Omitting side-holes in biliary stents does not improve drainage of the obstructed biliary system: a prospective randomized trial

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.

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

Background/Aims

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

Methods

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

Results

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

Conclusions

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

Biliary endoprosthesis: a prospective analysis of bacterial colonization and risk factors for sludge formation

Bacterial colonization of biliary stents is one of the driving forces behind sludge formation which may result in stent occlusion. Major focus of the study was to analyze the spectrum and number of microorganisms in relation to the indwelling time of stents and the risk factors for sludge formation. 343 stents were sonicated to optimize the bacterial release from the biofilm and identified by matrix-associated laser desorption/ionization-time of flight mass spectrometer (MALDI-TOF). 2283 bacteria were analyzed in total. The most prevalent microorganisms were Enterococcus species (spp.) (504;22%), followed by Klebsiella spp. (218;10%) and Candida spp. (188;8%). Colonization of the stents mainly began with aerobic gram-positive bacteria (43/49;88%) and Candida spp. (25/49;51%), whereas stents with an indwelling time>60 days(d) showed an almost equal colonization rate by aerobic gram-negative (176/184;96%) and aerobic gram-positive bacteria (183/184;99%) and a high proportion of anaerobes (127/184;69%). Compared to stents without sludge, more Clostridium spp. [(P = 0.02; Odds Ratio (OR): 2.4; 95% confidence interval (95%CI): (1.1-4.9)]) and Staphylococcus spp. [(P = 0.03; OR (95%CI): 4.3 (1.1-16.5)] were cultured from stents with sludge. Multivariate analysis revealed a significant relationship between the number of microorganisms [P<0.01; OR (95%CI): 1.3(1.1-1.5)], the indwelling time [P<0.01; 1-15 d vs. 20-59 d: OR (95%CI): 5.6(1.4-22), 1-15 d vs. 60-3087 d: OR (95% CI): 9.5(2.5-35.7)], the presence of sideholes [P<0.01; OR (95%CI): 3.5(1.6-7.9)] and the occurrence of sludge. Stent occlusion was found in 70/343(20%) stents. In 35% of cases, stent occlusion resulted in a cholangitis or cholestasis. In conclusion, microbial colonization of the stents changed with the indwelling time. Sludge was associated with an altered spectrum and an increasing number of microorganisms, a long indwelling time and the presence of sideholes. Interestingly, stent occlusion did not necessarily lead to a symptomatic biliary obstruction.

A comparative evaluation of early stent occlusion among biliary conventional versus wing stents

BACKGROUND AND STUDY AIMS

Conventional plastic stents with a lumen typically have limited patency. The lumenless wing stent was engineered to overcome this problem. The objective of this study was to compare the incidence of early stent occlusion (symptomatic occlusion/cholangitis necessitating re-insertion within 90 days) for wing stents and conventional plastic stents.

PATIENTS AND METHODS

Patients with biliary pathology treated with plastic biliary stenting during the period 2003-2009 comprised the study cohort. Patients who had at least one biliary wing stent placed comprised the wing stent group, whereas patients who underwent only conventional stent plastic placement comprised the conventional stent group. Patients were stratified by indication: benign biliary strictures (group 1), malignant biliary strictures (group 2), or benign biliary non-stricture pathology (group 3). The association of stent type with the occurrence of primary outcome by indication was analyzed by use of multivariable logistic regression.

RESULTS

Three-hundred and forty-six patients underwent 612 ERCP procedures with placement of plastic biliary stent(s). On multivariate analysis, early stent occlusion did not differ between the wing and conventional groups in groups 1, 2, and 3. Among patients who achieved primary outcome in group 2, significantly fewer patients in the wing group had cholangitis (6.7% vs. 39.1%, P = 0.03). Among patients who achieved primary outcome in group 3, significantly fewer patients in the wing group had cholangitis (10% vs. 50%, P = 0.03).

CONCLUSIONS

Early stent occlusion was similar for wing stents and conventional plastic stents. Wing stents, however, were associated with a lower incidence of cholangitis in patients with malignant biliary obstruction and benign non-stricturing biliary pathology.

Repeat Procedures Within 30 days in Patients Stented for Malignant Distal Biliary Strictures: Experience of 508 Patients at a Tertiary Referral Center

Background

Stent related occlusion and migration remains a problem despite attempts to improve stent design over this time period. Flanged polyethylene plastic stents (FPS) remains the stent of choice in most centers. Early failure of stents placed for malignant extrahepatic biliary strictures (MEBS) has not previously been studied in detail. We set out to determine the incidence and reasons for biliary stent change within 30 days of the index procedure in a large tertiary center population during a period where (FPS) was the sole plastic stent used.

Methods

Retrospective analysis of endoscopic retrograde cholangiography (ERCP) was undertaken in patients who were stented for presumed or known MEBS between 1993 and 2001. Patients who required repeat stenting within 30 days were identified.

Results

All 508 patients were stented for MEBS. 5.7% of patients had a total of 34 repeat stenting procedures within 30 days of the index procedure; 27of 29 index stents were plastic, 2 were self-expandable metal stents (SEMS), 20 (3.9%) patients had stent failure as the reason for a stent exchange (plastic stent occlusion n = 15, mean time to stent change 14 ± 8.3 days; metal stent occlusion n = 2, mean time to stent change 24.5 ± 7.8 days; plastic stent migration n = 3, mean time to stent change 25 ± 5.3 days). There was a statistically significant difference in the time to stent change between the occluded plastic stent and migrated plastic stent cases (P = 0.045, 95% CI -21.7 to -0.29). 6 patients spent at least 2 additional days in hospital as a result of stent failure.

Conclusions

Early stent failure is an uncommon problem, especially in patients with SEMS. Early plastic stent failure appears to occur sooner with stent occlusion than with stent migration. Early stent failure is associated with significant morbidity and bears an economic impact in additional procedures and hospital stay.

Efficacy of the new double-layer stent for unresectable distal malignant biliary obstruction: a single-center retrospective study

Background and Aims. For distal malignant biliary obstruction in cases with short life expectancy, occlusion of plastic stents (PSs) does not usually occur before death, and the application of such a procedure is considered adequate from the viewpoint of cost-effectiveness. Methods and Setting. A new commercially available DLS with side holes, a conventional DLS, and, uncovered self-expanding metal stents (SEMSs) were retrospectively evaluated in patients with jaundice due to unresectable distal malignant biliary obstruction. Results. A total of 64 patients received endoscopic biliary stenting (23 patients with the new DLS, 24 patients with conventional DLS, and 17 patients with uncovered SEMS) from December 2002 to August 2009. Median patency time was found to be 198 days for the new DLS group and 99 days for the conventional DLS group, revealing a significant difference between devices. There was, however, no significant difference in median patency time between the new DLS and the uncovered SEMS (198 days versus 344 days). Conclusion. The new DLS is efficient and safe and may be considered the first choice for unresectable distal malignant obstruction in cases with short life expectancy.

Management of empyema of gallbladder with percutaneous cholecysto-duodenal stenting in a case of hilar cholangiocarcinoma treated with common bile duct metallic stenting

Empyema of the gallbladder develops when the gallbladder neck is obstructed in the presence of infection, preventing pus from draining via the cystic duct. Treatment options include cholecystectomy or, in patients with comorbidities, drainage via percutaneous cholecystostomy, later followed by cholecystectomy. Here, we describe a 59-year-old man who presented with complaints of recurrent hiccups and was found to have cholangiocarcinoma causing obstruction to cystic duct drainage. The patient was managed successfully by percutaneous transhepatic cholecysto-duodenal self-expandable covered metal stent.

Percutaneous transhepatic cholecystoduodenal stent for empyema of the gallbladder

Acute cholecystitis is treated by antibiotics and cholecystectomy. When the gallbladder neck is obstructed in the presence of infection, preventing pus from draining via the cystic duct, an empyema of the gallbladder develops. Under these circumstances, treatment may be either cholecystectomy or, in the presence of significant comorbidity, by drainage via percutaneous cholecystostomy, followed at a later date by cholecystectomy. We present the case of a patient who presented acutely with an attack of cholecystitis and refused to undergo a cholecystectomy owing to previous respiratory arrest following general anaesthesia. She settled with intravenous antibiotic treatment and was discharged. However, she presented shortly afterwards with a further attack of cholecystitis that was refractory to intravenous antibiotics and so was treated initially with percutaneous drainage. This was subsequently replaced with interno-external drainage of the gallbladder (transpapillary cholecystoduodenal stent) with the use of a J-J ureteric stent, which was then fully internalised. She remained well following this procedure and was discharged home. The long-term patency of the stent is not known and we hope that no further intervention will be required, but if necessary the stent could be exchanged endoscopically, by a percutaneous route, or via a combined approach.

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.

Endobiliary stents for palliation in patients with malignant obstructive jaundice

BACKGROUND

Endobiliary drainage for malignant obstructive jaundice presents a viable palliative alternative. Its role and efficacy depend on factors related to the stent, procedure, and patient.

GOALS

To review the evidence in the literature in which settings plastic or metal stents are cost-effective, and whether adjuvant measures or patient-related factors affect duration of stent patency.

STUDY

Using databases a literature search was performed for papers published from 1979 to April 2004. All retrieved papers reporting experimental or clinical observations were rated according to strength of evidence, and carefully analyzed.

RESULTS AND CONCLUSIONS

Metal stents (Wallstent) stay patent longer than plastic stents (large-bore polyethylene with side-holes), overall median 250 and 110 days, respectively, and seem cost-effective in patients with longer than about 6 months survival, which cannot be accurately predicted. Antibiotics or choleretic agents do not prolong stent patency in clinical settings. In case of stent occlusion, indicated stent exchanges and insertion of a plastic stent, respectively, seem cost-effective in patients initially treated with plastic and metal stents.

The role of ciprofloxacin in prolonging polyethylene biliary stent patency: a multicenter, double-blinded effectiveness study

Plastic stents are the mainstay of the palliation of malignant jaundice but are complicated by recurrent obstruction. Previous trials have failed to demonstrate any improvement in patency with the use of antibiotics. Patients with malignant jaundice were randomized in a double-blind fashion, after polyethylene stent insertion, to receive ciprofloxacin or placebo. After successful stent decompression, there were 50 patients in the treatment arm and 44 in the placebo. There were 14 (33%) episodes of stent occlusion in the ciprofloxacin group versus 23 (49%) in placebo (chi(2) test, P=0.115). There was no significant difference in patency (log-rank test, P=0.17). There were significantly fewer episodes of cholangitis with ciprofloxacin: 10 (23%) versus 21 (42%) in the placebo (P=0.047). The ciprofloxacin group also demonstrated a significant improvement in the Social Function domain of the SF-36 Quality of Life Survey at 1 month (paired T test, P=0.03). The other domains of the SF-36 were not different, nor was survival (log rank, P=0.80). There is insufficient evidence to show that prophylactic ciprofloxacin can prolong plastic biliary stent patency. The observed trends suggest that ciprofloxacin significantly decreases the incidence of cholangitis and results in improvements in certain aspects of quality of life.

A prospective randomized trial of Tannenbaum-type Teflon-coated stents versus polyethylene stents for distal malignant biliary obstruction

OBJECTIVE

Stent clogging is a major limitation in the palliative treatment of malignant biliary obstruction. Preliminary studies suggested improved duration of patency of a Tannenbaum design stent with a stainless steel mesh and an inner Teflon coating (TTC). We compared the patency of a TTC stent with a conventional polyethylene (PE) stent in a prospective randomized trial.

METHODS

Between February 1998 and September 1998 we included 60 patients with distal malignant bile duct obstruction. Diagnosis included carcinoma of the pancreas (n = 57) and ampullary cancer (n = 3). There were 29 men and 31 women with a median age of 77 years. Stent diameter (10 Fr) and length (11 cm) were similar but both stent design and material were different: a Tannenbaum design stent with a stainless steel mesh and an inner Teflon coating, and an Amsterdam-type PE stent.

RESULTS

Sixty patients were evaluated; 30 in the TTC group and 30 in the PE group. Early complications occurred in two patients in each group. Stent dysfunction occurred in 18 of TTC stents and 12 of PE stents. Median stent patency was 102 days for TTC and 142 days for PE stents (P = 0.41). Median survival did not differ significantly for both treatment groups (TTC, 121 days; PE, 105 days). Stent migration, in all cases proximal into the common bile duct, occurred in four patients in the TTC group versus zero in the PE group (P = 0.038).

CONCLUSIONS

This study did not confirm improved patency of Tannenbaum-type Teflon-coated stents. Proximal migration prompts for additional design modifications.

Prospective, randomized, single-center trial comparing 3 different 10F plastic stents in malignant mid and distal bile duct strictures

BACKGROUND

The aim of this study was to determine whether patency rates differ with respect to the material, design, and surface texture of 3 different plastic stents.

METHODS

A total of 120 patients (median age 70.5 years; interquartile range 62-78 years) with malignant mid or distal bile duct strictures, seen between March 1996 and May 1999, were prospectively randomized to receive a 10F polyurethane stent, a Teflon Tannenbaum stent, or a hydrophilic hydromer-coated polyurethane stent. The primary study outcome measure was the interval between stent insertion and the first episode of clogging (or the presence of jaundice at death without stent exchange). All 3 types of stent were studied by scanning electron microscopy before insertion.

RESULTS

A total of 19 patients were excluded from long-term follow-up. Median duration of stent patency was 76 days overall (interquartile range 29-150 days) and 76 (interquartile range 30-110) days for hydrophilic hydromer-coated polyurethane, 108 (interquartile range 33-186) days for 10F polyurethane, and 58 (interquartile range 21-188) days for Teflon Tannenbaum stents. There were no statistically significant differences among stent types. The hydrophilic hydromer-coated stent had the smoothest surface, as visualized by scanning electron microscopy.

CONCLUSIONS

No significant differences in the patency of 3 types of stents were detected in this randomized trial. In particular, the hydrophilic hydromer-coated plastic stent did not provide clinical advantages despite its smooth surface.

Efficacy of plastic tube stents without side holes for middle and lower biliary strictures

BACKGROUND

Although biliary expandable metallic stents (EMS) improve patency, they are unsuitable for primary biliary stenting. Although plastic tube stents without side holes (PWOS) are also reported to prolong patency, their efficacy remains controversial.

GOALS

To evaluate clinical utility and relative advantages, we reviewed clinical results of three types of stents: plastic tube stents with side holes (PS), PWOS, and EMS.

STUDY

The 130 patients comprised 56 with pancreatic cancers, 26 with gallbladder cancers, 21 with bile duct cancers, and 27 with other malignant diseases. Plastic tube stents with side holes (10 French [Fr]), PWOS (10 Fr), and EMS (30 Fr) were inserted in 64, 28, and 38 cases, respectively.

RESULTS

Overall cumulative stent patency rates for EMS and PWOS groups were significantly higher than that of PS. This was also the case with middle and lower biliary tract strictures and with pancreas cancers. In Japan, medical costs with endoscopic retrograde cholangiopancreatography ($631.00) divided by the mean patent period with PS, PWOS, and EMS were $8.80/d, $4.60/d, and $20.40/d, respectively.

CONCLUSION

We recommend PWOS for primary biliary stenting of middle and lower biliary strictures, especially those caused by pancreatic cancer, based on its lower price and sufficient patency without replacement after diagnosis of inoperability.

A chemical analysis of the clogging process of polymeric biliary endoprostheses

Insertion of polymeric biliary endoprostheses is widely used as a method of palliation of malignant strictures of the biliary tree. Despite the success of this technique, clogging of the stent in a few months is still an existing problem. The aim of the present study has been to investigate the causes of the obstruction, considering both the stent material and the composition of the obstructing deposit. 16 ready-to-implant and 33 occluded retrieved prostheses were analysed by ATR-FTIR spectroscopy. The clogging sludge was recovered and studied by FTIR spectroscopy and pyrolysis derivatisation/gas chromatography/mass spectrometry (Py/GC/MS). The results of the analyses showed that the deposit was mainly formed by proteins, bilirubin, calcium palmitate and bilirubinate, cholesterol and its fatty acids salts. It was found that approximately 50% of the examined ready-to-implant samples were made of ethylene-vinylacetate copolymer (EVA) instead of polyethylene (PE), as was stated in the producer declaration. Moreover, 94% of the retrieved samples were found to be made of EVA indicating that this material is less suitable than PE for this application. All retrieved PE and EVA stents showed a protein-like black layer strongly absorbed on the surface.

Effect of antibiotic-loaded hydrophilic stent in the prevention of bacterial adherence: a study of the charge, discharge, and recharge concept using ciprofloxacin

BACKGROUND

Ciprofloxacin prophylaxis significantly prolonged stent patency in cats, but human studies produced conflicting results, possibly due to varying drug levels in bile. The uptake (charge) and release (discharge) of ciprofloxacin from a hydrophilic stent (HS) in an antibiotic solution and the effect of a ciprofloxacin-loaded stent (CHS) in inhibiting Escherichia coli adherence were tested. The adjuvant effect of ciprofloxacin perfusion (recharge) in the inhibition of E coli adherence was also tested.

METHODS

Uptake: segments of HS were immersed in 5 mL of ciprofloxacin solutions for 24 hours. Ciprofloxacin remaining in solution was measured to determine the uptake by the HS. Release: CHS were placed in 5 mL water for 24 hours, and released ciprofloxacin was measured. CHS were placed on culture plates with E coli and incubated; diameters of inhibited zones were measured. CHS 0.5 cm in length were incubated in separate 5 mL E coli suspension (10(7) colony forming units [CFU]/mL) in 2% ox bile for 4 hours. E coli adhered on CHS were measured and compared with control HS. An E coli (10(6) CFU/mL) suspension was perfused through a modified Robbins device (MRD)-containing CHS. Stents were removed at regular intervals and processed to determine the adherence of E coli; non-loaded HS served as controls. The experiment was repeated by using CHS together with perfusion of ciprofloxacin solution (0.3 microg/mL) into the MRD for up to 7 days; normal saline solution was used as a control in a second MRD. Stents were removed daily to determine the adherence of E coli.

RESULTS

Uptake and release of ciprofloxacin by HS and CHS, respectively, were related to concentration of ciprofloxacin. Between 50% to 90% of the drug was released in 24 hours. Zonal inhibition of E coli growth was proportional to the concentration of ciprofloxacin on the CHS. There was an initial 10-fold reduction in attached E coli on CHS compared with controls, but this effect diminished after 24 hours. With ciprofloxacin perfusion, there was a 100-fold reduction in adhered E coli on CHS, although there was no change in E coli concentration in bile.

CONCLUSIONS

There was a free exchange (uptake and release) of ciprofloxacin along a concentration gradient between the antibiotic solution and HS. CHS reduced the number of adhered E coli, but the effect was short-lived. Perfusion of ciprofloxacin offers an adjuvant benefit by enhancing inhibition of E coli adherence on CHS.

Endoscopic palliation for inoperable pancreatic cancer

BACKGROUND

The majority of patients with pancreatic cancer are not candidates for surgical resection. Palliative therapy remains the cornerstone of management of this population.

METHODS

We reviewed recent clinical and experimental studies on endoscopic palliative therapy of inoperable pancreatic cancer.

RESULTS

Endoscopic placement of a biliary stent is the preferred mode of palliation of obstructive jaundice in patients with pancreatic cancer. The techniques of endoscopic stent insertion are briefly described. Episodic recurrence of jaundice and cholangitis due to stent occlusion is a major drawback of biliary polyethylene stents. Self-expandable metal stents with large diameters have lower rates of stent occlusion and are cost effective in patients who are expected to survive beyond 3 months. Palliation of duodenal obstruction with self-expandable enteral stents and endosonography-guided celiac plexus neurolysis are emerging options for the treatment of patients with advanced pancreatic cancer.

CONCLUSIONS

Endoscopic therapy offers safe and effective management options for palliation of major symptoms associated with inoperable pancreatic cancer.

Is prophylactic ciprofloxacin effective in delaying biliary stent blockage?

BACKGROUND

Late stent blockage is a major complication of endoscopic stent insertion for malignant obstructive jaundice. Stents block as a result of bacterial infection and biofilm formation. We report a randomized but unblinded study using an animal model to evaluate the effect of prophylactic ciprofloxacin, which selectively suppresses gram-negative bacteria, in an attempt to prolong stent patency.

METHOD

Ten adult cats underwent surgical implantation of 5F polyethylene stents through common bile duct strictures created around the choledochotomy, with the tip of the stent left in the duodenum. Five animals received intravenous ciprofloxacin perioperatively and were then maintained on oral ciprofloxacin 25 mg twice daily. Control cats were not given antibiotics. The animals were sacrificed when signs of biliary obstruction or cholangitis persisted for more than 3 days or at the end of the 16-week study period. Stents were removed and examined for patency. In addition, the stents were cultured to recover the adherent bacteria.

RESULTS

All control animals developed stent blockage within 4 weeks. Two ciprofloxacin-treated cats developed stent blockage at 21 and 42 days, respectively, whereas the other 3 cats had patent stents for the entire study period. There was a significant difference between the median stent patency of 112 days for the ciprofloxacin group versus 16 days for the control group (p < 0.02). Bacteriologic cultures showed that the bile and blocked stents from the control group had predominantly gram-negative bacteria, whereas the bile and stents of the ciprofloxacin group had gram-positive and anaerobic bacteria, with an absence of gram-negative bacteria (p < 0.01).

CONCLUSION

Ciprofloxacin prophylaxis eliminates gram-negative bacterial infection in bile and minimizes sludge formation and may have a potential benefit in delaying stent blockage.

In vitro evaluation of antibiotic prophylaxis in the prevention of biliary stent blockage

BACKGROUND

Bacterial adherence and biofilm formation are important factors in the blockage of biliary stents. Clinical studies with oral antibiotic prophylaxis to prevent stent blockage have produced conflicting results. The aim of this study was to evaluate the in vitro effect of single antibiotic (ciprofloxacin, ceftazidime, or ampicillin) treatment on adherence of Escherichia coli and Enterococcus to plastic stents.

METHODS

Selected clinical isolates of E coli and Enterococcus were perfused through a modified Robbins device containing segments of polyethylene stents. The stents were removed daily and the number of bacteria attached was measured. The effect of antibiotic treatment on bacterial adherence was tested by the perfusion of individual antibiotics into separate modified Robbins devices using a side-arm adaptor and the results were compared with saline controls.

RESULTS

Compared with the saline controls, ciprofloxacin and ceftazidime caused a 10- to 100-fold reduction in the number of E coli attached to the stents, whereas ampicillin had no effect on adherence of E coli. Ampicillin caused a 5- to 10-fold reduction in Enterococcus adherence but there was no change with ceftazidime. Sustained reduction in E coli adherence was observed with prolonged ciprofloxacin perfusion.

CONCLUSION

Timely treatment with appropriate antibiotics reduced bacterial adherence in vitro and may be potentially beneficial in the prevention of stent blockage.

A scanning electron microscopic study of biliary stent materials

BACKGROUND

Clogging of biliary stents remains an important problem. In vitro studies have shown less sludge formation in Teflon stents. Recently, clinical studies with Teflon stents have produced contradictory results. The aim of this study was to investigate whether the surface properties of the endoprostheses could explain the variation observed in clinical studies.

METHODS

A total of 9 different types of unused 10F endoprostheses were examined by scanning electron microscopy (SEM): polyethylene Amsterdam-type, polyurethane Amsterdam-type, Teflon Amsterdam-type, Teflon Tannenbaum-type and a Tannenbaum-type stent with a thin stainless steel mesh between inner and outer layers.

RESULTS

All polyethylene stents had a relief with tiny lumps. All Teflon stents had multiple shallow pits and ridges along the entire longitudinal axis. Both Tannenbaum-type stents also had multiple particles protruding into the stent lumen with adjacent holes in the wall of the stent. The polyurethane stent had an extremely smooth surface.

CONCLUSION

SEM of Teflon made stents showed a markedly irregular inner surface, which may explain the controversial results of clinical studies. Our results indicate that the inner surface of a new stent should first be evaluated by SEM before clinical trials are initiated.

Polyethylene stent blockage: a porcine model

BACKGROUND

Endoscopic insertion of biliary stents is a useful treatment for obstructive jaundice resulting from unresectable tumors of the pancreas and biliary tree. The main drawback is the recurrence of jaundice due to clogging. The aim of this study was to establish an experimental model of polyethylene stent clogging in large white pigs.

METHODS

A straight polyethylene stent of 5F (group I), 7F (group II) or 10F size (group III) was inserted in the common bile duct. Animals were killed at 2 months, or earlier if physical signs suggesting stent clogging occurred. Chemicophysical analysis of stent deposition combined stereomicroscopy and identification of the contents by means of Fourrier transform infrared spectroscopy. Bacteriologic analyses included identification of aerobic and anaerobic bacteria and measurement of beta-glucuronidase, lecithinase and lipase activities.

RESULTS

Physical signs suggesting stent obstruction or death occurred in 8 of 8 animals in group I, 11 of 12 in group II, and 2 of 8 in group III (p < 0.001). The proportion of mucoprotein in the stent contents tended to fall with increasing stent diameter (mean 82%, 58% and 47% for 5F, 7F and 10F, respectively), whereas wheat starch and calcium bilirubinate content increased with increasing stent diameter (9% and 4%, 18% and 10%, and 29% and 23% for 5F, 7 F, and 10F, respectively), although none of these differences were statistically significant. A variety of bacteria were cultured from the stent deposits, including anaerobic strains. Clostridium species were associated with the highest enzyme activities.

CONCLUSIONS

In this model the major component of early stent deposits was mucoprotein, and numerous aerobic and anaerobic bacteria were isolated. Formation of calcium bilirubinate was a late phenomenon and poorly related to bacterial enzymatic activities.

Hydrophilic hydromer-coated polyurethane stents versus uncoated stents in malignant biliary obstruction: a randomized trial

BACKGROUND

Hydromer-coated polyurethane stents (HCPS) have a low coefficient of friction that may reduce sludge formation and potentially increase stent longevity.

METHODS

Eighty-three patients (39 men, mean age 69.3 years) with malignant mid or distal bile duct strictures were prospectively randomized to receive either 10F HCPS (n = 40) or standard polyethylene stents (n = 43).

RESULTS

Fifteen patients (18.1%) underwent surgery after stent insertion. Six patients were lost to follow-up (7.2%), whereas 34 died of the underlying disease without evidence of stent occlusion (15 HCPS group and 19 polyethylene group). Median survival was 75 days (range 15 to 372 days) and 108 days (range 25 to 325 days) in the HCPS and polyethylene stent groups, respectively (p = not significant). Stent occlusion was observed in 25 patients (42%), 16 with HCPS stents and 9 with polyethylene stents, with a median patency of 103 days (range 40 to 280 days) and 68 days (range 32 to 175 days), respectively (p = not significant).

CONCLUSIONS

HCPS do not appear to provide significant clinical advantages in terms of stent longevity over standard plastic prostheses.

Prospective randomized trial comparing Tannenbaum Teflon and standard polyethylene stents in distal malignant biliary stenosis

BACKGROUND

Our aim was to compare the clinical efficacy of the Tannenbaum (TB) biliary prostheses, a recently designed Teflon stent without side holes, with the Cotton-Huibregtse (CH) polyethylene stent.

METHODS

Fifty-seven patients (26 men, mean age 75.5 years) with unresectable malignant tumors and distal biliary stenosis were included (38 pancreatic head cancer, 17 cholangiocarcinoma, 2 ampullary cancer). Patients were prospectively randomized to have a 10F, 7 cm long TB (29 patients) or CH (28 patients) stent inserted endoscopically. Four patients (2 TB and 2 CH) were excluded: 3 because of the failure of stent insertion and 1 because of a protocol violation. The patients were evaluated clinically and, if necessary, with biochemical tests every month until death or until they needed surgery for symptoms of gastric outlet obstruction. When occlusion or dislocation occurred, the stent was replaced with one of the same type. Cumulative stent patency and patient survival were estimated with the Kaplan-Meier life-table analysis and compared by log-rank chi-square test.

RESULTS

The two groups were comparable in mean age, gender, and diagnosis. The patients were followed for a mean of 145.5 days (range 24 to 613); by the end of the study 47 patients (81%) had died or developed symptoms of gastric outlet obstruction. Median survival was 88 days (range 24 to 613) in the TB group and 75.6 days (23 to 486) in the CH group. Stent exchange (occlusion 16, dislocation 3) was necessary for 5 patients in the TB group and 7 in the CH group. No statistical difference was found on comparing the mean duration of function of the first, second, and third stents (analysis of variance, p = 0.80). The median duration of stent function was 96 days (range 11 to 613) in the TB group and 75.5 days (range 23 to 323) in the CH group. No significant difference was found in either survival time (p = 0.48) or stent patency (p = 0.12).

CONCLUSION

This study found no significant advantage of the Tannenbaum prostheses over the standard polyethylene stent in the palliation for patients with distal malignant biliary stenosis with regard to survival or length of stent patency.

Long-term ciprofloxacin treatment for the prevention of biliary stent blockage: a prospective randomized study

OBJECTIVE

In vitro experimental and animal studies have shown that quinolones reduce the adherence of bacteria on a polyethylene tube and prevent stent blockage. Our aim was to see whether ciprofloxacin prevents stent blockage in patients with malignant stricture of the biliary tract.

METHODS

Patients with inoperable biliary or pancreatic tumor not involving the bifurcation of the common hepatic duct were recruited. They were randomized to receive either endoscopic stenting alone or stenting with prophylactic treatment of ciprofloxacin (200 mg i.v. before stenting, followed by 250 mg orally twice per day). In each follow-up visit, clinical symptoms of cholangitis were documented and blood samples taken for blood counts, serum levels of bilirubin, and alkaline phosphatase. Stent blockage was defined as clinical symptom(s) of cholangitis with biochemical or radiological evidence of stent dysfunction.

RESULTS

Fifty-eight patients were recruited into the study. Three patients in the stenting group and three in the ciprofloxacin group were excluded after randomization. Eleven patients received stenting alone and five patients receiving ciprofloxacin had previous endoscopic stenting. Thirteen patients (50%) in the ciprofloxacin group and eight patients (31%) in the stenting group died before stent blockage. Ten patients (38%) in each group had stent blockage during the follow-up at 20 wk. The median stent patency was 11.6 wk and 11.9 wk in the ciprofloxacin group and the stenting group, respectively. Kaplan-Meier analysis of stent patency showed no difference between the two groups. Among patients who received endoscopic stenting for the first time, there was a trend favoring ciprofloxacin treatment, but the difference was not significant. The 30-day and 20-wk mortality between the groups were comparable.

CONCLUSION

Long-term use of ciprofloxacin does not prevent blockage of polyethylene biliary stents.

The effect of endoscopic sphincterotomy on acute and chronic complications of biliary endoprostheses

BACKGROUND

Endoscopically placed biliary stents have become routine therapy for bile duct obstruction and bile leaks. Controversy exists regarding the use of biliary sphincterotomy to facilitate placement of 10F plastic stents.

METHODS

We retrospectively studied the effect of sphincterotomy on acute and chronic complications of 10F stent therapy. Data for acute complications, 30-day mortality and stent migration were obtained for 130 patients undergoing placement of a single 10F plastic biliary stent. For 109 patients in whom prolonged stent therapy was undertaken, the occurrence of and time to stent dysfunction were also analyzed. Sphincterotomy was performed in 48 cases (36.9%) based on physician preference.

RESULTS

There were no failures in stent placement. The incidence of acute complications was higher in patients undergoing sphincterotomy (8.3% vs. 1.2%, p = 0.04). Stent migration was more common in the no sphincterotomy group versus the sphincterotomy group (8.5% vs. 0, p = 0.03).

CONCLUSIONS

Sphincterotomy is not necessary for placement of 10F plastic stents and increases acute procedural morbidity. Interestingly, a higher incidence of stent migration was seen in patients who did not undergo biliary sphincterotomy.

A combination of ciprofloxacin and Rowachol does not prevent biliary stent occlusion

BACKGROUND

Endoscopic insertion of biliary prostheses is now an established palliative treatment for frail and elderly patients with distal extrahepatic malignant biliary strictures who are unable to tolerate major surgery. The major limitation to long-term biliary stenting is late stent occlusion caused by bacterial adherence followed by encrustation with amorphous bacterial products. We studied the effect on the duration of stent patency of combination therapy with ciprofloxacin and Rowachol, a choleretic agent, in a group of patients who underwent stent insertion for extrahepatic malignant biliary strictures.

METHODS

Patients with this diagnosis were randomized to either active treatment with ciprofloxacin (500 mg twice daily) and Rowachol (2 tablets 3 times daily) or no drug treatment (control group). They were followed up prospectively and the end points of the study were stent occlusion and patient survival.

RESULTS

Forty-eight patients who had successful stent placement were recruited; 8 patients were excluded from the final analysis because of death in less than 1 month (5 patients) or stent replacement within a month because of persistent jaundice (3 patients). Twenty patients were randomized to the active and control groups. One patient in the active group withdrew because of nausea. The 2 groups were comparable with regard to age, gender, causes of extrahepatic malignant biliary strictures, and levels of serum alkaline phosphatase and bilirubin. There were significant reductions in mean serum bilirubin and alkaline phosphatase concentrations 1 month after stent placement. At the time of analysis, 12 patients were still alive (7 patients from the control group). Median survival was 23 weeks in both the active treatment group and the control group. There were 9 episodes (45%) of stent occlusions in the active treatment group and 10 episodes (50%) in the control group. The median time to stent occlusion was 23 (range 7 to 68) weeks for the active treatment group and 21 (range 6 to 56) weeks for the control group, p = 0.23. There was no significant difference in the duration of patient survival and of stent patency between the 2 groups. The lack of difference between treated and untreated patients in survival duration and stent patency was also shown if the results were analyzed on an intent-to-treat basis and the 8 patients who were excluded in the final analysis were also analyzed.

CONCLUSIONS

Prophylactic therapy with ciprofloxacin and Rowachol does not prolong stent patency or patient survival.

Endoscopic palliation for unresectable pancreatic carcinoma

Endoscopic stenting has revolutionized the palliation of malignant biliary obstruction. Individuals with biliary obstruction due to pancreatic malignancy are best managed by a team approach comprising individuals with expertise in oncology, surgery, endoscopy, and radiology. The clinical value of alleviating jaundice and associated symptoms of anorexia, pruritus, and malaise cannot be overestimated. These quality-of-life factors deserve more attention in future studies to define subgroups of patients most likely to derive benefit from the array of treatment options. Further technical improvements are required to solve the most important clinical problem of late stent occlusion. New developments such as expandable metallic stents and refinements in existing equipment and techniques have already resulted in measurable gains and hold great promise for future expansion of their use in malignant gastric outlet obstruction secondary to tumor infiltration of the duodenum. Corresponding advances are being made in the fields of percutaneous transhepatic intervention and hepatobiliary surgery such that further prospective randomized trials are necessary to define optimal therapy.

Bacterial biofilm and clogging of biliary stents

Endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, durable endoscopic stenting has been limited by the clogging of biliary stents, usually after 4-5 months, due to formation of an adherent bacterial biofilm. Various methods have been investigated for the prevention of bacterial adhesion and prolongation of stent patency. These include: 1) prophylactic use of antimicrobial agents and bile salts; 2) testing of new stent material and new designs for these biliary stents; and 3) the recent introduction of self-expandable metal stents. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding the problem of stent occlusion.

Endoscopic stenting for palliation of malignant biliary obstruction. A review of progress in the last 15 years

Since the late 1970s, endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, endoscopic stenting therapy has been limited by the clogging of biliary stents, usually after four to five months, due to formation of adherent bacterial biofilm and accumulation of biliary sludge. Various methods for the prevention of bacterial adhesion and prolongation of stent patency have been investigated, including prophylactic antimicrobial agents and bile salts, new stent materials, and new stent designs. Recently, the introduction of self-expandable metal stents has significantly improved the duration of stent patency but the cost is considerably higher. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding stent occlusion.