Ureteral Complications Following Renal Transplantation

Historically, the incidence of urologic complications following kidney transplantation, manifested primarily as ureteral leaks or obstruction, was as high as 10%.1,5 The complications often resulted in significant morbidity, graft loss, and occasional patient death. Improvements in surgical techniques, immunosuppression, and methods for diagnosing and treating the complications have led to a significant decline in the rate of urologic complications to the current reported incidence of 2% to 2½%.This has resulted in lower morbidity and rare loss of a kidney or patient to urologic complications. However, despite these changes, the need for diligence in diagnosing these complications and quickly addressing them remains as true today as in the past.

The most common cause for ureteral complications following kidney transplantation is technical error. Damage to the ureteral blood supply during graft harvest or transplantation can result in ureteral ischemia and subsequent leak or obstruction. Additional technical errors such as excessive tension at the ureteroneocystostomy site or hematoma development within the tunnel may also cause problems.With careful attention to detail, most of these problems can be minimized, especially in the early postoperative setting. Long-term or delayed ureteral obstruction may be the result of ischemic changes secondary to chronic rejection or a continuation of the spectrum of damage associated with the organ harvest and transplantation, and although not all are preventable, the incidence can be markedly reduced with good surgical technique.

URINARY LEAKS

In current practice most urinary leaks are the result of ureteral problems, s a majority of surgeons now employ an extravesical ureteroneocystostomy technique for implantation of the ureter. This results in a shorter ureter, decreased likelihood of ischemia, and a limited cystostomy that rarely leads to leakage from the bladder. The majority of leaks occur early after transplantation and are manifested by either drainage from the wound, unexplained graft dysfunction, or a pelvic fluid collection. Signs and symptoms can also include fever, graft tenderness, and lower extremity edema.

Early urinary leaks can be divided into two types according to the timing of presentation. The first usually occurs within the first 1 to 4 days and is almost always related to technical problems with the implantation. In this case, the ureter has usually pulled out of a tunnel. This is likely caused by excessive tension at the anastomosis. This complication appears to be more common with the extravesical ureteroneocystostomies.8 Some investigators have recommended use of a ureteral stent to lessen the likelihood of this complication.

The second type of early ureteral leak is associated with distal ureteral ischemia, which may be a consequence of injury during the donor recovery, technical causes such as tunnel hematoma, or distal stripping of the blood supply. This type usually presents between 5 and 10 days posttransplant.

To correct the early leak caused by excessive tension, it is often possible to do a repeat ureteroneocystostomy. In most other cases, especially with the current techniques of extravesical reimplantation, a different operative procedure is often more suitable.

URETERAL OBSTRUCTION

Ureteral obstruction can also be the result of ureteral ischemia but occurs later than ureteral leaks and usually presents as graft dysfunction. It can occur years after the transplant and in this situation may represent vascular injury associated not only with the technical complications but also with chronic rejection. The spectrum of ureteral ischemic injury extends from early necrosis and urinary leakage to delayed ureteral obstruction, presenting months to years after the actual transplantation.

DIAGNOSIS

Urinary leaks are often suspected because of increased drainage from the wound. The fluid should be tested for BUN/creatinine to see if it is urine. Radiographic tests of help include an abdominal ultrasound and nuclear renal scan. A renal scan demonstrating extravasation is the most sensitive method to differentiate a urine leak from other fluid collections such as lymphoceles or hematomas. A cystogram should be performed if a bladder leak is suspected.

Ureteral obstruction, usually manifested by graft dysfunction, requires evaluation, and again an ultrasound and nuclear renal scan are the most common screening studies. Additional radiographic studies such as a CT scan may be of assistance in some cases. With both ureteral leaks and obstruction, endourologic techniques can be both diagnostic and therapeutic.

INDICATIONS FOR SURGERY

Anything that causes graft dysfunction or results in disruption of the urinary tract in a renal transplant patient is of utmost concern and requires rapid diagnosis and treatment. In the case of ureteral leakage or obstruction, the goals of treatment include careful and accurate diagnosis of the exact cause and site. If the problem has a physical cause such as a leak or an obstruction and is not associated with an acute rejection episode, then treatment is directed at stabilization of the renal function, minimization of morbidity, and a restoration of the continuity and function of the urinary tract. If there is concomitant rejection, then definitive operative therapy is withheld pending the treatment of rejection.

ALTERNATIVE THERAPY

The need for immediate open operative surgical intervention has been replaced, to a large extent, by early endourologic intervention. The placement of a percutaneous nephrostomy can divert a leak or relieve obstruction and allow more definitive diagnosis. As described by Streem et al., endourologic management algorithms can select patients for whom the likelihood of successful nonoperative management is good. Depending on the selection criteria, the results of management of distal ureteral leaks with stenting and a nephrostomy tube show that approximately one-third of patients do well long term and require no additional treatment. For ureteral strictures or stenoses, approximately 45% of patients, carefully selected, will avoid an open operative repair. For the other patients, percutaneous access can allow stabilization of renal function and a more critical assessment before open surgical repair is carried out. In a few cases, percutaneous access can offer long-term treatment with chronic stent management. This choice, in my opinion, is of limited application in most patients with a well-functioning graft because of the long-term risks (i.e., stone formation, infection, etc.) and inherent costs. However, in patients who are not operative candidates and for some patients with marginal graft function, chronic endourologic treatment can be an alternative to definitive repair.

DESCRIPTION OF THE PROCEDURE

There are many procedures available to restore the continuity of the urinary tract. In our experience dealing with a difficult ureteral stenosis or a leak from significant ureteral ischemic necrosis, we favor the use of the native ureter to replace the transplant ureter. Advantages of this repair include: the native ureter is usually nonrefluxing, the results are reliable, there is a low likelihood of recurrence of the primary problem, and a tension-free anastomosis with good blood supply is easily attained. The focus of this operative description is on that surgical choice.

Surgical access to the transplanted kidney and ureters (transplant and native) is usually achieved by reopening the old incision. Occasionally, if extensive mobilization of transplanted kidney is anticipated or access to the contralateral native ureter is planned, a midline incision is an option. Surgical access to repair an early ureteral leak is usually simplified because dense fibrosis has not yet occurred, the fascial layers are easily opened, the peritoneum and its contents are freely mobilized medially and cephalad, and the kidney and ureter are identified without much difficulty. A primary repair can often be performed, and in most cases, a repeat ureteroneocystostomy at a new site in the bladder is the best choice. Use of a mechanical retractor greatly simplifies exposure and allows excellent access to the pelvis.

If the repair has been delayed because of attempted endourologic management or because of delay in presentation or diagnosis, then access to the ureter and kidney can be much more challenging and hazardous. In these cases, mandatory preoperative preparation includes a review of the operative note, especially if the operation was performed by someone else. It is important to know whether the kidney to be operated on was the donor’s right or left kidney. It is critical to know the position of the ureter and renal pelvis in relation to the renal vessels (below or above), and this depends on which kidney was used and into which side of the recipient’s pelvis it was transplanted. Additional information to be sought includes the type of vascular anastomosis performed (end-to-end versus end-to-side, etc.) and whether or not the iliac vessels (especially the iliac vein) were mobilized. All of this information can help to determine the likely position of the kidney in relation to the transplanted and native ureter and the anticipated ease in gaining access to these structures.. Note that this depicts a donor right kidney on the right side, as the renal pelvis is posterior to the renal vessels.

In terms of the recipient, it is critical to know the status of the recipient’s urinary tract. This is especially true if the recipient had a history of ureteral reflux or had undergone nephroureterectomy and might not have a suitable native ureter available to use for repair. Finally, the status of the recipient’s urinary bladder in terms of capacity, compliance, and function can be important in determining which other repair options are available.

Additional preoperative preparation involves stabilization of the patient and function of the graft. It is important to delay any open operative repair until concurrent rejection episodes have been adequately treated and renal function stabilized. All patients should be treated with preoperative antibiotics based on anticipated contaminants or cultures obtained from the urine. If there is a likelihood that bowel might be needed (a very unusual circumstance) to repair the urinary tract, then a full bowel prep is indicated.

The goals of surgery are to repair the ureteral defect, reestablish continuity of the urinary system, get rid of all foreign bodies as quickly as possible, and avoid graft or patient loss. With a well-planned and executed procedure, these goals should be easily obtained in essentially all cases.

Delayed surgical repair because of attempted endourologic management, delayed diagnosis, or late presentation of obstruction makes surgical exposure of the kidney and ureter very challenging. As noted earlier, access is almost always achieved through the old transplant incision, and cephalad extension of the incision is often needed in these cases because of perinephric fibrosis, the increased size of the kidney posttransplant, and to achieve access to the iliac vessels and native ureter. It is usually possible to extend the incision several centimeters cephalad. Additional exposure, if needed, can also be obtained by extending the inferior aspect of the incision across the midline, though this is rarely needed and should be delayed until the need is present.

With delayed repair, the normal tissue planes are obliterated, and a dense fibrosis has occurred around the graft. This makes it very easy to violate the “renal capsule” and get into significant bleeding. As a routine, it is preferable to operate from a position of “known to unknown” with good exposure. The surgeon should also plan to gain vascular control proximally and distally if it appears that the kidney may need to be mobilized in order to permit access to the renal pelvis. A three-way Foley catheter should always be placed into the bladder before the start of the surgery to allow for irrigation and filling with an antibiotic solution.

In order to assure a safe and adequate exposure, I usually open the peritoneum early in cases where there is dense fibrosis. This allows better cephalad exposure, protects the bowel, and gives good access to the bladder.

Because the transplant ureter usually crosses the external iliac vessels below the renal vessels, one should take care to avoid these structures while gaining access to the ureter. This is a critical feature of this operative procedure because exact visualization of the renal vascular structures is often difficult, and many times one is operating based on the expected, not visualized, location of these structures. In some cases a percutaneous nephrostomy tube will be placed as well as a ureteral stent. If present, the nephrostomy tube should be accessible during a procedure as injection of saline or methylene blue may aid in identifying the ureter and renal pelvis. In some cases, because of the dense fibrosis, the ureter is identified only when it is actually cut. The routine placement of a ureteral stent is of limited value in most cases because the fibrosis is so dense, it is hard to discern the presence of the catheter. If the ureter is not in dense fibrosis, then access is usually easy.

Once access to the bony pelvis is obtained, careful dissection along the lateral wall of the bladder usually leads to the ureter. Once it is identified, care must be used in mobilizing the ureter to avoid any further vascular injury. When the site of leakage and/or obstruction has been identified, the most commonly used repairs include (a) a repeat ureteroneocystostomy, (b) use of the bladder (Boari flap or bladder hitch) to help bridge the gap, or (c) use of a native ureter to perform a ureteroureterostomy or ureteropyelostomy. Repeat ureteroneocystostomies are indicated only to repair early leaks when the problem was from tension at the anastomosis or distal ureteral ischemia and a well-vascularized minimally fibrosed ureter is present. In most circumstances, especially late, with a lot of periureteral reaction or ischemia, the preferred option is the use of the ipsilateral native ureter if it is present and of adequate caliber. If not, then a Boari flap is an excellent choice.

Access to the native ureter is obtained by identifying it as it crosses the common iliac vessels. Care must be used in mobilizing the ureter down into the pelvis to the level of the superior vesical artery to avoid injury to the ureter blood supply. The ureter is divided well above the iliac vessels, and the proximal end of the ureter is doubly ligated. In our experience of over 30 cases, this has not resulted in problems with the native kidney or ureter requiring any further intervention. The operative positioning of the native ureter depends on access to the transplant ureter and/or pelvis. In addition, whether a side-to-side ureteral anastomosis or a ureteropyelostomy is to be performed may make a difference to the exact positioning of the native ureter. All of these factors relate to the extent of fibrosis and the appearance of the transplant ureter. To prevent any additional future problem, a tension-free, widely spatulated anastomosis of well-vascularized ureter to either transplant ureter or renal pelvis is critical. The anastomosis is performed using 5-0 Maxon (Davis and Geck, Danbury, CT) or Polydioxanone (PDS, Ethicon, Somerville, NJ) in a watertight single layer. The critical aspect is to obtain a mucosa-to-mucosa approximation avoiding tension, devascularization, and urinary leak. A 12-cm 4.7 double-J stent is routinely used on all anastomoses. The anastomosis may be additionally wrapped in omentum or peritoneal flap, if available, to decrease further the risk of leak. The wound is well irrigated with antibiotic solution, and if no preoperative infection was present, we close the wound without a drain. If there is concern about urinary leak, lymphatic leak, or possible infection, one or two Jackson Pratt drains are indicated. The fascia is closed in layers with a 0 or #1 permanent monofilament suture. The subcutaneous tissue is not closed. The skin is usually closed with staples. A nephrostomy tube, if present, is removed at day 5 to 7 after an antegrade nephrostogram has been obtained to be sure that there is no leak. The ureteral catheter is left in for 4 to 6 weeks.

OUTCOMES


Complications

Complications that can occur postprocedure include infection, urinary leak, bleeding, recurrence of the stricture, and possible loss of graft. In all series, these are very uncommon complications.

Results

We have performed over 30 native-to-transplant ureteroureterostomies or ureteropyelostomies to treat ureteral obstruction or ureteral leaks or to deal with damaged ureters at the time of the transplant. In our experience, all kidneys involved have been “salvaged,” and none lost to urologic complications. There have been no significant postoperative complications and no patient deaths. We have not had to repeat any procedures in any of the patients we have treated and have not had any recurrence of either leak or stricture. As noted earlier, we routinely tie off the proximal native ureter, do not do a nephrectomy, and have not had any problems related to the native kidney. We feel that routine native nephrectomy is not indicated, and if one is ever subsequently indicated, a laparoscopic nephrectomy would be our choice.

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