In children and adolescents, 20–30% of end stage renal disease (ESRD) is caused by urological disease, leading to challenging management dilemmas. Posterior urethral valves (PUV), prune-belly syndrome and neurogenic bladder are common causes of lower urinary tract dysfunction (LUTD) leading to ESRD, whereas vesicoureteral reflux (VUR) is a less common etiology.¹ Renal transplantation (RT) is the preferred treatment modality for ESRD in the pediatric population;² however, there is a concern that in patients with ESRD due to LUTD, RT would lead to less patient and graft survival.¹ Recent series have attempted to answer the question of whether pediatric kidney graft survival is worse for children with LUTD compared to nonurological (NU) patients.^1–3 It is becoming clearer that durable RT outcomes can be achieved in patients with LUTD, as long as the bladder dysfunction has been treated before RT and meticulously monitored afterwards.

Evaluation of bladder dysfunction is paramount in children with LUTD prior to RT. Many of these patients, especially those with PUV or neurogenic bladder, have a hostile bladder with low compliance, high bladder pressures and elevated post-void residuals, which can put the allograft in danger. Urologists should employ familiar imaging and pressure-flow studies to identify bladder dysfunction and direct treatment. Pre-RT evaluation should at least include a renal/bladder ultrasound and, if the child is toilet trained, uroflowmetry. Urodynamics should be included for patients with PUV, neurogenic bladder, hydronephrosis, VUR or recurrent UTI.

There are many effective, routine management options that can be employed after workup. Anticholinergics should be administered for patients with a high pressure, low compliance bladder. In children with an elevated post-void residual, clean intermittent catheterization via the native urethra or a continent catheterizable channel should be considered before RT. If a hostile bladder does not respond to nonoperative modalities, augmentation cystoplasty (ACP) should be considered. The proper timing to perform ACP is still up for debate. Some experts believe that any reconstructive surgery should be done before RT to avoid any direct damage from the low-capacity dysfunctional bladder to the graft.⁴ On the contrary, Jesus and Pippi Salle, after a literature review of RT patients with PUV, concluded that preemptive ACP should only be performed if the risk of increased bladder pressure to the graft exceeds the risks, notably recurrent UTI, associated with ACP.³ They also suggest that ACP is feasible after RT in the PUV population if needed, since many of these patients develop myogenic failure and therefore do not need ACP.

Figure. Grade 4 vesicoureteral reflux into transplant ureter of an adolescent with recurrent febrile UTIs who ultimately required a nonrefluxing extravesicular reimplant.

Recent data have shown equivalent RT outcomes in pediatric patients with LUTD compared to NU patients. Fine and colleagues compared RT in boys with a history of PUV to NU boys and found that those with PUV do not have a higher graft failure rate.⁵ We recently reported our experience, finding that children requiring RT due to urological causes had no disadvantage in graft survival compared to children with ESRD of NU causes.² In our cohort we found an association between post-transplantation UTI and graft loss, which has also been shown by other groups, highlighting the morbidity of febrile UTI after RT to both graft function and the patient.^2,6 Bagga and colleagues evaluated trends in RT using a transplant registry and found that for patients with congenital urinary tract disorders, better management has lead to a delay in time to RT, which actually translated into improved RT graft and patient survival.⁷

Several urological considerations should be taken into account during RT surgery in the pediatric population. Since kidney graft hydronephrosis is common, a nonrefluxing extravesicular reimplant into the native bladder is preferred when feasible. If the bladder is too small or thick-walled to safely implant the ureter, a uretero-ureterostomy with the native ureter is an excellent option in the absence of VUR. Managing the graft ureter in the urologically complex child is an excellent opportunity for collaboration between pediatric urologists and the transplant team.

Despite these techniques, post-transplant hydronephrosis may occur in up to 50% of patients after RT, and lead to an increased risk of pyelonephritis and worsening graft function.⁸ Any patient with graft hydronephrosis should be promptly evaluated with both urodynamics and VCUG to identify if high bladder pressure or VUR are contributing. In patients with concomitant bladder dysfunction and VUR, the bladder should be addressed first as this may resolve the VUR.

Isolated transplanted kidney VUR can be difficult to treat, although fortunately most patients are asymptomatic.⁶ In the absence of UTI, low grade VUR can be observed with antibiotic prophylaxis. Higher grade VUR and/or breakthrough UTI will require surgical correction to prevent pyelonephritis and graft damage (see figure). Unfortunately, endoscopic management of post-RT VUR only has a 26% success rate and should be used sparingly.⁹ Nonrefluxing extravesicular ureteroneocystotomy is preferred, with uretero-ureterostomy to a native ureter without VUR as another option.

Another controversy in RT is whether or not to perform native nephrectomy, and when it should be done. Ideally, the native kidneys should remain in situ unless there is significant proteinuria, uncontrollable hypertension, recurrent UTI with or without VUR, severe polyuria and kidney stones.¹⁰ If native nephrectomy is necessary, it should be performed before or at the time of RT, especially if there is concern that leaving the native renal units will exacerbate the LUTD and risk graft survival. Another option is to perform ureteral ligation at the time of RT instead of native nephrectomy, which would leave the native ureter for future reconstruction if needed.¹⁰

Although historically RT in patients with ESRD from LUTD seemed dangerous, we have learned that RT outcomes are similar to those with NU ESRD when bladder dysfunction is properly managed prior to transplantation and monitored afterwards. In the urologically complex child, the pediatric urologist should collaborate with the transplant team prior to and after transplantation to help ensure long-term graft survival.