The thermo-expandable metallic stent for managing benign prostatic hyperplasia: a systematic review

OBJECTIVES: To systematically review published reports of the safety, effectiveness and durability of a self-expanding metallic prostatic stent (Memokath, Engineers & Doctors A/S Ltd., Denmark) in patients with benign prostatic hyperplasia (BPH) who are unfit for surgery. METHODS: We systematically searched the Medline and Embase databases from 1992. The reference lists of included studies and the bibliographies of review articles were also searched. We contacted the manufacturer of Memokath for additional information. The primary outcomes were treatment failure (stent removal, replacement or repositioning) and urological symptom scores. Secondary outcomes were urodynamic indices and minor complications. Two reviewers independently assessed the methodological quality of the studies and extracted data. Data were synthesized using narrative techniques. RESULTS: In all, 14 case series described the use of the Memokath stent in 839 men with BPH. All patients were at high operative risk. Most studies were of poor quality with an inadequate follow-up. Treatment failure rates were 0-48% but the duration of follow-up was often unclear. Five studies reported International Prostate Symptom Scores and found reductions of 11-19 points after stent insertion. All seven studies that reported on maximum urinary flow rates found that these increased, and the four that described residual urine volumes found that these decreased. Minor complications were inconsistently reported. CONCLUSIONS: The Memokath stent can provide an effective treatment for BPH in men at high operative risk; it also appears to be safe, but inadequate follow-up does not allow firm conclusions on stent durability.     

Self-expanding stent insertion for urethral strictures: a 10-year follow-up

OBJECTIVE: To evaluate the safety and efficacy of the Urolume endourethral self-expandable metallic stent (American Medical Systems, MI, USA) in treating urethral strictures, based on a follow-up of> 10 years. PATIENTS AND METHODS: Between November 1989 and June 1990, the Urolume stent was inserted into 15 patients (aged 25-77 years) who had recurrent urethral strictures. The mean duration of stricture before stent insertion was 10.9 years. The patients (all men) were followed using a questionnaire and uroflowmetry, and if necessary, retrograde cysto-urethrography and/or urethroscopy and/or X-ray urodynamics. RESULTS: Two failures were caused by excessive tissue proliferation in the stent, which ended in stent removal or a suprapubic catheter. Another two stents were removed because of discomfort or pain. Two patients developed stenosis in the stent after 7 and 9 years. In the final evaluation only two of the 15 patients were satisfied with their stent. The mean maximum urinary flow rate at the last follow-up was 15 mL/s, and half the patients noted 'stent' incontinence. Lower urinary tract infections, urge and stress incontinence, and discomfort with ejaculation, were all symptoms perceived at the last follow-up. CONCLUSION: The long-term results of the Urolume stent in this study weaken the optimistic early results. Only two of the 15 patients were satisfied with their stent.     

The ‘buoy’ stent: evaluation of a prototype indwelling ureteric stent in a porcine model

OBJECTIVE

To assess a prototype ureteric ‘buoy’ stent with a 10 F upper body tapering to a 3F tail, developed to potentially reduce stent‐related irritative symptoms while providing an adequate mould for healing after endopyelotomy.

MATERIALS AND METHODS

Eighteen Yucatan minipigs had the stent placed either into the intact ureter (phase I) or after Acucise proximal endoureterotomy (phase II). Buoy stents were compared to 10/7 F endopyelotomy stents and to standard 7 F stents in phases I and II, respectively. The pigs were assessed for vesico‐ureteric reflux, hydronephrosis and infection, before stent insertion and at harvest. Stents were weighed before and after placement and the removal force was measured. Pressure/flow studies, antegrade nephrostograms and specimens for histopathology from the renal pelvis, ureter and vesico‐ureteric junction (VUJ) were obtained at harvest.

RESULTS

Thirteen minipigs survived the entire study. Ureteric flow with the stents in situ was better for buoy stents than for 10/7 F stents (P < 0.005). Ureteric flow after endoureterotomy and subsequent stent removal was similar for buoy stents and standard 7 F stents. None of the stents refluxed. There was no difference between stents in removal force, weight change or incidence of hydronephrosis. At 1 and 12 weeks, buoy stents tended to produce lower histopathological alteration scores than control stents, especially at the VUJ (phase I, 2.0 vs 3.9, P = 0.092; phase II, 0.6 vs 1.7, P = 0.18).

CONCLUSIONS

The novel buoy stents are easily placed and removed via the urethra. They can cause less VUJ inflammation than standard stents while allowing for adequate ureteric flow and healing after proximal endoureterotomy.     

Ureteric stenting after ureteroscopy for ureteric stones: a prospective randomized study assessing symptoms and complications

OBJECTIVE: To compare patients with and with no stenting after ureteroscopy for ureteric calculi, as placing such stents is routine, although many patients complain of pain and urinary symptoms. PATIENTS AND METHODS: In all, 45 patients with ureteric calculi amenable to ureteroscopic management were prospectively randomized into a stented (23) or an unstented (22) group. Standard ureteroscopic basketing and lithotripsy was used, through a ureteroscope (8.5 F) with or without ureteric dilatation. Symptom questionnaires were completed by the patients after treatment, and they were followed radiographically to assess stone-free rate and evidence of obstruction. RESULTS: There was no statistically significant difference in age, stone size, operative duration or hospital stay between the groups (P > 0.05). Furthermore, there was no statistical difference in flank pain or urinary symptoms (P > 0.05), except haematuria, between the groups; haematuria was more severe and prolonged in the stented group (P = 0.001). CONCLUSIONS: Uncomplicated ureteroscopy for removing calculi is safe with no stent after treatment, and after considering complications and side-effects we think that the routine use of ureteric stents after uncomplicated ureteroscopy for stone extraction is unnecessary.     

支架置入或经皮穿刺胃造瘘术治疗颈段高位食管狭窄20例

目的探讨支架置入或经皮穿刺胃造瘘在颈段高位食管狭窄治疗中的可行性和安全性。方法食管狭窄位于C7～T3 13例，在X线监视下经口置入球型单丝编织带膜的镍钛合金支架；食管狭窄位于C7以上7例，在内镜（1例）或X线透视引导下（6例）经皮穿刺胃造瘘术。结果手术全部成功，无严重并发症。置入食管内支架13例，术后吞咽困难程度改善0级10例，Ⅰ级3例。5例食管一气管瘘封堵成功。2例术后l周支架向下轻度移位，但仍能覆盖病变全长，未做处理。支架置入11例随访l～30个月，平均18个月，食管再狭窄3例，死亡8例，无支架嵌入气管诱发食管一气管瘘发生。经皮穿刺胃造瘘术7例，均在术后2d经饲管注入胃肠营养液及流质食物。1例术后1周出现造瘘口周围红肿感染，1例5个月造瘘管松动，无腹腔感染、腹膜炎和造瘘口内瘘等并发症。经皮穿刺胃造瘘7例随访1～18个月，5例死亡。结论颈段高位食管狭窄并非内支架置入治疗禁区。透视引导下经皮穿刺胃造瘘术，安全性高，并发症少，可作为改善生活质量、延长生存时间的首选治疗方法。     

Endoscopic biliary stenting: Plastic stent or expandable metallic stent?

Since its introduction 1979, endoscopic biliary stenting has become the method of first choice to treat cholestasis in malignant or benign biliary obstuction or leakage of biliary fistulas. The success rate of endoscopic biliary stenting generally exceeds 90% and procedure-related complications are rare. Although metal stents are becoming more popular, plastic stents are still the first choice. Their major drawback is occlusion with sludge mediated by bacteria. Pharmaco-chemical measures failed to prevent occlusion. With Teflon material and a 10-French stent, stent exchange rates were reduced to 15% in patients with malignant biliary obstruction, the shape without sideholes showing the best results. Stent exchange is easily feasable. Metal stents are expensive and more difficult to handle. Occlusion with sludge is rare, but patency is limited by tumor ingrowth. Metal stents may be indicated in selected patients, such as those with recurrent stent occlusion causing cholangitis. If only a small-caliber prosthesis (7-Fr) can be placed (e.g. in Klatskin tumor) metal stents may have a longer patency than plastic stents. Metal stents should not be used in benign biliary obstruction because these stents are not removable.     

食管支架置入术的临床应用

目的探讨食管支架置入术对良、恶性食管狭窄和食管瘘的治疗方法、疗效和并发症的处理。方法对55例不同原因所致良、恶性食管狭窄和食管瘘患者采用食管金属支架置入术。结果食管狭窄的主要症状吞咽困难、呛咳得到改善，近期疗效达100％。出现的并发症主要为疼痛和大便隐血，发生率分别为100％和92．7％，其余依次为胃食管返流、食管再狭窄、支架脱落，经过治疗后得到缓解或消失。结论金属支架置入术是治疗中晚期食管癌、狭窄的有效方法之一，对食管良性狭窄和瘘效果亦好。并发症可以预防，处理后大部分缓解。     

Analysis of ureteric stent kinking forces: the role of curvature in stent failure

OBJECTIVE

To further characterize the kinking forces and degree of curvature that result in failure of various stents, as malignant obstruction of the ureter causes failure of about half of ureteric stents.

MATERIALS AND METHODS

Several stents (Silhouette 4.6 F and 6 F, Applied Medical, Rancho Santa Margarita, CA; Sof‐Curl^TM Tecoflex 6 F, Gyrus ACMI, Southborough, MA; Polaris^TM Ultra 6 and 7 F, and Percuflex® 6, 7 and 8 F stents, Boston Scientific, Natick, MA, USA) were tested. The amount of force necessary to result in kinking of the stent was measured, and the degree of curvature at failure was calculated for each stent.

RESULTS

The Silhouette 4.6 and 6 F stents were the most resistant to failure by kinking and curvature. In general, smaller stents allowed more curvature before failing than their larger counterparts.

CONCLUSIONS

The greater allowable curvature and resistance to kinking achieved by the Silhouette ureteric stents might result in fewer stent failures in cases of malignant obstruction or other retroperitoneal processes.     

The self-expanding metallic ureteric stent in the long-term management of benign ureteric strictures

OBJECTIVE: To evaluate and assess the long-term complications of using the thermo-expandable, nickel-titanium alloy stent (Memokath 051, Engineers & Doctors A/S, Hornbaek, Denmark) for managing benign ureteric strictures. PATIENTS AND METHODS: Over a 3-year period, 13 Memokath stents were inserted in 11 patients (mean age 58 years, range 35-85) with 12 lower ureteric strictures. The cause of the stricture was benign in all cases, i.e. radiation fibrosis in three, retroperitoneal fibrosis, ischaemic uretero-ileal anastomosis and scarring after ureteroscopy in two each, and diathermy damage, extraluminal endometriosis and stone passage in one each. Four stents were 9 F with proximal expansion to 17 F and the other nine used were 10.5 F with proximal expansion to 20 F. The patients were followed for a mean (range) of 18 (1.5-33) months. RESULTS: No complications or side-effects occurred with nine stents; four stents were removed at a mean (range) of 16.3 (4-33) months. Three of these had become encrusted, two of which had been placed in patients who had either a history of stone disease or recurrent urinary tract infection. The other stent had migrated. CONCLUSION: The Memokath stent appears to have a useful role in managing benign ureteric strictures, but it must be closely monitored in patients who are predisposed to encrustation.     

Self-expanding silicone stent for treatment of postoperative colorectal stricture in an infant with Hirschsprung's disease: a case report

Benign colorectal strictures can be a complication of intestinal surgery, with limited options for endosopic intervention. In this report, we describe a case where a removable silicone stent was temporarily placed to successfully treat a benign post operative stricture in an infant with Hirschprung's disease.     

The efficacy and safety of ureteral dilation and long-term type ureteral stent for patients with ureteral obstruction

ObjectiveThis study was conducted to investigate the efficacy and safety of ureteral dilation and placement of a long-term ureteral stent for patients with various types of ureteral obstructions.MethodsWe retrospectively reviewed the records of 39 patients presenting with ureteral obstruction secondary to malignant strictures (n = 9) or nonmalignant strictures (n = 30). The mean age of these patients was 55.8 ± 16.1 years (range, 13–87 years). All patients underwent retrograde ureteral balloon dilation and placement of one to three ureteral stents. Stent patency rate and complications including febrile urinary tract infection, stent encrustation, and stent fragmentation were recorded.ResultsA total of 117 ureteral stents were implanted during the 83 procedures. Three stents were placed in seven patients and two stents in 20 patients. The patency rate was 95.2% with a mean 75-day follow-up. There was no encrustation in 104 stents and Grade 1 in 13 stents. The patency rate was similar between the patients with malignant strictures and those with nonmalignant strictures (100% vs. 94.7%, p = 0.57). However, three episodes of febrile urinary tract infection were noted only in patients with malignant strictures. The improvement of hydronephrosis and complications were also comparable between those patients with ureteral stents indwelling for >90 days and those for <90 days. No stent fragmentation was found in any of the patients.ConclusionWe demonstrated that ureteral dilation and placement of a single or multiple ureteral stents was effective and safe for patients with ureteral obstruction.     

胆道良性狭窄金属支架置入术后并发症及其处理

目的探讨金属支架置人治疗胆道良性狭窄的并发症。方法随访5例胆道良性狭窄应用金属支架治疗的病人，由于反复出现寒战发热，合并支架内结石形成，胆管阻塞，其中4例行手术取出支架。结果4例病人手术取出金属支架，术中见金属支架被胆泥堵塞，胆管壁黏膜破坏，支架取出困难；行胆肠吻合胆管内置管引流。2例病人因置人金属支架后反复胆管炎，胆汁性肝硬化，肝功衰竭死亡。结论金属支架不适合应用于良性胆道狭窄。     

A bioresorbable urethral stent

Summary The aim of the present study was to examine the suitability of biodegradable polymers as materials for a urethral stent. A new urethral stent made of biodegradable self-reinforced poly-l-lactide (SR-PLLA) was implanted in 16 male rabbits after urethrotomy. Seven stents of stainless steel served as controls. The dimensions of the two types of stents were identical: length 15 mm, diameter 8.2 mm. The mechanical construction was a helical spiral. The SR-PLLA spiral was sustained with three microspirals, and the whole device was coated withdl-lactide to achieve an active initial tissue reaction and better tissue penetration. The SR-PLLA stent showed more favourable implantation properties than the steel one. Within 6 months all PLLA stents had implanted, and the tissue reaction around the stent material was minimal. The helical spiral of stainless steel induced a remarkable inflammatory reaction due to poor implantation properties. We suggest that biodegradable SR-PLLA is a promising material for a urethral stent to prevent re-stenosis of urethral strictures.     

Diagnosis and management of ureteric injury: an evidence-based analysis

The Consensus on Genitourinary Trauma continues this month with an evidence‐based analysis, by a team of experts under the chairmanship of Dr Jack McAninch, of current reports on the diagnosis and management of ureteric trauma. This is quite a unique document, and of interest to all urologists; not only as a consensus on how this condition should be managed, but also as a model of how to review current publications.      

前尿道内支架管在治疗前尿道狭窄中的应用

目的:观察在前尿道狭窄患者中留置前尿道支架管的临床疗效。方法:选取2005年1月至2008年5月在本院住院治疗及进行门诊尿道扩张的患者共38例作为治疗组,并将同期在本院采取尿道扩张器扩张的患者38例纳入对照组,通过最大尿流率(Qmax)及扩张次数等指标对两组的临床疗效进行对比分析。结果:尿流率检测表明留置支架管后所有患者的Qmax均较术前明显增加,对拔管后6个月随访结果进行分析,治疗组Qmax>15ml/s的患者显著多于对照组(P<0.05)。结论:采用前尿道内留置支架管治疗前尿道狭窄不但显著减少扩张次数,减轻患者的经济负担,也显著改善患者的生活质量,前尿道狭窄患者中留置前尿道内支架管不失为临床上一种较好的治疗手段,并取得了良好的预期效果,简单易行,效果确切,值得推广。     

Synthetic bioabsorbable stent material for duct-to-duct biliary reconstruction

Biliary stricture remains a significant cause of morbidity after liver transplantation. We performed duct-to-duct biliary anastomosis by using an absorbable stent tube with a diameter equal to that of pig common bile duct as an internal stent. The stent tube was constructed using a synthetic biodegradable material-a lactic glycolic acid and epsilon-caprolactone copolymer. Three pigs were alive without cholestasis for 180 d; however, 1 pig died on the 65th postoperative d, and autopsy revealed no cholestasis or biliary sledge in the biliary stent tube. The 3 pigs were euthanized for histological examinations 180 d after surgery; the biliary stent tube was completely absorbed by this time. These experimental results showed the good patency of the absorbable biliary stent tube. In the future, the absorbable biliary stent tube is expected to be clinically developed as a biliary stent for biliary anastomosis, which may protect the biliary anastomotic stricture.