暂时性食管支架成形术治疗儿童食管良性狭窄

目的 评价儿童食管良性狭窄使用暂时性食管支架成形术治疗的疗效.方法 儿童烧灼性食管狭窄及食管术后吻合口狭窄患儿10例,支架置入前均先行食管吞钡检查,吞咽评分为3,并置入覆膜可回收支架.结果 支架置入后,所有患儿无明显并发症,并安全回收.支架置放期间所有患儿能进食固体食物,无吞咽困难.支架取出后6～12个月随访,患儿均能正常进食,吞咽评分为0.结论 应用暂时性支架成形术治疗儿童食管良性狭窄安全、有效.     

Malignant tracheobronchial strictures: palliation with covered retrievable expandable nitinol stent

PURPOSE: To evaluate the safety and clinical effectiveness of a covered retrievable expandable nitinol stent for the treatment of malignant tracheobronchial stricture and/or esophagorespiratory fistula (ERF). MATERIALS AND METHODS: With fluoroscopic guidance, stents were placed in 35 symptomatic patients with malignant tracheobronchial stricture and/or ERF in most cases caused by lung or esophageal cancer. The site of stricture was most commonly at the trachea or left main bronchus. If there were complications, the stent was removed with a retrieval set. Nine patients had combined symptomatic ERF. RESULTS: A total of 47 tracheobronchial stents were placed and were technically successful and well-tolerated in all patients. Improvement of dyspnea was achieved in 92% of the patients (24 of 26 patients). Associated ERF in nine patients was effectively treated with tracheobronchial stent placement with or without esophageal stent placement. Stent migration, tumor overgrowth, symptomatic sputum retention, and hemoptysis occurred in 17% (6/35), 6% (2/35), 20% (7/35), and 17% (6/35) of patients, respectively. There were no documented cases of tumor ingrowth. Stent removal was performed easily in five patients when stent migration (n = 2), severe pain (n = 1), tumor overgrowth (n = 1), or persistent gastrobronchial fistula (n = 1) developed. All patients died 2 days to 26 weeks (mean, 9.62 weeks) after stent placement because of disease progression (n = 18), pneumonia (n = 9), hemoptysis (n = 5), or unknown cause (n = 3). CONCLUSION: Use of a covered retrievable expandable nitinol stent is a safe and effective method for relieving dyspnea. This procedure contributed to improved quality of life for patients with malignant tracheobronchial stricture and/or ERF. Stent retrievability was useful in resolving stent-related complications.     

Treatment of tracheobronchial obstruction with a polytetrafluoroethylene-covered retrievable expandable nitinol stent

PURPOSE: To evaluate the clinical effectiveness of polytetrafluoroethylene (PTFE)-covered retrievable expandable nitinol stents in tracheobronchial strictures. MATERIALS AND METHODS: With fluoroscopic guidance, PTFE-covered retrievable expandable nitinol stents were placed in 15 symptomatic patients with benign (n = 6) or malignant (n = 9) tracheobronchial strictures. Complications and improvement in respiratory status were evaluated. Stents were removed electively 6 months after placement in benign strictures or if complications occurred. Membrane degradation or separation from the wire mesh was evaluated in removed stents. RESULTS: A total of 17 stents were successfully placed and were well tolerated in all patients. Sputum retention, stent migration, and tissue hyperplasia occurred in 23.5% (n = 4), 17.6% (n = 3), and 17.6% (n = 3) of stents, respectively. A total of 11 stents were successfully removed electively 6 months after placement (n = 4) or when complications occurred (n = 7). All 11 such stents were removed without difficulty with use of standard techniques, antecedent balloon dilation being necessary in two cases as a result of tissue hyperplasia. No removed stent showed signs of membrane degradation, and two removed stents showed signs of membrane separation from the mesh. CONCLUSIONS: PTFE-covered retrievable expandable nitinol stents were effective in the treatment of tracheobronchial strictures. Stent removal was easy with use of standard techniques, and no removed stent showed evidence of membrane degradation.     

Temporary placement of covered retrievable expandable nitinol stents with barbs in high-risk surgical patients with benign prostatic hyperplasia: work in progress

Purpose

To report the use of a newly constructed, covered, retrievable, expandable nitinol stent with barbs to overcome the problem of stent migration associated with conventional covered prostatic expandable stents and to evaluate prospectively the technical feasibility and clinical effectiveness of the stents in patients with benign prostatic hyperplasia (BPH).

Materials and Methods

A covered retrievable expandable nitinol stent with four barbs was placed with use of an 18-F stent delivery system in seven consecutive patients with symptomatic BPH who had high operative risks. Age range of patients was 62–83 years (mean 74 years). In cases in which the stent migrated, it was replaced with a stent with eight barbs. The stents were routinely removed 4 months after placement using a 21-F stent removal set.

Results

Stent placement was technically successful and well tolerated in six of the seven patients. The remaining patient needed a second stent placement after removal of the first stent. The stent with four barbs migrated into the urinary bladder in four patients (57%); three of these patients received a second stent with eight barbs with good results, and the fourth patient did not need further treatment because his symptoms improved. Routine removal of the stent 4 months after placement was performed in three of the seven patients with good results.

Conclusions

Retrievable stents with eight barbs seem to overcome the problem of stent migration associated with conventional prostatic expandable stents. Preliminary results suggest that stents with barbs are both feasible and effective in patients with BPH.     

Retrievable covered nitinol stents: experiences in 108 patients with malignant esophageal strictures

PURPOSE: The authors report their experience with three types of retrievable covered nitinol stents in patients with malignant esophageal strictures. MATERIALS AND METHODS: Three types of retrievable covered nitinol stents were designed. Type A stents were placed in 45 patients, type B stents were placed in 29 patients, and type C stents were placed in 34 patients. The stents were removed with use of a stent retrieval set under fluoroscopic guidance when the stents caused complications. Stent patency, symptom relief, survival rate, and complications were analyzed relative to stent type and radiation therapy. RESULTS: The timing of radiation and the stent type have significant effects on occurrence of complications such as stent migration and fistula formation (P =.002 and P = 0.029, respectively). Complications were significantly more frequent in patients with the type B stent than those with type A or type C stents (P =.008). Patients who underwent radiation therapy before stent placement or who underwent no radiation therapy experienced substantially less complications than those who underwent radiation therapy after stent placement (P =.005 and P <.001, respectively). The survival period was significantly longer in patients who underwent radiation therapy after stent placement than in the other groups (P =.034). Stents were removed from 15 patients (14%) 2 days to 16 weeks (mean, 4 weeks) after stent placement as a result of severe pain (n = 7), stent migration (n = 6), or stent deformity (n = 2). Stent removal was well tolerated in all patients. CONCLUSION: Use of retrievable covered nitinol stents seems to be a safe and effective method of treatment in patients with malignant esophageal strictures. However, removal of the stents was needed in 14% of the patients because of complications. Patients who underwent radiation therapy after stent placement and those with the type B stent experienced more complications than other patients.     

Results of temporary placement of covered retrievable expandable nitinol stents for tuberculous bronchial strictures

Covered retrievable expandable nitinol stents were successfully placed in nine patients with tuberculous bronchial strictures refractory to balloon dilation. Complications included stent migration (n = 1) and tissue hyperplasia at the proximal portion of the stent (n = 2). During the follow-up period (5-52 months), stricture recurred in three of five patients (60%) after temporary stent placement for 2 months, whereas stricture did not recur in the other four patients after temporary stent placement for 6 months. Temporary placement of covered retrievable stents appears to be an effective method for the treatment of patients with tuberculous bronchial strictures refractory to balloon dilation.     

Comparison of temporary and permanent stent placement with concurrent radiation therapy in patients with esophageal carcinoma

PURPOSE: To assess the clinical effectiveness of temporary metallic stent placement with concurrent radiation therapy in patients with esophageal carcinoma by comparing it with permanent stent placement with concurrent radiation therapy. MATERIALS AND METHODS: Covered retrievable expandable nitinol stents were placed in 47 patients with esophageal carcinoma 1 week before starting radiation therapy; the stents were electively removed 4 weeks after placement in 24 patients (group A), while not electively removed in the other 23 patients (group B). In cases of complications, the stents were also removed from patients in groups A and B. The dysphagia score, complications (severe pain, granulation tissue formation, stent migration, esophagorespiratory fistula, and hematemesis), tumor overgrowth/regrowth, reintervention rates, and dysphagia-progression-free and overall survival rates were compared in the two groups. RESULTS: Stent placement or removal was technically successful and well tolerated in all patients. The dysphagia score was significantly improved in both groups after stent placement (P < .01). Each of the stent-related complications was less in group A than in group B but there was no significant difference. However, the total number of patients with one or more than one complications and who needed related reinterventions was significantly less in group A than in group B (P = .042 and .030, respectively). Tumor overgrowth/regrowth and the total number of patients who required related reinterventions was not significantly different (P = 1.00 and .517, respectively). Dysphagia-progression-free and overall survival rates were significantly longer in group A than in group B (P = .005 and .001, respectively). CONCLUSION: Temporary placement of a covered retrievable expandable metallic stent with concurrent radiation therapy for patients with esophageal carcinoma is beneficial for reducing complications and related reinterventions and for increasing resultant survival rates compared with permanent esophageal stent placement.     

Fate of migrated esophageal and gastroduodenal stents: experience in 70 patients

PURPOSE: To investigate the frequency of esophageal and gastroduodenal stent migration and the fate of such stents. MATERIALS AND METHODS: The authors studied five types of covered metal stents. Type A stents were nonretrievable polyurethane-covered stents with shouldered ends (n = 169), type B stents were retrievable polyurethane-covered stents with shouldered ends (n = 62), type C stents were retrievable polyurethane-covered stents with flared ends (n = 72), type D stents were retrievable polytetrafluoroethylene-covered stents with shouldered ends (n = 369), and type E stents were separated stents (n = 216). Types A-D stents were esophageal stents, and the type E stent was a gastroduodenal stent. Stents were placed in 888 patients with either benign (n = 43) or malignant (n = 845) causes of stricture. The rate of stent migration was analyzed relative to completeness of migration, the cause of obstruction, stent type, and stent placement location. The fate of migrated stents and the treatment of patients were evaluated. RESULTS: Stent migration occurred in 70 of the 888 patients (7.9%). Migration occurred in 11 of the 43 patients (25%) with benign cause of strictures and 591 of the 845 patients (7.0%) with malignant cause. The migration rates for types A, B, C, D, and E stents were 10%, 4.8%, 24%, 7.3% and 2.8%, respectively. Of the 70 migrated stents, 45 had complete migration and 25 had partial migration. The anastomotic sites were the areas most commonly associated with migration (16%), but this was not statistically significant. Forty of the 70 migrated stents were removed with retrieval devices under fluoroscopic guidance because they were not passed with stool and possibility of complications related to migrated stents. The remaining 30 stents exited via the rectum (n = 15), remained in the body without complications (n = 12), or were surgically removed because they caused complicated intestinal obstructions (n = 3). CONCLUSION: The overall migration rate for esophageal and gastroduodenal stents was 7.9%. Most migrated stents were removed nonsurgically, exited the body spontaneously, or remained in the body in an uncomplicated state. Surgical stent removal was necessary in three patients (4.3%) due to complicated intestinal obstructions.     

Removal of retrievable esophageal and gastrointestinal stents: experience in 113 patients

OBJECTIVE: Although there are frequent clinical situations in which esophageal and gastrointestinal stents should be removed, nonsurgical stent removal has been difficult. The purpose of our study was to describe the safety and efficacy of removing the retrievable nitinol stents with a retrieval hook. MATERIALS AND METHODS: Under fluoroscopic guidance, the removal of 119 esophageal, six gastroduodenal, and five rectal retrievable stents was attempted in 113 patients using a retrieval hook. Indications for stent removal included migration (n = 35), severe pain (n = 23), formation of a new stricture (n = 13), incomplete stent expansion (n = 7), airway compression (n = 2), esophagorespiratory fistula (n = 2), malpositioned stent (n = 1), and hematemesis (n = 1). The remaining 46 stents were electively removed. RESULTS: Of the 130 stents, 127 (97.7%) were successfully removed despite the following difficulties: untied drawstrings (n = 4), separation of the stent (n = 3), and fracture (n = 2) or disconnection (n = 2) of a retrieval hook. The removal procedure failed in three cases (2.3%). The causes of failure were the inability to place the hook into the migrated stent (n = 2) and a tight stricture above the migrated stent (n = 1). The procedure-related complications included minor (n = 4) and major (n = 1) bleeding and intramural rupture (n = 3). One patient died of major bleeding after removal of an esophageal stent. CONCLUSION: The stent retrieval hook is useful for removing retrievable esophageal and gastrointestinal stents.     

Treatment of a benign anastomotic duodenojejunal stricture with a polytetrafluoroethylene-covered retrievable expandable nitinol stent

Temporary placement of a polytetrafluoroethylene (PTFE)-covered retrievable expandable nitinol stent was performed to treat a benign anastomotic duodenojejunal stricture that was refractory to repeated balloon dilation procedures. The procedure provided a favorable outcome for the patient and was completed without complications. This result suggests that successful treatment of benign strictures of the gastric outlet or duodenum is possible with use of retrievable stents.     

Temporary metallic stent placement in the treatment of refractory benign esophageal strictures: results and factors associated with outcome in 55 patients

The purpose of this study was to evaluate the effectiveness of temporary metallic stenting in 55 patients with treatment-resistant benign esophageal strictures and to identify factors associated with clinical outcomes. Under fluoroscopic guidance, covered retrievable stents were placed in 55 patients with benign esophageal strictures and were removed with retrieval hook 1 week to 6 months after placement. Stent placement was successful in all patients, and the mean dysphagia score was reduced from 2.8 to 1.3 (p < 0.001). The most common complications were tissue hyperproliferation (31%), severe pain (24%), and stent migration (25%). During follow-up (mean: 38 months), recurrence of the stricture necessitating balloon dilation was seen in 38 (69%) of 55 patients. Maintained patency rates after temporary stenting at 1, 3, and 6 months and 1, 2, and 4 years were 58%, 43%, 38%, 33%, 26%, and 21%, respectively. In multivariate analysis, length (p = 0.003) of the stricture was the only significant factor associated with maintained patency after temporary stenting. In conclusion, temporary metallic stenting for refractory benign esophageal strictures may be effective during the period of stent placement, but is disadvantaged by the high recurrence rates after stent removal, particularly in patients with a long length of stricture (>7 cm).     

Nitinol Esophageal Stents: New Designs and Clinical Indications

Purpose To evaluate the clinical use of covered and noncovered, knitted nitinol stents in patients presenting new stent indications. Methods Self-expandable, knitted nitinol stents were implanted in four patients for treatment of dysphagia. In two patients who had malignant strictures and had esophago-respiratory fistulae and in one patient with an esophagocutaneous fistula, polytetrafluoroethylene (PTFE)-covered stents were implanted. One patient received a noncovered stent, but a retrograde approach through a percutaneous endoscopic gastrostomy (PEG) fistula had to be chosen for recanalization of an esophageal occulusion. Two patients received stents for treatment of benign strictures. Results Recanalization of the stricture and stent implantation were performed under fluoroscopic control without any procedure-related morbidity or mortality. Dysphagia improved in all patients and the esophageal fistulae could be sealed off by covered stents. During a maximum follow-up of 18 months, there was no stent migration or esophageal perforation. Complications observed were stent stenosis due to food impaction (1/4) and benign stent stenosis (2/2). Most complications could be treated by the interventional radiologist. Conclusion Self-expandable, covered Nitinol stents provide an option for the treatment of dysphagia combined with esophageal fistulae. In combination with interventional radiology techniques, even complex strictures are accessible. For benign strictures, the value of stent treatment has not yet been proven.     

Malignant esophageal-tracheobronchial strictures: parallel placement of covered retrievable expandable nitinol stents

Purpose: To assess the safety and clinical effectiveness of the parallel placement of covered retrievable expandable metallic stents in the palliative treatment of malignant esophageal and tracheobronchial strictures.

Material and Methods: Under fluoroscopic guidance, parallel stents were placed in 12 symptomatic patients with both malignant esophageal and tracheobronchial strictures. Seven of these 12 patients also had an esophagorespiratory fistula (ERF) and one patient had an esophagocutaneous fistula. Technical success, clinical improvement, complications, and survival rates were evaluated.

Results: A total of 28 esophageal and airway stents were successfully placed. The grade of dysphagia and dyspnea score significantly decreased after stent placement (P = 0.002 and 0.003, respectively). ERF and esophagocutaneous fistula were sealed off in all eight patients after esophageal stent placement; however, the esophagocutaneous fistula reopened 1 month later. Complications included stent migration or expectoration (n = 3), tracheal compression by the esophageal stent (n = 3), new fistula development due to covering membrane degradation of the esophageal stent (n = 1), and symptomatic sputum retention (n = 1). Stent removal was easily performed for two stents; one migrated stent and the other with covering membrane degradation. All 12 patients died within the mean survival period of 72.50 days (range 7-375 days).

Conclusion: Parallel placement of covered retrievable expandable metallic stents is safe and effective for the palliative treatment of malignant esophageal and tracheobronchial strictures.     

Covered metallic stent placement in the management of cervical esophageal strictures

PURPOSE: To describe the authors' experience with self-expandable covered metallic stents in 16 patients with malignant and benign cervical esophageal strictures. MATERIALS AND METHODS: Sixteen expandable covered metallic stents were placed with fluoroscopic guidance in 16 patients (14 men, two women; mean age, 60 years; age range, 26-75 years) with malignant and benign strictures of the cervical esophagus. The causes of strictures were ingestion of corrosive agents (n = 3), biopsy-proved squamous cell carcinoma (n = 12), and postsurgical scarring (n = 1). The mean dysphagia scores at presentation were compared with those after stent placement by using the Wilcoxon signed rank test. RESULTS: Stent placement was technically successful in all patients. The reduction in the mean dysphagia score after stent placement was statistically significant (P = .0327). All patients complained of mild to severe foreign body sensation, with four reporting severe pain necessitating immediate stent removal. With the exception of one patient with limited follow-up, complications requiring intervention occurred in all patients, including migration in nine patients and tissue hyperproliferation in two. Of the 12 patients with a malignant stricture of the esophagus, four patients eventually underwent gastrostomy for the placement of a feeding tube and one patient underwent surgery. All four patients with a benign cervical stricture failed to achieve long-lasting improvement with temporary stent placement. CONCLUSIONS: Although the placement of covered metallic stents in the cervical esophagus provides adequate initial palliation, it is associated with poor patient tolerance and a high complication rate.     

Malignant gastric outlet obstructions: treatment by means of coaxial placement of uncovered and covered expandable nitinol stents

PURPOSE: To assess whether coaxial placement of uncovered and covered expandable nitinol stents overcomes the disadvantages of the increased migration rate seen with covered stents and the tumor ingrowth seen in uncovered stents in the treatment of malignant gastric outlet obstructions. MATERIALS AND METHODS: Two types of expandable nitinol stent were designed: an uncovered stent and a covered stent. Under fluoroscopic guidance, the uncovered and covered stents were placed coaxially with complete overlap in 39 consecutive patients with malignant gastric outlet obstruction caused by stomach cancer. Food intake capacity was graded on a scale of 0-4. Stent patency rate was estimated by the Kaplan-Meier method. RESULTS: Technical success rate was 97% (38 of 39 patients). After stent placement, food intake capacity improved at least one grade in 36 patients. Stent migration occurred in three patients (8%), that is, partial (n = 2) or complete (n = 1) upward migration of the inner covered stent into the stomach. Two of these patients were treated by placement of an additional covered stent. During the mean follow-up period of 134 days (range, 15-569 d), 10 patients developed recurrent symptoms of obstruction with tumor overgrowth being the most common cause. Nine underwent placement of an additional covered stent with good results. The median period of primary stent patency was 157 days (mean, 278 d). The 30-, 60-, and 180-day patency rates were 97%, 91%, and 39%, respectively. Four patients (10%) died within 1 month after the procedure. CONCLUSION: Coaxial stent placement technique seems to contribute to decreasing the migration rate of the stent and decrease the rate of recurrent obstruction by preventing or delaying tumor ingrowth.     

Treatment of Esophagopleural Fistulas Using Covered Retrievable Expandable Metallic Stents

PurposeTo evaluate the clinical efficacy of placement of covered retrievable expandable metallic stents for esophagopleural fistulas (EPFs).Materials and MethodsDuring the period 1997–2013, nine patients with EPF were treated using covered retrievable expandable metallic stents. The underlying causes of EPF were esophageal carcinoma (n = 6), lung cancer (n = 2), and postoperative empyema for Boerhaave syndrome (n = 1).ResultsTechnical success was achieved in eight patients (88.9%). In one patient, incomplete EPF closure was due to incomplete stent expansion. Clinical success, defined as complete EPF closure within 7 days, was achieved in five patients (55.6%). Overall fistula persistence (n = 1) or reopening (n = 4) occurred in five patients (55.6%) 0–15 days after stent placement. The causes of reopening were due to the gap between the stent and the esophagus (n = 3) or stent migration (n = 1). For fistula persistence or reopening, additional interventional management, such as gastrostomy, stent removal, or stent reinsertion, was performed. Stent migration occurred as a complication in one patient with EPF from a benign cause secondary to postoperative empyema. In the eight patients who died during the follow-up period, the mean and median survival times were 78.8 days and 46 days, respectively.ConclusionsPlacement of a covered expandable metallic esophageal stent for the palliative treatment of EPF is technically feasible, although the rate of clinical success was poor secondary to fistula persistence or reopening. Fistula reopening was caused by the gap between the stent and the esophagus or by stent migration, and additional interventional treatment was useful to ensure enteral nutritional support.     

Malignant gastroduodenal obstructions: treatment by means of a covered expandable metallic stent-initial experience

PURPOSE: To investigate the technical feasibility and clinical effectiveness of a polyurethane-covered expandable nitinol stent in the treatment of malignant gastroduodenal obstructions. MATERIALS AND METHODS: The stent was constructed in-house by weaving a single thread of 0.2-mm nitinol wire in a tubular configuration and was covered with polyurethane solution by means of a dipping method. With fluoroscopic guidance, the stent was placed in 19 consecutive patients with malignant gastric outlet obstruction (n = 15) or duodenal obstruction (n = 4). All patients had severe nausea and recurrent vomiting, and their obstructions were inoperable. RESULTS: Stent placement was technically successful in all but one patient. After stent placement, symptoms improved in all but one patient, who had another stenosis at the proximal jejunum. One patient with stent placement in the second portion of the duodenum became jaundiced. During the mean follow-up of 11 weeks, stent migration occurred in five patients 1-4 days after the procedure. All patients with stent migration were treated by means of placing a second, uncovered nitinol stent. Two of these five patients showed recurrence of stricture because of tumor ingrowth; they underwent coaxial placement of a third, covered nitinol stent with good results. CONCLUSION: Placement of a polyurethane-covered expandable nitinol stent seems to be technically feasible and effective for palliative treatment of inoperable malignant gastroduodenal obstructions. Stent migration, however, is problematic and requires further investigation.     

Covered retrievable tracheobronchial hinged stent: an experimental study in dogs.

PURPOSE: To evaluate the safety and technical feasibility of the use of a covered retrievable tracheobronchial hinged stent and investigate the histopathologic airway changes after placement and removal of the stent in dogs. MATERIALS AND METHODS: The experimental stent was composed of tracheal and bronchial stents that were connected together at their ends. Each stent was woven from a single thread of 0.2-mm-diameter nitinol wire filament in a tubular configuration and covered with polyurethane solution by a dipping method. Drawstrings were attached at the upper end of the tracheal stent for stent removal. Under fluoroscopic guidance, 20 stents were placed at the lower trachea and left main bronchus in 20 dogs and were electively removed 4 weeks (n = 10) or 8 weeks (n = 10) after placement. Ten dogs were killed just after stent removal and the remaining 10 were killed 2 weeks after stent removal. RESULT: Stents were successfully placed in all dogs. Pneumonia was observed in three dogs. Stent migration occurred in seven dogs (35%). Except for two cases of stent expectoration, 18 stents were easily removed within a few minutes. There was considerable granulation tissue proliferation and inflammatory reaction in the airways of the dogs that were killed just after stent removal. The pathologic changes of the airways returned to almost-normal conditions 2 weeks after stent removal. CONCLUSION: Placement and removal of a covered retrievable tracheobronchial hinged stent seems to be feasible, and histopathologic changes of the airway related to the stents returned to normal 2 weeks after stent removal.     

Recurrent traumatic urethral strictures near the external sphincter: treatment with a covered,retrievable, expandable nitinol stent--initial results

PURPOSE: To investigate the clinical effectiveness of a covered, retrievable, expandable nitinol stent in treating traumatic urethral strictures near the external sphincter. MATERIALS AND METHODS: The stent was 10 mm in diameter when fully expanded and 40-50 mm long. To make it removable, two nylon drawstrings were attached to its lower inner margin. Twelve consecutive men (19-67 years; mean age, 47 years) with traumatic urethral strictures near the external sphincter that were refractory to endoscopic urethrotomy were treated. With fluoroscopic guidance, a stent was placed to completely bridge the external sphincter. The stent was electively removed with a retrieval hook wire 2 months after placement. Stent placement and removal were successful in all patients, with no procedural complications. RESULTS: Mean maximum urine flow rate was 5 mL/sec (range, 3-7 mL/sec) before stent placement and 27 mL/sec (range, 16-40 mL/sec) at 1 week after placement. During the mean follow-up of 20 months (range, 2-37 months) after the first stent removal, strictures recurred in eight of 12 patients. For the eight patients with recurrence, a second stent was placed and 4 months later was removed from seven of the eight patients. During the mean follow-up of 18 months (range, 4-32 months) after the second stent removal, strictures recurred in two patients, in whom a third stent was placed and then removed 4 months later, with good results. Four (33%) of 12 patients, five (62%) of eight patients, and two (100%) of two patients were successfully treated with placement of the first stent, the second stent, and the third stent, respectively. In the remaining patient, the second stent remains in place. CONCLUSION: Placement of a covered, retrievable, expandable nitinol stent seems to be effective in treating urethral strictures near the external sphincter and warrants further investigation.     

Renal cyst pseudoenhancement: evaluation with an anthropomorphic body CT phantom

PURPOSE: To evaluate the feasibility of using a retrievable urethral stent and to evaluate whether granulation tissue resolves after stent removal in a canine urethra. MATERIALS AND METHODS: Polyurethane-covered retrievable 0.10-mm-thick (n = 11) or 0.15-mm-thick (n = 10) nitinol wire stents were placed in the urethras of 20 dogs. In one dog, a second stent was placed in the urethra because of complete migration of the first stent into the urinary bladder. The stents were removed with retrieval hook wires 4 weeks (n = 10) and 8 weeks (n = 10) after placement. Fourteen dogs were sacrificed just after stent removal, and the other six dogs were sacrificed 2 weeks after stent removal. Information concerning procedure success, stent migration, and tissue response was obtained. RESULTS: Stent placement was technically successful in all dogs. Follow-up urethrograms showed partial (n = 4) or complete (n = 1) stent migration. Stent removal failed in two dogs due to partial or complete migration. Granulation tissue was observed at both ends of the stent in 17 dogs. Urethrograms and urethral specimens obtained 2 weeks after stent removal showed diminished granulation tissue and decreased thickness of the papillary projections of the epithelium compared with results obtained immediately after stent removal. CONCLUSION: Although some design modifications are necessary to reduce current complications, the polyurethane-covered retrievable nitinol stent seems feasible for use in the urethra. Stent-induced granulation tissue formation improved after stent removal.