Polyurethane Stents Research Articles

Nasolacrimal Stents in the Management of Epiphora: Medium-term Results of a Multicenter Prospective Study

To evaluate in a prospective multicenter setting the clinical utility of polyurethane stents in the percutaneous management of epiphora. Patients (N = 163; age range = 22-85 y, mean = 52 y; 29 men, 134 women) with severe epiphora had stents (n = 183) inserted under fluoroscopic guidance in 180 lacrimal systems (unilateral = 146; bilateral = 17) to treat complete (n = 172) or partial (n = 8) obstruction of the nasolacrimal duct or sac. The junction between sac and duct was the most frequent location (n = 102), followed by the sac alone (n = 48), and the duct alone (n = 30). The etiology of the obstruction was idiopathic in 113 cases (63%) and chronic dacryocystitis in 67 (37%). The set designed by Song was used in all patients and the original technique was slightly modified by the authors. All patients were treated on an outpatient basis. Average time of the procedure was 14 minutes (range = 3-70 min). Initial technical success rate of stent placement was 97%. Resolution of epiphora was complete in 175 eyes and partial in five. On follow-up (mean = 450 d; range = 8-730 d), 157 of 183 stents remained patent (85.8%). Of the 24 obstructed, 19 were easily withdrawn and 17 of these patients remained asymptomatic for a mean of 15 months (secondary patency rate = 89.5%). The procedure is simple and safe. It can be performed on an outpatient basis and the original technique could be improved with some technical modifications. It is well tolerated by patients and may be considered as a valid alternative technique for the resolution of epiphora.

Preliminary results of a prospective randomized study of hydrophylic polymer-coated polyurethane versus polyethylene stents for distal malignant biliary obstruction

Preliminary results of a prospective randomized study of hydrophylic polymer-coated polyurethane versus polyethylene stents for distal malignant biliary obstruction

Treatment of nasolacrimal duct obstruction in adults with polyurethane stent

PURPOSE: To evaluate the efficacy of polyurethane nasolacrimal duct stents in the treatment of epiphora resulting from primary acquired nasolacrimal duct obstruction in adults. MATERIALS AND METHODS: In 25 patients (21 women and four men with mean age of 44 years, range 20 to 74 years) with nasolacrimal duct obstruction, 28 hollow polyurethane stents designed by Song and associates were placed under fluoroscopic guidance. The obstruction was complete in 20 lacrimal drainage systems and partial in eight. The lacrimal sac size was normal or large on dacryocystogram in all lacrimal drainage systems. A Ritleng probe was introduced through the upper punctum and advanced past the obstruction. A guide wire with a flexible tip was then introduced through the probe, over which the stent was advanced in retrograde fashion and placed into the lacrimal sac and nasolacrimal duct. Clinical success was defined by the demonstration of a completely patent lacrimal drainage pathway through saline irrigation and no or minimal complaint of epiphora. RESULTS: Stent placement was technically successful in 26 of 28 lacrimal drainage systems (93%). The mean time of fluoroscopy screening was 3.2 minutes (range, 1.4 to 5.8 minutes). The overall success rate was 82% (23 of 28 lacrimal drainage systems). Two stents were completely occluded. In one lacrimal drainage system with minimal epiphora, the stented drainage pathway was partially occluded. The patients were followed up from 4 to 22 months (mean, 7.2 months). CONCLUSIONS: Retrograde placement of a hollow polyurethane nasolacrimal duct stent is a technique that is simple and well tolerated by patients. This method achieves a high success rate and may be suggested as a nonsurgical procedure for adults with primary nasolacrimal duct obstruction and proper lacrimal sac size. The Ritleng probe facilitates the procedure.

Nasolacrimal Polyurethane Stent Placement for Epiphora: Technical Long-term Results

To assess technical problems related to implantation of a polyurethane stent to treat obstructive epiphora, and to assess the long-term patency of the nasolacrimal system. Fluoroscopically guided placement of a polyurethane nasolacrimal stent was performed in 70 obstructed lacrimal systems of 62 patients with grade 3-4 obstructive epiphora. Follow-up was conducted for 1-20 months (average, 11.3 months). The obstruction was at the lacrimal sac in six systems, at the junction between the lacrimal sac and the nasolacrimal duct in 60 systems, and at the nasolacrimal duct in four systems. The cause of the obstruction was idiopathic in all cases but was probably residual to dacryocystitis. Of these 70 procedures, stent placement was technically successful in 61 systems (87%). On long-term follow-up, 41 (67.2%) stents remained in place, with resolution or clinical improvement, and 18 (29.5%) stents were removed (because of occlusion in 17 systems), with stent malpositioning in the duct in six cases. There were seven cases of malpositioning in all. Statistical analysis was performed to evaluate patency, compare patency in properly positioned stents and malpositioned stents, and establish the relationship between malpositioning and the need for irrigation to maintain stent patency. Of the total 70 stents originally placed, 41 (58.6%) were still in place and functional at long-term follow-up. At 1 year, 73% of properly positioned stents remained patent versus 0% of improperly positioned stents. Median stent patency in the former group was 20 months and was 1 month in the latter group (P = .00002). Eleven percent of properly positioned stents required irrigation versus 57% of incorrectly positioned stents (P = .01). After follow-up for 1 year, recurrence of epiphora brought on by stent obstruction was 28%. Early stent blockage and the need for periodic irrigation may be indicative of malpositioning of the stent.

Evaluation of a chronic indwelling prototype mesh ureteral stent in a porcine model

Objectives. Ureteral stents all share one general goal, drainage, and one major drawback, irritative symptoms in the kidney and bladder. In an effort to preserve drainage while minimizing irritation, a lightweight, self-expanding mesh stent was designed. Herein, we compare the in vivo tissue reaction and flow characteristics of the mesh stent to a standard 7F double-pigtail polyurethane stent. Methods. Eight female Yucatan minipigs had bilateral stents placed: a mesh stent on one side and a standard 7F stent on the opposite side. Imaging and flow measurements were obtained in 4 pigs at 1 week and in another 4 pigs at 6 weeks. Following this procedure, the stents were removed, and the kidneys, ureters, and bladder were harvested en bloc for a blinded histopathologic analysis. Results. The degree of stent-related tissue reactivity was low for both stents and appeared similar for the ureter and bladder. Overall, the mesh stent resulted in a decrease in inflammation along the urinary tract at 1 week, but this result was statistically insignificant ( P = 0.55). Flow rate through the mesh stent tended to be greater than for the polyurethane stent both at 1 week and at 6 weeks. Conclusions. Overall, the mesh stent appeared to be well tolerated and provided for excellent flow.

CURRENT MANAGEMENT OF SEVERELY ENCRUSTED URETERAL STENTS WITH A LARGE ASSOCIATED STONE BURDEN

No AccessJournal of UrologyCLINICAL UROLOGY: Original Articles1 Sep 2000CURRENT MANAGEMENT OF SEVERELY ENCRUSTED URETERAL STENTS WITH A LARGE ASSOCIATED STONE BURDEN PRODROMOS G. BORBOROGLU and CHRISTOPHER J. KANE PRODROMOS G. BORBOROGLUPRODROMOS G. BORBOROGLU More articles by this author and CHRISTOPHER J. KANECHRISTOPHER J. KANE More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(05)67272-2AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract Purpose: We review our recent experience with encrusted retained ureteral stents associated with a large stone burden as well as current endoscopic options available for management. Materials and Methods: One man and 3 women presented to our department between May 1998 and April 1999 for treatment of an encrusted retained ureteral stent. One patient had a history of 3 episodes of ureteral stent encrustation during the last 6 years. We reviewed the management of these stents and the associated stone burden. Results: Average patient age was 32.5 years (range 25 to 41). Average interval that the encrusted stent remained in place was 7 months (range 3 to 12). In the 3 women pregnancy was associated with the retained stent. All patients required 2 to 6 endourological approaches (average 4.2) performed at 1 or multiple sessions to render them stone-free and stent-free. Postoperatively sepsis in 1 case necessitated a prolonged intensive care unit stay with eventual recovery. Conclusions: Successful management of a retained encrusted stent requires combined endourological approaches. Percutaneous nephrostolithotomy and ureteroscopy are often necessary for treating a severely encrusted stent and the associated stone burden. References 1 : Polyurethane internal stents in treatment of stone patients: morbidity related to indwelling times. J Urol1991; 146: 1487. Link, Google Scholar 2 : The forgotten indwelling ureteral stent: a urological dilemma. J Urol1995; 153: 1817. Link, Google Scholar 3 : Endourological management of severely encrusted ureteral stents. J Endourol1999; 13: 377. Google Scholar 4 : Encrustation and stone formation: complication of indwelling ureteral stents. Urology1985; 25: 616. Google Scholar 5 : Extracorporeal shock-wave lithotripsy to remove calcified ureteral stents. Urology1990; 36: 164. Google Scholar 6 : Management of forgotten or retained indwelling ureteral stents. Urology1996; 47: 431. Google Scholar 7 : The effect of patient position on intrarenal anatomy. J Endourol1999; 13: 257. Google Scholar 8 : Double-J ureteric stent encrustations: clinical study on crystal formation on polyurethane stents. Urol Int1997; 58: 100. Google Scholar 9 : Pregnancy as a state of physiologic absorptive hypercalciuria. Am J Med1986; 81: 451. Google Scholar 10 : Urinary tract stones in pregnancy. Surg Clin North Am1995; 75: 123. Google Scholar 11 : Stones in pregnancy and in children. J Urol1992; 148: 1076. Link, Google Scholar 12 : Nephrolithiasis in pregnancy. Am J Kidney Dis1987; 9: 354. Google Scholar 13 : Detection, significance, and therapy of bacteriuria in pregnancy. Update in the managed health care era. Infect Dis Clin North Am1997; 11: 593. Google Scholar From the Department of Urology, Naval Medical Center San Diego, San Diego, California© 2000 by American Urological Association, Inc.FiguresReferencesRelatedDetailsCited byKrishna S, Abello A and Steinberg P (2021) Forget Forgotten Stents: Review of Ureteral Stent Tracking SystemsUrology Practice, VOL. 8, NO. 6, (645-648), Online publication date: 1-Nov-2021.Tomer N, Garden E, Small A and Palese M (2020) Ureteral Stent Encrustation: Epidemiology, Pathophysiology, Management and Current TechnologyJournal of Urology, VOL. 205, NO. 1, (68-77), Online publication date: 1-Jan-2021.Jain R, Chaparala H, Omar M, Ganesan V, Sivalingam S, Noble M and Monga M (2017) Retained Ureteral Stents at a Tertiary Referral Stone Center—Who is at Risk?Urology Practice, VOL. 5, NO. 6, (452-457), Online publication date: 1-Nov-2018.Weedin J, Coburn M and Link R (2010) The Impact of Proximal Stone Burden on the Management of Encrusted and Retained Ureteral StentsJournal of Urology, VOL. 185, NO. 2, (542-547), Online publication date: 1-Feb-2011.Haleblian G, Kijvikai K, de la Rosette J and Preminger G (2007) Ureteral Stenting and Urinary Stone Management: A Systematic ReviewJournal of Urology, VOL. 179, NO. 2, (424-430), Online publication date: 1-Feb-2008.BUKKAPATNAM R, SEIGNE J and HELAL M (2018) 1-Step Removal of Encrusted Retained Ureteral StentsJournal of Urology, VOL. 170, NO. 4 Part 1, (1111-1114), Online publication date: 1-Oct-2003.LINGEMAN J, PREMINGER G, BERGER Y, DENSTEDT J, GOLDSTONE L, SEGURA J, AUGE B, WATTERSON J and KUO R (2018) Use of a Temporary Ureteral Drainage Stent After Uncomplicated Ureteroscopy: Results From a Phase II Clinical TrialJournal of Urology, VOL. 169, NO. 5, (1682-1688), Online publication date: 1-May-2003.Auge B, Ferraro R, Madenjian A and Preminger G (2018) Evaluation Of A Dissolvable Ureteral Drainage Stent In A Swine ModelJournal of Urology, VOL. 168, NO. 2, (808-812), Online publication date: 1-Aug-2002. Volume 164Issue 3 Part 1September 2000Page: 648-650 Advertisement Copyright & Permissions© 2000 by American Urological Association, Inc.Keywordscalculiureterurinary catheterizationstentMetricsAuthor Information PRODROMOS G. BORBOROGLU More articles by this author CHRISTOPHER J. KANE More articles by this author Expand All Advertisement PDF downloadLoading ...

Clinical efficacy of the polyurethane stent without fluoroscopic guidance in the treatment of nasolacrimal duct obstruction

Purpose To evaluate the clinical efficacy of the polyurethane (Song) stent in the treatment of nasolacrimal duct obstruction without fluoroscopic guidance, especially at the junction between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct. Design Retrospective noncomparative case series. Participants This study evaluated 59 cases of nasolacrimal duct obstruction in 53 patients, with mean epiphora of 36 months (range, 2 months–17 years). Methods Without the assistance of a radiologist, a polyurethane nasolacrimal stent was placed by introducing a guidewire through the superior or inferior punctum into the canaliculus and advancing it across the obstruction into the opening of the inferior meatus of the nasal cavity. The mean follow-up period was 22 months (range, 12 months–48 months). Main outcome measures Patency of the lacrimal passage to irrigation and the duration of this procedure. Results Complete resolution of epiphora was accomplished in 55 (93.2%) of the 59 eyes. There was recurrence of epiphora in four cases because of obstruction of the stent in three cases and obstruction of the common canaliculus by recurrent dacryocystitis in one case. Conclusions Polyurethane stenting without fluoroscopic guidance seems to be a valuable technique for primary management of nasolacrimal duct obstruction before dacryocystorhinostomy.

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. (Gastrointest Endosc 2000;51:19-22.)

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. (Gastrointest Endosc 2000;51:8-11.)

気道・食道のステント治療 食道癌による食道狭窄のステント治療

The purpose of this study was to evaluate the results of esophageal stents implanted in patients with inoperable esophageal carcinoma. From May 1984 to February 2000, 81 patients with inoperable carcinoma of the esophagus were treated by placement of 51 plastic prostheses and 30 metallic stents. The plastic prostheses consisted of 30 silicone stents, 19 polyurethane stents and 2 polyuronide stents in our series. Twenty-nine of the 30 patients treated with metallic stents were treated with Ultraflex (a self-expanding nitinol stent) and one case with Wallstent (a self-expanding stainless steel stent). The overall rate of palliation of dysphagia with the esophageal stents was 86% in our series. The rate of successful palliation for 31 cases with tracheoesophageal fistula was 90%. There were no differences between the plastic prosthesis group and metallic stent group in these rates. The overall median survival time after treatment with stent was 54 days. There was no difference between the stent groups in survival curves by the Kaplan-Meier method. Complaints of sore throat were much more common in the plastic prosthesis group than in the metallic stent group, and that was the only statistically difference between the two groups in terms of complications after the insertion of the stents (p < 0.05). This might have been due to the fact that the metallic stent was slimer than the plastic prosthesis at the insertion point.

Lacrimal system obstruction treated with lacrimal polyurethane stents: outcome of removal of occluded stents.

To describe the short- and long-term outcomes of the removal of occluded stents. With fluoroscopic guidance, 571 lacrimal polyurethane stents were placed in 502 patients with epiphora due to obstruction of the lacrimal system. Of the 571 stents, 142 were removed 2 weeks to 42 months (mean, 7 months) after placement because of recurrent epiphora, and the lacrimal system was irrigated with saline solution through the lacrimal point. Stent removal was well tolerated. Mild epistaxis occurred in one patient and was controlled with a nasal pack. Recurrent epiphora was due to obstruction of the stent with mucoid material in 49 (35%) of 142 systems and granulation tissue in 93 (65%) systems. After stent removal, 73 (51%) of the 142 lacrimal systems showed improvement of epiphora, with a patent lacrimal system at 7-day follow-up dacryocystography. During the follow-up of 2 weeks to 49 months (mean, 22 months) after stent removal, patency was maintained in 24 (33%) of the 73 lacrimal systems. Removal of an occluded lacrimal plastic stent was easy and safe. Recurrent epiphora after placement of lacrimal plastic stents can be treated with removal of the occluded stents an irrigation with saline solution through the lacrimal point, which resulted in a patent lacrimal system in 33% of cases in this study.

An in vitro biocompatibility evaluation of double-J stents

Objectives. For several years, studies performed to estimate in vitro biocompatibility of urinary catheters have been carried out using permanent cell lines. However, for a rational design of the testing procedure, the cell culture model should depend on the material application. We assess the biocompatibility of 13 double-J stents using an in vitro model of normal human urothelial cells (HUC). This article aims to mimic in vitro, on HUC monolayers, the close contact existing in vivo between the urothelium and double-J stents and to evaluate the subsequent effect on these cells. Methods. Fragments of each stent were deposited into the wells containing confluent HUC, with close contact maintained between the material and the cells. The same procedure with either no material or fragments of latex catheter was undertaken to provide the negative and positive controls, respectively. The contact was maintained for 1, 3, and 8 days. At the end of the incubation period, fragments of stent were removed and cell activity tests were performed (neutral red assay, MTT assay, and cell proliferation). Results. One of the silicone stents is significantly deleterious on HUC as determined by three tests after 8 days of contact. For two copolymers, a tendency to increase cell proliferation was noted. Concerning polyurethanes, we observed significant decreases in HUC viability and cell metabolic activity for five stents after 8 days of contact. All seven polyurethane stents significantly inhibited cell proliferation. Conclusions. The HUC culture model may be of relevance for the screening of materials intended for use as double-J stents.

Role of antimicrobial-impregnated polymer and teflon in the prevention of biliary stent blockage

Biliary stent blockage and microbial colonization is a common complication associated with polyurethane stents used for the relief of bile-duct obstruction caused by benign or malignant disease. In an attempt to overcome this problem the application of a ‘Teflon” (polytetrafluoroethylene) stent and an antimicrobial benzalkonium chloride (BZC) impregnated polymer were investigated. The effects of these materials on microbial colonization were compared to a polyurethane stent in vitro in broth or bile. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of BZC for three commonly isolated biliary stent pathogens, Staphylococcus epidermidis, Enterococcus faecium and Enterobacter cloacae were also determined. All the isolates were sensitive to BZC. The growth kinetics of the three organisms in broth and in human pooled bile were similar. Adherence to the BZC impregnated polymer was significantly reduced as compared to the polyurethane and Teflon stents (P < 0·05) in nutrient broth. In bile, fewer organisms attached to the Teflon as compared with the polyurethane stent (P < 0·05) for all organisms. For two of the three test organisms there was less bacterial adherence to the Teflon than to the BZC impregnated polymer. The Teflon and antimicrobial stent materials studied may prevent biliary stent blockage resulting from microbial colonization.

Treatment of complete and partial obstruction of the nasolacrimal system with polyurethane stents: initial experience.

To present our experience in the treatment of nasolacrimal occlusion by means of polyurethane stents. Forty polyurethane stents were placed under fluoroscopic guidance in 35 consecutive patients with epiphora due to total or partial obstruction of the nasolacrimal system. The set designed by Song was used in all patients. The procedure was performed by introducing a guidewire through the superior punctum into the canaliculus and advancing it across the obstruction into the inferior meatus of the nasal cavity. After pulling out the guidewire, the stent was advanced in retrograde fashion and released into the sac and the nasolacrimal duct. The technical success rate was 100%. The average time for the procedure was 25 min (range 10-60 min). Immediate complications were: mild pain (n = 5), severe pain (n = 1), minimal epistaxis (n = 7), and moderate epistaxis (n = 1). No major complications occurred. The last clinical control revealed complete resolution of epiphora in 35 eyes and partial resolution in four; one patient did not improve. This technique for treatment of obstruction of the nasolacrimal system is simple and safe, and may obviate the use of more invasive procedures.

Polyurethane stent for treatment of urethral strictures.

The use of stents in the treatment of urethral strictures is offered as an alternative to repeated internal urethrotomies, urethral dilations, and urethroplasties. We report our experience in 42 patients with bulbar and membranous strictures (33 and 9 patients, respectively). In 10 patients, the stent was removed after 3 to 5 months, and the treatment was curative in 4 patients in this group. In 16 patients, the stent was removed after 12 months, and in 6 it was removed after 24 months. Thirty-two patients voided satisfactorily after stent insertion. The stent did not prevent recurrent strictures after its removal in most of the patients, but if changed regularly, once a year, it may avert repeated urethrotomies, dilations, and urethroplasties, which makes it a valid alternative in elderly patients.

Mechanical performance of polyurethane ureteral stents in vitro and ex vivo

A serious problem associated with the use of ureteral stents is fracture in situ. Following clinical observations of fracture of polyurethane stents in vivo, this study examined the mechanical properties of 17 polyurethane stents (double-J containing drainage holes) retrieved from patients over a 24-week period of insertion. In addition, stents were immersed in human and artificial urine in an in vitro model at 37 °C to determine their general propensity to fracture. Mechanical properties of ureteral stents were examined using the standard ASTM D-412 tensile test and by the novel application of dynamic mechanical analysis (DMA). The ultimate tensile strength and elongation at break (but not the Young's modulus) of unused polyurethane stent sections containing side-drainage holes were greater than stent sections devoid of side-drainage holes. No correlations were observed between increased or decreased Young's modulus, ultimate tensile strength or elongation at break of polyurethane stents and their time of immersion in either human urine or artificial urine in simulated upper urinary tract conditions of 37 °C and 5% CO 2. Similarly, no correlations were observed between Young's modulus, ultimate tensile strength or elongation of polyurethane stents and stent dwell time in situ. DMA of retrieved stents revealed that their tan δ value and storage modulus did not differ significantly from unused stents following dwell times in situ of up to 24 weeks. No changes in the glass transition temperatures were observed in retrieved stents. Although patient variation was observed, the results indicate that the polyurethane stents examined in vitro and following removal from patients did not exhibit any greater propensity to fracture than their unused counterparts. Fracture of retrieved polyurethane stents, arising in vivo and also during subsequent tensile testing, was observed to occur along the drainage holes, suggesting that elimination of these holes will reduce the incidence of polyurethane ureteral stent fracture in use.

Nonsurgical placement of a nasolacrimal polyurethane stent: long-term effectiveness.

To evaluate the long-term effectiveness of a polyurethane stent in the treatment of obstruction of the lacrimal sac and the nasolacrimal duct. Fluoroscopically guided placement of a polyurethane nasolacrimal stent was evaluated in 283 obstructed lacrimal systems of 236 patients, with a follow-up period of more than 1 year (range, 52-134 weeks). The obstruction was at the junction between the lacrimal sac and the nasolacrimal duct in 192 systems, at the lacrimal sac in 52, and at the nasolacrimal duct in 39. The causes of obstruction were traumatic in 34 and idiopathic in 249 systems. Stent placement was technically successful in 270 systems (95%). At 7 days after stent placement, 235 (87%) of the 270 systems with successful placement demonstrated complete resolution of epiphora, 27 (10%) had partial resolution, and the remaining eight (3%) had no resolution. There was recurrence in 81 systems due to obstruction of the stent (n = 77) or obstruction of the common canaliculus (n = 4). The recurrence rate was much higher in the systems with obstruction at the lacrimal sac (64%) than in the systems with obstruction at the junction (26%) between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct (15%). Stent placement in the obstructed lacrimal system below the junction between the lacrimal sac and the nasolacrimal duct is valuable as an initial therapy.

Lacrimal canaliculus obstruction: nonsurgical treatment with a newly designed polyurethane stent.

A newly designed polyurethane stent was used to successfully treat 30 eyes (in 28 patients) with epiphora resulting from obstruction of the lacrimal canaliculus. After stent placement, epiphora resolved in all eyes. During follow-up, epiphora recurred in 20 eyes, but epiphora did not recur and the lacrimal canaliculus was patent in 12 eyes after the stent was removed. The stent appears to be valuable for nonsurgical treatment of obstruction of the lacrimal canaliculus.

Le coin du Neuro-Gourmand

Summary A Song’s nasolacrimal duct stent was placedin a patient with epiphora due to primary naso-lacrimal duct obstruction and the stent was keptfor 32 months. Mitomycin C 0.02% eye dropsfour times a day were prescribed for four weeksfollowing polyurethane stent placement proce-dure. No epiphora-related complaints occurredfor thirty months after then the epiphora started.Nasolacrimal stent was removed from nasal cav-ity endoscopially and the tissues within the ex-truded stent were examined histopathologically.The patient’s complaints were relieved followingstent removal. Dacryocystogram revealed nor-mal passage and a filling defect within thelacrimal sac. Macroscopic evaluation of the stentrevealed a firm mass in the stent mushroom,causing complete obstruction. Pathological ex-amination of the mass revealed chronic inflam-mation, increased connective tissue and vascularproliferation.Nasolacrimal polyurethane stents can be re-moved easily by nasal approach. Nasolacrimalpassage may be left open temporarily after stentremoval.The use of Mitomycin C drop is a nov-el approach in nasolacrimal stent placement cas-es. However, when the long-term results of endo-scopic and external dacryocystorhinostomy areconsidered, further research is needed on thebiocompatibility of stent material.

Fracture of polyurethane double pigtail stents: an in vivo retrospective and prospective fluoroscopic study.

To study the behaviour of pigtail polyurethane ureteric stents during breathing and change in body habitus and thereby explain some side-effects of stenting, particularly spontaneous stent fracture. The study comprised retrospective evaluation of records and radiographs of seven patients (five men and two women, mean age 41; SD 10.9 years) who were admitted with fractured polyurethane pigtail stents, and a prospective fluoroscopic study of the behaviour of 14 stents in 12 patients (11 men and one woman; mean age 40; SD 9.3 years) during breathing, spinal flexion, extension and rotation. Five of the seven pigtail stents fractured where the stent crossed the lateral edge of psoas muscle, 7-10 cm below the renal coil of the stent. The sixth stent was fractured at its lower third and the seventh fractured just proximal to the stent's bladder coil. The prospective study revealed a 20-80 degrees bend in the upper third of 11 of the 14 stents and a 35 degrees bend in the lower third of two stents. A 1-5 cm craniocaudal movement and a 0-2 cm vertical movement of the stents occurred during breathing and spinal flexion and extension. There were no changes in stent configuration during spinal lateral rotation or at the sacral promontary. The bend in the upper third of the ureter was profound in two stents whose vertical movement was restricted by other conditions. As the kidney-to-bladder distance shortens during inspiration and spinal flexion, the stent adapts by bending and/or moving. Fracture of the stent may be caused by repeated mechanical stress, particularly across the side-holes, and by diminution of its tensile strength by depolymerization during long indwelling times. Large polyurethane stents tended to bow, displacing the upper ureter anteriorly, while small, soft stents conformed to the anatomical course of the ureter, suggesting that they should be used after open or endoscopic surgery to the upper two-thirds of the ureter. Stress on the stent can be minimized by choosing the correct length, particularly where vertical stent movement is limited by other conditions.