Transrenal ureteral embolization

Occlusive Properties of Transrenal Ureteral Occlusion Self-Expandable Metallic Stents: 3D-Printed Phantom and Ex Vivo Studies

Newly developed transrenal ureteral occlusion self-expanding metallic stents (SEMSs) are applied in patients with inoperable fistulas. In this study, the occlusive properties of M- and D-type occlusion SEMSs were investigated in 3D-printed phantom and ex vivo porcine urinary tracts. In the former, the mean bursting pressure causing leakage of contrast medium through the occlusion SEMS was relatively higher in M-types (42.8 ± 3.8 mmHg) than in D-types (38.8 ± 3.8 mmHg), without a statistical difference (p = 0.075). In the latter, the bursting pressure causing leakage through the M-type occlusion SEMS (110.7 ± 8.6 mmHg) was significantly higher than that of the D-type occlusion SEMS (93.8 ± 11.2 mmHg, p = 0.015); however, the mean bursting pressures causing contrast blowout did not differ between the two types (178.7 ± 11.2 mmHg vs. 176.2 ± 11.8 mmHg, p = 0.715). In conclusion, M- and D-type occlusion SEMSs showed similar efficacy in occlusive properties in the 3D phantom study; however, the M-type was superior in the ex vivo porcine urinary tract model. Further in vivo experimental studies are required to confirm these experimental results.

In Vitro Evaluation of the Occlusive Properties of the ArtVentive Endoluminal Occlusion System Occlusion Device for Transrenal Ureteral Occlusion

PURPOSE

Current techniques for percutaneous ureteral occlusion are either technically difficult or not satisfactory because of frequent ureteral recanalization. The purpose of this in vitro study was to evaluate the occlusive properties of an "off the shelf" solution (Endoluminal Occlusion System [EOS™]; ArtVentive Medical Group, Inc., Carlsbad, CA) for transrenal ureteral occlusion.

MATERIALS AND METHODS

Both 8 and 11 mm expanded polytetrafluoroethylene-covered ArtVentive EOS devices were used in 10 porcine models. Experiments were performed in explanted porcine ureters to simulate physiologic conditions. EOS devices were deployed in a midureteral position using a transrenal approach. Contrast agent (Iopamidol 300) diluted in saline solution was infused into the renal pelvis under continuous fluoroscopic guidance. Intrapelvic pressure measurements were performed until leakage, plug dislocation, or until pelvic blow out occurred.

RESULTS

All EOS devices were deployed effectively and achieved prompt total ureteral occlusion. Ureteral leakage occurred with intraureteral pressures between 60 to 109 cm H₂O (8 mm EOS) and between 65 and 125 cm H₂O (11 mm EOS). Before leakage, tubular reflux was seen in all cases, pelvic blowout occurred in half of the cases.

CONCLUSIONS

The ArtVentive EOS occlusive device is an effective tool for "off the shelf" ureteral occlusion. Both the 8 mm and the 11 mm devices fully occluded ureters at pressure levels that are to be expected in vivo.

The Upper Urinary Tract

Pyelography is superior to all other imaging techniques for the demonstration of fine detail in the pelveocalyceal system and the ureter. For almost 90 years it has been performed through a retrogradely inserted catheter, but during the recent 30 years antegrade injection via a transparenchymally inserted needle or catheter has become an accepted alternative, especially in case of a dilated upper urinary tract. Both methods have their advantages and their disadvantages. This article presents a review of indications, techniques, and complications. Furthermore, interventional procedures on the upper urinary tract—such as stent placement and balloon dilatation—are now handled by the radiologist, mainly through an antegrade approach. These therapeutic procedures are also reviewed.

Postoperative ureteral leak treated using a silicone-covered nitinol stent

Ureteral fistula is a serious complication of abdomino-pelvic surgeries, often resulting in poor outcomes owing to lack of proper treatment. We report the case of a 49-year-old woman who underwent placement of a silicone-covered ureteral occlusion stent in her right ureter for the management of ureteral leakage after pelvic surgery. A ureterogram obtained 18 months following the stent placement confirmed that there was no stent migration or additional urine leakage. We propose that the silicone-covered ureteral occlusion stent is practical, fast, and safe for the management of ureteral leakage.

In vitro evaluation of the occlusive properties of latex-covered amplatzer vascular plugs for transrenal ureteral occlusion

PURPOSE

To evaluate the occlusive properties of latex-covered Amplatzer Vascular Plugs (AVPs) for transrenal ureteral occlusion in vitro.

MATERIALS AND METHODS

Latex-covered AVPs type I and II (diameter 8, 10, 12, 14, and 16 mm) were used as occlusive devices. Radial force of an AVP was measured using simulated ureteral diameters of 4 to 12 mm. Occlusive properties were examined in a silicone tube (inner diameter 6 mm) with measurement of drainage time of a 40 cm water column. In complete occlusion, the maximum pressure that the plug was able to withstand was determined at different temperature levels. Statistical analysis of drainage time was performed in a general linear model (GLM) and using correlation analyses. Explanted porcine ureters were used to simulate physiologic conditions. Pressure measurements were performed until leakage, plug dislocation, or rupture of the ureter occurred.

RESULTS

Radial force depended on AVP type, size, ureteral diameter, and temperature. The 16-mm AVP II showed the highest radial force of more than 5 N (ureteral diameter 4 mm, body temperature). All AVP I showed water leakage and plug dislocation. Drainage time of the AVP II depended significantly on plug size and temperature and correlated with radial force (r=0.731, P<0.001). In complete occlusion, water leakage occurred at 500 to 1000 cm H2O and dislocation between 500 to more than 2000 cm H2O. In porcine ureters, leakage occurred at room temperature between 19 to 93 cm H2O. At body temperature, all AVP II occluded the ureter completely.

CONCLUSION

Latex-covered AVP II (diameter 8-16 mm) can effectively occlude the ureter, especially considering remodeling of the nitinol at body temperature. Large plug diameters can exert enough radial force even in dilated ureters to allow for successful occlusion. Because deployment of a 16-mm latex-covered AVP II can be technically difficult, we advocate the use of 12- or 14-mm AVP II for transrenal ureteral occlusion. AVP Is are not suitable for ureteral occlusion.

Ureteric embolization: an alternative treatment strategy for urinary fistulae complicating advanced pelvic malignancy

OBJECTIVE

To report experience with a minimally invasive technique for palliation of urinary fistula/incontinence complicating advanced pelvic malignancy or its treatment.

PATIENTS AND METHODS

We used ureteric embolization with permanent nephrostomy drainage in eight renal units in five patients for palliation of symptoms. All procedures were done under local anaesthesia as day-case procedures. Nephrostomy tubes were changed at regular intervals on an outpatient basis. Embolization was repeated when required.

RESULTS

The follow-up was 2-84 months; four patients died from the underlying malignancy during the follow-up. All patients were continent and had effective palliation of their symptoms. Two patients required repeat embolization. There were no embolization-related complications.

CONCLUSIONS

Ureteric embolization is a safe and effective minimally invasive palliative treatment option in urinary fistulae or incontinence complicating advanced pelvic malignancy.

Ureteric embolization with stainless-steel coils for managing refractory lower urinary tract fistula: a 12-year experience

OBJECTIVE

To report our 12-year experience with radiological treatment (ureteric embolization) for refractory urinary fistula, as malignancy, radiation therapy, and/or chronic inflammation increase the risk of lower urinary tract fistula after surgical urinary diversion, which can lead to significant morbidity, and for patients who are not surgical candidates permanent nephrostomy drainage and ureteric embolization offer an alternative form of urinary diversion.

PATIENTS AND METHODS

We retrospectively reviewed patients who had ureteric occlusion for refractory urinary fistula at our institution between 1993 and 2005. Stainless-steel coils, with or without gelatine sponge, were placed antegradely through a percutaneous nephrostomy tract. Patients were then managed by long-term nephrostomy drainage until death or definitive reconstructive surgery.

RESULTS

In all, 29 patients (23 women and six men; mean age 59 years, sd 16) were identified who had urinary fistulae that were refractory to nephrostomy drainage alone. One patient had a history of severe perineal trauma and the remaining 28 had a history of cancer. Seventeen fistulae occurred in the setting of previous surgery, 20 patients had received adjunctive pelvic irradiation and 11 had had chemotherapy. In all, 52 ureters were embolized; occlusion was successful in all cases, with complete or near-complete (<1 pad/day) dryness within 3 days. No repeat embolization was required and there were no significant complications. Two patients were lost to follow-up. Three patients had definitive urinary diversion surgery and currently are well. One patient is alive and living with nephrostomy tubes; 23 patients have died.

CONCLUSION

Ureteric embolization is a viable option for managing complex lower urinary tract fistulae in patients with a poor performance status. It can be used as definitive management in patients with a limited life-expectancy or as a temporary measure in those for whom another management plan is anticipated.

Ureterocutaneous fistula and urostomy exclusion with use of a covered wallstent

The present report describes a case of urostomy breakdown and failed urinary diversion with bilateral nephrostomy drainage treated with transrenal placement of a covered stent. Covered stents can be used successfully for the exclusion of ureterocutaneous fistulas and urostomies with the potential for ureteric occlusion.

Fistulas of the Lower Urinary Tract: Percutaneous Approaches for the Management of a Difficult Clinical Entity

Fistulas of the lower urinary tract are uncommon conditions that may occur spontaneously or after therapy in patients with various pelvic abnormalities. When present, these fistulas are associated with urine leakage, which is often socially distressing and disabling. Unfortunately, factors that lead to the formation of genitourinary fistulas often increase their complexity or preclude surgical repair. A high failure rate is associated with surgical repair, and many patients are not optimal surgical candidates. For such patients, a percutaneous treatment approach is highly desirable. Percutaneous ureteral occlusion combined with insertion of a functioning nephrostomy tube allows complete diversion of urine in those patients in whom nephrostomy alone does not provide adequate relief. Many approaches to percutaneous ureteral occlusion have been used with variable success, including coils and gelatin sponge, isobutyl-2-cyanoacrylate, detachable balloons, radiofrequency electrocautery, ureteral clipping, and solid and soft polymer agents. Furthermore, percutaneous or retrograde ureteral stents may be used to preserve antegrade urine flow, and surgical options are also available. It is essential that the interventional radiologist involved in the care of these patients be familiar with these different techniques as well as with the limitations, pitfalls, and possible complications of their use.

Ureteral occlusion prosthesis

Although temporary or definitive complete ureteral occlusion is rarely needed, there is a considerable number of reports introducing different devices to achieve this goal, most of which can be inserted with minimally invasive procedures. Easy placement is considered of paramount importance, as the candidates are very often in bad general condition as a result of previous surgery, radiotherapy, or other palliative treatments for cancer. A device that can be inserted and removed percutaneously is presented herein. It can be employed in cases of ureteral fistulas resulting from radiotherapy and ureterosigmoidostomy with good results. The technique is simple and not time consuming.

Experimental evaluation of a new device for percutaneous transrenal ureteral occlusion

PURPOSE

To develop a device for percutaneous transrenal ureteral occlusion.

MATERIALS AND METHODS

The device was a double-body Gianturco-Rösch biliary stent constrained at the junction of the two stents to create an hourglass shape. One stent was coated with silicone. One device was percutaneously placed in each of nine pigs through a 9-F Teflon sheath. Urographic and hematologic follow-up was performed for up to 12 weeks.

RESULTS

Seven pigs showed immediate, complete ureteral occlusion, and two pigs exhibited persistent incomplete high-grade obstruction. All animals exhibited varying degrees of hydronephrosis and hydroureter. No device migration was noted. Minor complications were encountered during device placement in three pigs. Mucosal folds and villus-like projections that arose from the lamina propria protruded into the lumen of the ureter at the cranial end of the covered stent and around the wire of the caudal stent. Varying degrees of mural inflammation and edema were noted.

CONCLUSION

Transrenal ureteral occlusion with the described device appears to be a viable method for treating urinary fistulas.

Endoscopic placement of coaxial balloon dilating catheter to facilitate open ureteral surgery

After urinary diversion, access to the distal ureter for either resection or repair, especially in patients with history of infection, extravasation, radiation, or other abdominal surgery, can be hazardous. We report two cases where the endoscopic placement of a coaxial balloon dilating catheter prior to open exploration greatly facilitated ureteral identification and localization in a difficult surgical field.

Catheter modification for transrenal temporary total ureteral obstruction: the "occlusive" nephroureteral catheter

When temporary diversion of urine is desired and a simple nephrostomy catheter is insufficient or passage of a ureteral stent cannot be achieved, a standard 8 or 10 F nephroureteral catheter can be modified to provide a single nephrostomy drainage catheter with an occluded ureteral segment that provides total diversion of urine. The "occlusive" nephroureteral catheter is exchangeable over a guide wire as necessary. When healing of the ureteral or bladder process has occurred, the catheter is removable, allowing restoration of normal urine flow.

Percutaneous ureteral occlusion with use of Gianturco coils and gelatin sponge. Part II. Clinical experience

A previous report described the use of coils and gelatin sponge pledgets as a means of producing ureteral occlusion to achieve urinary diversion in patients with urinary fistulas. The authors have performed this procedure in nine ureters of six patients. Five of the patients had urinary leaks with extensive pelvic tumor, and one had severe chronic cystitis. Ureters were occluded with use of Gianturco coils and gelatin sponge pledgets placed via a sheath through a percutaneous nephrostomy tract. The procedure was successful in all patients as judged by means of antegrade nephrostogram or intravenous pyelogram and by marked improvement or complete resolution of symptoms.

Endoluminal thermal occlusion of the ureter with the electromagnetic field-focusing device

The authors attempted ureteral occlusion by means of heat application in nine ureters (24 sites) of New Zealand White rabbits with the electromagnetic field-focusing (EFF) device. The EFF device generates heat at the tip of a grounded probe by focusing eddy currents that have been induced within the tissues by an external radio-frequency field. The power settings were varied from 30 to 150 W. Heat was applied at multiple sites in each ureter. Immediate functional occlusion was seen in all nine ureters. Long-term complete occlusion was seen in six ureters at power settings ranging from 40 to 150 W, while long-term partial occlusion was seen in two ureters at 30-50 W. All sites at 30 W resulted in partial occlusions. Perforation of the ureter resulted in urinoma formation in one ureter at a site that was treated with 150 W. The EFF device can be used to endoluminally occlude the ureter by causing a fibrotic reaction to thermal injury. The effective power range for this application appears to be 40-100 W.

Percutaneous transrenal ureteral occlusion: indication and technique

Several techniques for achieving palliative ureteral occlusion in cases of underlying malignant diseases are known to exist. We performed nine ureteral occlusions on seven patients, using two different techniques (occlusion by detachable balloon and by "Harzmann Olive"). Initially, complete occlusion of all ureters was attained; in two cases a second occluding intervention had to be carried out after a period of 6 and 14 weeks. Six of seven patients enjoyed a marked improvement of their quality of life after occlusion. Complications were down to a minimum. In comparison with other techniques described in the literature, Harzmann's method seems to be the simplest, as well as the most fully developed one. It may also be recommended for patients in an advanced tumor stage.

Interventional procedures in the upper urinary tract

The introduction and acceptance of percutaneous nephrostomy as a safe and effective alternative to surgical nephrostomy served as the impetus for the development and expansion of an ever-increasing number of techniques that are encompassed by the term "interventional uroradiology." This article reviews many of the nonvascular interventional techniques that have proliferated during the past decade and that are currently used in the kidney, ureter, and perinephric space. The authors emphasize those procedures that are most frequently employed, as well as their own preferences and perspectives on these procedures.

Therapeutic transrenal occlusion of the ureter: solution of plug migration problem

Vesicovaginal fistulas in three patients and a vesicocutaneous fistula in one patient were treated by percutaneous transrenal occlusion of the ureter with a commercially available silicone occluder (Angiomed, Karlsruhe, Germany) which was secured by means of histoacryl placed on top. Urinary flow was diverted by a permanent nephrostomy tube. We observed no complications (e.g., urinary tract infection, occluder migration, or recurrence of urine discharge) at an average follow-up period of 9.1 months.

Percutaneous ureteral fulguration: a nonsurgical technique for ureteral occlusion

Three patients with lower urinary tract fistulas after multiple operations and radiation therapy for pelvic cancer were treated with percutaneous ureteral fulguration and nephrostomy tube drainage. This technique occluded the ureter and allowed for maintenance of a dry fistula site in all 3 patients. There were no complications. The longest followup in these patients was 21 months. The procedure is simple technically and it can be performed with the patient under local anesthesia. The technique of percutaneous ureteral fulguration is described and other techniques for nonoperative occlusion of the ureter are discussed.

Percutaneous occlusion of ureteral leaks and fistulae using nondetachable balloons

High-output ureteral fistulae were managed percutaneously in 3 patients with pelvic malignancies. Urine flow was diverted by combining percutaneous nephrostomy catheter drainage with transrenal balloon occlusion of the affected ureter proximal to the site of extravasation. This technique can be used either alone as the definitive method of treatment or as the initial procedure to preserve renal function and reverse the inflammatory reaction prior to subsequent surgical repair; its primary application is in patients in whom antegrade or retrograde ureteral stenting is not feasible or possible.

Renal artery embolization to control urinary cutaneous fistula after partial resection of a horseshoe kidney

We describe a patient with a chronic urinary cutaneous fistula following partial nephrectomy of a previously separated horseshoe kidney, who was treated successfully by stainless steel coil embolization of the renal artery. Thus, a major reoperation was avoided.