Urol Radiol 14:234-236 (1992)
Urologic Radiology © Springer-VerlagNewYorkInc. 1992
Update on Interventional Treatment of Urinary Obstruction Andrea F. Abramson and Harold A. Mitty Department of Radiology, Mount Sinai Medical Center of CUNY, New York, New York, USA
Abstract. During the last 20 years percutaneous nephrostomy has evolved as one of the basic procedures in the management of obstructive uropathy. This procedure is now widely available, it is relatively safe, and it offers rapid treatment of urinary obstruction regardless of underlying cause. Percutaneous nephrostomy is also the first step in a variety of antegrade ureteral procedures, including stent placement and ureteral dilation. Key words: Percutaneous nephrostomy -- Urinary obstruction -- Ureteral stenting -- Ureteral dilation.
Percutaneous Nephrostomy Present indications include: (1) diversion of urinary flow for obstruction arising from calculus, intrinsic tumor, extrinsic tumor, inflammatory, traumatic, and congenital causes; (2) diversion of flow for closure of ureteral fistulas and leaking ureteroenteric anastomoses; (3) calculus removal, dissolution, or as an adjunct to extracorporeal shock wave lithotripsy (ESWL); (4) physiological tests (e.g., Whitaker test); and (5) drainage of renal/perirenal abscess or urinoma. Most commonly, a patient is referred for percutaneous nephrostomy after an imaging study has shown hydroureteronephrosis. Often, imaging studies will elucidate the cause and anatomic level of the obstruction, as well as provide information as
Address offprint requests to: Andrea F. Abramson, M.D., Department of Radiology, Mount Sinai Medical Center, Box 1234, One Gustave L. Levy Place, New York, NY 10029, USA
to kidney size and residual renal parenchymal function. Preprocedural laboratory values (i.e., PT, PTT, BUN, serum creatinine, hemoglobin, and platelets) are obtained. When coagulation values are abnormal, fresh-frozen plasma or platelets are given. Intravenous lines are placed routinely for administration of analgesia and sedation during the procedure. Electrocardiogram monitoring is continuous. Transcutaneous oxymetry is now used for all patients who have been sedated. The patient is positioned in either the prone or the prone-oblique position. The choice of position depends on the kind of fluoroscopic equipment available, as well as the experience of the operator. Sonographic guidance is also of value in cases without collecting system opacification. A skin puncture site is chosen which is infracostal and lateral to the renal outline, approximately seven fnger breadths lateral to midline. Local anesthesia is liberally administered from the skin site deep to the level of the renal fascia along the proposed course of the catheter into the kidney. A 22gauge skinny needle is advanced superomedially at an angle of approximately 45* in order to enter the kidney, which is usually opposite L2. Care should be taken to pass well below the inferior margin of the 12th rib, as a catheter rubbing across the intercostal nerve in the area is very painful. Lateral placement of the catheter avoids the discomfort of the patient lying on the catheters and minimizes the risk of catheter kinking. The kidney is punctured through the cortex at its posterolateral margin. This point of entry avoids the major vessels of the kidney and renal pelvic area. One should never enter the renal pelvis directly, as major vessels may be crossed with the initial skinny
A.F. Abramson and H.A. Mitty: Treatment of Urinary Obstruction needle puncture. These vessels would then be at risk during dilation of the tract. In addition, the parenchymal support of renal cortex is necessary for the antegrade placement of the catheter and is especially important if stent placement is a goal. If a stent is to be inserted, a middle posterior calyx should be entered so that subsequent pushing forces can be directed towards the ureteropelvic junction. Most percutaneous extractions of pelvic and ureteral stones can be approached from a posterior calyx. In fact, this is rarely a consideration in today's practice where ESWL is the major method of dealing with calculi. Following initial puncture, a urine sample may be withdrawn for culture. Then a small amount of contrast can be injected to confirm the needle position and calyceal entry site. In a dilated collecting system, a larger volume of contrast may be required to opacify the system adequately. Care should be taken to remove a volume of urine that is greater than the volume of contrast to be injected. If the proper calyx was not punctured, the needle is left in place to provide route for opacification. A second skinny needle is then directed into the optimal position in the collecting system. When the needle is in proper location, passage of the guidewire, dilation of the tract, and placement of the nephrostomy tube are accomplished. A variety of puncture sets using coaxial needle and/or sheaths are commercially available. In our practice, the Neffset (Cook-Bloomington, IN, USA) and One-Stick Set (Medi-Tech, Watertown, MA, USA) are used. A Chiba needle is used for the initial puncture. Thus, minimal renal trauma is produced until the correct calyx is entered. Complications related to percutaneous nephrostomy are of three types: hemorrhage, infection, and catheter related. Some bleeding is inherent in placing a tube through the vascular renal parenchyma. The urine in the collection bag is generally pink in color for several days after nephrostomy. If significant bleeding in the form of grossly bloody urine or clot formation occurs, our first treatment is the placement of a slightly larger diameter catheter to further tamponade the vessel bleeding in the tract. Bleeding which is gross and does not respond to a larger catheter is rare. In a high-risk emergency procedure group, such as that reported by Patel, 2.6% had persistent hematura requiring transfusion [1]. Such cases may need angiography and selective embolization [2]. Infection as a result of placing a percutaneous nephrostomy tube is rarely a problem, since the tube
235 provides drainage which is the basic treatment of an infected space. On the other hand, placing a tube into an infected system may precipitate a sepsis. This is most likely to occur when injection of contrast material through the tube overdistends an infected collecting system, forcing infected urine into the urinary sinus or interstitial tissues. Under such circumstances, episodes of shaking chills and fever may occur. In Patel's high-risk group of 152 patients, all has postprocedural fever [ 1]. Patients with fever or other signs of infection should not have antegrade studies until the system is adequately drained and antibiotic coverage is provided. Injection of contrast material should only be in a volume which replaces a portion of the urine already drained. In general, we do not perform antegrade nephrostograms until the patient has drained for at least 24 h and is afebrile. Catheter-related complications are usually in the form of dislodgement or occlusion of the lumen. Dislodgement is rarely a problem if a self-retaining loop-type catheter is used. Malecot- and Foley-style catheters are more prone to being pulled out. It is important to look under dressings to be sure that catheters are not kinked and occluded. Most percutaneous catheters should be replaced every 3-6 months as a routine. A recently developed dissolvable-tip nephrostomy catheter (Temp-Tip, MediTech) provides a large end hole for improved drainage and facilitated catheter exchange. Ureteral Stents
Once a nephrostomy access has been established, ureteral stent placement may be considered in two major groups of patients: those with ureteral obstruction from malignant tumors and those with benign ureteral problems related to fistulas, strictures, and calculi. In addition, stents may be placed across surgical ureteroenteric anastomoses which are either leaking or strictured. The ideal stent is easily inserted and retrieved and does not migrate. It is biocompatible, chemically stable, and resists occlusion. Stent material should be radiopaque for easy plain film evaluation of position. Double pigtail stents are most popular, but another option for short-term use, or when cystoscopic exchange is not possible, is the nephroureteral stent. Stents may be inserted by antegrade or retrograde route. In difficult cases, a combined approach may be necessary. Stent success may be defined as (1) stent patency for manufacturer's recommended duration of use; and (2) stent patency at time of elective removal or patient's death.
236
A variety o f materials have been used in the manufacture of ureteral stents. The most popular materials are polyurethane, copolymers, and silicone. In our practice, the copolymer, Percuflex (Medi-Tech), 8- and 10-French 22- to 24-cm long sizes, stents are most commonly used. This coaxial delivery system is designed for antegrade insertion. A suture loop is provided for final positioning. This loop may be removed so that retrograde placement is also an option. Replacement every 6 months is recommended by the manufacturer, although Rackson et al. show mean patencies of 10 months [3]. Occasionally, stent placement is technically difficult. In such cases, antegrade transurethral passage of the guidewire can be used. This allows both ends of the guidewire to be grasped so that both pushing and pulling forces are possible. A transrenal sheath may be used to protect the renal parenchyma while a transurethral rubber catheter protects the urethra [4]. Transurethral retrieval and replacement of ureteral stents under fluoroscopic control is an option. The bladder end of the stent can be engaged with a Dormia basket or a "gooseneck" snare via a urethral catheter. A standard guidewire exchange is performed so that a new stent can be inserted [5]. In recent years the number of ureteroileal conduits and continent diversions has increased. These patients are usually referred for leaking or obstruction at the level of the anastomosis. Retrograde attempts to cross the ureteroenteric anastomosis are usually not possible, so percutaneous nephrostomy is performed. Several days later a guidewire--catheter combination is manipulated in antegrade manner through the enteric portion and the stoma. Then a standard nephrostomy catheter is passed retrograde over the guidewire through the stoma and pouch, leaving the catheter tip in the renal pelvis while the luer lock hub exits the stoma to a collecting bag. This "'upside down" orientation reduces the possibility of mucus from the enteric segment block-
A.F. Abramson and H.A. Mitty: Treatment of Urinary Obstruction
ing the drainage holes o f the catheter. Thus, both diversion of urine flow and ureteral stenting are provided. The standard nephrostomy catheter usually suffices for this type of drainage from continent pouches. In the case of longer ileal conduits, we have had manufacturers supply appropriate longer length catheters for drainage. Dilatation of Strictures
Improvements in guidewire technology, including coatings of hydrophilic polymers ("Glidewire," Medi-Tech, Terumo) have made crossing ofureteral strictures easier by both antegrade and retrograde routes. Dilatation of benign ureteroenteric anastomotic strictures showed a high rate of initial success. Longterm follow-up, however, at 1 year by Shapiro et al. shows only 16% remain successfully dilated [6]. Thus, patients undergoing stricture dilation require long-term follow-up. In the event of recurrence of the stricture, repeat dilation or surgical intervention or placement of chronic indwelling ureteral stents should be considered.
References 1. Patel S, Lee WJ: Emergency percutaneous nephrostomy: Analysis of 152 cases. RSNA 1991 2. Cope C, Zert RM: Pseudoaneurysms after nephrostomy. A JR 139:225, 1982 3. Rackson ME, Mitty HA, et al.: Biocompatible ureteral stent: Maintenance ofpateney beyond 9 months. AJR 153:783-784, 1989 4. Mitty HA: Ureteral stenting facilitated by antegrade transurethral passage of guide wire. AJR 142:831-832, 1984 5. Mitty HA, Dan SJ, Train J: Antegrade ureteral stents: Technical and catheterlrelated problems with polyethylene and polyurethane. Radiology 165:439--443, 1987 6. Shapiro MJ, Banner MP, Amendola MA, Gordon RL, Pollack HM, Wein AJ: Balloon catheter dilation of ureteroenteric strictures: Long term results. Radiology 168:385-387, 1988
Urologic Radiology © Springer-VerlagNewYorkInc. 1992
Update on Interventional Treatment of Urinary Obstruction Andrea F. Abramson and Harold A. Mitty Department of Radiology, Mount Sinai Medical Center of CUNY, New York, New York, USA
Abstract. During the last 20 years percutaneous nephrostomy has evolved as one of the basic procedures in the management of obstructive uropathy. This procedure is now widely available, it is relatively safe, and it offers rapid treatment of urinary obstruction regardless of underlying cause. Percutaneous nephrostomy is also the first step in a variety of antegrade ureteral procedures, including stent placement and ureteral dilation. Key words: Percutaneous nephrostomy -- Urinary obstruction -- Ureteral stenting -- Ureteral dilation.
Percutaneous Nephrostomy Present indications include: (1) diversion of urinary flow for obstruction arising from calculus, intrinsic tumor, extrinsic tumor, inflammatory, traumatic, and congenital causes; (2) diversion of flow for closure of ureteral fistulas and leaking ureteroenteric anastomoses; (3) calculus removal, dissolution, or as an adjunct to extracorporeal shock wave lithotripsy (ESWL); (4) physiological tests (e.g., Whitaker test); and (5) drainage of renal/perirenal abscess or urinoma. Most commonly, a patient is referred for percutaneous nephrostomy after an imaging study has shown hydroureteronephrosis. Often, imaging studies will elucidate the cause and anatomic level of the obstruction, as well as provide information as
Address offprint requests to: Andrea F. Abramson, M.D., Department of Radiology, Mount Sinai Medical Center, Box 1234, One Gustave L. Levy Place, New York, NY 10029, USA
to kidney size and residual renal parenchymal function. Preprocedural laboratory values (i.e., PT, PTT, BUN, serum creatinine, hemoglobin, and platelets) are obtained. When coagulation values are abnormal, fresh-frozen plasma or platelets are given. Intravenous lines are placed routinely for administration of analgesia and sedation during the procedure. Electrocardiogram monitoring is continuous. Transcutaneous oxymetry is now used for all patients who have been sedated. The patient is positioned in either the prone or the prone-oblique position. The choice of position depends on the kind of fluoroscopic equipment available, as well as the experience of the operator. Sonographic guidance is also of value in cases without collecting system opacification. A skin puncture site is chosen which is infracostal and lateral to the renal outline, approximately seven fnger breadths lateral to midline. Local anesthesia is liberally administered from the skin site deep to the level of the renal fascia along the proposed course of the catheter into the kidney. A 22gauge skinny needle is advanced superomedially at an angle of approximately 45* in order to enter the kidney, which is usually opposite L2. Care should be taken to pass well below the inferior margin of the 12th rib, as a catheter rubbing across the intercostal nerve in the area is very painful. Lateral placement of the catheter avoids the discomfort of the patient lying on the catheters and minimizes the risk of catheter kinking. The kidney is punctured through the cortex at its posterolateral margin. This point of entry avoids the major vessels of the kidney and renal pelvic area. One should never enter the renal pelvis directly, as major vessels may be crossed with the initial skinny
A.F. Abramson and H.A. Mitty: Treatment of Urinary Obstruction needle puncture. These vessels would then be at risk during dilation of the tract. In addition, the parenchymal support of renal cortex is necessary for the antegrade placement of the catheter and is especially important if stent placement is a goal. If a stent is to be inserted, a middle posterior calyx should be entered so that subsequent pushing forces can be directed towards the ureteropelvic junction. Most percutaneous extractions of pelvic and ureteral stones can be approached from a posterior calyx. In fact, this is rarely a consideration in today's practice where ESWL is the major method of dealing with calculi. Following initial puncture, a urine sample may be withdrawn for culture. Then a small amount of contrast can be injected to confirm the needle position and calyceal entry site. In a dilated collecting system, a larger volume of contrast may be required to opacify the system adequately. Care should be taken to remove a volume of urine that is greater than the volume of contrast to be injected. If the proper calyx was not punctured, the needle is left in place to provide route for opacification. A second skinny needle is then directed into the optimal position in the collecting system. When the needle is in proper location, passage of the guidewire, dilation of the tract, and placement of the nephrostomy tube are accomplished. A variety of puncture sets using coaxial needle and/or sheaths are commercially available. In our practice, the Neffset (Cook-Bloomington, IN, USA) and One-Stick Set (Medi-Tech, Watertown, MA, USA) are used. A Chiba needle is used for the initial puncture. Thus, minimal renal trauma is produced until the correct calyx is entered. Complications related to percutaneous nephrostomy are of three types: hemorrhage, infection, and catheter related. Some bleeding is inherent in placing a tube through the vascular renal parenchyma. The urine in the collection bag is generally pink in color for several days after nephrostomy. If significant bleeding in the form of grossly bloody urine or clot formation occurs, our first treatment is the placement of a slightly larger diameter catheter to further tamponade the vessel bleeding in the tract. Bleeding which is gross and does not respond to a larger catheter is rare. In a high-risk emergency procedure group, such as that reported by Patel, 2.6% had persistent hematura requiring transfusion [1]. Such cases may need angiography and selective embolization [2]. Infection as a result of placing a percutaneous nephrostomy tube is rarely a problem, since the tube
235 provides drainage which is the basic treatment of an infected space. On the other hand, placing a tube into an infected system may precipitate a sepsis. This is most likely to occur when injection of contrast material through the tube overdistends an infected collecting system, forcing infected urine into the urinary sinus or interstitial tissues. Under such circumstances, episodes of shaking chills and fever may occur. In Patel's high-risk group of 152 patients, all has postprocedural fever [ 1]. Patients with fever or other signs of infection should not have antegrade studies until the system is adequately drained and antibiotic coverage is provided. Injection of contrast material should only be in a volume which replaces a portion of the urine already drained. In general, we do not perform antegrade nephrostograms until the patient has drained for at least 24 h and is afebrile. Catheter-related complications are usually in the form of dislodgement or occlusion of the lumen. Dislodgement is rarely a problem if a self-retaining loop-type catheter is used. Malecot- and Foley-style catheters are more prone to being pulled out. It is important to look under dressings to be sure that catheters are not kinked and occluded. Most percutaneous catheters should be replaced every 3-6 months as a routine. A recently developed dissolvable-tip nephrostomy catheter (Temp-Tip, MediTech) provides a large end hole for improved drainage and facilitated catheter exchange. Ureteral Stents
Once a nephrostomy access has been established, ureteral stent placement may be considered in two major groups of patients: those with ureteral obstruction from malignant tumors and those with benign ureteral problems related to fistulas, strictures, and calculi. In addition, stents may be placed across surgical ureteroenteric anastomoses which are either leaking or strictured. The ideal stent is easily inserted and retrieved and does not migrate. It is biocompatible, chemically stable, and resists occlusion. Stent material should be radiopaque for easy plain film evaluation of position. Double pigtail stents are most popular, but another option for short-term use, or when cystoscopic exchange is not possible, is the nephroureteral stent. Stents may be inserted by antegrade or retrograde route. In difficult cases, a combined approach may be necessary. Stent success may be defined as (1) stent patency for manufacturer's recommended duration of use; and (2) stent patency at time of elective removal or patient's death.
236
A variety o f materials have been used in the manufacture of ureteral stents. The most popular materials are polyurethane, copolymers, and silicone. In our practice, the copolymer, Percuflex (Medi-Tech), 8- and 10-French 22- to 24-cm long sizes, stents are most commonly used. This coaxial delivery system is designed for antegrade insertion. A suture loop is provided for final positioning. This loop may be removed so that retrograde placement is also an option. Replacement every 6 months is recommended by the manufacturer, although Rackson et al. show mean patencies of 10 months [3]. Occasionally, stent placement is technically difficult. In such cases, antegrade transurethral passage of the guidewire can be used. This allows both ends of the guidewire to be grasped so that both pushing and pulling forces are possible. A transrenal sheath may be used to protect the renal parenchyma while a transurethral rubber catheter protects the urethra [4]. Transurethral retrieval and replacement of ureteral stents under fluoroscopic control is an option. The bladder end of the stent can be engaged with a Dormia basket or a "gooseneck" snare via a urethral catheter. A standard guidewire exchange is performed so that a new stent can be inserted [5]. In recent years the number of ureteroileal conduits and continent diversions has increased. These patients are usually referred for leaking or obstruction at the level of the anastomosis. Retrograde attempts to cross the ureteroenteric anastomosis are usually not possible, so percutaneous nephrostomy is performed. Several days later a guidewire--catheter combination is manipulated in antegrade manner through the enteric portion and the stoma. Then a standard nephrostomy catheter is passed retrograde over the guidewire through the stoma and pouch, leaving the catheter tip in the renal pelvis while the luer lock hub exits the stoma to a collecting bag. This "'upside down" orientation reduces the possibility of mucus from the enteric segment block-
A.F. Abramson and H.A. Mitty: Treatment of Urinary Obstruction
ing the drainage holes o f the catheter. Thus, both diversion of urine flow and ureteral stenting are provided. The standard nephrostomy catheter usually suffices for this type of drainage from continent pouches. In the case of longer ileal conduits, we have had manufacturers supply appropriate longer length catheters for drainage. Dilatation of Strictures
Improvements in guidewire technology, including coatings of hydrophilic polymers ("Glidewire," Medi-Tech, Terumo) have made crossing ofureteral strictures easier by both antegrade and retrograde routes. Dilatation of benign ureteroenteric anastomotic strictures showed a high rate of initial success. Longterm follow-up, however, at 1 year by Shapiro et al. shows only 16% remain successfully dilated [6]. Thus, patients undergoing stricture dilation require long-term follow-up. In the event of recurrence of the stricture, repeat dilation or surgical intervention or placement of chronic indwelling ureteral stents should be considered.
References 1. Patel S, Lee WJ: Emergency percutaneous nephrostomy: Analysis of 152 cases. RSNA 1991 2. Cope C, Zert RM: Pseudoaneurysms after nephrostomy. A JR 139:225, 1982 3. Rackson ME, Mitty HA, et al.: Biocompatible ureteral stent: Maintenance ofpateney beyond 9 months. AJR 153:783-784, 1989 4. Mitty HA: Ureteral stenting facilitated by antegrade transurethral passage of guide wire. AJR 142:831-832, 1984 5. Mitty HA, Dan SJ, Train J: Antegrade ureteral stents: Technical and catheterlrelated problems with polyethylene and polyurethane. Radiology 165:439--443, 1987 6. Shapiro MJ, Banner MP, Amendola MA, Gordon RL, Pollack HM, Wein AJ: Balloon catheter dilation of ureteroenteric strictures: Long term results. Radiology 168:385-387, 1988
