January 1, 2009 1 Comment
Ureteral strictures may result from a variety of causes, including stone passage, endoscopic urologic procedures, radiation therapy, open or laparoscopic surgery, and penetrating traumatic injuries. The incidence of ureteral strictures has increased in recent years, largely as a result of the introduction and widespread use of upper urinary tract endoscopy. Several factors may contribute to the development of ureteral strictures following ureteroscopy, which may be seen in as many as 3% to 11% of patients. These include stone impaction, relative ischemia, often because of the use of larger instruments for prolonged intervals, ureteral injury with extravasation of urine, and direct mechanical or thermal trauma. Ureteral injury leading to stricture, fistula formation, or obstruction may also be seen following a variety of open surgical procedures, including abdominal and vaginal hysterectomy, repair of vascular lesions, and pelvic exploration in patients with prostate, colon, and rectal malignancies.
Although the need for surgical repair of a ureteral injury may be immediately evident in some cases, many patients with ureteral obstruction and/or fistulas do not present until weeks or months following surgery. In particular, ureteral strictures that result from endoscopic manipulation of the upper urinary tract may not be noted for prolonged intervals because of the slow development of ureteral fibrosis. The presentation of patients with ureteral strictures is variable and may range from acute flank pain with sepsis and pyelonephritis to the incidental finding of hydronephrosis in an asymptomatic individual. As a result, the initial evaluation and treatment of patients with suspected ureteral obstruction must be tailored to the clinical situation.
A variety of diagnostic procedures are available to evaluate patients suspected to have ureteral strictures. Those patients presenting with acute pain and/or upper urinary tract infection will likely require immediate decompression of the obstructed kidney by internal (ureteral stent) or external (percutaneous nephrostomy) drainage. In these cases, immediate or delayed radiographic imaging of the affected renal unit may be performed in an antegrade or retrograde fashion. Those patients not requiring immediate intervention may be evaluated by intravenous pyelography (IVP), renal scintigraphy or computerized tomographic (CT) scanning. Advantages of an IVP include the ability to assess renal function as well as the level and degree of obstruction. Nuclear studies provide limited anatomic detail but allow for a more precise quantification of renal function and drainage. CT scans provide an assessment of perirenal and periureteral structures, which may be important in some patients with ureteral strictures.
INDICATIONS FOR SURGERY
The indications for surgical management of ureteral strictures, disruptions, and fistulas are dependent on the etiology of the lesion and the clinical situation. Ureteral disruption that results from external violence will generally require immediate repair. Similarly, iatrogenic injuries to the ureter noted during open pelvic or abdominal surgery should be repaired without delay. In contrast, initial attempts at conservative or endoscopic management of patients with ureteral injuries detected several days or weeks following surgery may be appropriate in some cases. Ureteral strictures that result from upper urinary tract endoscopy may be managed successfully with endoscopic dilation and/or incision (endoureterotomy) , with open surgical repair reserved for patients with recurrent obstruction.
Many patients with ureteral strictures can be successfully managed using a variety of endourologic methods. Balloon dilation via a percutaneous, antegrade, or transurethral, retrograde approach is generally simple to perform with little risk of significant morbidity. Alternatively, full-thickness endoscopic incision of the stricture (endoureterotomy) followed by stent placement may have a higher long-term success rate than dilation but entails a greater risk of vascular and/or intestinal injury. In general, endourologic techniques appear to be most successful in patients with short, nonirradiated strictures of the distal ureter. Overall, an initial attempt at endoscopic management is appropriate in most patients with ureteral strictures because the potential morbidity and the recovery period are generally less with these procedures. In addition, a failed endoscopic procedure does not appear to jeopardize the success of subsequent open surgical repairs. Finally, some patients with complex ureteral strictures and/or disruption may be best managed by nephrectomy or cutaneous ureterostomy. This approach may be particulary appropriate in those with significant comorbid disease or patients in whom a urine leak could be disastrous, such as those with vascular grafts in the area of the ureteral injury.
This procedure is most appropriate in patients with short ureteral strictures involving the abdominal ureter (superior to the bifurcation of the iliac vessels). In addition, direct anastomosis of the ureter can be performed in patients with intraoperative injuries and those with ureteral damage secondary to external violence. If ureteroureterostomy is to be performed as a separate procedure, a flank, anterolateral, or midline approach is appropriate based on the level of the ureteral injury. In general, an incision that allows for renal mobilization is helpful in case additional ureteral length is necessary.
Initially, the ureter is identified through either an extraperitoneal or intraperitoneal approach. If the ureter is difficult to locate, it can be reliably found as it crosses the bifurcation of the common iliac artery. In patients who have undergone previous surgery or those with severe ureteral distortion, the ureter may be confused with other structures such as the gonadal vein. Careful dissection and aspiration with a small needle may be helpful in such cases. Once identified, the ureter is freed by blunt and sharp dissection with abundant soft tissue left surrounding the structure. It is essential to avoid damage to the ureteral adventitia because this may lead to ischemia and poor healing of the anastomosis. In cases in which the ureter has been surgically transected or completely divided by a penetrating knife or gunshot wound, both ends of the ureter must be identified.
In patients with ureteral strictures, the narrowed segment is excised after the ureter has been well mobilized both proximally and distally. It is important to remove all damaged tissue and to perform the anastomosis with healthy, well-vascularized ureter. After removal of the strictured area, stay sutures of 4-0 or 5-0 chromic catgut or absorbable synthetic suture, such as Vicryl or Dexon, are placed on each end of the ureter. It is essential that the anastomosis be performed without tension, and additional ureteral length can be obtained by mobilization of the kidney. The ureteral ends should be transected obliquely to allow for a wide-mouthed anastomosis. In addition, spatulation of each end of the ureter 180 degrees apart over a length of 2 to 4 mm may also facilitate the repair. Alternatively, a fishmouth or Z-plasty anastomosis can be performed, although these are used less commonly. In patients with high-velocity missile injuries to the ureter, extensive debridement of the ureteral ends should be performed because the degree of tissue devitalization is often underestimated at the time of surgery.
Once the ends of the ureter have been prepared, two sutures of 4-0 or 5-0 Vicryl or Dexon are placed through the apex of the spatulated area on one end and out the middle of the nonspatulated area on the other end. The knots should lie outside the ureteral lumen. These two initial sutures should be located 180 degrees apart and are held to facilitate the completion of the anastomosis. Running or interrupted sutures are placed approximately 2 mm apart on one side of the anastomosis, and the holding sutures are then rotated to help expose the opposite side. A double-pigtail stent may then be placed by initially passing the guide wire into the bladder and then threading the stent over the wire. The guide wire is then removed. In order to assure proper distal positioning of the stent, have an assistant fill the bladder through the urethral catheter with saline mixed with an ampule of indigo carmine. Visualization of blue-stained solution at the level of the anastomosis assures that the stent is in the bladder, except in unusual cases of preexistent vesicoureteral reflux. The guide wire is then passed proximally into the renal pelvis, and the stent is threaded over the opposite end of the wire, which is brought out through a side hole in the stent.
The stent is then passed proximally until it is straightened in the ureter, and the wire is removed. The anastomosis is completed with interrupted or running sutures. If the repair is tenuous or in patients who have previously received radiation therapy, the ureteral anastomosis may be wrapped with omentum to facilitate healing. This may also be helpful in patients with associated injuries to the bowel or pancreas or those in whom a vascular graft has also been placed. A closed suction drain is placed lateral to the anastomosis and brought out through a separate stab incision before closure of the abdomen. The stent may be left in place for 2 to 4 weeks.
Psoas Hitch Procedure
The psoas hitch procedure is the simplest method for substitution of the lower third of the ureter.5 With this technique, the bladder can be mobilized in a cephalad direction to a level well above the bifurcation of the iliac vessels. In most cases, adequate mobilization of the bladder can be achieved to avoid the need for a technically more difficult and less often successful Boari flap procedure (see below). The choice of incision is based on surgeon preference, and options include a lower midline, Pfannenstiel, or suprapubic V approach. The ureter is initially identified and carefully dissected at or above the crossing of the common iliac vessels. It is generally best to approach the ureter at a level above the site of obstruction and then proceed distally after encircling the uninvolved ureter with a small Penrose drain or vessel loop. Care is taken to avoid damage to the ureteral blood supply. The ureter is sharply divided at or below the pelvic inlet, based on the extent of ureteral pathology, and a stay suture is placed. The distal ureteral stump is ligated with a 2-0 chromic catgut suture.
After the ureter is dissected, the bladder is mobilized to allow it to be hitched to the psoas muscle. The peritoneum is dissected from the dome of the bladder and the space between the rectum and bladder is opened. The superior and middle vesical pedicles are ligated and divided on the contralateral side, leaving the inferior vesical pedicle as the only attachment on the contralateral side of the bladder. The blood supply on the ipsilateral side rarely needs to be divided to provide sufficient upward mobilization of the bladder. The initial incision into the bladder is then made transversely across the middle of the anterior wall at the level of its maximum diameter. The bladder should be opened slightly more than halfway around. A common mistake is to open the bladder over too short a distance, which limits the cephalad displacement that can be achieved. The bladder is then brought to the psoas muscle at a point superior and lateral to the bifurcation of the iliac vessels by placing two fingers into the fundus of the bladder. The ureter can then be gently pulled toward the bladder to determine if an adequate anastomosis without tension can be achieved. If further length is needed, the kidney can be mobilized downward, or the contralateral endopelvic fascia can be opened. Once it is determined that an adequate anastomosis can be performed, the bladder is fixed to the psoas minor tendon or psoas major muscle using three to six 2-0 Vicryl sutures. These sutures should be carefully placed to avoid injury to the genitofemoral nerve. In addition, femoral neuropathy has also been reported after the psoas hitch procedure, and care should be taken not to place the tacking sutures too deeply into the muscle.
Before sutures are tied between the bladder and psoas muscle or tendon, the site of the ureteroneocystostomy should be selected. It is important to anastomose the ureter to an immobile portion of the bladder base so that intermittent obstruction of ureteral drainage does not occur as the bladder fills to varying degrees. The ureter is drawn through the bladder wall by passing a small clamp from inside the bladder and grasping a stay suture that has been placed through the distal ureter. The ureter should not be trimmed until it has been brought into the bladder, and it is clear that there is sufficient length to perform a tension-free anastomosis. If there is adequate ureteral length, a tunneled, nonrefluxing anastomosis may be performed. However, a direct, refluxing ureteroneocystostomy is also acceptable in most adults. The anastomosis is performed using interrupted 4-0 or 5-0 Vicryl sutures after the ureter has been spatulated on its anterior surface. At the distal apex of the anastomosis, one to three sutures are placed deeply into the bladder muscle and then through the tip of the ureter. The remaining sutures are taken through bladder mucosa and the ureter. The ureteral adventitia is loosely attached to the bladder wall where it exits using two or three 4-0 Vicryl sutures placed longitudinally.
An 8-Fr infant feeding tube or double-pigtail stent is then placed into the renal pelvis. The feeding tube is generally preferred because it can be brought out the anterior bladder and body wall through a stab incision. This allows for direct monitoring of drainage; the tube can be irrigated if it becomes obstructed, and the need for stent removal by cystoscopy is avoided. The feeding tube is loosely tied to the bladder mucosa adjacent to the anastomosis using a 5-0 chromic suture to avoid inadvertent displacement during the perioperative period. A suprapubic tube can be placed if desired, although a urethral catheter is generally adequate. The bladder is closed vertically in watertight fashion using two layers of 2-0 and 3-0 chromic catgut. A Penrose or closed suction drain is positioned laterally in the perivesical area. A cystogram and ureterogram are performed through the externally draining stent 7 to 10 days postoperatively to assure adequate healing.
Boari Flap Procedure
A bladder flap operation is rarely needed in patients with distal ureteral strictures and/or fistulas. In most cases, a psoas hitch procedure is adequate to replace the lost or damaged section of ureter. If a Boari flap is necessary, the choice of incision, dissection of the ureter, and initial bladder mobilization are identical to that described above for patients undergoing a psoas hitch ureteral reimplantation. When renal and ureteral mobilization, as well as the psoas hitch, are inadequate to allow a tension-free anastomosis to be performed, a bladder flap may be used. A psoas hitch should accompany the Boari flap to help decrease the length of flap that is needed.
Once the bladder has been mobilized and a psoas hitch performed, the site for the base of the flap should be identified on a fixed portion of the bladder, and the length of flap needed should be measured. A stay suture is placed at each end of the base of the flap, which should be approximately 4 cm wide. In order to assure adequate vascularity of the flap, the base should be wider if a longer flap is necessary. A stay suture is placed at each end of the apex of the flap, which should be 3 cm in width. If needed, a longer flap can be created using a spiral incision in the bladder. The flap should be developed by incising the bladder wall using electrocautery. The flap is then brought up to the ureter, which may be anastomosed to the apex using either a direct or tunneled technique. A 5- to 8-Fr infant feeding tube or double-pigtail stent should be placed. The bladder is closed, and the flap is rolled into a tube over the stent using a running 3-0 chromic catgut suture on the mucosa and interrupted 2-0 chromic catgut suture on the muscularis and adventitia. A perivesical drain is placed, and radiographic evaluation of the bladder and ureter is performed before the ureteral and urethral catheters are removed.
Prolonged urinary drainage is the most common problem in the early postoperative period in patients undergoing ureteroureterostomy, psoas hitch reimplantation, or the Boari flap procedure. In most cases, the leak will seal as long as adequate drainage of the upper urinary tract and bladder is assured. If there is concern regarding the site of leakage, a cystogram and/or ureterogram may be obtained. If an externally draining ureteral catheter is not present, an intravenous pyelogram may be helpful. Rarely, injury to the contralateral ureter may occur, and this possibility should be considered in patients with unusual or complicated problems. In patients with unexplained fever and/or sepsis, the presence of an undrained urine collection (urinoma) should be considered. Ultrasonography or CT scans may be useful in such cases both in establishing the presence of a fluid collection and guiding percutaneous placement of a drainage catheter.
The most significant long-term risk associated with the surgical repair of ureteral strictures is recurrent obstruction. Although some patients may present with flank pain and/or infection, others will remain asymptomatic, presumably because of the slow development of a recurrent stricture. For this reason, all patients should undergo radiographic evaluation of the upper urinary tract 6 to 12 weeks following stent removal and again 6 to 12 months after surgery. Risk factors that increase the likelihood of recurrent obstruction include previous ureteral and bladder surgery, a history of pelvic or lower abdominal irradiation, devascularization of the ureter at the time of surgery, and an anastomosis performed under tension. If detected early, recurrent strictures may respond favorably to balloon dilation and/or endoureterotomy, and these procedures should be considered before resorting to open surgical revision.
Surgical repair of ureteral strictures is associated with excellent long-term success rates. The most important factors responsible for these results include selection of the most appropriate surgical technique, based on the site and length of stricture. In addition, consideration of preoperative issues, such as a history of irradiation or prior bladder and ureteral surgery, is also essential to avoiding recurrent obstruction. In general, as long as a tension-free anastomosis can be performed using well-vascularized ureteral tissue, the long-term success of open surgical repair of ureteral strictures should be assured in the vast majority of patients.