Background

Most nonmalignant strictures manifest within 2 years of the initial urinary diversion [8] and multiple factors are believed to contribute to their occurrence. Benign UES have been reported in all types of urinary diversions and are thought to be associated with ischemic changes in the ureter [9]. Multiple studies have noted an increased stricture rate on the left side, possibly related to the greater degree of ureteral dissection, as well as tunneling and kinking of the ureter through the mesentery [4, 8–11]. Several studies have investigated effects of technical variations at the time of diversion, although some are contradictory or provide results that do not reach significance due to a lack of subjects and statistical power. A running suture at the anastomosis may increase the incidence of strictures [12]. Use of a nonrefluxing anastomosis has been shown to raise the rates of stricture formation in comparison to a refluxing anastomosis [13]. The most studied technical consideration has been comparison of the Wallace (adjoined ureters implanted end to end) and Bricker (individually implanted) ureteral anastomoses, which has generally shown no difference in stricture frequency [10, 14]. The use of ureteral stents at the time of anastomosis is also controversial. Historically believed to assist in healing and alignment, and decrease the risk of urine leak, other studies have associated ureteral stenting with a greater likelihood of infection, and possible increased stricture formation [15–17]. Body mass index of >30 kg/m² and prior pelvic radiation [10] are also thought to influence the risk of developing a stricture.

Presentation and diagnosis

Signs and symptoms of UES can include flank pain, malaise, failure to thrive, pyelonephritis, sepsis, hematuria, and worsening renal function [18, 19]. Some patients may develop strictures slowly and remain asymptomatic with only a rising creatinine level. This heterogeneity in presentation necessitates routine laboratory and radiographic surveillance and close clinical follow‐up [20]. Initial evaluation generally consists of serum chemistries and radiographic imaging. Renal ultrasound or computed tomography (CT) are most frequently utilized in the screening of hydronephrosis (Figure 54.1). Since reflux can mimic obstruction, it should be ruled out with other anatomic or functional studies. Free reflux of contrast into the ureter on loopography essentially excludes anastomotic stricture. If no reflux is seen on loopogram and renal function is adequate, renal scintigraphy can aid in the diagnosis of obstruction. Antegrade contrast studies such as intravenous urography, CT urography, and antegrade nephrostogram can also help diagnose a stricture and characterize its length and location as well as evaluate for filling defects that may herald recurrence of malignancy. Such a recurrence is relatively rare in comparison to benign etiologies of stricture, but should be considered if appearing at more than 6 months after initial diversion [21–23]. Urine cytology and biopsy may be indicated before definitive treatment of the stricture.

Indications for therapy

Patients who develop symptomatic strictures generally require early relief of obstruction. Asymptomatic patients also benefit from decompression, as poorer treatment outcomes have been observed with an ipsilateral renal function of less than 25% [24]. Indications for urgent intervention include intractable flank pain, obstructive pyelonephritis, rising creatinine, and impending sepsis. Due to the inherent difficulty of retrograde approaches in patients with urinary diversions, percutaneous nephrostomy is most often utilized to relieve obstruction. Placing a nephrostomy tube also facilitates antegrade diagnostic studies to assist in stricture localization, characterization, and surgical planning.

Endourologic techniques

Treatment of UES has largely developed from techniques used for ureteral stricture disease. Approaches can be retrograde, antegrade, or a combination of both. Because initial management of UES involves decompression of the collecting system with a percutaneous nephrostomy, this, in combination with the technical challenges of identifying the ureteral anastomosis in a conduit or neobladder, make an antegrade approach preferred.

Since the key manipulations required to treat UES occur in the distal ureter, it is important to have a percutaneous access which will allow easy passage of instruments to this area. Therefore, upper pole or upper interpolar renal access is preferable to lower pole access. If the patient has a lower pole nephrostomy tube that was previously placed simply to drain the kidney, strong consideration should be given to relocating the access to the upper or mid collecting system. If the patient does not have a nephrostomy tube at the time of definitive management, access is usually obtained with ultrasound guidance and confirmed with fluoroscopy. A urine culture should be obtained and any bacteriuria treated prior to definitive endoscopic treatment of a UES.

Video 54.1 demonstrates endoscopic treatment of UES in detail. After induction of general anesthesia, patients with ileal conduits are placed in flank position to provide easy access to the nephrostomy as well as the urostomy, and both the flank and abdomen are sterilely prepared and draped. For left‐sided strictures, which are most common, the patient is placed in the right lateral decubitus position and for right‐sided strictures the patient is positioned in left lateral decubitus. Standard cushioning done for flank approaches, including an axillary role, is utilized. Patients with neobladders are positioned prone with a urethral catheter in place. The technique used for a patient with a neobladder is similar to that used for a benign ureteral stricture treated with an antegrade approach, so the following description will be limited to the method used for patients with ileal conduits.

The procedure begins with antegrade injection of contrast through the nephrostomy to demonstrate the stricture (Figure 54.2) and the renal and ureteral anatomy, as well as to assess for any filling defects in the kidney and ureter. A 0.038 or 0.035 inch hydrophilic tip guidewire is passed through the nephrostomy tube into the collecting system and manipulated through the ureteropelvic junction and down the ureter. Various 4 or 5 Fr angle‐tipped catheters (Kumpe™, Cobra™) can assist in these manipulations. After incising the fascia along the wire with a scalpel, an 8/10 Fr coaxial dilator/safety wire introducer is passed over the working wire. A safety wire can then be placed down the ureter. Next, a 13 or 14 Fr short ureteral access sheath is advanced over the working wire. Further dilation or placement of a larger sheath is typically unnecessary. The renal collecting system and ureter can then be examined with a flexible fiber‐optic or digital ureteroscope (Figures 54.3 and 54.4). Any suspicious lesions should be biopsied at this point. If the ipsilateral ureter happens to be very dilated, the tract can be upsized to a larger access sheath using an Amplatz dilating system, and an 18 Fr sheath can be placed in order to use a flexible cystoscope for subsequent manipulations. However, this is not typically necessary.

After establishing working access, any of the various treatment modalities reviewed herein can be employed. At the conclusion of treatment a ureteral stent is positioned to maintain patency during healing.

Balloon dilation

The use of balloon dilation in urology was first described in the nineteenth century for the treatment of urethral strictures [25]. It was not until the 1980s that dilation was used in the treatment of ureteral strictures [26]. Since then, the use of ureteral balloon dilation has become commonplace in endourology. Balloon dilation may be used as primary endoscopic treatment, or in combination with other modalities. An advantage of balloon dilation when used as monotherapy is that it can be accomplished under local anesthesia and can be done by an interventional radiologist. The renal tract does not need to be dilated nor a working sheath placed. Once wire access is established, the dilation balloon is positioned under fluoroscopic guidance across the strictured area. The balloon is then slowly inflated with diluted radiographic contrast media until it assumes the typical hourglass shape caused by the stricture. Inflation continues until the hourglass shape gives way and the balloon is completely inflated (Figure 54.5). The dilation is then held for approximately 3–5 minutes before deflation. This cycle may be repeated as necessary until the entire stricture is treated. Figure 54.6 shows the endoscopic appearance of a UES immediately after balloon dilation.

Endoureterotomy

Endoureterotomy, or incision of the ureter, was introduced due to the disappointing long‐term success of balloon dilation. Endoureterotomy may be performed using a variety of instruments, including cold knife, electrocautery, or laser. Additionally, the Acucise™ cutting balloon catheter combines electrocautery with balloon dilation of the ureter. The primary goal of each modality is to create a full‐thickness incision that extends approximately 1 cm beyond each end of the stricture and into peri‐ureteral fat. This is confirmed by visualization of peri‐ureteral fat or extravasation of contrast on fluoroscopy [27]. For dense strictures, endoscopic injection of 3–5 ml of 40 mg/ml triamcinolone into the incised stricture has been advocated to improve outcome [24, 28].

Cold‐knife endoureterotomy

Cold‐knife treatment typically requires a semirigid ureteral resectoscope for retrograde incision of the stricture. Because of the larger diameter and lack of flexibility, the extent of narrowing that can be treated under direct vision is limited. An alternative method has been described in which a flexible wire‐mounted cold knife is passed antegrade through a nephrostomy and then withdrawn to perform an endoureterotomy [29]. This may be performed under fluoroscopic guidance or visually in conjunction with a ureteroscope. Regardless, several incisions may be required. Cauterization of urothelial or mucosal bleeding is not necessary and should be avoided because of the risk of thermal damage [30]. Ureteral stents are typically utilized as the ureter heals.

Electrocautery endoureterotomy

Electrocautery is typically performed under direct visualization through a semirigid or flexible ureteroscope. Safety wires should be insulated to avoid application of electrical current outside the target treatment area. A 2 or 3 Fr Greenwald electrode is advanced through the ureteroscope and incision is made on pure cutting current at a power of 75 W. Multiple controlled incisions into the fibrotic tissue may be made under direct visual control. It is challenging, but imperative, to maintain precise, linear, incision tracking with a flexible ureteroscope to avoid surrounding thermal damage. Lovaco and associates reported a method in which a guidewire is passed antegrade and a dilation balloon is passed retrograde, inflated at the stricture, and pulled down to intussuscept the stricture into the bowel segment. The stricture is thus well exposed and can be incised precisely from below [19]. This method seems to provide a theoretical advantage of decreased injury to retroperitoneal blood vessels and bowel, but no subsequent publications of this technique have been forthcoming.

Acucise balloon catheter endoureterotomy

The Acucise™ cutting balloon catheter (Applied Medical, Rancho Santa Margarita, CA, USA), comprising a monopolar electrocautery cutting wire and a 24 Fr 3 cm balloon can be used to treat strictures throughout the ureter [31]. After identification of the stricture, the device is deployed over a guidewire and positioned so the radiopaque markers straddle the stricture. Special attention must be given to the location of the cutting wire after visual inspection to avoid any peri‐ureteral vessels. Treatment begins with inflation of the balloon with 2 ml of dilute contrast media along with simultaneous activation of the cutting wire at 75  for a maximum of 5 seconds. Similar to pure balloon dilation, Acucise balloon inflation may be maintained for 3–5 minutes. The manufacturer suggests no more than two treatments be undertaken at one time. Presence of a safety wire during electrocautery activation is not recommended because of potential conduction injury.

Laser endoureterotomy

Laser endoureterotomy for UES may be performed with a variety of lasers, but the holmium:YAG laser is preferred because of its favorable safety characteristics with a depth of tissue penetration of only 0.4 mm [27]. Incision is performed visually through a flexible ureteroscope with a 200 µm fiber set at 1 J and 10 Hz (10 W) (Figures 54.7 and 54.8). Direct visual inspection prior to incision is necessary to avoid any pulsations representing peri‐ureteral vessels and, afterwards can confirm the presence of fat. Again, care must be taken to make precise cuts to avoid thermal damage to a wide area of the ureteral circumference, which can be quite challenging with a flexible ureteroscope. After incision, contrast injection into the ureter should reveal extravasation (Figure 54.9).

Post‐treatment ureteral stenting

Regardless of the primary method used to treat UES, ureteral stenting is commonly employed to allow healing, limit extravasation of urine, and maintain patency. Ideal duration of stenting in the postoperative period is undefined, and four to six weeks may be reasonable. There is some evidence to suggest that prolonged stenting may be detrimental and lead to tissue overgrowth and fibrosis [27]. There is also disagreement as to the optimal stent diameter. Some recommend larger stents or even double stents, while others that argue an excessively large stent may induce ischemia and scarring [24, 32, 33].

Ureteral stents may be deployed either forward or retrograde in a through‐and‐thorough fashion over a guidewire with fluoroscopic assistance. Synthetic double‐J stents are most commonly used. For patients with ileal conduits, a nephroureterostomy tube can be positioned in reverse fashion, with the distal pigtail in the renal pelvis and the proximal port in the urostomy bag [34].

For patients with severe comorbidities or those who do not want to attempt a definitive procedure, chronic ureteral stenting may be acceptable, despite the risk of encrustation, infection, and the need for frequent exchanges (every 3–6 months). This method is often successful in relieving obstruction but does not treat the underlying stricture.

To alleviate some of the problems with polymer stents, the use of metal stents has been investigated. Metal stents offer the benefits of resistance to compression and increased exchange interval [35]. Metal stents have been used previously in the setting of malignant obstruction with some success, but their use in benign stricture disease is controversial [36]. Their use in UES is even more limited. Many studies evaluate their use in the context of general ureteral obstructions, both benign and malignant, and report on only a handful of UES as a subgroup.

A variety of metal stents have been used: self expandable, balloon expandable, thermo‐expandable shape memory, covered, and double pigtail stents [37]. Each type has its own manufacturer‐provided deployment device and instructions. Many require dilation of the stricture before insertion. Details regarding the frequency of exchanges is device‐specific. The following metal stents have been used primarily in ureteral strictures of both benign and extrinsic malignant obstructions, but have also been reported in UES in small numbers. There are few direct comparisons of these products in treatment of ureteral obstruction, and fewer in the setting of UES.

Resonance (Cook Medical, Bloomington, IN, USA) is made of a magnetic resonance imaging (MRI)‐compatible nickel‐cobalt‐chromium‐molybdenum alloy without a lumen and is similar in shape to a double‐J stent. It is deployed through an 8 Fr sheath introducer. The Memokath 051 (Endotherapeutics, Epping, NSW, Australia) is a thermo‐expandable shape memory stent made of nitinol and has a lumen. The stent is deployed over a guidewire with the provided sheath. The stent is then expanded in situ with the injection of normal saline at 65 °C [38]. The Allium URS stent (Allium Medical, Caesarea Industrial Park South, Israel) is a nickel‐titanium alloy mesh invested with a biocompatible polymer to prevent tissue ingrowth and encrustation. It is available in two sizes, 30 and 24 Fr, and can be retrieved endoscopically. It is deployed over a guidewire in conjunction with the provided 10 Fr sheath [39]

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