Ureteral Leak

Ureteral leaks are reported in 1% to 3% of renal transplants. The two most common causes are surgical error and ureteral ischemia with resultant necrosis. Technical errors include misplacement of ureteral sutures, unrecognized ureteral transection or renal pelvis laceration, and insufficient ureteral length that places tension on the anastomosis. Other rare causes of urine leaks include outflow obstruction (as caused by a blocked Foley catheter or urinary retention) with disruption of the ureterovesical anastomosis, acute ureteral obstruction with perforation through a renal calyx, and extrusion of a ureteral stent. Leaks resulting from technical errors often occur within the first 24 hours, whereas leaks resulting from ischemia and necrosis usually occur within the first 14 days. However, kidneys with delayed graft function may not have an evident leak until suitable diuresis ensues.

Preservation of periureteral tissue is essential, especially in living donors procured laparoscopically. Whereas the early experience with laparoscopic donor nephrectomy was associated with high rates of urinary leaks, improvements in surgical techniques have led to a decline in the rate to be almost as good as open donors. A ureter that appears compromised at the time of surgery or fails to become pink and bleed after reperfusion should be cut as proximally as necessary to reach well-perfused tissue. This may necessitate an alternative technique to achieve urinary continuity, either by anastomosis to the ipsilateral native ureter or by an extension technique of the bladder, such as a psoas hitch or Boari flap (see later).

The clinical presentation of ureteral leaks can be obvious or subtle. The clearest clinical scenario is a patient with excellent recovery of renal function whose urine output suddenly decreases or stops completely, associated with drainage of fluid through the wound or increased drain output. More often, however, confounding factors, including high urine output produced by the native kidneys, delayed graft function that may limit urine output, and a preexisting lymphocele or seroma make the presentation more subtle. Urine leak should be part of the differential diagnosis in the early posttransplant period whenever there is poor urine output, a new fluid collection, new wound drainage, or delayed graft function. Any new fluid drainage or aspirated fluid collection should be sent for creatinine measurement, and the value should be compared with serum. Several imaging studies may be diagnostic. A ^99m Tc-MAG-3 renogram may show tracer outside the anatomic confines of the urinary tract but can be indeterminate, a cystogram may show the leak, particularly if it is located at the ureterovesical junction, and an ultrasound or computed tomography (CT) scan may show a fluid collection, but not its source. For more precise diagnosis and localization of a urinary leak, single-photon emission CT (SPECT)/CT fusion imaging can be performed ( Fig. 29.2 ).

(A, B) Fusion single-photon emission computed tomography SPECT/CT images demonstrating a urine leak ( arrows ) outside confines of the urinary bladder.

Management of a ureteral leak can be endoscopic or operative. In a patient with an indwelling ureteral stent and no Foley catheter, replacing the catheter often resolves the leak, unless the entire distal ureter is necrotic. If this is effective, the catheter should remain in place for at least 2 weeks, followed by a confirmatory cystogram before catheter removal. If no ureteral stent was placed, treatment modalities include stenting or immediate surgical exploration. Placement of a retrograde stent in a transplant ureter can be technically challenging because of the ectopic position of the ureteric orifice and lack of periureteral supports. Furthermore, percutaneous nephrostomy with antegrade stent placement can be challenging because of the lack of hydronephrosis with urine leaks. In the case of ureteral necrosis, it is preferable to explore and repair these leaks early.

Multiple surgical approaches exist to repair a ureteral leak depending on the location and extent of ureteral necrosis. Regardless of the technique, we prefer to use a three-way Foley catheter connected to irrigation that can intermittently fill and empty the bladder to identify the leak better. If the ureter is well perfused and a leak at the ureterovesical junction is the result of a technical problem with the anastomosis, the leak can be repaired by placing additional interrupted sutures. If the distal portion of the ureter is necrotic, it should be resected back to healthy tissue. If the ureteral loss is minor, a simple reimplant of the transplant ureter is sufficient. Because a urine leak often results in local inflammation and tissue edema, all ureteral repairs or reimplantations should be performed over a stent.

If a tension-free anastomosis cannot be achieved because of limited ureteral length, several options are available ( Table 29.1 ). With a psoas hitch, the bladder is brought closer to the ureter by mobilizing its attachments, in particular, by severing the contralateral obliterated umbilical artery. The bladder is incised transversely and reconfigured by closing the bladder incision in line with the ureter, displacing the bladder toward the transplant ureter ( Fig. 29.3 ). The bladder, now elongated in the direction of the ureter, is fixed to the ipsilateral psoas muscle to allow a tension-free ureteral reimplant. This technique, however, may not provide sufficient length in a small bladder, as is found in long-standing oliguric patients. Alternatively, or in addition to the psoas hitch, a Boari flap of bladder can be created to bridge the gap for an anastomosis either to the transplant ureter or to the transplant renal pelvis ( Fig. 29.4 ).

A psoas hitch can provide 5 cm of additional length. The contralateral peritoneal bladder attachments are divided to bring the bladder closer to the ureter. The bladder is incised transversely, and the ureter is reimplanted with a submucosal tunnel superolateral to the dome of the bladder. The bladder is then tacked down to the fascia of the ipsilateral psoas muscle. A double-J ureteral stent is placed, and the bladder is closed in two layers.

A Boari flap can provide 10 to 15 cm of additional length. The bladder is mobilized as in the psoas hitch. A full-thickness U-shaped bladder flap is created. The length of the flap varies depending on the length of the gap that needs to be bridged. To assure adequate blood supply, the base of the flap should be at least 2 cm greater than the apex, and the width of the flap should be three to four times the diameter of the ureter. The ureter is then anastomosed with a submucosal tunnel or in an end-to-end fashion with the flap. A double-J ureteral stent is placed, and the bladder flap is closed in two layers. For a tension-free anastomosis, the tip of the flap can be secured to the ipsilateral psoas muscle.

Because a Boari flap reduces the total bladder volume, its use may be inappropriate in the atrophied bladder of a previously anuric patient. The preferred technique here is to anastomose the ipsilateral ureter, if present, to either the transplant ureter or the allograft renal pelvis ( Fig. 29.5 ). Typically, the proximal native ureter can be tied off without the need for ipsilateral native nephrectomy. The advantages of this technique include excellent ureteral blood supply, a large segment of native ureter that can be repositioned without tension, and no compromise of bladder volume. If native urothelium is unavailable, an ileal ureter can bridge the bladder and transplant renal pelvis (see Chapters 11 and 12).

Repair of transplant ureteral necrosis by ureteroureterostomy. (A) Distal ureteral necrosis. Note the distal ureter, proximal ureter, and accumulation of urine in the wound. (B) After repair. The native ureter was transected and rotated to the proximal transplant ureter. The anastomosis was made end-to-end over a double-J stent using 5-0 PDS suture. The proximal native ureter was tied off without native nephrectomy.

Ureteral Stenosis

Stenosis of the transplant ureter occurs in approximately 3% of transplant recipients. The obstruction can be extraluminal (compression from a lymphocele or spermatic cord), intrinsic (ureteral ischemia), or intraluminal (renal stone, fungal ball, sloughed renal papilla, or foreign body). Ureteral stenosis may occur months or years after an otherwise successful transplant. Risk factors for late ureteral stenosis include advanced donor age, delayed graft function, and kidneys with more than two arteries. Human polyomavirus (BK virus) can also lead to ureteral stenosis due to ureteritis. Although ureteral stenting at the time of transplant reduces the incidence of early stenosis, it has no effect on the rate of late ureteral stenosis.

The clinical presentation of ureteral stenosis can vary according to its location, degree, and speed of onset. Most commonly, ureteral stenosis is gradual and asymptomatic, with an unexplained increase in serum creatinine and the discovery of hydronephrosis on ultrasound. Pain over the allograft is rare, unless the obstruction is sudden and high-grade. Hydronephrosis is not always synonymous with obstruction, however. Dilation of the renal pelvis and calices can occur without obstruction in the setting of prior obstruction (e.g., long-standing ureteropelvic junction obstruction in the donor), reflux, or loss of renal cortex parenchyma, such as in chronic allograft nephropathy. Patients with new-onset hydronephrosis should also be screened for urinary retention by checking a postvoid residual volume.

After discovering hydronephrosis, two further confirmatory tests include a diuretic ^99m Tc-MAG-3 renogram or a percutaneous antegrade nephrostogram ( Fig. 29.6 ). A diuretic renogram suggests obstruction if the clearance curve shows pelvicaliceal hold-up, especially after diuretic administration. False-negative results can occur in patients with poor renal function, and false-positive results can occur with bladder outlet obstruction or vesicoureteral reflux. Antegrade pyelography is the preferred test when obstruction is strongly suspected. A hydronephrotic transplant kidney is easily accessible with a small spinal needle to inject contrast medium. If obstruction is confirmed, the needle can be converted to a nephrostomy tube over a wire, and antegrade stenting can be performed immediately or after the renal function and ureteral edema improve.

Antegrade nephrostogram in a transplanted kidney showing an obstructed distal ureter.

Endoscopic management of transplant ureteral strictures is preferable to surgery, which can be difficult when done months or years after the original transplant surgery. The stricture can be accessed in an antegrade or retrograde fashion. If a stent does not pass easily over a wire, the stricture can be balloon-dilated or an endoureterotomy can be performed with a laser or a cutting balloon. The endoscopic approach is successful in about 50% to 65% of cases; however, recurrent strictures may result from inadequate primary therapy or failure because of extensive ischemia. Although patients with recurrent strictures can be managed with long-term indwelling ureteral stents, recurrent strictures are best treated with an open approach. When the site of obstruction is identified and the diseased segment of the ureter is excised, the operative approach is similar to that for a ureteral leak (e.g., psoas hitch, Boari flap, ureteropyelostomy, pyelocystostomy, or ileal ureter). Successful treatment of transplant ureteral stenosis is critical, because long-term graft survival is improved.