Urinary leaks generally present early after transplantation however can present after removal of a ureteral stent or later occasionally. Leaks are the most common ureteral complication occurring in up to 1% to 5% of transplants (4,5). Presenting signs and symptoms include urine leaking from wound, increased surgical drain output (fluid creatinine levels twofold serum creatinine levels indicates urine), decreased urine output (in patients anuric prior to transplantation), pelvic fluid collections, pain, or unexplained graft dysfunction. Suspicion of a urinary leak should be promptly evaluated. If the diagnosis is obvious, then further testing may be unnecessary. Imaging studies such as abdominal/transplant renal ultrasound or nuclear renogram may aid in the diagnosis. A renal scan demonstrating extravasation is the most sensitive imaging to differentiate a urine leak from other fluid collections such as lymphoceles or hematomas. Differentiating fluid collections as a urine leak from a lymphocele or hematoma is critical because their management is very different. Occasionally, fine needle aspiration and laboratory analysis of a fluid sample may be needed to confirm a urine leak. Voiding cystourethrogram or cystogram may help delineate bladder leaks however are limited in demonstrating leaks at the ureteroneocystostomy site where urine leaks most commonly occur following transplantation. Proximal leaks occur in the ureteropelvicalyceal system when there is concurrent obstruction or infarction. Leakage may also result from injury during recovery, transplantation, or renal biopsy. Bladder leaks are rare because contemporary surgical techniques almost exclusively perform extravesical ureteroneocystostomies. Of note, if a urine leak is detected in the first 4 days following transplant, the cause is most likely technical with the reimplantation. If a leak develops 5 to 10 days posttransplant, the cause is often necrosis from poor ureteral blood supply.

Ureteral obstruction typically presents as graft dysfunction. This ureteral complication occurs in 1% to 3% of all transplants (4,5). Patients might develop signs and symptoms around the time of surgery or many years after transplantation. The onset can be sudden or gradual depending on the underlying etiologies (Table 1). Commonly, the onset is gradual and asymptomatic with steadily increasing serum creatinine levels prompting an ultrasound or computerized tomography scan demonstrating hydronephrosis. Pain is rare unless the obstruction is sudden. Again, prompt diagnosis is mandatory in order to undertake the appropriate management. Urinary retention and ureteral reflux must be excluded. A full bladder encountered on examination or imaging warrants decompression with a Foley catheter and careful assessment of postvoiding residuals and serum creatinine monitoring to exclude urinary retention. In some cases of ureteral obstruction, hydronephrosis is minimal. A diuretic nuclear renogram may be useful to reveal ureteral obstruction. When hydronephrosis is present, we prefer to proceed directly to immediate placement of a nephrostomy tube if obstruction is diagnosed. This provides the most definitive diagnosis and allows for relief of the obstruction in a timely manner. Antegrade nephrostogram can more accurately determine the location of obstruction.

Vesicoureteral reflux (VUR) of urine is common and seen in up to 79% of transplanted kidneys (6). Development of febrile urinary tract illness by reflux of infected urine into the allograft kidney eventually leads to scarring and potential graft loss particularly in pediatric patients (7,8). VUR can be clinically silent; however, worrisome presentation would be in the setting of allograft pyelonephritis (fever, chills, graft tenderness with or without dysfunction along with pyuria, and positive urine cultures). Diagnosis of VUR usually depends on
identifying reflux on voiding cystourethrogram. In particular, underlying bladder and voiding dysfunction should be carefully evaluated and addressed. Treatment of any infection should be completed prior to any surgical reconstruction of the refluxing ureter.