Ureter stenting

In some patients, a stone may be able to be seen only after a narrow tube called a stent is placed in the ureter. The patient is first put under anesthesia. Then the... 

Percutaneous stenting of the ureter is commonly requested after a failed cystoscopic retrograde stenting or when there is a percutaneous nephrostomy in place. Whether one or both kidneys are drained depends on the renal function, the general condition of the patient and the ease with which the stents can be inserted. 

When a percutaneous nephrostomy is being inserted with the intention of dilating and stenting a ureteric stricture either at the same sitting or at a later date, a middle or (preferably) upper caliceal track will facflitate subsequent manipulations down the ureter. The track is dilated to 8 F, and an angled catheter is inserted in order to direct a guidewire down the ureter. The first problem that may be encountered is that an obstructed ureter may be kinked or tortuous (Fig. 7.1). As in angiography, this is approached... 

Fig. 7.3a-<. This patient had carcinoma of the prostate encasing both ureters, a The difficult angle prevented stenting at cystoscopy - right side only shown, b Right nephrostomy, c Antegrade J1 stents...

Fig. 7.4a-d. Nodal encasement of the ureter from carcinoma of the cervix, a Ureterogram via ureteroscope. b Following insertion of an antegrade ureteric catheter, a guidewire was grasped by the ureteroscope. c A 5-mm balloon passed antegradely. d The lower end of a 22-cm, 8-F JJ stent passed antegradely... 

There are now various expandable meshed metallic stents used in the ureter such as Wallstents (Schneider, Minneapolis, Minn.), Palmaz-Schatz (Johnson and Johnson Interventional Systems, Warren, N.J.) and Ultraflex (Boston Scientific, Boston, Mass.) stents. The Wallstent consists of multiple stainless steel filaments (0.14 mm in caliber), woven in a crisscross pattern to form a tubular mesh that self-expands to a predetermined diameter and length. The stent is compliant and flexible it moulds to the lumen of the ureter but leaves more than 75% of its surface free of metal. Expandable metal stents have received widespread recognition in the treatment of a variety of occlusive diseases, particularly in the arterial and biliary systems. The advantages over plastic polymers are their larger luminal diameter, the ease of placement, the ability to limit the length of the area the stent covers so that it closely... 

All types of metallic stents used in the ureter have produced similar results. An Austrian group reported the use of self-expanding Wallstent endoprostheses (Boston Scientific) for palliative treatment of malignant ureteral obstruction in 23 patients (30 ureters) (Lugm AYR and Pauer 1992). They used the following four criteria for patient selection (1) life expectancy of at least 6 months, (2) current chemotherapy, (3) increasing levels of serum creatinine and (4) severe clinical signs and symptoms associated with hydronephrosis. These were implanted endoscopically... 

Fig. 7.7. Patient with a leak from an ileal conduit. (Pelvic malignancy and radiotherapy resulted in poor healing.) Urine diversion was achieved via bilateral nephrostomies and a JJ stent crossing from one ureter to other. Stent snared at 6 weeks and removed via the nephrostomy track...

Irwin RJ, Lopez-Martinez RA, LaNasa J Jr, Kasabian N, Watson RA (1998) Placement of metallic stents in ureters obstructed by carcinoma of the cervix to maintain renal function in patients undergoing long-term chemotherapy. AJR Am J Roentgenol 171 1595-1599... 

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. 

Barbaric ZL, GOthlin JH, Davies RS (1977) Transluminal dilatation and stent placement in obstructed ureters in dogs through the use of percutaneous nephropyelostomy. Invest Radiol 12 534-536... 

In rare cases (the bladder cannot be reached because the ureter is too short), it is possible to reestablish urinary continuity by using the recipient s ureter a classical pyeloureteral anastomosis is protected by a double-J stent, according to the Ander-sen-Hynes pyeloplasty technique. 

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