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Application of memory metallic stents to urinary tract disorders in pediatric patients
Journal of Pediatric Surgery (2005) 40, E43 – E45
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Application of memory metallic stents to urinary tract disorders in pediatric patients Shinkichi Kamata*, Noriaki Usui, Masafumi Kamiyama, Akihiro Yoneda, Yuko Tazuke, Takaharu Ooue Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan Index words: Memory metallic stent; Ureteral stenosis; Neurogenic bladder
Abstract The use of memory metallic stents for the urinary tract in pediatric patients has not been reported. The authors report on 2 patients with urinary tract disorders who were successfully treated with a memory metallic stent. A thermoexpandable, nickel-titanium alloy stent was placed at the urethroureteral junction of a 4-year-old boy with ureteral stenosis associated with cloacal exstrophy for 18 months and at the urethra of a 2-year-old girl with ischuria after a repair of cloacal anomaly for 6 months. Temporary insertion of a memory metallic stent is a safe and effective alternative for organic stricture or functional obstruction of the urinary tract in pediatric patients. D 2005 Elsevier Inc. All rights reserved.
Metallic stents have been used successfully in the biliary tract, cardiovascular system, and urinary system [1]. However, meshed metallic stents allow urothelial ingrowth and become incorporated into the wall of the ureter [2]. A relatively new metallic stent is made from an alloy of nickel and titanium that has a shape memory feature; it softens at a temperature below 108C but regains its original shape when warmed to 508C and is therefore easy to insert and remove [2]. It has a closed, tight, and spiral structure that prevents urothelial ingrowth. However, the size of a memory stent is meant for adults and is therefore relatively large for pediatric use.
of 12 F with proximal end expansion to 34 F, was used. Various lengths were available for use (30-70 mm). To insert the stent, the length of the lesion was measured by fiberscopy and ureterography to choose the appropriate length of the stent. A guide wire was negotiated across the lesion and a balloon catheter was used to dilate the lesion. The stent, mounted on its introducer, was aligned across the lesion and the guide wire was removed. The catheter was then flushed with sterile water preheated to 508C. This allowed the alloy to expand so that it filled the lesion, and the proximal end opened into a funnel shape. The introducing catheter was then removed. To remove the stent, cold water was flushed near the stent. The distal or proximal end of the spiral alloy was grasped by forceps and pulled out under fluoroscopy.
1. Method A memory metallic stent (MEMOKATH 028, Engineers & Doctors A/S, Hombaek, Denmark), with a shaft diameter * Corresponding author. Tel.: +81 6 6879 3753; fax: +81 6 6879 3759. E-mail address: [email protected] (S. Kamata). 1531-5037/05/4003-0042$30.00/0 D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2004.11.014
2. Case report 2.1. Case 1 A 3-year-old Japanese boy who had undergone a repair of cloacal exstrophy and vesicourethroplasty at birth
E44
S. Kamata et al.
Fig. 1 Ureterography before (A) and after (B) insertion of the stent. After a guide wire was antegradely inserted through the kidney puncture, a balloon catheter and an introducer containing the stent (40 mm in length) were retrogradely inserted.
presented with decreased urinary output. After the initial surgery, he developed left hydronephrosis. After nephrostomy for 3 weeks, the left hydronephrosis had been followed under subclinical conditions. A computed tomography scan revealed bilateral hydronephrosis with hydroureter. A guide wire was antegradely inserted through the kidney puncture to the ureter. Ureterography demonstrated a bilaterally elongated ureter and its opening to constructed
urethra with severe stenosis. Although the right hydroureter improved after balloon dilation, the left hydroureter continued and was managed by nephrostomy. Then, at the age of 4 years, a memory metallic stent (40 mm in length) was inserted. After a guide wire was antegradely inserted through the kidney puncture, a balloon catheter and an introducer containing the stent were retrogradely inserted (Fig. 1). Eighteen months after the placement, he developed
Fig. 2 Urethrography before insertion of the stent (A) and vesicography after insertion of the stent (B). The vagina was seen through the urethrovaginal fistula (arrow) behind the bladder. After a guide wire was antegradely inserted through the opening created by vesicostomy, a balloon catheter and an introducer containing the stent (30 mm in length) were antegradely inserted. The stent covered the urethrovaginal fistula.
Memory metallic stent in urinary tract hematuria. Because fiber optic examination revealed stent migration to the urethral side with erosion of the urethral wall caused by compression of the proximal end expansion of the stent, the metallic stent was removed safely through the urethra. Eighteen months after the removal of the stent, the left hydroureter deteriorated to require ureterostomy.
2.2. Case 2 A 2-year-old Japanese girl with a rectocloacal fistula had undergone anorectovaginourethroplasty at the age of 1 year. After that surgery, she developed ischuria and a urethrovaginal fistula. Although she required catheterization to the bladder because of ischuria and bilateral vesicoureteral reflux, it was difficult to insert the catheter to the bladder because the catheter was mislodged into the vagina through the urethrovaginal fistula (Fig. 2). Vesicostomy was established 2 months after that surgery. Placement of a memory metallic stent in the urethra and closure of the opening created by vesicostomy were performed for management by selfcatheterization. After a guide wire was antegradely inserted through the opening, a balloon catheter and an introducer containing the stent (30 mm in length) were antegradely inserted (Fig. 2). The opening created by vesicostomy was simultaneously closed. After stenting, urination was unexpectedly obtained without self-catheterization. Because stent migration into the bladder was observed 2 months later with no symptoms including dysuria, the metallic stent was removed safely through the urethra 6 months after placement. For 15 months, the patient had no problems involving urination with continence.
3. Discussion Surgical correction of cloacal exstrophy and cloacal anomalies is still challenging. Urological complications during these treatments frequently occur. The management of ureteral stenosis can become a complex problem in adults [3]. The classical therapeutic approach has been retrograde balloon dilation with or without incision or surgical correction if this is not successful [4]. However, current endourological percutaneous techniques make it possible to manage ureteral stenosis by transluminal balloon dilation therapy. Early results with this technique have been
E45 promising, with reported success rates that range from 55% to 80% [4]. In addition, the use of a self-expanding metallic stent has recently been reported and results have been encouraging in adults [3]. In case 1, because the boy’s parents refused surgery and right ureteral stenosis was successfully managed by balloon dilation, inserting a metallic stent was challenged for left stenosis after temporary use of nephrostomy. As complications of memory metallic stents, stent migration and encrustation have been reported [5]. Although replacement of the stent should be performed after stent migration [2,5], we expected improvement of urethral stenosis without a stent. Because the opening established by nephrostomy becomes easily dislodged and infected and ureterostomy yields stoma complications and requires stoma care, temporary insertion of a memory metallic stent may be a safe and effective alternative to surgical correction in pediatric patients. Ischuria is a frequent problem after cloacal repair. Pena et al [6] reported in their large series 24% of patients requiring intermittent catheterization through the native urethra. In our case, vesicostomy was established because of difficulties in catheterization and associated vesicoureteral reflux. However, vesicostomy requires stoma care and makes it difficult to confirm recovery of bladder function. Inserting a stent may not only improve urination but may also make it easier to insert a catheter through the urethra and to confirm recovery of bladder function.
References [1] Chapple CR, Milroy EG. Use of stents for treating obstruction of urinary outflow. BMJ 1989;299:795. [2] Kulkarni RP, Bellamy EA. A new thermo-expandable shape-memory nickel-titanium alloy stent for the management of ureteric strictures. BJU Int 1999;83:755 - 9. [3] Reinberg Y, Ferral H, Gonzalez R, et al. Intraureteral metallic selfexpanding endoprosthesis (Wallstent) in the treatment of difficult ureteral strictures. J Urol 1994;151:1619 - 22. [4] Lang EK. Interventional radiology of the lower urinary tract. In: Mueller PR, editor. Syllabus: a categorical course in diagnostic radiologyinterventional radiology. Chicago7 RSNA Publications; 1991. p. 49 - 55. [5] Arya M, Mostafid H, Patel HR, et al. The self-expanding metallic ureteric stent in the long-term management of benign ureteric strictures. BJU Int 2001;88:339 - 42. [6] Pena A, Levitt MA, Hong A, et al. Surgical management of cloacal malformations: a review of 339 patients. J Pediatr Surg 2004;39:470 - 9.
www.elsevier.com/locate/jpedsurg
Application of memory metallic stents to urinary tract disorders in pediatric patients Shinkichi Kamata*, Noriaki Usui, Masafumi Kamiyama, Akihiro Yoneda, Yuko Tazuke, Takaharu Ooue Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan Index words: Memory metallic stent; Ureteral stenosis; Neurogenic bladder
Abstract The use of memory metallic stents for the urinary tract in pediatric patients has not been reported. The authors report on 2 patients with urinary tract disorders who were successfully treated with a memory metallic stent. A thermoexpandable, nickel-titanium alloy stent was placed at the urethroureteral junction of a 4-year-old boy with ureteral stenosis associated with cloacal exstrophy for 18 months and at the urethra of a 2-year-old girl with ischuria after a repair of cloacal anomaly for 6 months. Temporary insertion of a memory metallic stent is a safe and effective alternative for organic stricture or functional obstruction of the urinary tract in pediatric patients. D 2005 Elsevier Inc. All rights reserved.
Metallic stents have been used successfully in the biliary tract, cardiovascular system, and urinary system [1]. However, meshed metallic stents allow urothelial ingrowth and become incorporated into the wall of the ureter [2]. A relatively new metallic stent is made from an alloy of nickel and titanium that has a shape memory feature; it softens at a temperature below 108C but regains its original shape when warmed to 508C and is therefore easy to insert and remove [2]. It has a closed, tight, and spiral structure that prevents urothelial ingrowth. However, the size of a memory stent is meant for adults and is therefore relatively large for pediatric use.
of 12 F with proximal end expansion to 34 F, was used. Various lengths were available for use (30-70 mm). To insert the stent, the length of the lesion was measured by fiberscopy and ureterography to choose the appropriate length of the stent. A guide wire was negotiated across the lesion and a balloon catheter was used to dilate the lesion. The stent, mounted on its introducer, was aligned across the lesion and the guide wire was removed. The catheter was then flushed with sterile water preheated to 508C. This allowed the alloy to expand so that it filled the lesion, and the proximal end opened into a funnel shape. The introducing catheter was then removed. To remove the stent, cold water was flushed near the stent. The distal or proximal end of the spiral alloy was grasped by forceps and pulled out under fluoroscopy.
1. Method A memory metallic stent (MEMOKATH 028, Engineers & Doctors A/S, Hombaek, Denmark), with a shaft diameter * Corresponding author. Tel.: +81 6 6879 3753; fax: +81 6 6879 3759. E-mail address: [email protected] (S. Kamata). 1531-5037/05/4003-0042$30.00/0 D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2004.11.014
2. Case report 2.1. Case 1 A 3-year-old Japanese boy who had undergone a repair of cloacal exstrophy and vesicourethroplasty at birth
E44
S. Kamata et al.
Fig. 1 Ureterography before (A) and after (B) insertion of the stent. After a guide wire was antegradely inserted through the kidney puncture, a balloon catheter and an introducer containing the stent (40 mm in length) were retrogradely inserted.
presented with decreased urinary output. After the initial surgery, he developed left hydronephrosis. After nephrostomy for 3 weeks, the left hydronephrosis had been followed under subclinical conditions. A computed tomography scan revealed bilateral hydronephrosis with hydroureter. A guide wire was antegradely inserted through the kidney puncture to the ureter. Ureterography demonstrated a bilaterally elongated ureter and its opening to constructed
urethra with severe stenosis. Although the right hydroureter improved after balloon dilation, the left hydroureter continued and was managed by nephrostomy. Then, at the age of 4 years, a memory metallic stent (40 mm in length) was inserted. After a guide wire was antegradely inserted through the kidney puncture, a balloon catheter and an introducer containing the stent were retrogradely inserted (Fig. 1). Eighteen months after the placement, he developed
Fig. 2 Urethrography before insertion of the stent (A) and vesicography after insertion of the stent (B). The vagina was seen through the urethrovaginal fistula (arrow) behind the bladder. After a guide wire was antegradely inserted through the opening created by vesicostomy, a balloon catheter and an introducer containing the stent (30 mm in length) were antegradely inserted. The stent covered the urethrovaginal fistula.
Memory metallic stent in urinary tract hematuria. Because fiber optic examination revealed stent migration to the urethral side with erosion of the urethral wall caused by compression of the proximal end expansion of the stent, the metallic stent was removed safely through the urethra. Eighteen months after the removal of the stent, the left hydroureter deteriorated to require ureterostomy.
2.2. Case 2 A 2-year-old Japanese girl with a rectocloacal fistula had undergone anorectovaginourethroplasty at the age of 1 year. After that surgery, she developed ischuria and a urethrovaginal fistula. Although she required catheterization to the bladder because of ischuria and bilateral vesicoureteral reflux, it was difficult to insert the catheter to the bladder because the catheter was mislodged into the vagina through the urethrovaginal fistula (Fig. 2). Vesicostomy was established 2 months after that surgery. Placement of a memory metallic stent in the urethra and closure of the opening created by vesicostomy were performed for management by selfcatheterization. After a guide wire was antegradely inserted through the opening, a balloon catheter and an introducer containing the stent (30 mm in length) were antegradely inserted (Fig. 2). The opening created by vesicostomy was simultaneously closed. After stenting, urination was unexpectedly obtained without self-catheterization. Because stent migration into the bladder was observed 2 months later with no symptoms including dysuria, the metallic stent was removed safely through the urethra 6 months after placement. For 15 months, the patient had no problems involving urination with continence.
3. Discussion Surgical correction of cloacal exstrophy and cloacal anomalies is still challenging. Urological complications during these treatments frequently occur. The management of ureteral stenosis can become a complex problem in adults [3]. The classical therapeutic approach has been retrograde balloon dilation with or without incision or surgical correction if this is not successful [4]. However, current endourological percutaneous techniques make it possible to manage ureteral stenosis by transluminal balloon dilation therapy. Early results with this technique have been
E45 promising, with reported success rates that range from 55% to 80% [4]. In addition, the use of a self-expanding metallic stent has recently been reported and results have been encouraging in adults [3]. In case 1, because the boy’s parents refused surgery and right ureteral stenosis was successfully managed by balloon dilation, inserting a metallic stent was challenged for left stenosis after temporary use of nephrostomy. As complications of memory metallic stents, stent migration and encrustation have been reported [5]. Although replacement of the stent should be performed after stent migration [2,5], we expected improvement of urethral stenosis without a stent. Because the opening established by nephrostomy becomes easily dislodged and infected and ureterostomy yields stoma complications and requires stoma care, temporary insertion of a memory metallic stent may be a safe and effective alternative to surgical correction in pediatric patients. Ischuria is a frequent problem after cloacal repair. Pena et al [6] reported in their large series 24% of patients requiring intermittent catheterization through the native urethra. In our case, vesicostomy was established because of difficulties in catheterization and associated vesicoureteral reflux. However, vesicostomy requires stoma care and makes it difficult to confirm recovery of bladder function. Inserting a stent may not only improve urination but may also make it easier to insert a catheter through the urethra and to confirm recovery of bladder function.
References [1] Chapple CR, Milroy EG. Use of stents for treating obstruction of urinary outflow. BMJ 1989;299:795. [2] Kulkarni RP, Bellamy EA. A new thermo-expandable shape-memory nickel-titanium alloy stent for the management of ureteric strictures. BJU Int 1999;83:755 - 9. [3] Reinberg Y, Ferral H, Gonzalez R, et al. Intraureteral metallic selfexpanding endoprosthesis (Wallstent) in the treatment of difficult ureteral strictures. J Urol 1994;151:1619 - 22. [4] Lang EK. Interventional radiology of the lower urinary tract. In: Mueller PR, editor. Syllabus: a categorical course in diagnostic radiologyinterventional radiology. Chicago7 RSNA Publications; 1991. p. 49 - 55. [5] Arya M, Mostafid H, Patel HR, et al. The self-expanding metallic ureteric stent in the long-term management of benign ureteric strictures. BJU Int 2001;88:339 - 42. [6] Pena A, Levitt MA, Hong A, et al. Surgical management of cloacal malformations: a review of 339 patients. J Pediatr Surg 2004;39:470 - 9.