had pancreatic cancer and received NAT before surgical resection. Meta-analysis showed that the rate of endoscopic reintervention in MS (26/143, 18%) group was lower than that of PS (122/153, 80%) group (P < 0.05). The rate of stent-related complications in MS group was lower (18/118, 15%) than that of PS (52/117, 44%) group (P = 0.02). But there were no significant differences in operative time, operative blood loss, overall postoperative complications, postoperative hospitalization days and total medical costs between the two groups. For operable pancreatic cancer patients undergoing NAT surgery, MS was preferred over PS in terms of the incidence of endoscopic reintervention and stent-related complications. More clinical trials are needed in the future to confirm these data with higher levels of evidence.

Micro-/Nanorobots in Antimicrobial Applications: Recent Progress, Challenges, and Opportunities

The evolution of drug-resistant pathogenic bacteria remains one of the most urgent threats to public health worldwide. Even worse, the bacterial cells commonly form biofilms through aggregation and adhesion, preventing antibiotic penetration and resisting environmental stress. Moreover, biofilms tend to grow in some hard-to-reach regions, bringing difficulty for antibiotic delivery at the infected site. The drug-resistant pathogenic bacteria and intractable biofilm give rise to chronic and recurrent infections, exacerbating the challenge in combating bacterial infections. Micro/nanorobots (MNRs) are capable of active cargo delivery, targeted treatment with high precision, and motion-assisted mechanical force, which enable transport and enhance penetration of antibacterial agents into the targeted site, thus showing great promise in emerging as an attractive alternative to conventional antibacterial therapies. This review summarizes the recent advances in micro-/nanorobots for antibacterial applications, with emphasis on those novel strategies for drug-resistance bacterium and stubborn biofilm infections. Insights on the future development of MNRs with good functionality and biosafety offer promising approaches to address infections in the clinic setting.

Survival, stent patency, and cost-effectiveness of plastic biliary stent versus metal biliary stent for palliation in malignant biliary obstruction in a developing country tertiary hospital

Background and Aim

Patients with advanced malignant obstructive jaundice often require biliary drainage. Resources restraint makes clinicians need to outweigh effectiveness of each biliary stents and their costs. Hence, a cost‐effectiveness analysis is necessary.

Methods

A retrospective cohort study was done on malignant biliary obstruction patients undergoing palliative biliary stenting between January 2015 and December 2018. We evaluated 180‐day survival rate using log‐rank test and stent patency duration using Mann–Whitney U test. Effectiveness was defined as stent patency, while cost was calculated using hospital perspective using decision tree model and reported as incremental cost‐effectiveness ratio.

Results

A total of 81 men and 83 women were enrolled in this study. One hundred and eighty days survival rate was 35.9% (median 76 days, 95% confidence interval [CI] 50–102 days) and 33.3% (median 55 days, 95% CI 32–78 days), while average stent patency was 123 (8) days versus 149 (13) days for plastic and metal stent groups, respectively (P > 0.05). Metal stent could save Indonesian Rupiah (IDR) 1 217 750 to get additional 26 days of patency.

Conclusion

There were no differences in survival and stent patency between the two groups. Metal biliary stent is more cost‐effective than plastic stent for palliation in malignant biliary obstruction.

Antimicrobial d-Peptide Hydrogels

Biofilms are widely involved in human lives, such as in medical infection, environmental remediation, and industrial processes. However, the control of the biofilm has still been a challenge because of its strong drug resistance. Here, we designed and synthesized an amphipathic antimicrobial peptide (Ac-^DK^DH^DH^DQ^DK^DL^DV^DF^DF^DA^DK-NH₂ (KKd-11)) that was composed of d-amino acids (DAAs). KKd-11 was found to self-assemble into a hydrogel with an improved long-term antimicrobial ability and a better antiprotease activity as compared to the hydrogel formed by Ac-^LK^LH^LH^LQ^LK^LL^LV^LF^LF^LA^LK-NH₂ (KK-11). Our results indicated that KKd-11 was not only able to inhibit the formation of biofilms but also could effectively damage preformed mature biofilms and kill the bacteria within the biofilms. Besides, cell viability assays indicated that the KKd-11 peptide had very good biocompatibility. We think d-peptide hydrogels may have great potential in the treatment of biofilm-induced infections.

Could saline irrigation clear all residual common bile duct stones after lithotripsy? A self-controlled prospective cohort study

BACKGROUND

A previous study showed that irrigation with 100 mL saline reduced residual common bile duct (CBD) stones, which potentially cause recurrent stones after endoscopic retrograde cholangiopancreatography.

AIM

To determine whether saline irrigation can improve CBD clearance after lithotripsy.

METHODS

This prospective self-controlled study enrolled patients receiving mechanical lithotripsy for large (> 1.2 cm) CBD stones. After occlusion cholangiography confirmed CBD stone clearance, peroral cholangioscopy (POC) was performed to determine clearance scores based on the number of residual stones. The amounts of residual stones spotted via POC were graded on a 5-point scale (score 1, worst; score 5, best). Scores were documented after only stone removal (control) and after irrigation with 50 mL and 100 mL saline, respectively. The stone composition was analyzed using infrared spectroscopy.

RESULTS

Between October 2018 and January 2020, 47 patients had CBD clearance scores of 2.4 ± 1.1 without saline irrigation, 3.5 ± 0.7 with 50 mL irrigation, and 4.6 ± 0.6 with 100 mL irrigation (P < 0.001). Multivariate analysis showed that CBD diameter > 15 mm [odds ratio (OR) = 0.08, 95% confidence interval (CI): 0.01-0.49; P = 0.007] and periampullary diverticula (PAD) (OR = 6.51, 95%CI: 1.08-39.21; P = 0.041) were independent risk factors for residual stones. Bilirubin pigment stones constituted the main residual stones found in patients with PAD (P = 0.004).

CONCLUSION

Irrigation with 100 mL of saline may not clear all residual CBD stones after lithotripsy, especially in patients with PAD and/or a dilated (> 15 mm) CBD. Pigment residual stones are soft and commonly found in patients with PAD. Additional saline irrigation may be required to remove retained stones.

Pre-operative stenting and complications following pancreatoduodenectomy for pancreatic cancer: an analysis of the ACS-NSQIP registry

BACKGROUND

Historically, pre-operative biliary stenting has been associated with higher infectious complication rates following pancreatoduodenectomy. However, alleviation of biliary obstruction is necessary for consideration of pre-operative chemotherapy, which may improve disease-free survival, or for mitigation of symptoms while awaiting surgery. Our aim is to compare contemporary post-operative complication risk among patients with pre-operative endoscopic retrograde cholangiopancreatography (ERCP) stenting compared to those without.

METHODS

Patients who underwent a pancreatoduodenectomy for pancreatic cancer with biliary obstruction within the ACS-NSQIP registry from 2014 to 2017 were identified. The primary outcome was to compare the risk of 30-day complication (composite outcome) between patients with and without pre-operative ERCP stenting. Propensity score matching was used to ensure balanced baseline characteristics and log-binomial regression models were used to estimate risk ratios for overall perioperative complication between groups.

RESULTS

From 6073 patients with obstructive jaundice undergoing pancreatoduodenectomy for pancreatic cancer, 92% (5564) were eligible for the study. After performing a propensity score matching on 20 baseline characteristics, 952 patients without stenting were matched to up to four patients who received pre-operative ERCP stenting (n = 3467) for a matched cohort of 4419. A total of 1901 (55%) patients with pre-operative ERCP stenting experienced a post-operative complication compared to 501 (53%) patients without stenting (risk ratio 1.04, 95% CI 0.97-1.11, p = 0.23).

CONCLUSION

Pre-operative ERCP stenting was not associated with an increased risk of post-operative complication in patients undergoing pancreatoduodenectomy with obstructive jaundice. Biliary stenting may be safely considered for symptom relief and to potentially facilitate pre-operative chemotherapy for pancreatic cancer.

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.

Role of the biliary microbiome in gallstone disease

Gallstone disease is caused by multiple pathogenic factors and is common worldwide. Most studies have focused on the significance of the biliary microbiome in gallstone pathogenesis. Areas covered: In this study, the epidemiology of gallstone diseases and the existence, composition, origin, and mechanisms of the biliary microbiota were reviewed. Mechanisms involved in promoting the formation of different types of gallstones were also emphasized. The antibiotic susceptibility of the biliary microbiota is briefly discussed because it may guide clinical strategies. Expert commentary: The biliary microbiome facilitates the formation of brown pigment stones. Although glycoprotein (mucin) may be pivotal for many promoting substances to coagulate and integrate relevant components, new mechanisms involving prostaglandins, oxysterols, oxygen free radicals, and lipopolysaccharides have been discovered. Furthermore, specific bacterial species such as Helicobacter and Salmonella are involved in the pathogenesis of cholesterol gallstones. Recently, metabolomics of the biliary microbiome has been used to determine the detailed mechanisms that promote gallstone formation. Previously, the bacterial effects involved in the pathogenesis of brown pigment stones have not been analyzed in detail. Whether the administration of antibiotics is related to prophylaxis for gallstone formation and gallstone-associated infections remains unclear.

Plastic vs. Self-Expandable Metal Stents for Palliation in Malignant Biliary Obstruction: A Series of Meta-Analyses

OBJECTIVES

Self-expandable metal stents (SEMS) are thought to have an advantage over plastic stents in achieving biliary drainage.

METHODS

We performed a systematic search of MEDLINE, EMBASE, Scopus, CENTRAL, and ISI Web of knowledge databases, from January 1980 to September 2015, for randomized-controlled trials (RCTs) comparing SEMS vs. plastic stents in the palliation of malignant biliary obstruction. Primary outcomes were durations of stent patency, patient survival, and 30-day mortality. Numerous secondary outcomes were assessed, and extensive sensitivity and subgroup analyses were performed.

RESULTS

In all, 20 RCTs totaling 1,713 patients yielded a weighted mean difference (WMD) in time to stent patency (4 studies) of 4.45 months (95% confidence interval (CI), 0.31, 8.59; GRADE=moderate) favoring SEMS. There were no differences in overall patient survival (5 studies) WMD=0.67 months (95% CI, -0.66, 1.99; GRADE=moderate), or 30-day mortality (8 studies) odds ratio (OR)=0.80 (95% CI, 0.52, 1.24; GRADE=moderate) but there was a higher symptom-free survival at 6 months (4 studies) OR=5.96 (95% CI, 1.71, 20.81; GRADE=moderate). SEMS use resulted in lower rates of late complications (11 studies) OR=0.43 (95% CI, 0.26, 0.71; GRADE=moderate), sepsis or cholangitis (14 studies) OR=0.53 (95% CI, 0.37, 0.77; GRADE=high), blocking from sludge (8 studies) OR=0.11(95% CI, 0.07, 0.17; GRADE=moderate), and mean number of re-interventions (8 studies) WMD=-0.83 interventions (95% CI, -1.64, -0.02; GRADE=moderate). There was a longer patency of SEMS for those without a prior drainage attempt (2 studies) WMD 7.70 months (95% CI, 7.14, 8.25; GRADE=high). Although a survival advantage was found when an uncovered SEMS was used (3 studies) WMD 1.31 months (95% CI, 0.30, 2.32; GRADE=high), but not partially or fully covered SEMS (2 studies) WMD -0.66 months (95% CI, -1.02, -0.30; GRADE=high) vs. plastic stents, and for SEMS in the setting of pre- or post-procedural antibiotic administration (2 studies) WMD 1.49 months (95% CI, 0.27, 2.70; GRADE=high), and performance of a sphincterotomy (2 studies) WMD 1.63 months (95% CI, 0.42, 2.84; GRADE=high).

CONCLUSIONS

Keeping in mind the noted risk of bias in source data, the use of SEMS compared with plastic stents, in the palliation of patients with malignant biliary obstruction results in longer stent patency, lower complications rates, and fewer re-interventions, whereas exhibiting survival benefits in selected subgroups of patients.

Systematic review and meta-analysis of metal versus plastic stents for preoperative biliary drainage in resectable periampullary or pancreatic head tumors

BACKGROUND

Preoperative biliary drainage (PBD) with stenting increases complications compared with surgery without PBD. Metallic stents are considered superior to plastic stents when considering stent-related complications. Aim of the present systematic review and meta-analysis is to compare the rate of endoscopic re-intervention before surgery and postoperative outcomes of metal versus plastic stents in patients with resectable periampullary or pancreatic head neoplasms.

METHODS

We conducted a bibliographic research using the National Library of Medicine's PubMed database, including both randomized controlled trials (RCTs) and non-RCTs. Quantitative synthesis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Statistical heterogeneity was assessed using the I(2) tests.

RESULTS

One RCT and four non-RCTs were selected, including 704 patients. Of these, 202 patients (29.5%) were treated with metal stents and 502 (70.5%) with plastic stents. The majority of patients (86.4%) had pancreatic cancer. The rate of endoscopic re-intervention after preoperative biliary drainage was significantly lower in the metal stent (3.4%) than in the plastic stent (14.8%) group (p < 0.0001). The rate of postoperative pancreatic fistula was significantly lower in the meta stent group as well (5.1% versus 11.8%, p = 0.04). The rate of post-operative surgical complications and of - post-operative mortality did not differ between the two groups.

CONCLUSIONS

Although the present systematic review and meta-analysis demonstrates that metal stent are more effective than plastic stents for PBD in patients with resectable periampullary tumors, randomized controlled trials are needed in order to confirm these data with a higher level of evidence.

Outcomes and risk factors for cancer patients undergoing endoscopic intervention of malignant biliary obstruction

Background

Malignant bile duct obstruction is a common problem among cancer patients with hepatic or lymphatic metastases. Endoscopic retrograde cholangiography (ERC) with the placement of a stent is the method of choice to improve biliary flow. Only little data exist concerning the outcome of patients with malignant biliary obstruction in relationship to microbial isolates from bile.

Methods

Bile samples were taken during the ERC procedure in tumor patients with biliary obstruction. Clinical data including laboratory values, tumor-specific treatment and outcome data were prospectively collected.

Results

206 ERC interventions in 163 patients were recorded. In 43 % of the patients, systemic treatment was (re-) initiated after successful biliary drainage. A variety of bacteria and fungi was detected in the bile samples. One-year survival was significantly worse in patients from whom multiresistant pathogens were isolated than in patients, in whom other species were detected. Increased levels of inflammatory markers were associated with a poor one-year survival. The negative impact of these two factors was confirmed in multivariate analysis.

In patients with pancreatic cancer, univariate analysis showed a negative impact on one-year survival in case of detection of Candida species in the bile. Multivariate analysis confirmed the negative prognostic impact of Candida in the bile in pancreatic cancer patients.

Conclusion

Outcome in tumor patients with malignant bile obstruction is associated with the type of microbial biliary colonization. The proof of multiresistant pathogens or Candida, as well as the level of inflammation markers, have an impact on the prognosis of the underlying tumor disease.

Metagenomic sequencing of bile from gallstone patients to identify different microbial community patterns and novel biliary bacteria

Despite the high worldwide prevalence of gallstone disease, the role of the biliary microbiota in gallstone pathogenesis remains obscure. Next-generation sequencing offers advantages for systematically understanding the human microbiota; however, there have been few such investigations of the biliary microbiome. Here, we performed whole-metagenome shotgun (WMS) sequencing and 16S rRNA sequencing on bile samples from 15 Chinese patients with gallstone disease. Microbial communities of most individuals were clustered into two types, according to the relative enrichment of different intestinal bacterial species. In the bile samples, oral cavity/respiratory tract inhabitants were more prevalent than intestinal inhabitants and existed in both community types. Unexpectedly, the two types were not associated with fever status or surgical history, and many bacteria were patient-specific. We identified 13 novel biliary bacteria based on WMS sequencing, as well as genes encoding putative proteins related to gallstone formation and bile resistance (e.g., β-glucuronidase and multidrug efflux pumps). Bile samples from gallstone patients had reduced microbial diversity compared to healthy faecal samples. Patient samples were enriched in pathways related to oxidative stress and flagellar assembly, whereas carbohydrate metabolic pathways showed varying behaviours. As the first biliary WMS survey, our study reveals the complexity and specificity of biliary microecology.

Plastic biliary stent patency in patients with locally advanced pancreatic adenocarcinoma receiving downstaging chemotherapy

BACKGROUND

Plastic stents in patients with biliary obstruction caused by pancreatic adenocarcinoma are typically exchanged at 3-month intervals. Plastic stents may have reduced durability in patients receiving chemotherapy.

OBJECTIVE

To determine the duration of plastic biliary stent patency in patients undergoing chemotherapy for pancreatic adenocarcinoma.

DESIGN

Retrospective, multicenter cohort study.

SETTING

Three tertiary academic referral centers.

PATIENTS

A total of 173 patients receiving downstaging chemotherapy for locally advanced or borderline resectable pancreatic adenocarcinoma from 1996 to 2013.

INTERVENTIONS

Placement of 10F or larger plastic biliary stents.

MAIN OUTCOME MEASUREMENTS

Primary outcome was overall duration of stent patency. Secondary outcomes included the incidence of premature stent exchange (because of cholangitis or jaundice) and hospitalization rates.

RESULTS

A total of 233 plastic stents were placed, and the overall median duration of stent patency was 53 days (interquartile range [IQR] 25-99 days). Eighty-seven stents were removed at the time of surgical resection, and 63 stents were exchanged routinely per protocol. The remaining 83 stent exchanges were performed for worsening liver function test results, jaundice, or cholangitis, representing a 35.6% rate of premature stent exchange. The median stent patency duration in the premature stent exchange group was 49 days (IQR 25-91 days) with a 44.6% hospitalization rate. The overall rate of cholangitis was 15.0% of stent exchanges, occurring a median of 56 days after stent placement (IQR 26-89 days).

LIMITATIONS

Retrospective study.

CONCLUSIONS

Plastic biliary stents placed during chemotherapy/chemoradiation for pancreatic adenocarcinoma have a shorter-than-expected patency duration, and a substantial number of patients will require premature stent exchange. Consideration should be given to shortening the interval for plastic biliary stent exchange.

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

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

Multicenter study evaluating factors for stent patency in patients with malignant biliary strictures: development of a simple score model

BACKGROUND

Self-expanding metal stents (SEMS) are known to have a significantly higher patency rate than plastic stents. We aimed to identify prognostic factors, besides stent type, for stent patency and to develop a score model that could further aid in guiding stent choice for the palliation of a malignant biliary stricture.

METHODS

A retrospective multicenter study was conducted. Data on consecutive patients who had a stent placed between January 2002 and July 2009 were collected. Cumulative stent occlusion rates were analyzed by Kaplan-Meier curves and log rank testing, and prognostic factors were assessed by Cox regression analysis.

RESULTS

A total of 690 stents (512 plastic stents, 174 SEMS) were endoscopically placed in 390 patients. At 8 weeks, stent occlusion had occurred in 32% of the plastic stents and 11% of the SEMS. Multivariate analysis indicated that plastic stents (hazard ratio [HR] 2.5, 95% confidence interval [CI] 1.9-3.5), a tight stricture requiring preceding dilation (HR 1.8, 95% CI 1.3-2.5), and a high initial bilirubin level (>50 μmol/L (HR 1.3, 95% CI 1.0-1.7) were independently associated with an increased risk of stent occlusion. A score model based on these 3 factors was able to distinguish between stent procedures with a relatively high and low risk of stent occlusion (median 14 vs. 26 weeks, respectively).

CONCLUSION

Besides plastic stents, stricture severity requiring preceding dilation, and initial higher bilirubin level were associated with a shorter period of stent patency. A simple score model based on these factors was able to predict stent occlusion and may aid in choosing the most appropriate stent type in individual patients.

Effectiveness of percutaneous metal stent placement in cholangiocarcinoma patients with midterm follow-up: Single center experience

PURPOSE

Patients with advanced cholangiocarcinoma present with high rate of local complications. The primary aim of this study is to report clinical course of advanced cholangiocarcinoma patients those who were presented with biliary obstruction and treated with percutaneous biliary stenting.

MATERIAL AND METHODS

Patients with unresectable locally advanced or metastatic cholangiocarcinoma followed by our center for a period of 4 years were analyzed. For statistical analysis demographic and clinical characteristics of patients, primary biliary drainage method, metal stent occlusion rate, time to stent occlusion, and overall survival rates were recorded.

RESULTS

A total of 34 eligible patients were analyzed. 27 patients had metal stent placement. These 27 patients formed the basis of this study. Median overall survival (OS) was 6.0 months. After metal stent deployment bilurubin levels were normalized within a mean of 10 days. During the follow-up period, 13 patients were experienced metal stent occlusion. Median TtSO was 10 weeks. Cytotoxic chemotherapy was administered to 14 (52%) patients. Patients without stent dysfunction had significantly higher rate of chemotherapy exposure rate (p=0.021). Statistical analysis, however, failed to exhibit significant effect of stent dysfunction on OS.

CONCLUSION

In advanced cholangiocarcinoma, relief of bile duct obstruction is an important part of the initial patient management. This study therefore described the clinical value of percutaneous metal stent in cholangiocarcinoma patients and raises the question about patency of metal stent in cholangiocarcinoma whether we can expect success similar to the success achieved in pancreas carcinoma.

Nitinol biliary stent versus surgery for palliation of distal malignant biliary obstruction

BACKGROUND

Curative resection of pancreatic and biliary malignancies is rare. Most tumors are inoperable at presentation, and palliation of jaundice often is the goal. Biliary decompression can be achieved by surgical diversion or endoscopic biliary stents. This study aimed to compare clinical outcomes between surgical bypass and endoscopic uncovered nitinol stents in the palliation of patients with malignant distal common bile duct obstruction.

METHODS

A multicenter, retrospective, cohort study investigated 86 patients with inoperable malignant distal common bile duct strictures at tertiary referral centers in Medellín, Colombia. These patients had undergone surgery (group 1) or placement of an uncovered 30-Fr self-expandable nitinol stent produced locally in Medellín, Colombia (group 2). The main outcome measurements included cumulative biliary patency, hospital stay, and patient survival.

RESULTS

The study enrolled 86 patients (mean age, 66 years; range, 43-78 years) including 40 patients in group 1 and 46 patients in group 2. Both groups were similar in terms of age, gender, liver metastasis, and diagnosis. Technical success was achieved for 38 patients in group 1 (95%) and 43 patients in group 2 (93%). Functional biliary decompression was obtained in for 35 of the surgical patients (88%) and 42 of the stented patients (91%). Group 2 had lower rates for procedure-related mortality (2 vs. 7.5%; p = 0.01), a lower frequency of early complications (8.7 vs. 45%; p = 0.02), and a shorter hospital stay (median, 6 vs. 12 days; p = 0.01). Recurrent jaundice occurred for three patients in group 1 (7.5%) and eight patients in group 2 (17.3%) (p = 0.198). Late gastric outlet obstruction occurred for 12.5% of the patients in group 1 and 13% of the patients in group 2 (p = 0.73). Despite the early benefits of stenting, no significant difference in the median overall survival between the two groups was found (group 1, 163 days; group 2, 178 days; p = 0.11). The limitations of this study included the small number of patients and the retrospective design.

CONCLUSIONS

Endoscopic stenting and surgery are effective palliation. The former is associated with fewer early complications and the latter with fewer late complications. Patients who do not qualify for curative resection may be better managed by stent placement. Surgery should be reserved for patients more likely to survive longer.

Sphincter of Oddi hypomotility and its relationship with duodenal-biliary reflux, plasma motilin and serum gastrin

AIM: To detect whether patients with a T tube after cholecystectomy and choledochotomy have duodenal-biliary reflux by measuring the radioactivity of Tc99m-labeled diethylene triamine penta-acetic acid (DTPA) in the bile and whether the patients with duodenal-biliary reflux have sphincter of Oddi hypomotility, by measuring the level of plasma and serum gastrin of the patients. Finally to if there is close relationship among sphincter of Oddi hypomotility, duodenal-biliary reflux and gastrointestinal peptides.

METHODS: Forty-five patients with a T tube after cholecystectomy and choledochotomy were divided into reflux group and control group. The level of plasma and serum gastrin of the patients and of 12 healthy volunteers were measured by radioimmunoassay. Thirty-four were selected randomly to undergo choledochoscope manometry. Sphincter of Oddi basal pressure (SOBP), amplitude (SOCA), frequency of contractions (SOF), duration of contractions (SOD), duodenal pressure (DP) and common bile duct pressure (CBDP) were scored and analyzed.

RESULTS: Sixteen (35.6%) patients were detected to have duodenal-biliary reflux. SOBP, SOCA and CBDP in the reflux group were much lower than the control group (t = 5.254, 3.438 and 3.527, P < 0.001). SOD of the reflux group was shorter than the control group (t = 2.049, P < 0.05). The level of serum gastrin and plasma motilin of the reflux group was much lower than the control group (t = -2.230 and -2.235, P < 0.05). There was positive correlation between the level of plasma motilin and SOBP and between the level of serum gastrin and SOBP and CBDP.

CONCLUSION: About 35.9% of the patients with a T tube after cholecystectomy and choledochotomy have duodenal-biliary reflux. Most of them have sphincter of Oddi hypomotility and the decreased level of plasma motilin and serum gastrin. The disorder of gastrointestinal hormone secretion may result in sphincter of Oddi dysfunction. There is a close relationship between sphincter of Oddi hypomotility and duodenal-biliary reflux.

Do the benefits of metal stents justify the costs? A systematic review and meta-analysis of trials comparing endoscopic stents for malignant biliary obstruction

BACKGROUND

A variety of stent designs has been studied for endoscopic stenting of the bile duct in patients with malignant biliary obstruction. Although metal stents are associated with longer patency, their costs are significantly higher than plastic stents.

AIMS

To compare clinical outcome and cost-effectiveness of endoscopic metal and plastic stents for malignant biliary obstruction by a systematic review and meta-analysis of all randomized controlled trials in this area.

METHODS

We conducted searches to identify all randomized controlled trials in any language from 1966 to 2006 using electronic databases and hand-searching of conference abstracts. Meta-analysis was performed with RevMan software [Review Manager (RevMan) version 4.2 for Windows. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2003].

RESULTS

Seven randomized controlled trials were identified that met the inclusion criteria, and 724 participants were randomized to either metal or plastic endoscopic stents. No significant difference between the two stent types in terms of technical success, therapeutic success, 30-day mortality or complications was observed. Metal stents were associated with a significantly less relative risk (RR) of stent occlusion at 4 months than plastic stents [RR, 0.44; 95% confidence interval (CI) 0.3, 0.63; P<0.01]. The overall risk of recurrent biliary obstruction was also significantly lower in patients treated with metal stents (RR, 0.52; 95% confidence interval 0.39, 0.69; P<0.01). The median incremental cost-effectiveness ratio of metal stents was $1820 per endoscopic retrograde cholangiopancreatography prevented.

CONCLUSION

Endoscopic metal stents for malignant biliary obstruction are associated with significantly higher patency rates than plastic stents as early as 4 months after insertion. Metal stents will be cost-effective if the unit cost of additional endoscopic retrograde cholangiopancreatographies per patient exceeds $1820.

Gallstones containing bacteria are biofilms: bacterial slime production and ability to form pigment solids determines infection severity and bacteremia

OBJECTIVE

Gallstone bacteria provide a reservoir for biliary infections. Slime production facilitates adherence, whereas beta-glucuronidase and phospholipase generate colonization surface. These factors facilitate gallstone formation, but their influence on infection severity is unknown.

METHODS

Two hundred ninety-two patients were studied. Gallstones, bile, and blood (as applicable) were cultured. Bacteria were tested for beta-glucuronidase/phospholipase production and quantitative slime production. Infection severity was correlated with bacterial factors.

RESULTS

Bacteria were present in 43% of cases, 13% with bacteremia. Severe infections correlated directly with beta-glucuronidase/phospholipase (55% with vs 13% without, P < 0.0001), but inversely with slime production (55 vs 8%, slime <75 or >75, P = 0.008). Low slime production and beta-glucuronidase/phospholipase production were additive: Severe infections were present in 76% with both, but 10% with either or none (P < 0.0001). beta-Glucuronidase/phospholipase production facilitated bactibilia (86% with vs 62% without, P = 0.03). Slime production was 19 (+/-8) vs 50 (+/-10) for bacteria that did or did not cause bacteremia (P = 0.004). No bacteria with slime >75 demonstrated bacteremia.

CONCLUSIONS

Bacteria-laden gallstones are biofilms whose characteristics influence illness severity. Factors creating colonization surface (beta-glucuronidase/phospholipase) facilitated bacteremia and severe infections; but abundant slime production, while facilitating colonization, inhibited detachment and cholangiovenous reflux. This shows how properties of the gallstone biofilm determine the severity of the associated illness.

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

BACKGROUND

The mechanisms leading to occlusion of plastic biliary stents (PBS) are not known.

OBJECTIVE

To evaluate the impact of reducing duodenobiliary reflux on stent patency rate.

DESIGN

A newly designed antireflux PBS (AR-PBS) was tested in vitro by using ox bile. A prospective randomized trial in human beings was conducted.

SETTING

Tertiary medical center.

PATIENTS

Patients with malignant bile-duct strictures were studied.

INTERVENTIONS

A PBS or an AR-PBS stent was placed by using standard techniques, and the patients were followed at regular intervals. Patients presenting with stent occlusion underwent re-stent placement with either a PBS or a metal stent.

MAIN OUTCOME MEASUREMENTS

In vitro: resistance to retrograde flow and comparison of the basal and peak antegrade flow pressures between the 2 stents. In vivo: stent patency rates, complications, and the efficacy of the stents in improving the liver test.

RESULTS

The AR-PBS stent could withstand a retrograde pressure gradient of >320 mm Hg compared with <1 mm Hg for the PBS. Secondary to the siphon effect of the valve, the antegrade flow resistance offered by the AR-PBS was on the negative side for all flow rates compared with PBS (P < .001). The median patency of the AR-PBS in human studies was 145 days (range, 52-252 days) compared with 101 days (range, 41-210 days) for the PBS (P = .002). Both stents were equally effective in improving the liver test, and complication rates were similar in the 2 groups.

LIMITATIONS

The occluded stents were not examined microscopically.

CONCLUSIONS

The antireflux biliary stent remains patent for a longer time and hence duodenobiliary reflux may be contributing to stent occlusion.

Plastic biliary stent occlusion: factors involved and possible preventive approaches

Endoscopic biliary stenting is today the most common palliative treatment for patients suffering from obstructive jaundice associated with malignant hepatobiliary tumors or benign strictures. However, recurrent jaundice, with or without cholangitis, is a major complication of a biliary endoprosthesis insertion. Thus, stent removal and replacement with a new one frequently occurs as a consequence of device blockage caused by microbial biofilm growth and biliary sludge accumulation in the lumen. Factors and mechanisms involved in plastic stent clogging arising from epidemiological, clinical and experimental data, as well as the possible strategies to prevent biliary stent failure, will be reviewed and discussed.

The current standard of care in the periprocedural management of the patient with obstructive jaundice

This review provides a literature-based guide to the optimal management of the patient with obstructive jaundice with emphasis placed on prevention of complications.

Malignant distal biliary obstruction: a systematic review and meta-analysis of endoscopic and surgical bypass results

BACKGROUND

Surgical bypass and endoscopic stents are available for palliative bypass of malignant distal biliary obstruction.

AIM

Comparison of reported outcomes in randomized controlled trials (RCTs) which included surgery, endoscopic plastic stents or endoscopic metal stents in palliative relief of malignant distal biliary obstruction.

METHODS

Systematic review and meta-analysis of published literature and conference proceedings review to June 2006.

RESULTS

We found 24 studies, containing 2436 patients, which met our inclusion criteria. Endoscopic stenting with plastic stents (three studies) is associated with a lower risk of complications (RR 0.60, 95% CI 0.45-0.81), but a higher risk of recurrent biliary obstruction (RR 18.59, 95% CI 5.33 -64.86) than traditional surgical bypass. Self-expanding metal stents (seven studies) are associated with a significantly reduced risk of recurrent biliary obstruction at 4 months (RR 0.44, 95% CI 0.3, 0.63), or prior to death or end of study (RR 0.52, 95% CI 0.39-0.69), but are not superior to plastic stents in terms of technical success, therapeutic success, mortality or complications. Cost-effectiveness outcomes were not suitable for meta-analysis. No other plastic stent designs have been demonstrated to be superior to polyethylene stents (12 studies).

CONCLUSIONS

Endoscopic metal stents are the intervention of choice in patients with malignant distal biliary obstruction, producing similar outcomes to plastic stents, but with improved patency rates.

Biliary bacterial factors determine the path of gallstone formation

BACKGROUND

Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation.

METHODS

A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed.

RESULTS

Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons).

CONCLUSIONS

Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.

Antireflux biliary stents: are they the solution to stent occlusions?

Endoscopic insertion of plastic or metal stents is a well-established treatment for malignant biliary obstruction. The major limitation of this technique is stent occlusion. Duodenobiliary reflux has been considered a key contributor to stent occlusion. The presence of plant fibers in 35% to 60% of occluded stents on confocal laser microscopy has further confirmed the presence of reflux when the stent is placed across the papilla. Antireflux stents address this problem by allowing normal antegrade flow but preventing reflux. Recent studies comparing these antireflux stents with the standard Tannenbaum stents have shown significantly prolonged patency. Although initial results are encouraging, larger randomized trials are required to establish efficacy.

Palliative biliary stents for obstructing pancreatic carcinoma

BACKGROUND

Palliative endoscopic stents or surgical by-pass are often required for inoperable pancreatic carcinoma to relieve symptomatic obstruction of the distal biliary tree. The optimal method of intervention remains unknown.

OBJECTIVES

To compare surgery, metal endoscopic stents and plastic endoscopic stents in the relief of distal biliary obstruction in patients with inoperable pancreatic carcinoma.

SEARCH STRATEGY

We searched the databases of the Cochrane Upper Gastrointestinal and Pancreatic Group specialised register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CancerLit, Current Concepts Database and BIDS (September 2002 to September 2004). The searches were re-run in December 2005 and we are awaiting further details on two trials. Reference lists of articles and published abstracts from UEGW and DDW were hand-searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing surgery to endoscopic stenting, endoscopic metal stents to plastic stents, and different types of endoscopic plastic and metal stents, used to relieve obstruction of the distal bile duct in patients with inoperable pancreatic carcinoma.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Adverse effects information was collected from the trials.

MAIN RESULTS

Twenty-one trials involving 1,454 people were included. Based on meta-analysis, endoscopic stenting with plastic stents appears to be associated with a reduced risk of complications (RR 0.60, 95% CI 0.45 - 0.81), but with higher risk of recurrent biliary obstruction prior to death (RR 18.59, 95% CI 5.33 - 64.86) when compared with surgery. There was a trend towards higher 30-day mortality in the surgical group (p=0.07, RR 0.58, 95% CI 0.32, 1.04). There was no evidence of a difference in technical or therapeutic success. Other outcomes were not suitable for meta-analysis. No trials comparing endoscopic metal stents to surgery were identified. In endoscopic stent comparisons, metal biliary stents appear to have a lower risk of recurrent biliary obstruction than plastic stents (RR 0.52, 95% CI 0.39 - 0.69). There was no significant statistical difference in technical success, therapeutic success, complications or 30-day mortality using meta-analysis. A narrative review of studies of the cost-effectiveness of metal stents drew conflicting conclusions, but results may be dependent on the patients' length of survival.Neither Teflon, hydrourethane, or hydrophilic coating appear to improve the patency of plastic stents above polyethylene in the trials reviewed. Only perflouro alkoxy plastic stents had superior outcome to polyethylene stents in one trial. The single eligible trial comparing types of metal stents reported higher patency with covered stents, but also a higher risk of complications. These results are based on review of the trials individual results only.

AUTHORS' CONCLUSIONS

Endoscopic metal stents are the intervention of choice at present in patients with malignant distal obstructive jaundice due to pancreatic carcinoma. In patients with short predicted survival, their patency benefits over plastic stents may not be realised. Further RCTs are needed to determine the optimal stent type for these patients.

Palliative biliary stents for obstructing pancreatic carcinoma

BACKGROUND

Palliative endoscopic stents or surgical by-pass are often required for inoperable pancreatic carcinoma to relieve symptomatic obstruction of the distal biliary tree. The optimal method of intervention remains unknown.

OBJECTIVES

To compare surgery, metal endoscopic stents and plastic endoscopic stents in the relief of distal biliary obstruction in patients with inoperable pancreatic carcinoma.

SEARCH STRATEGY

We searched the databases of the Cochrane Upper Gastrointestinal and Pancreatic Group specialised register, Cochrane Central Register of Controlled Trials , MEDLINE, EMBASE, CancerLit, Current Concepts Database and BIDS (September 2002 to September 2004). Reference lists of articles and published abstracts from UEGW and DDW were hand-searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing surgery to endoscopic stenting, endoscopic metal stents to plastic stents, and different types of endoscopic plastic and metal stents, used to relieve obstruction of the distal bile duct in patients with inoperable pancreatic carcinoma.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Adverse effects information was collected from the trials.

MAIN RESULTS

Twenty-one trials involving 1,454 people were included. Based on meta-analysis, endoscopic stenting with plastic stents appears to be associated with a reduced risk of complications (RR 0.60, 95% CI 0.45 - 0.81), but with higher risk of recurrent biliary obstruction prior to death (RR 18.59, 95% CI 5.33 - 64.86) when compared with surgery. There was a trend towards higher 30-day mortality in the surgical group (p=0.07, RR 0.58, 95% CI 0.32, 1.04). There was no evidence of a difference in technical or therapeutic success. Other outcomes were not suitable for meta-analysis. No trials comparing endoscopic metal stents to surgery were identified. In endoscopic stent comparisons, metal biliary stents appear to have a lower risk of recurrent biliary obstruction than plastic stents (RR 0.52, 95% CI 0.39 - 0.69). There was no significant statistical difference in technical success, therapeutic success, complications or 30-day mortality using meta-analysis. A narrative review of studies of the cost-effectiveness of metal stents drew conflicting conclusions, but results may be dependent on the patients' length of survival. Neither Teflon, hydrourethane, or hydrophilic coating appear to improve the patency of plastic stents above polyethylene in the trials reviewed. Only perflouro alkoxy plastic stents had superior outcome to polyethylene stents in one trial. The single eligible trial comparing types of metal stents reported higher patency with covered stents, but also a higher risk of complications. These results are based on review of the trials individual results only.

AUTHORS' CONCLUSIONS

Endoscopic metal stents are the intervention of choice at present in patients with malignant distal obstructive jaundice due to pancreatic carcinoma. In patients with short predicted survival, their patency benefits over plastic stents may not be realised. Further RCTs are needed to determine the optimal stent type for these patients.

Expandable metal biliary stents before pancreaticoduodenectomy for pancreatic cancer: a Monte-Carlo decision analysis

BACKGROUND & AIMS

Endoscopic placement of plastic or self-expandable metal biliary stents (SEMS) relieves obstructive jaundice from pancreatic cancer. Short-length, distally placed SEMS do not preclude subsequent pancreaticoduodenectomy. We sought to determine whether SEMS placement in patients whose surgical status is uncertain is cost-effective for management of obstructive jaundice.

METHODS

A Markov model was constructed to evaluate costs and outcomes associated with endoscopic biliary stenting for obstructive jaundice. Strategies evaluated were: (1) initial plastic stent with plastic stents for subsequent occlusions in nonsurgical candidates after staging (plastic followed-up by [f/u] plastic), (2) initial plastic with subsequent SEMS (plastic f/u metal), (3) initial short-length SEMS with subsequent plastic (metal f/u plastic), and (4) initial short-length SEMS with subsequent expandable metal stent (metal f/u metal). Published stent occlusion rates, ERCP complication rates and outcomes, cholangitis rates and outcomes, pancreatic cancer mortality rates, and Whipple complication rates were used. Costs were based on 2004 Medicare standard allowable charges and were accrued until all patients reached an absorbing health state (death or pancreaticoduodenectomy) or 24 cycles (24 mo) ended.

RESULTS

Average costs per patient from Monte Carlo simulation were: (1) metal f/u metal, $19,935; (2) plastic f/u metal, 20,157 dollars; (3) metal f/u plastic, 20,871 dollars; and (4) plastic f/u plastic, 20,878 dollars. For initial plastic stents to be preferred over short-length metal stents, 70% or more of pancreatic cancers would need to be potentially resectable by pancreaticoduodenectomy.

CONCLUSIONS

In patients undergoing ERCP before definitive cancer staging, short-length SEMS is the preferred initial cost-minimizing strategy.

Inhibition of bacterial adherence on the surface of stents and bacterial growth in bile by bismuth dimercaprol

Bacterial infection and biofilm formation on the surface of biliary stents is believed to be one of the main factors in stent occlusion. This study explored the role of the new reagent, bismuth dimercaprol, in preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stents. Sterile porcine bile preparations, infected separately with Escherichia coli, Klebsiella pneumoniae, Enterobacter, and Enterococcus, were used as the perfusion media in an in vitro perfusion system. The bacterial growth in the media and the bacterial adherence on the surface of stents were tested when different concentrations of bismuth dimercaprol were used in the perfusion media. BisBAL (5 microM) did not inhibit the growth of any of the tested bacterial species. It did, however, significantly decrease the amount of bacteria adhering to the surface of stents for all bacterial strains except Escherichia coli. Bismuth dimercaprol (20 microM) significantly inhibited the growth of Escherichia coli, Klebsiella pneumoniae, and Enterobacter and, thereby, significantly decreased the amount of these bacteria adhering to the surface of stents. The unique bactericidal and anitbiofilm activities of bismuth thiols might contribute to delaying the process of biliary stent occlusion if the effective concentrations of bismuth thiols could be delivered to the target sites. The feasibility of this application of bismuth thiols deserves further investigation.

The prevalence and clinical significance of amniotic fluid 'sludge' in patients with preterm labor and intact membranes

OBJECTIVE

To determine the prevalence and clinical significance of amniotic fluid (AF) 'sludge' observed during transvaginal ultrasound examination of the cervix in patients with preterm labor and intact membranes, and in those with uncomplicated pregnancies.

METHODS

This retrospective study included patients with preterm labor and intact membranes (n = 84) and those with uncomplicated term pregnancies (n = 298). The outcome variables included the occurrence of documented microbial invasion of the amniotic cavity (MIAC), histological chorioamnionitis, examination-to-delivery interval, admission to the neonatal intensive care unit (NICU), a composite neonatal morbidity, perinatal death, and delivery within 48 h, 7 days, and < 35 weeks and < 32 weeks. Statistical analysis included Chi-square test, stepwise logistic regression analysis and survival analysis.

RESULTS

The prevalence of AF 'sludge' was 1% (3/298) in patients with uncomplicated term pregnancies and 22.6% (19/84) in those with preterm labor and intact membranes. Among patients with preterm labor and intact membranes: (1) cervical length < or = 15 mm was present in 58.3% (49/84) of the patients; (2) the prevalence of MIAC and histological chorioamnionitis was 12.1% (7/58) and 32.9% (25/76), respectively; (3) the rate of spontaneous preterm delivery within 48 h, 7 days, and < 32 weeks and < 35 weeks of gestation was 13.6% (8/59), 28.8% (17/59), 39.5% (17/43) and 50.8% (30/59), respectively; (4) patients with AF 'sludge' had a higher frequency of positive AF cultures [33.3% (6/18) vs. 2.5% (1/40), P = 0.003] and histological chorioamnionitis [77.8% (14/18) vs. 19% (11/58), P < 0.001] than those without AF 'sludge'; (5) a higher proportion of neonates born to patients with AF 'sludge' was admitted to the NICU [64.3% (9/14) vs. 12.9% (8/62), P < 0.01], had a composite neonatal morbidity [36.8% (7/19) vs. 13.8% (9/65), P = 0.04] and died in the perinatal period [36.8% (7/19) vs. 4.6% (3/65), P = 0.001] than those born to women without 'sludge'; (6) a higher proportion of patients with AF 'sludge' had spontaneous delivery within 48 h [42.9% (6/14) vs. 4.4% (2/45), P = 0.001], within 7 days [71.4% (10/14) vs. 15.6% (7/45), P < 0.001], < 32 weeks [75% (9/12) vs. 25.8% (8/31), P = 0.005] and < 35 weeks [92.9% (13/14) vs. 37.8% (17/45), P < 0.001] than those without AF 'sludge'; and (7) patients with AF 'sludge' had a shorter examination-to-delivery interval than those without AF 'sludge' [AF 'sludge' median, 1 (IQR, 1-5) days vs. no AF 'sludge' median, 33 (IQR, 18-58) days; P < 0.001].

CONCLUSION

The presence of AF 'sludge' in patients with preterm labor and intact membranes is a risk factor for MIAC, histological chorioamnionitis and impending preterm delivery.

Novel bactericidal surface: Catechin-loaded surface-erodible polymer prevents biofilm formation

We developed a novel bactericidal surface based on a catechin-loaded surface-erodible polymer. (-)-Epigallocatechin-3-gallate (EGCg), which is the main constituent of tea catechins, showed a dose-dependent inhibitory effect on Escherichia coli biofilm formation and a dose-dependent enhanced destructive effect on biofilm. EGCg-immobilized surfaces were prepared by photopolymerization of liquid biodegradable polyesters. The releasing rate was enhanced with an increase in surface-erosion rate of photocured polymers. Polymers with high releasing capacity dose-dependently reduced biofilm formation on the surfaces. The confocal laser scanning microscopic and scanning electron microscopic observations revealed that EGCg induced biofilm-destructing activities, which include bacterial membrane damage, degradation of exopolysaccharides, and detachment of colonized cells. From these results, potential advantages of the clinical use of catechin-loaded polymer-coated implants or catheters are discussed in terms of a reduced occurrence of biomaterial-centered infections without substantial toxicity or adverse effects.

Examination of expandable metallic stent removed at autopsy

OBJECTIVE

We evaluated the damage to expandable metallic stents (EMS) based upon analysis of EMS removed at autopsy.

METHODOLOGY

Seventeen EMS were obtained during autopsy from the main bronchi of nine patients with lung cancer. Each EMS was categorized into one of the following three groups, according to the degree of EMS damage: no damage at all (ND), damage to part of the EMS (PD), and marked damage (MD) that caused loss of function of the airway stent. The removed EMS were examined using a scanning electron microscope.

RESULTS

Of the 17 stents, ND occurred in 13 (7/9 primary, 6/8 secondary), PD in four (all secondary), and MD in none. None of the stents had completely lost the ability to function as an airway stent. Bacterial biofilm formation (BBF) was detected on EMS from four patients.

CONCLUSIONS

Bacterial biofilm forms on EMS implanted into the airway. Some physical damage was present in four of 17 EMS, but all remained functional.

Confocal imaging of biofilm formation process using fluoroprobedEscherichia coli and fluoro-stained exopolysaccharide

We developed a novel method of evaluating biofilm architecture on a synthetic material using green fluorescent protein-expressing Escherichia coli and red fluorescence staining of exopolysaccharides. Confocal laser scanning microscopy observation revealed the time course of the change in the in situ three-dimensional structural features of biofilm on a polyurethane film without structural destruction: initially adhered cells are grown to form cellular aggregates and secrete exopolysaccharides. These cells were spottily distributed on the surface at an early incubation time but fused to form a vertically grown biofilm with incubation time. Fluorescence intensity, which is a measure of the number of cells, determined using a fluorometer and biofilm thickness determined from confocal laser scanning microscopy vertical images were found to be effective for quantification of time-dependent growth of biofilms. The curli (surface-located fibers specifically binding to fibronectin and laminin)-producing Escherichia coli strain, YMel, significantly proliferated on fibronectin-coated polyurethane, whereas the curli-deficient isogenic mutant, YMel-1, did not. The understanding of biofilm architecture in molecular and morphological events and new fluorescence microscopic techniques may help in the logical surface design of biomaterials with a high antibacterial potential.

Aeromonas veronii biovar veronii septicaemia and acute suppurative cholangitis in a patient with hepatitis B

Gram-negative bacilli of the genus Aeromonas are widespread in aquatic environments and can be responsible for human infections. Although Aeromonas extraintestinal and systemic infections have been reported with growing frequency in recent years, Aeromonas septicaemia remains an uncommon finding, often associated with serious underlying disease and predominantly related to the species Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas caviae. Here, a case of A. veronii biovar veronii septicaemia and acute suppurative cholangitis is reported in a patient with chronic hepatitis B.

Bile glycoprotein mucin in sludge occluding biliary stent

Endoscopic biliary stenting is a common treatment for the palliation of obstructive jaundice caused by inoperable malignant hepatobiliary tumors and benign strictures. The biliary stent, however, often becomes nonfunctional as a result of occlusion. In this study, we sought to confirm that bile glycoprotein mucin was a factor in stent occlusion and to investigate its possible role in biliary-stent blockage. The high-molecular-weight glycoprotein fraction was isolated from stent sludge with the use of gel filtration and a cesium chloride density gradient. This fraction was analyzed for amino-acid and carbohydrate compositions and was identified by means of immunoblotting with a specific monoclonal antibody against human gallbladder mucin. Furthermore, the distribution of bile glycoprotein mucin in stent sludge was immunologically demonstrated with fluorescent antibody, and the relationship between bile glycoprotein mucin and bacteria (demonstrated with DAPI stain) was observed. The high-molecular-weight glycoprotein extracts isolated from 11 patients' stent sludge showed strongly positive immunoreactivity with the monoclonal antibody against human gallbladder mucin. Immunofluorescence studies showed that very bright fluorescent signals of bile glycoprotein mucin often appeared on the surface of pigmented deposits, at the periphery of clumps of bacteria and along the inner wall of stents. In nonpigmented sludge, we noted fluorescent signals of bile glycoprotein mucin dispersed among clumps of bacteria. Bile glycoprotein mucin is a constituent of stent sludge. It may play a role in stent occlusion by affecting bacterial adherence to the stent surface or by promoting stent-sludge accumulation as one kind of cement among substances such as calcium bilirubinate and clumps of bacteria.

New ePTFE/FEP-covered stent in the palliative treatment of malignant biliary obstruction

PURPOSE

To determine the technical efficacy and safety of an expanded polytetrafluoroethylene and fluorinated ethylene propylene (ePTFE/FEP)-covered metallic stent in the management of malignant biliary obstruction and to evaluate its clinical efficacy by estimating stent patency and patient survival rates.

MATERIALS AND METHODS

Twenty-six patients with common bile duct stricture caused by malignant disease were treated by placement of 29 stents. The stent consists of an inner ePTFE/FEP lining and an outer supporting structure of nitinol wire. Multiple wire sections elevated from the external surface provide anchoring. Stents are available in two versions, with or without holes in the proximal stent lining. Holes should provide drainage of the cystic duct or biliary side branches when covered by the proximal stent end. Clinical evaluation and assessment of serum bilirubin and liver enzyme levels were done before stent placement and at 1, 3, 6, and 9 months. Average follow-up duration was 5.4 months (range, 5 d to 12.5 mo).

RESULTS

Placement was successful in all cases. The 30-day mortality rate was 11.5%. The survival rates were 40% and 15% at 6 and 12 months, respectively. Eighty-four percent of patients had adequate palliative drainage during their lifetime. The stent patency rates were 91%, 77%, and 77% at 3, 6, and 12 months, respectively. Four patients (16%) presented with stent occlusion and needed repeat intervention. No migration occurred. Complications other than stent occlusion occurred in five patients (19%); among these, acute cholecystitis was observed in three patients (12%).

CONCLUSION

Preliminary results suggest that placement of this ePTFE/FEP-covered stent is feasible and effective in achieving biliary drainage. The percentage of patients undergoing lifetime palliation and the midterm patency are promising. However, the incidence of acute cholecystitis is high. Treatment of a larger group of patients is mandatory to validate these long-term results.