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Percutaneous ureteral surgery and stenting
PERCUTANEOUS URETERAL SURGERY AND STENTING ARTHUR D. SMITH, M.D. From the Division of Urology, Long Island Jewish-Hillside Medical Center, New Hyde Park, New York
percutaneous nephrostomy tract provides ready access with a nephroscope to the upper ureter directly allowing the urologist to remove stones and to perjorm operative procedures such as endopyelotomy. The tract also permits antegrade insertion of ureteral stents and ureteral catheters to which other instruments can be attached, this facilitating stone basketing, controlled ureteral meatotomy, and retrograde stent insertion.
ABSTRACT-The
Widespread application of the technique of percutaneous nephrostomy has made the ureter accessible for a number of procedures that formerly could be done only by open operation or-often with considerable difficulty-by cystoscopy. This is a review of some approaches to ureteral calculi, ureteral surgery and stents. Endourologic
Approach to Ureter
The position of the nephrostomy tract is critical in obtaining ready access to the ureter; the site should be high and peripheral to create a transparenchymal route to a middle calyx or infundibulum. If one punctures the collecting system by a direct posterior route or through a lower-pole calyx that forms an angle of less than 60 degrees with the ureteropelvic junction, the ureter may be inaccessible. On occasion, it may be necessary to puncture the kidney above the twelfth rib. This should be done only after one has determined the relation of the diaphragm to the rib fluoroscopically. The technique of percutaneous nephrostomy for ureteral access has been reviewed by Miller et al.’ During tract dilatation, a second safety guidewire is advanced down the ureter, preferably past the stone, so that if the guidewire one is using to pass the instruments becomes dislodged, the nephrostomy tract will not be lost. As added insurance, a 5-F catheter can be passed over the safety guidewire and sutured to the skin. Several methods are available for dilating a nephrostomy tract. If one intends to proceed with
SPECIAL
stone removal in the same session, dilatation can be done with a Gruntzig or Olbert balloon catheter, and some believe that these methods are less traumatic, and thus cause less bleeding, than do fascial and coaxial dilators.2 Personally, I find the Amplatz dilator set* to be effective, safe, and relatively inexpensive since they can be resterilized.
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Ureteral Calculi The old rule against manipulation of ureteral stones larger than 0.5 cm and those located above the iliac vessels is no longer valid. The principle underlying the rule was that the diameter of the ureter distal to the stone was so small that traction on the object, especially in the mobile portion of the ureter, was likely to cause avulsion. However, now that stones can be approached via the dilated proximal part of the ureter, closed extraction can be a relatively simple and atraumatic procedure. Thus, to the traditional retrograde approach, one can add two others: antegrade and a combination antegrade-retrogrades3 Antegrade
approach
After the tract has been dilated, a nephroscope can be introduced into the renal pelvis. With its help, the pelviureteral junction can be seen readily, and a stone basket can be advanced down the ureter. The stone is then either captured in the basket or *Cook Urological,
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ceps or graspers; fluoroscopy is used in either case. Alternatively, a stone basket can be advanced through the safety guidewire introducer. Anyone who has tried basketing under fluoroscopy will readily appreciate the advantages of using direct vision. The advent of the flexible nephroscope with its graspers and baskets has made this direct approach far easier than it was in the past, although the operator will need considerable practice with the instrument to become proficient in its use. Also, in some cases a rigid nephroscope or panendoscope will be suitable. Unfortunately, the stone basket does not always work no matter how it is manipulated, and in such cases it may be advisable to grasp the stone under direct vision. A panendoscope that can accommodate 7-F flexible alligator forceps is suitable for most ureter-al stones less than 8 mm in diameter located above the transverse process of L4 (in thin patients) or L3 (in obese patients). Larger stones can be removed with rigid forceps introduced via a nephroscope or, if they are wedged in the ureter, by ultrasonic lithotripsy. Retrograde approach This subject is discussed elsewhere in this issue. The introduction of new instruments such as the uretero-renoscope has changed the indication for retrograde removal of ureteral stones, and there is some debate about the “best” approach to various stones. In my experience, ureteroscopy is most suitable for stones below L3-L4, whereas other operators find the technique suitable for stones in the renal pelvis as well. I suspect that the relative familiarity of the operators with the antegrade and retrograde approaches is a significant factor in their preferences for one or the other. Combined approach Because of the ease with which loose stones can be removed from the renal pelvis, some uroradiologic teams have devised ways to push ureteral stones upward-ureteral catheters and stone baskets are popular. A particularly promising method is to occlude the ureter with a balloon below the stone and “blast” the stone into the renal pelvis with a jet of saline, contrast medium, or carbon dioxide. A working sheath in a previously created percutaneous nephrostomy prevents sudden increase in intrapelvic pressure, which could cause parenchymal damage, and provides immediate access to the newly liberated stone. In more than 20 cases, CastanedaZuniga et al.’ have had no failures with this method. Approach in patient with a conduit Ureteral calculi in patients with ureteroileal conduits are a unique problem, as the retrograde approach is exceptionally difficult. In one of our ear-
38
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~~~uuuru~o~c stone-removal procedures,5 advanced an angiographic catheter down the ure via a percutaneous nephrostomy, retrieved its I from the conduit, and attached a stone baskl which was then pulled up into the ureter so the sto could be basketed under fluoroscopic control. Simultaneous pressure on the basket handle fra below and the angiographic catheter from abo opened the basket wider than usual, enabling it ensnare the stone more readily We have utilized tl same method in patients with multiple stones in tl lower ureter, because it may be difficult to pass basket repeatedly by the usual methods. An inherent weakness of this do-it-yourself syste is the ligature fixing the stone basket to the angil graphic catheter: sometimes, it breaks. This pro1 lem has been overcome by development, at the Un versity of Minnesota, of a stone basket mounted in shaft that will extend from the nephrostomy site bc yond the ureteral meatus. llWl
Comments Early reports of the percutaneous approach t ureteral calculi were not encouraging, with succe! rates of no more than 70 per cent, compared to mor than 90 per cent for renal stones. However, newe techniques and instruments are leading to rapid im provements, and I suspect that within a short tim nearly all ureteral calculi will be removable b closed procedures. Operations
on Ureteropelvic
Junction
The most extensive experience with incision of thl ureteropelvic junction is that of Whitfield in Grea Britain.B He incises the tissue in the inferolatera angle until fat can be seen nephroscopically. The ureter is then stented for four to six weeks. We have used a similar procedure, which we call “endopy elotomy” in 5 patients and have been impressed wit1 the simplicity of the procedure. In all our patients. the area of narrowing was short, and in all cases the ureteropelvic junction snapped open after the incision was made to reveal normal-caliber ureter distal to the strictured area. In our patients, the ureter wa stented for six weeks with a Universal (Smith) stent. i Although our follow-up has been too short to assess the eventual effect of this approach, all patients have done well to date, and there have been no complications. Clayman et aZ.*also have described making incisions in the collecting system and ureteropelvic junction endourologically (percutaneous electrosurgery) to free trapped and impacted stones. They emphasize the need to have a clear mental picture of the renal vascular anatomy and to examine the area nephroscopically for arterial pulsations before making any incisions. Another approach to narrowing of the ureteropelvic junction is described by King,e who used balloon dilatation. Presumably, balloon dilatation will
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be most effective long term when the tissue around the narrowing has not become heavily scarred. Banner et ~2.‘~ recently reported on ureteral strictures associated with dense scar tissue or long segments of devitalized tissue. Operations Ureteral
on Distal Ureter
meatotomy
Repeated resections of bladder tumors may lead to ureteral meatal stenosis; making the orifice difficult to see cystoscopically. A percutaneous nephrostomy will allow an angiographic catheter to be passed down into the bladder. The stenotic meatus can then be incised over the catheter with a Callings knife or a resectoscope knife. Alternatively, a ureteral catheter with a l-cm length of steel stylet exposed can be passed through the meatal orifice. When the stylet is positioned against the stenotic tissue, the proximal end of the stylet is connected to electrocautery to incise the area, the stylet being repositioned for a series of incisions until the junction has been opened satisfactorily. Application of this method to ureteroileal strictures was one of the first endourologic operations performed.” The area is usually stented for several weeks. When the stricture is short and there is no marked periureteral fibrosis, the long-term results of these controlled meatotomies are good. However, even after several months of stenting, long ischemic strictures usually restenose when the stent is removed. Dilatation
of strictures
and stenoses
Endourologic stretching of ureteral strictures or usually with balloon catheters stenosis, (transluminal ureteroplasty) is discussed by Rutner in this issue (pages 44-53). In properly selected patients, the success rate is high; but unfortunately some of the most common ureteral strictures, such as those secondary to injury during radical hysterectomy, seldom respond well.1a Among the successors of balloon dilatation are some involving stenoses in allograft ureters.i2 One of the more interesting reports of the endourologic treatment of ureteral narrowing concerns the successful dilatation of ureter inadvertently ligated with absorbable suture during emergency cesarean section. l3 Graded Teflon dilators and coaxial techniques were used. This method probably should be applied only when absorbable sutures are involved and be timed to take place shortly after maximal resorption. Management
of fistulas
Although percutaneous nephrostomy and ureteral stenting have made it possible to delay or even avoid
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many open operarious IVI IIJCU~~~,cAnVJ. . . . - ------ -offer in the many cases, such as patients with cancer, in which the ureter has little potential for healing itself. In these cases, some have occluded the ureter permanently with a balloon catheter passed through a percutaneous nephrostomy and established permanent nephrostomy drainage or embolized the kidney to make it nonfunctional. The latter would seem to be an approach of last resort to avoid open nephroureterectomy.
Ureteral stents There is no ideal ureteral stent despite the many types available. A particular problem is the ease with which all can become occluded if the urinary output is decreased in the presence of infection. Basically, there are two types of ureteral stents: those with and those without external communication. The advantages of the entirely internal stent is that there is no dressing on the nephrostomy site, with its attendant bother; the disadvantage is that when the stent becomes occluded, the immediate stent exchange or percutaneous nephrostomy is mandatory to drain the kidney. Stents with external communication do not carry a great risk of infection and provide immediate nephrostomy drainage and sometimes can be reopened by flushing. Four materials have been used in ureteral stents. Polyethylene is easy to insert and, with a low ratio between the internal and external diameters of the stents, has a good flow rate. However, its rigidity causes discomfort, and it depolymerizes when bathed in urine. This makes it brittle and proves to fracture after six months of continuous use. Therefore, polyethylene is no longer used in stent manufacture. Polyurethane is less brittle, and usually more flexible, than polyethylene and is approximately four times as resistant to breakage as is silicone rubber. Flow rates are good. However, scanning electron microscopy shows a polyurethane surface to be far more irregular than one of silicone rubber, and this could encourage encrustation. Silicone rubber, the standard against which other stent materials are judged, is a thermostat elastomerice polymer that is biocompatible and chemically stable. It can be made in various consistencies; the form used in stents generally produces a smaller internal diameter than a stent of the same outer French size made from polyethylene. Its tensile strength is low, but it has good elasticity. Its softness makes it more comfortable for the patient, but more difficult to advance over a guidewire. C-Flex14 is a newly introduced copolymer with a tensile strength twice that of silicone rubber and similar surface characteristics. With it, a stent can be made with a larger internal diameter than is possible for a silicone rubber stent of the same outer French size. The long-term results of C-Flex stents are not yet known.
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FIGURE 1.
right-Finney
Ureteral Stents. (A) Left to right-Bard coil, Gibbons, Combination and Universal. (B) Left tl ureterointestinal stent, double-J, double-pigtail, and Mardis stent.
Indications for stenting Ureteral stents are used to provide urinary drainage on a short or long-term basis when the ureter is stenotic, strictured, fistulous, or being compressed by an extrinsic mass. There is an ethical problem about stenting in patients with metastatic cancer (see review by Ortlip and Fraley15). Certainly, if there is some modality of treatment that has not yet been tried, stenting is indicated.
Internal stents The original Gibbons stent was introduced in 1967 and since that time has been upgraded constantly (Fig. 1A). It is fabricated of radial compression-resistant silicone rubber tubing with radiopaque barbs to prevent proximal migration. It also has a retrieval tail. The Gibbons stent is available in several sizes, but precise matching of stent and ureteral length is not necessary. Bladder discomfort is minimal. If the stent becomes occluded, it can be reopened with a guidewire inserted transcystoscopitally. The principal indication for a Gibbons stent is obstruction in the lower half of the ureter. This stent is contraindicated as a splint for an anastomosis or fistula because of the barbs. This stent may be inserted transcystoscopically or, if this fails, by a combination transcystoscopic-endourologic technique. l8 The double-J, or Finney, stent is of silicone elastomer and is molded at both ends into a hook (the “J”) to prevent migration (Fig. 1B). There are drainage holes every centimeter. A guide strip marked in centimeters is imprinted in order to be visible through the cystoscope during insertion. The stent is available in 6 F to 8.5 F diameters and lengths of 16 to 30 cm. When properly positioned, the upper end of the Finney stent lies in the renal pelvis and 1 to 2 cm of
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SPECIAL
the lower end in bladder. Excessive length in th bladder will cause discomfort, and thus accuratl preinsertion measurement of ureteral length is net essary. This can be done with a ureteral catheter o radiologically (with allowance for the approxi mately 10 per cent magnification on an intravenou pyelogram). The Finney stent can be inserted a open operation or transcystoscopically Also Kahn’ has described an antegrade method in which lubri cation of the guidewire with sterile mineral oi minimizes resistance to stent passage. The Bard coil stent is similar to the double-J stem in that it is made of radiopaque silicone rubber with side holes 1 cm apart (Fig. 1A). There are retention coils at both ends to prevent migration. The distal end has a series of helical coils 25 cm long that is cut to the proper length to fit ureters 16 to 30 cm long, this can be done either before insertion or, with cystoscopy scissors, after the stent has been placed in the ureter. The stent is available in 5 F to 8 F sizes. Although designed only for cystoscopic insertion, the Bard coil could be inserted at open operation or endourologically. The chief advantage of this stent is that it reduces inventory because fewer sizes must be available to insure a proper fit. The double-pigtail stent is made of polyurethane and is available in diameters of 5F to 8F and lengths of 8 to 30 cm (Fig. 1B). It can be inserted at open operation, cystoscopically, and endourologically, and the ease with which it can be passed over a guidewire explains much of its popularity. Proper selection of the length is important, because excessive length in the bladder will cause discomfort and irritative voiding symptoms. The Van-Tee Mardis multipurpose stent’ is made of the new copolymer, C-Flex (Fig. 1B). It is a *Van-Tee.
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(A) Peel-away FIGURE 2. stent introducer is advanced over 0.038~inch guidewire down ureter to bladder. (B) 9F Teflon catheter and guidewire have been removed, and 11-F Peel-away sheath is in ureter. (C) The 0.032-inch Lunderquist wire is in pre-cut Universal stent, and this is advanced through 11-F Peelaway introducer down to bladder. (0) Universal stent is held in place by Lunderquist guidewire and Peel-away stent is progressively withdrawn until it is totally removed. Lunderquist guidewire is then removed and position of stent checked.
A
C
double-pigtail stent that, like the Finney, is closed at one end. It is available in 5F to 8F sizes in lengths of 10 to 34 cm. It has flow rates similar to those of polyurethane stents but is softer and thus perhaps more comfortable. It can be inserted fairly easily cystoscopically and at open operation, but when advanced antegrade over a guidewire through a nephrostomy tract, it tends to bind to tissue and the wire. Stents with external communications At present, there are two types of these stents: the Universal (Smith) design and the Van-Tee combination stent. The Universal stent is made of radial compressionresistant silicone rubber tubing that has a linear barium-strip marker (Fig. 1A). Drainage holes are positioned along a 4-cm length in the middle of the
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stent, and this zone is labeled with a radiopaque band at both ends. There also is a labeled zone of drainage holes in the terminal 15 cm (Fig. 1B). A Luer-Lok adaptor at the proximal end protrudes from the nephrostomy site and permits drainage, irrigation, and radiographic studies. For internal drainage, the adaptor is capped. The patient is instructed to remove the cap if pain or fever appears. In patients with malignant obstruction, the ability of the kidney to recover is often in doubt. In these patients, the Universal stent is an excellent choice, since it allows one to monitor the urine output of the kidney while relieving the obstruction. If desired, it can be replaced with an internal stent after two to three months. Similarly, the Universal stent is helpful if renal failure may be impending. With an internal stent, it can be difficult to determine whether a patient admitted with oliguria or anuria has an occluded stent or is truly in renal failure, yet it is not
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~IICL lapace me stent(s). If a Universal stent is in place, it can simply be uncapped; if it does prove to be occluded, it can be replaced or removed without cystoscopy. The Universal stent can be inserted at open surgery and has been used extensively to splint pyeloplasties, ureteral reimplantations, and ileal conduit.7 For closed insertion, an antegrade approach is necessary. One technique, in which the stent is pulled into place with the aid of an angiographic catheter, has been described.’ We have since found that the easiest way to insert this stent is with a Peelaway stent introducer, which consists of a 9-F Teflon catheter within an 11-F Teflon Peel-away sheath. A percutaneous nephrostomy is performed and the tract dilated to 11-E The Peel-away stent introducer is advanced over a 0.038 inch torque guide wire down to the bladder (Fig. 2A). The guide wire and 9-F catheter are removed, leaving only the 11-F sheath in place (Fig. 2B). The pre-cut Universal stent is threaded over a well-lubricated 0.032 inch Lunderquist guide wire so that only 2 cm of the floppy tip of the guide wire protrudes from the stent and is inserted down to the bladder through the lumen of Peel-away sheath (Fig. 2C). The stent is held in position by slight pressure on its proximal portion while the Peel-away sheath is pulled back and separated until it has been totally removed (Fig. 2D). The Lunderquist wire is then removed, and the stent is positioned so that the side holes are located in the renal pelvis. This can be checked by injecting contrast material. The stent is then fixed to the skin with one or two silk sutures. Once the urine is clear, usually after one to two days, the stent is flushed with water or saline and capped to allow only internal drainage. If the stent is capped without flushing, the stagnant urine can crystallize and occlude the stent. The proximal portion of the stent is coiled and a povidone-iodine (Betadine) dressing applied to the flank. The dressing is changed twice a week. Combination stents are available in 7-F and 8-F sizes (Fig. 1) and have a loop-locking retention system in the renal pelvis and either a distal pigtail to be positioned in the bladder or a tapered tip that ends in the middle of the ureter. The loop is created in the renal pelvis by pulling a nylon thread to approximate the ends of the loop. There were some technical problems with the nylon thread mechanism in the initial stents, but this is being corrected. The combination stent can be advanced over a guidewire only with difficulty and is perhaps better managed with the Peel-away introducer. I~
--------
~Jy~~o~vy’J
Care of Patients with Ureteral Stents Microhematuria and pyuria are common in patients with indwelling stents, but severe infections are uncommon and usually indicate stent occlusion. Reflux, although expected, occurs in only half of the
42
SPECIAL
patients unless very high intravesical pressures a generated. Urine cultures should be obtains monthly, and patients should take an appropria suppressive antibiotic. Encrustation occurs with ; stents and can best be prevented by a high output acid urine. Irritative bladder problems usually indicate th: the stent is too long. If symptoms persist, the ster should be replaced, perhaps with a Gibbons steni which leaves little foreign material in the bladder. After a baseline has been established, regula follow-up by intravenous urography or radionuclid scans and by renal function tests is essential. Conclusion No stent gist to be indications dures are grade and stents will
is ideal, so it is encumbent on the urolo familiar with the various types and the] and modes of insertion. As more proce performed on the ureter in both a retro antegrade fashion, the need for uretera increase. New Hyde Park, New York 1104: References
1. Miller RP, Reinke DB, Clayman RV, and Lange PH: Percu. taneous approach to the ureter, Urol Clin North Am 9: 31 (1982) 2. Clayman RV, et ~2: Dilatation of a nephrostomy tract with s balloon catheter for percutaneous stone removal, Radiology 147: 884 (1983). 3. Smith AD: Percutaneous approach to ureteral calculi, Br J Urol (in press). 4. Castaneda-Zuniga WR, et al: Flushing techniques for renal and ureteral calculi, Semin Intervent Radio1 1 (in press). 5. Smith AD, Lange PH, Reinke DB, and Miller RP: Extraction of ureteral calculi from patients with ileal loops: a new technique, J Urol 120: 523 (1978). 6. Wickham JEA: Percutaneous pyelolysis, in Wickham JAE and Miller RA (Eds): Percutaneous Renal Surgery, Edinburgh, Churchill-Living&one, chap 6, 1983. 7. Smith AD: The Universal ureteral stent, Ural Clin North Am 9: 103 (1982). 8. Clayman RV, et al: Percutaneous intrarenal electrosurgery, J Urol (in press). 9. King LR: Percutaneous endoscopic incision to relieve secondary ureteropelvic junction obstruction in children, (abstr 197), Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983. 10. Banner MP, Pollack HM, Ring EJ, and Wein AJ: Catheter dilatation of benign ureteral strictures, Radiology 147: 427 (1983). 11. Smith AD, Lange PH, Miller RP, and Reinke DB: Controlled ureteral meatotomy, J Urol 121: 587 (1979). 12. Lieberman SF, Keller FS, Barry JM, and Rosch J: Percutaneous antegrade transluminal ureteroplasty for renal allograft ureteral stenosis, ibid 128: 122 (1982). 13. Kaplan JO, et al: Dilatation of a surgically ligated ureter through a percutaneous nephrostomy AJR 139: 188 (1982). 14. Mardis HK: A new self-contained ureteral stent, (abstr. 287). Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983. 15. Ortlip SA, and Fraley EE: Indications for palliative urinary diversion in patients with cancer, Urol Clin North Am 9: 79 (1982). 16. Smith AD, et al: Insertion of Gibbons ureteral stents using endourologic techniques, Urology 14: 330 (1979). 17. Kahn R: Percutaneous antegrade indwelling silicone ureteral stent, (Abstr. 398), Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983.
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percutaneous nephrostomy tract provides ready access with a nephroscope to the upper ureter directly allowing the urologist to remove stones and to perjorm operative procedures such as endopyelotomy. The tract also permits antegrade insertion of ureteral stents and ureteral catheters to which other instruments can be attached, this facilitating stone basketing, controlled ureteral meatotomy, and retrograde stent insertion.
ABSTRACT-The
Widespread application of the technique of percutaneous nephrostomy has made the ureter accessible for a number of procedures that formerly could be done only by open operation or-often with considerable difficulty-by cystoscopy. This is a review of some approaches to ureteral calculi, ureteral surgery and stents. Endourologic
Approach to Ureter
The position of the nephrostomy tract is critical in obtaining ready access to the ureter; the site should be high and peripheral to create a transparenchymal route to a middle calyx or infundibulum. If one punctures the collecting system by a direct posterior route or through a lower-pole calyx that forms an angle of less than 60 degrees with the ureteropelvic junction, the ureter may be inaccessible. On occasion, it may be necessary to puncture the kidney above the twelfth rib. This should be done only after one has determined the relation of the diaphragm to the rib fluoroscopically. The technique of percutaneous nephrostomy for ureteral access has been reviewed by Miller et al.’ During tract dilatation, a second safety guidewire is advanced down the ureter, preferably past the stone, so that if the guidewire one is using to pass the instruments becomes dislodged, the nephrostomy tract will not be lost. As added insurance, a 5-F catheter can be passed over the safety guidewire and sutured to the skin. Several methods are available for dilating a nephrostomy tract. If one intends to proceed with
SPECIAL
stone removal in the same session, dilatation can be done with a Gruntzig or Olbert balloon catheter, and some believe that these methods are less traumatic, and thus cause less bleeding, than do fascial and coaxial dilators.2 Personally, I find the Amplatz dilator set* to be effective, safe, and relatively inexpensive since they can be resterilized.
ISSUE TO UROLOGY
/ MAY 1984
/ VOLUME
Ureteral Calculi The old rule against manipulation of ureteral stones larger than 0.5 cm and those located above the iliac vessels is no longer valid. The principle underlying the rule was that the diameter of the ureter distal to the stone was so small that traction on the object, especially in the mobile portion of the ureter, was likely to cause avulsion. However, now that stones can be approached via the dilated proximal part of the ureter, closed extraction can be a relatively simple and atraumatic procedure. Thus, to the traditional retrograde approach, one can add two others: antegrade and a combination antegrade-retrogrades3 Antegrade
approach
After the tract has been dilated, a nephroscope can be introduced into the renal pelvis. With its help, the pelviureteral junction can be seen readily, and a stone basket can be advanced down the ureter. The stone is then either captured in the basket or *Cook Urological,
XXIII,
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~_____
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ceps or graspers; fluoroscopy is used in either case. Alternatively, a stone basket can be advanced through the safety guidewire introducer. Anyone who has tried basketing under fluoroscopy will readily appreciate the advantages of using direct vision. The advent of the flexible nephroscope with its graspers and baskets has made this direct approach far easier than it was in the past, although the operator will need considerable practice with the instrument to become proficient in its use. Also, in some cases a rigid nephroscope or panendoscope will be suitable. Unfortunately, the stone basket does not always work no matter how it is manipulated, and in such cases it may be advisable to grasp the stone under direct vision. A panendoscope that can accommodate 7-F flexible alligator forceps is suitable for most ureter-al stones less than 8 mm in diameter located above the transverse process of L4 (in thin patients) or L3 (in obese patients). Larger stones can be removed with rigid forceps introduced via a nephroscope or, if they are wedged in the ureter, by ultrasonic lithotripsy. Retrograde approach This subject is discussed elsewhere in this issue. The introduction of new instruments such as the uretero-renoscope has changed the indication for retrograde removal of ureteral stones, and there is some debate about the “best” approach to various stones. In my experience, ureteroscopy is most suitable for stones below L3-L4, whereas other operators find the technique suitable for stones in the renal pelvis as well. I suspect that the relative familiarity of the operators with the antegrade and retrograde approaches is a significant factor in their preferences for one or the other. Combined approach Because of the ease with which loose stones can be removed from the renal pelvis, some uroradiologic teams have devised ways to push ureteral stones upward-ureteral catheters and stone baskets are popular. A particularly promising method is to occlude the ureter with a balloon below the stone and “blast” the stone into the renal pelvis with a jet of saline, contrast medium, or carbon dioxide. A working sheath in a previously created percutaneous nephrostomy prevents sudden increase in intrapelvic pressure, which could cause parenchymal damage, and provides immediate access to the newly liberated stone. In more than 20 cases, CastanedaZuniga et al.’ have had no failures with this method. Approach in patient with a conduit Ureteral calculi in patients with ureteroileal conduits are a unique problem, as the retrograde approach is exceptionally difficult. In one of our ear-
38
SPECIAL
~~~uuuru~o~c stone-removal procedures,5 advanced an angiographic catheter down the ure via a percutaneous nephrostomy, retrieved its I from the conduit, and attached a stone baskl which was then pulled up into the ureter so the sto could be basketed under fluoroscopic control. Simultaneous pressure on the basket handle fra below and the angiographic catheter from abo opened the basket wider than usual, enabling it ensnare the stone more readily We have utilized tl same method in patients with multiple stones in tl lower ureter, because it may be difficult to pass basket repeatedly by the usual methods. An inherent weakness of this do-it-yourself syste is the ligature fixing the stone basket to the angil graphic catheter: sometimes, it breaks. This pro1 lem has been overcome by development, at the Un versity of Minnesota, of a stone basket mounted in shaft that will extend from the nephrostomy site bc yond the ureteral meatus. llWl
Comments Early reports of the percutaneous approach t ureteral calculi were not encouraging, with succe! rates of no more than 70 per cent, compared to mor than 90 per cent for renal stones. However, newe techniques and instruments are leading to rapid im provements, and I suspect that within a short tim nearly all ureteral calculi will be removable b closed procedures. Operations
on Ureteropelvic
Junction
The most extensive experience with incision of thl ureteropelvic junction is that of Whitfield in Grea Britain.B He incises the tissue in the inferolatera angle until fat can be seen nephroscopically. The ureter is then stented for four to six weeks. We have used a similar procedure, which we call “endopy elotomy” in 5 patients and have been impressed wit1 the simplicity of the procedure. In all our patients. the area of narrowing was short, and in all cases the ureteropelvic junction snapped open after the incision was made to reveal normal-caliber ureter distal to the strictured area. In our patients, the ureter wa stented for six weeks with a Universal (Smith) stent. i Although our follow-up has been too short to assess the eventual effect of this approach, all patients have done well to date, and there have been no complications. Clayman et aZ.*also have described making incisions in the collecting system and ureteropelvic junction endourologically (percutaneous electrosurgery) to free trapped and impacted stones. They emphasize the need to have a clear mental picture of the renal vascular anatomy and to examine the area nephroscopically for arterial pulsations before making any incisions. Another approach to narrowing of the ureteropelvic junction is described by King,e who used balloon dilatation. Presumably, balloon dilatation will
ISSUE TO UROLOGY
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/ VOLUME
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NUMBER 5
be most effective long term when the tissue around the narrowing has not become heavily scarred. Banner et ~2.‘~ recently reported on ureteral strictures associated with dense scar tissue or long segments of devitalized tissue. Operations Ureteral
on Distal Ureter
meatotomy
Repeated resections of bladder tumors may lead to ureteral meatal stenosis; making the orifice difficult to see cystoscopically. A percutaneous nephrostomy will allow an angiographic catheter to be passed down into the bladder. The stenotic meatus can then be incised over the catheter with a Callings knife or a resectoscope knife. Alternatively, a ureteral catheter with a l-cm length of steel stylet exposed can be passed through the meatal orifice. When the stylet is positioned against the stenotic tissue, the proximal end of the stylet is connected to electrocautery to incise the area, the stylet being repositioned for a series of incisions until the junction has been opened satisfactorily. Application of this method to ureteroileal strictures was one of the first endourologic operations performed.” The area is usually stented for several weeks. When the stricture is short and there is no marked periureteral fibrosis, the long-term results of these controlled meatotomies are good. However, even after several months of stenting, long ischemic strictures usually restenose when the stent is removed. Dilatation
of strictures
and stenoses
Endourologic stretching of ureteral strictures or usually with balloon catheters stenosis, (transluminal ureteroplasty) is discussed by Rutner in this issue (pages 44-53). In properly selected patients, the success rate is high; but unfortunately some of the most common ureteral strictures, such as those secondary to injury during radical hysterectomy, seldom respond well.1a Among the successors of balloon dilatation are some involving stenoses in allograft ureters.i2 One of the more interesting reports of the endourologic treatment of ureteral narrowing concerns the successful dilatation of ureter inadvertently ligated with absorbable suture during emergency cesarean section. l3 Graded Teflon dilators and coaxial techniques were used. This method probably should be applied only when absorbable sutures are involved and be timed to take place shortly after maximal resorption. Management
of fistulas
Although percutaneous nephrostomy and ureteral stenting have made it possible to delay or even avoid
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many open operarious IVI IIJCU~~~,cAnVJ. . . . - ------ -offer in the many cases, such as patients with cancer, in which the ureter has little potential for healing itself. In these cases, some have occluded the ureter permanently with a balloon catheter passed through a percutaneous nephrostomy and established permanent nephrostomy drainage or embolized the kidney to make it nonfunctional. The latter would seem to be an approach of last resort to avoid open nephroureterectomy.
Ureteral stents There is no ideal ureteral stent despite the many types available. A particular problem is the ease with which all can become occluded if the urinary output is decreased in the presence of infection. Basically, there are two types of ureteral stents: those with and those without external communication. The advantages of the entirely internal stent is that there is no dressing on the nephrostomy site, with its attendant bother; the disadvantage is that when the stent becomes occluded, the immediate stent exchange or percutaneous nephrostomy is mandatory to drain the kidney. Stents with external communication do not carry a great risk of infection and provide immediate nephrostomy drainage and sometimes can be reopened by flushing. Four materials have been used in ureteral stents. Polyethylene is easy to insert and, with a low ratio between the internal and external diameters of the stents, has a good flow rate. However, its rigidity causes discomfort, and it depolymerizes when bathed in urine. This makes it brittle and proves to fracture after six months of continuous use. Therefore, polyethylene is no longer used in stent manufacture. Polyurethane is less brittle, and usually more flexible, than polyethylene and is approximately four times as resistant to breakage as is silicone rubber. Flow rates are good. However, scanning electron microscopy shows a polyurethane surface to be far more irregular than one of silicone rubber, and this could encourage encrustation. Silicone rubber, the standard against which other stent materials are judged, is a thermostat elastomerice polymer that is biocompatible and chemically stable. It can be made in various consistencies; the form used in stents generally produces a smaller internal diameter than a stent of the same outer French size made from polyethylene. Its tensile strength is low, but it has good elasticity. Its softness makes it more comfortable for the patient, but more difficult to advance over a guidewire. C-Flex14 is a newly introduced copolymer with a tensile strength twice that of silicone rubber and similar surface characteristics. With it, a stent can be made with a larger internal diameter than is possible for a silicone rubber stent of the same outer French size. The long-term results of C-Flex stents are not yet known.
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FIGURE 1.
right-Finney
Ureteral Stents. (A) Left to right-Bard coil, Gibbons, Combination and Universal. (B) Left tl ureterointestinal stent, double-J, double-pigtail, and Mardis stent.
Indications for stenting Ureteral stents are used to provide urinary drainage on a short or long-term basis when the ureter is stenotic, strictured, fistulous, or being compressed by an extrinsic mass. There is an ethical problem about stenting in patients with metastatic cancer (see review by Ortlip and Fraley15). Certainly, if there is some modality of treatment that has not yet been tried, stenting is indicated.
Internal stents The original Gibbons stent was introduced in 1967 and since that time has been upgraded constantly (Fig. 1A). It is fabricated of radial compression-resistant silicone rubber tubing with radiopaque barbs to prevent proximal migration. It also has a retrieval tail. The Gibbons stent is available in several sizes, but precise matching of stent and ureteral length is not necessary. Bladder discomfort is minimal. If the stent becomes occluded, it can be reopened with a guidewire inserted transcystoscopitally. The principal indication for a Gibbons stent is obstruction in the lower half of the ureter. This stent is contraindicated as a splint for an anastomosis or fistula because of the barbs. This stent may be inserted transcystoscopically or, if this fails, by a combination transcystoscopic-endourologic technique. l8 The double-J, or Finney, stent is of silicone elastomer and is molded at both ends into a hook (the “J”) to prevent migration (Fig. 1B). There are drainage holes every centimeter. A guide strip marked in centimeters is imprinted in order to be visible through the cystoscope during insertion. The stent is available in 6 F to 8.5 F diameters and lengths of 16 to 30 cm. When properly positioned, the upper end of the Finney stent lies in the renal pelvis and 1 to 2 cm of
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the lower end in bladder. Excessive length in th bladder will cause discomfort, and thus accuratl preinsertion measurement of ureteral length is net essary. This can be done with a ureteral catheter o radiologically (with allowance for the approxi mately 10 per cent magnification on an intravenou pyelogram). The Finney stent can be inserted a open operation or transcystoscopically Also Kahn’ has described an antegrade method in which lubri cation of the guidewire with sterile mineral oi minimizes resistance to stent passage. The Bard coil stent is similar to the double-J stem in that it is made of radiopaque silicone rubber with side holes 1 cm apart (Fig. 1A). There are retention coils at both ends to prevent migration. The distal end has a series of helical coils 25 cm long that is cut to the proper length to fit ureters 16 to 30 cm long, this can be done either before insertion or, with cystoscopy scissors, after the stent has been placed in the ureter. The stent is available in 5 F to 8 F sizes. Although designed only for cystoscopic insertion, the Bard coil could be inserted at open operation or endourologically. The chief advantage of this stent is that it reduces inventory because fewer sizes must be available to insure a proper fit. The double-pigtail stent is made of polyurethane and is available in diameters of 5F to 8F and lengths of 8 to 30 cm (Fig. 1B). It can be inserted at open operation, cystoscopically, and endourologically, and the ease with which it can be passed over a guidewire explains much of its popularity. Proper selection of the length is important, because excessive length in the bladder will cause discomfort and irritative voiding symptoms. The Van-Tee Mardis multipurpose stent’ is made of the new copolymer, C-Flex (Fig. 1B). It is a *Van-Tee.
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(A) Peel-away FIGURE 2. stent introducer is advanced over 0.038~inch guidewire down ureter to bladder. (B) 9F Teflon catheter and guidewire have been removed, and 11-F Peel-away sheath is in ureter. (C) The 0.032-inch Lunderquist wire is in pre-cut Universal stent, and this is advanced through 11-F Peelaway introducer down to bladder. (0) Universal stent is held in place by Lunderquist guidewire and Peel-away stent is progressively withdrawn until it is totally removed. Lunderquist guidewire is then removed and position of stent checked.
A
C
double-pigtail stent that, like the Finney, is closed at one end. It is available in 5F to 8F sizes in lengths of 10 to 34 cm. It has flow rates similar to those of polyurethane stents but is softer and thus perhaps more comfortable. It can be inserted fairly easily cystoscopically and at open operation, but when advanced antegrade over a guidewire through a nephrostomy tract, it tends to bind to tissue and the wire. Stents with external communications At present, there are two types of these stents: the Universal (Smith) design and the Van-Tee combination stent. The Universal stent is made of radial compressionresistant silicone rubber tubing that has a linear barium-strip marker (Fig. 1A). Drainage holes are positioned along a 4-cm length in the middle of the
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stent, and this zone is labeled with a radiopaque band at both ends. There also is a labeled zone of drainage holes in the terminal 15 cm (Fig. 1B). A Luer-Lok adaptor at the proximal end protrudes from the nephrostomy site and permits drainage, irrigation, and radiographic studies. For internal drainage, the adaptor is capped. The patient is instructed to remove the cap if pain or fever appears. In patients with malignant obstruction, the ability of the kidney to recover is often in doubt. In these patients, the Universal stent is an excellent choice, since it allows one to monitor the urine output of the kidney while relieving the obstruction. If desired, it can be replaced with an internal stent after two to three months. Similarly, the Universal stent is helpful if renal failure may be impending. With an internal stent, it can be difficult to determine whether a patient admitted with oliguria or anuria has an occluded stent or is truly in renal failure, yet it is not
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~IICL lapace me stent(s). If a Universal stent is in place, it can simply be uncapped; if it does prove to be occluded, it can be replaced or removed without cystoscopy. The Universal stent can be inserted at open surgery and has been used extensively to splint pyeloplasties, ureteral reimplantations, and ileal conduit.7 For closed insertion, an antegrade approach is necessary. One technique, in which the stent is pulled into place with the aid of an angiographic catheter, has been described.’ We have since found that the easiest way to insert this stent is with a Peelaway stent introducer, which consists of a 9-F Teflon catheter within an 11-F Teflon Peel-away sheath. A percutaneous nephrostomy is performed and the tract dilated to 11-E The Peel-away stent introducer is advanced over a 0.038 inch torque guide wire down to the bladder (Fig. 2A). The guide wire and 9-F catheter are removed, leaving only the 11-F sheath in place (Fig. 2B). The pre-cut Universal stent is threaded over a well-lubricated 0.032 inch Lunderquist guide wire so that only 2 cm of the floppy tip of the guide wire protrudes from the stent and is inserted down to the bladder through the lumen of Peel-away sheath (Fig. 2C). The stent is held in position by slight pressure on its proximal portion while the Peel-away sheath is pulled back and separated until it has been totally removed (Fig. 2D). The Lunderquist wire is then removed, and the stent is positioned so that the side holes are located in the renal pelvis. This can be checked by injecting contrast material. The stent is then fixed to the skin with one or two silk sutures. Once the urine is clear, usually after one to two days, the stent is flushed with water or saline and capped to allow only internal drainage. If the stent is capped without flushing, the stagnant urine can crystallize and occlude the stent. The proximal portion of the stent is coiled and a povidone-iodine (Betadine) dressing applied to the flank. The dressing is changed twice a week. Combination stents are available in 7-F and 8-F sizes (Fig. 1) and have a loop-locking retention system in the renal pelvis and either a distal pigtail to be positioned in the bladder or a tapered tip that ends in the middle of the ureter. The loop is created in the renal pelvis by pulling a nylon thread to approximate the ends of the loop. There were some technical problems with the nylon thread mechanism in the initial stents, but this is being corrected. The combination stent can be advanced over a guidewire only with difficulty and is perhaps better managed with the Peel-away introducer. I~
--------
~Jy~~o~vy’J
Care of Patients with Ureteral Stents Microhematuria and pyuria are common in patients with indwelling stents, but severe infections are uncommon and usually indicate stent occlusion. Reflux, although expected, occurs in only half of the
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patients unless very high intravesical pressures a generated. Urine cultures should be obtains monthly, and patients should take an appropria suppressive antibiotic. Encrustation occurs with ; stents and can best be prevented by a high output acid urine. Irritative bladder problems usually indicate th: the stent is too long. If symptoms persist, the ster should be replaced, perhaps with a Gibbons steni which leaves little foreign material in the bladder. After a baseline has been established, regula follow-up by intravenous urography or radionuclid scans and by renal function tests is essential. Conclusion No stent gist to be indications dures are grade and stents will
is ideal, so it is encumbent on the urolo familiar with the various types and the] and modes of insertion. As more proce performed on the ureter in both a retro antegrade fashion, the need for uretera increase. New Hyde Park, New York 1104: References
1. Miller RP, Reinke DB, Clayman RV, and Lange PH: Percu. taneous approach to the ureter, Urol Clin North Am 9: 31 (1982) 2. Clayman RV, et ~2: Dilatation of a nephrostomy tract with s balloon catheter for percutaneous stone removal, Radiology 147: 884 (1983). 3. Smith AD: Percutaneous approach to ureteral calculi, Br J Urol (in press). 4. Castaneda-Zuniga WR, et al: Flushing techniques for renal and ureteral calculi, Semin Intervent Radio1 1 (in press). 5. Smith AD, Lange PH, Reinke DB, and Miller RP: Extraction of ureteral calculi from patients with ileal loops: a new technique, J Urol 120: 523 (1978). 6. Wickham JEA: Percutaneous pyelolysis, in Wickham JAE and Miller RA (Eds): Percutaneous Renal Surgery, Edinburgh, Churchill-Living&one, chap 6, 1983. 7. Smith AD: The Universal ureteral stent, Ural Clin North Am 9: 103 (1982). 8. Clayman RV, et al: Percutaneous intrarenal electrosurgery, J Urol (in press). 9. King LR: Percutaneous endoscopic incision to relieve secondary ureteropelvic junction obstruction in children, (abstr 197), Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983. 10. Banner MP, Pollack HM, Ring EJ, and Wein AJ: Catheter dilatation of benign ureteral strictures, Radiology 147: 427 (1983). 11. Smith AD, Lange PH, Miller RP, and Reinke DB: Controlled ureteral meatotomy, J Urol 121: 587 (1979). 12. Lieberman SF, Keller FS, Barry JM, and Rosch J: Percutaneous antegrade transluminal ureteroplasty for renal allograft ureteral stenosis, ibid 128: 122 (1982). 13. Kaplan JO, et al: Dilatation of a surgically ligated ureter through a percutaneous nephrostomy AJR 139: 188 (1982). 14. Mardis HK: A new self-contained ureteral stent, (abstr. 287). Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983. 15. Ortlip SA, and Fraley EE: Indications for palliative urinary diversion in patients with cancer, Urol Clin North Am 9: 79 (1982). 16. Smith AD, et al: Insertion of Gibbons ureteral stents using endourologic techniques, Urology 14: 330 (1979). 17. Kahn R: Percutaneous antegrade indwelling silicone ureteral stent, (Abstr. 398), Annual Meeting AUA, Las Vegas, Nevada, April 17, 1983.
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