Ureteral stents

Siloxane-containing devices have also been used as contact lenses, tracheostomy vents, tracheal stents, antireflux cuffs, extracorporeal dialysis, ureteral stents, tibial cups, synovial fluids, toe joints, testes penile prosthesis, gluteal pads, hip implants, pacemakers, intra-aortic balloon pumps, heart valves, eustachian tubes, wrist joints, ear frames, finger joints, and in the construction of brain membranes. Almost all the siloxane polymers are based on various polydimethylsiloxanes. 

Pergolide 3 mg/day has been associated with retroperitoneal fibrosis in an 83-year-old woman after 18 months (8). She required ureteric stents, which were removed 2 years later, after her renal function had remained stable. Because of deterioration in her Parkinson s disease the non-ergot dopamine receptor agonist ropinirole was started and treatment was uneventful after 12 months. 

Treatment of sulfadiazine nephrotoxicity consists in stopping sulfadiazine or decreasing its dosage. The acute kidney injury, however, may resolve despite continuation of the treatment [41]. Hydration and especially alkalinization are the basis for the treatment. Urinary tract obstruction may require placement of ureteral stents [13] or nephrostomy [33]. This complication is essentially reversible and dialysis is rarely needed [27]. 

Rosman BM, Barbosa JA, Passerotti CP, Cendron M, Nguyen HT. Evaluation of a novel gel-based ureteral stent with biofilm-resistant characteristics. Int Urol Nephrol. 46(6) (2014) 1053-1058. 

Fig. 11 Illustration of the principle of an SMP ureteral stent from oCG-DMAC derived network. Figure from [43]. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with...

Ureteric stents are not permanent and need to be replaced. This is usually done cystoscopically after 6 months. If the urine is not concentrated because of poor renal function the stents can be left in place for longer. This decision is generally made at the time of the first stent change. If at 6 months the stent is clear with no sign of encrustation the period until the next exchange can be extended to 9 or 12 months. 

Ureteric stents with multiple side holes are ineffective, but stents with drainage holes at each end but none in the shaft, combined with a well draining nephrostomy, can help to heal a fistula (Fig. 7.7) (Lang 1982). 

Arya M,Mostafid H,Patel HRH,Kellett MJ,Philp T (2001) The self-expanding ureteric stent in the long-term management of ureteric strictures. Br J Urol Int 28 339-342... 

Smith AD, Lange PH, Miller R et al. (1979) Percutaneous dilatation of ureteroileal strictures and insertion of Gibbons ureteral stents. Urology 13 24... 

Lange D, Chew BH. Update on ureteral stent technology. Ther Adv Urol. 2009 1 143-8. 

J.D. Denstedt, G. Reid, M. Sofer, Advances in ureteral stent technology. World Journal of... 

XPS was used, with SEM and electron microprobe analysis, to examine conditioning films, biofilms, and encrustations on ureteral stents recovered from patients or incubated in vitro. ... 

Fig. 18.6. Plain radiography after ureteric reimplantation. There is malposition of the ureteric stent, which lies in the...

Percutaneous treatment of diseases affecting the urinary tract most often begins with accessing a collecting system and placing a nephrostomy tube. Thus, nephrostomy insertion is the basic technique upon which percutaneous surgical procedures are built. This chapter discusses nephrostomy tube insertion, ureteral stent insertion, ureteral stricture dilatation, nephrostomy tract dilatation, percutaneous removal of calculi, endopyelotomy techniques used in the treatment of UPJ strictures and percutaneous renal angioplasty for treatment of renovascular hypertension. 

Endurology is minimally invasive therapy involving the urinary tract. It is the natural evolution of techniques developed for treatment of renal obstruction using percutaneous access. Access to the collecting system is via a puncture identical to that used in placement of percutaneous nephrostomy. Sequential dilatation of the track allows for placement of an introducer sheath that allows for the endosurgical treatment of a variety of conditions. Endourologic procedures include ureteral dilatation, ureteral stenting, calculus removal (percutaneous nephrolithotomy), and endopyelotomy (percutaneous pyelo-plasty). 

Indications for ureteral stenting include relief of a ureteral obstruction from any cause, providing drainage while a ureteral injury heals, maintaining ureteral caliber until edema or mass effect subsides, stone removal, or surgery. The antegrade placement of a stent may be performed after failure of the endoscopic approach due to unfavorable anatomy. 

Next, a nephrostomy catheter is inserted and secured to the skin. The nephrostomy catheter should be equal to the diameter of the track to prevent leakage of urine. The nephrostomy tube may be left in place as long as is clinically indicated. If another procedure is necessary, the nephrostomy is left in place for access. If no procedure is planned and no problem has occurred, the nephrostomy tube is removed after 24-72 h. Prior to removal, a nephrostogram is obtained to confirm satisfactory position and functioning of the stent. If the ureter drains well, the nephrostomy is removed and covered with a dry, sterile dressing. The child is usually followed clinically, and when the ureteral stent is no longer needed, it is removed cystoscopically from the bladder. In rare cases, the stent may be removed from above after a nephrostomy track has been reestablished. 

Latinos, E., Perimenis, P., Koutsoukos, P., and Barbalias, G. (2004) Assessment of encrustations in polyurethane ureteral stents. J. Endourol, 18, 550. 

Lumiaho, J., Heino, A., Kauppinen, T., et al. Drainage and antireflux characteristics of a biodegradable self-reinforced, self-expanding X-ray-positive poly-L, D-lactide spiral partial ureteral stent an experimental study. J. Endourol. Endourol. Soc. 21, 1559-1564 (2007). doi 10.1089/end.2005.0085... 

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