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Percutaneous Ureteral Stents: A Modified System to Facilitate Antegrade Placement
Technical Developments and Instrumentation
Percutaneous Ureteral Stents: A Modified System to Facilitate Antegrade Placement1 Robert D'Agostino, MD Robert M. Goldberg, MD
PERCUTANEOUS antegrade placement of ureteral stents has become a common procedure for intewentional radiologists. Many technical problems associated with stent placement have been eliminated by including a "pusher" catheter for antegrade positioning and a suture on the proximal end of the stent for final retrograde positioning (1,2). The pusher and suture system is incorporated into several brands of currently available ureteral stent kits. Unfortunately, this system is subject to occasional diffreult suture removals during stent placement. The manipulation required to remove the suture may then lead to stent damage or malpositioning (3). In our experience, this occurs most often in cases in which small-caliber and hydrophiliccoated stents are used. We have devised a modification of the pusher and suture system in the Medi-tech/Boston Scientific (Watertown, Mass) ureteral stent kit to assist in final stent positioning and avoid problematic suture removal.
1
Index term: Ureter, prostheses, 82.1269
'From the Department of Fhdiology, Boston University School of Medicine, 88 E Newton St,Boston. MA 02118. Received November 15,1995;revision requested January 3, 1996;revision received January 23; accepted January 26.Address correspondence to R.D.
TECHNIQUES
The modification involves the addition of a side hole in the pusher catheter 2 em from the distal end. The nylon suture loop of the stent is cut and restrung through the distal opening of the pusher and out again via the new side hole (Fig 1).The cut suture is retied into a loop, and the new system is loaded over a guide wire that has been placed in the ureter. When the wire is removed, the proximal pigtail will form, with the pusher kept close to the stent by the suture loop (Fig2). The pusher catheter is then advanced along the taut suture to meet and become flush against the stent (Fig 3). With the system in this configuration, the stent will be held in its exact position as the suture is cut and pulled out. The pusher also remains positioned for acquisition of an antegrade nephrostogram or for nephrostomy tube placement if needed. In practice, the suture is radiolucent, but the stent is visible in its
entirety and the pusher is easily located by its radiopaque marker (Fig 4). This technique has been used in eight consecutive stent placements in seven patients and has been successful in all cases. The cause of ureteral obstruction was bladder carcinoma in two, prostate carcinoma in two, and ureteral stones in three patients. There have been no complications, and this technique is now the preferred approach at our institution.
1
DISCUSSION
Through many successive refinements described in the literature, antegrade ureteral stent placement has become an effective and widely used procedure. The pusher catheter and percutaneous sheath have overcome the technical difficulties of traversing the soft tissues of the back (1). The addition of a suture through the proximal pigtail has also enabled the retrograde control and final positioning of the stent (1,2).Both resorbable and nonresorbable suture materials have been recommended as well as alternative routes for stringing the suture through - the stent and pusher (1,2). Salazar et a1 (1) in 1983 threaded the suture through two side holes in the middle of the proximal pigtail curve of the stent without traversing the pusher. This allows formation of the proximal pigtail in the renal pelvis prior to stent placement; however, it does not allow stent stabilization during suture removal. Hackethorn et al (2) in 1985 threaded the suture through the most proximal side hole of the stent and the end hole of the proximal pigtail. One limb of the suture runs through the pusher and the other runs outside of it. With this method the stent can be stabilized by using the pusher; however, the proximal pigtail cannot be formed until the suture is removed. In the ureteral stent kits from Medi-techA3oston Scientific containing the Percuflex stents, first introduced in 1988 (31, and the
428
Journal of Vascular and Interventional Radiology
May-June 1996
Figures 1-3. (1) Pusher catheter and stent shown in over-wire position prior to stent deployment. Note new pusher catheter side hole and course of suture loop. (2) Modified system with wire removed and formation of stent pigtail. (3) Apposition of pusher and stent with suture loop pulled taut. Suture is then cut and removed.
a. b. C. Figure 4. Radiographs of stent deployment with use of the modified system. (a) Pusher catheter with radiopaque marker (arrowhead) and stent (open arrow) loaded over a guide wire in renal collecting system. Transverse colon contains barium from prior radiologic examination. (b) Guide wire pulled back into pusher with formation of stent pigtail (arrow). ( c ) Stent held in exact position by adjacent pusher (arrow) during suture removal.
Glidex hydrophilic-coated stents, the suture is threaded through two holes in the proximal shaft of the stent, again not traversing the pusher. This allows for proximal pigtail formation before stent placement but does not enable stent stabilization during suture removal. Our
method of stringing the suture is advantageous, since it allows complete formation of the proximal pigtail prior to final stent placement and provides continuous stent stabilization during suture removal. Difficult suture removals potentiating
stent damage or displacement into a calix or the body wall via its percutaneous tract have been described (3). Shearing of a nephrostomy catheter during suture removal following ureteral stent placement has been reported (4). Nonabsorbable suture material should be com-
D'Agostino and Goldberg
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Volume 7 Number 3
pletely removed from the renal collecting system, as it may promote infection or stone formation. Hematuria due t o a retained suture following antegrade ureteral stent placement has also been reported (5). Mitty et aI (3) propose a remedy for difficult suture removals that involves passing a vessel dilator over a limb of the cut suture until it contacts the stent shaft. This dilator may then be used to stabilize the stent as the suture is withdrawn. Our method is advantageous since it allows the pusher to accomplish the same task in every stent
placement without additional steps or equipment. Access to the collecting system for a nephrostogram or nephrostomy tube placement i s also continuously maintained. The modification may be equally suited to perurethral retrograde as well as percutaneous antegrade ureteral stent placements. References 1. Salazar JE, Johnson JB, Scott R, Pinstein M. A simplified method for placement of internal ureteral stents. AJR 1983; 140:611-612. 2. Hackethorn JC, Boren SR, Dotter CT, Rosch J. Antegrade internal ureteral
stcnting: a technical refinement. Radiology 1985; 1562327-828. 3. Mitty HA, Rackson ME, Dan SJ, Train JS. Experience with a new ureteral stent ~ n a d eof a biocompalible copolymer. IZadiology 1988; 168:557-559. 4. Sussman SK, Okr Ed, Perlmutt LM, Dunnick NR. Shearing of percutaneous nephrostomy catheter during indwelling ureteral stent placement. AJR 1986; 147:83=33. 5. Hoe WM, Tan EC. Percutaneous removal of retained suture following antegrade ureteral stenting. Australas Radio1 1992; 36:174-175.
Percutaneous Ureteral Stents: A Modified System to Facilitate Antegrade Placement1 Robert D'Agostino, MD Robert M. Goldberg, MD
PERCUTANEOUS antegrade placement of ureteral stents has become a common procedure for intewentional radiologists. Many technical problems associated with stent placement have been eliminated by including a "pusher" catheter for antegrade positioning and a suture on the proximal end of the stent for final retrograde positioning (1,2). The pusher and suture system is incorporated into several brands of currently available ureteral stent kits. Unfortunately, this system is subject to occasional diffreult suture removals during stent placement. The manipulation required to remove the suture may then lead to stent damage or malpositioning (3). In our experience, this occurs most often in cases in which small-caliber and hydrophiliccoated stents are used. We have devised a modification of the pusher and suture system in the Medi-tech/Boston Scientific (Watertown, Mass) ureteral stent kit to assist in final stent positioning and avoid problematic suture removal.
1
Index term: Ureter, prostheses, 82.1269
'From the Department of Fhdiology, Boston University School of Medicine, 88 E Newton St,Boston. MA 02118. Received November 15,1995;revision requested January 3, 1996;revision received January 23; accepted January 26.Address correspondence to R.D.
TECHNIQUES
The modification involves the addition of a side hole in the pusher catheter 2 em from the distal end. The nylon suture loop of the stent is cut and restrung through the distal opening of the pusher and out again via the new side hole (Fig 1).The cut suture is retied into a loop, and the new system is loaded over a guide wire that has been placed in the ureter. When the wire is removed, the proximal pigtail will form, with the pusher kept close to the stent by the suture loop (Fig2). The pusher catheter is then advanced along the taut suture to meet and become flush against the stent (Fig 3). With the system in this configuration, the stent will be held in its exact position as the suture is cut and pulled out. The pusher also remains positioned for acquisition of an antegrade nephrostogram or for nephrostomy tube placement if needed. In practice, the suture is radiolucent, but the stent is visible in its
entirety and the pusher is easily located by its radiopaque marker (Fig 4). This technique has been used in eight consecutive stent placements in seven patients and has been successful in all cases. The cause of ureteral obstruction was bladder carcinoma in two, prostate carcinoma in two, and ureteral stones in three patients. There have been no complications, and this technique is now the preferred approach at our institution.
1
DISCUSSION
Through many successive refinements described in the literature, antegrade ureteral stent placement has become an effective and widely used procedure. The pusher catheter and percutaneous sheath have overcome the technical difficulties of traversing the soft tissues of the back (1). The addition of a suture through the proximal pigtail has also enabled the retrograde control and final positioning of the stent (1,2).Both resorbable and nonresorbable suture materials have been recommended as well as alternative routes for stringing the suture through - the stent and pusher (1,2). Salazar et a1 (1) in 1983 threaded the suture through two side holes in the middle of the proximal pigtail curve of the stent without traversing the pusher. This allows formation of the proximal pigtail in the renal pelvis prior to stent placement; however, it does not allow stent stabilization during suture removal. Hackethorn et al (2) in 1985 threaded the suture through the most proximal side hole of the stent and the end hole of the proximal pigtail. One limb of the suture runs through the pusher and the other runs outside of it. With this method the stent can be stabilized by using the pusher; however, the proximal pigtail cannot be formed until the suture is removed. In the ureteral stent kits from Medi-techA3oston Scientific containing the Percuflex stents, first introduced in 1988 (31, and the
428
Journal of Vascular and Interventional Radiology
May-June 1996
Figures 1-3. (1) Pusher catheter and stent shown in over-wire position prior to stent deployment. Note new pusher catheter side hole and course of suture loop. (2) Modified system with wire removed and formation of stent pigtail. (3) Apposition of pusher and stent with suture loop pulled taut. Suture is then cut and removed.
a. b. C. Figure 4. Radiographs of stent deployment with use of the modified system. (a) Pusher catheter with radiopaque marker (arrowhead) and stent (open arrow) loaded over a guide wire in renal collecting system. Transverse colon contains barium from prior radiologic examination. (b) Guide wire pulled back into pusher with formation of stent pigtail (arrow). ( c ) Stent held in exact position by adjacent pusher (arrow) during suture removal.
Glidex hydrophilic-coated stents, the suture is threaded through two holes in the proximal shaft of the stent, again not traversing the pusher. This allows for proximal pigtail formation before stent placement but does not enable stent stabilization during suture removal. Our
method of stringing the suture is advantageous, since it allows complete formation of the proximal pigtail prior to final stent placement and provides continuous stent stabilization during suture removal. Difficult suture removals potentiating
stent damage or displacement into a calix or the body wall via its percutaneous tract have been described (3). Shearing of a nephrostomy catheter during suture removal following ureteral stent placement has been reported (4). Nonabsorbable suture material should be com-
D'Agostino and Goldberg
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Volume 7 Number 3
pletely removed from the renal collecting system, as it may promote infection or stone formation. Hematuria due t o a retained suture following antegrade ureteral stent placement has also been reported (5). Mitty et aI (3) propose a remedy for difficult suture removals that involves passing a vessel dilator over a limb of the cut suture until it contacts the stent shaft. This dilator may then be used to stabilize the stent as the suture is withdrawn. Our method is advantageous since it allows the pusher to accomplish the same task in every stent
placement without additional steps or equipment. Access to the collecting system for a nephrostogram or nephrostomy tube placement i s also continuously maintained. The modification may be equally suited to perurethral retrograde as well as percutaneous antegrade ureteral stent placements. References 1. Salazar JE, Johnson JB, Scott R, Pinstein M. A simplified method for placement of internal ureteral stents. AJR 1983; 140:611-612. 2. Hackethorn JC, Boren SR, Dotter CT, Rosch J. Antegrade internal ureteral
stcnting: a technical refinement. Radiology 1985; 1562327-828. 3. Mitty HA, Rackson ME, Dan SJ, Train JS. Experience with a new ureteral stent ~ n a d eof a biocompalible copolymer. IZadiology 1988; 168:557-559. 4. Sussman SK, Okr Ed, Perlmutt LM, Dunnick NR. Shearing of percutaneous nephrostomy catheter during indwelling ureteral stent placement. AJR 1986; 147:83=33. 5. Hoe WM, Tan EC. Percutaneous removal of retained suture following antegrade ureteral stenting. Australas Radio1 1992; 36:174-175.