19.10 Long-Term Outcomes

–Bladder dysfunction with poor compliance

–Elevated leak point pressures

–The need for clean intermittent catheterization

•Vesicoureteral reflux:

–Vesicoureteral reflux is commonly associated with PUVs and is present in as many as one third of patients.

–Vesicoureteral reflux is generally secondary to elevated intravesical pressures.

–Therefore, the treatment of vesicoureteral reflux in patients with PUVs involves treatment of intravesical pressures using:

•Anticholinergics

•Timed voiding

•Double voiding

•Clean intermittent catheterization

•Bladder augmentation

•Urinary tract infections:

–Recurrent UTIs are common in patients with PUV.

–This is predisposed to by several factors:

•Elevated intravesical pressures predispose these patients to infection, possibly by altering urothelial blood flow.

•Elevated post void residual urine volumes, leading to stasis of urine.

•Dilated upper urinary tracts, with or without vesicoureteral reflux.

–The management and prevention of UTIs include:

•Lowering bladder pressures by anticholinergic medications

•Lowering post void residual urine volume via clean intermittent catheterization

•Administering prophylactic antibiotics

•Urinary incontinence:

–It is important to follow these patients with urodynamic studies.

–To improve urinary continence, it is important to:

•Lower bladder pressure

•Improve bladder compliance

•Minimize post void residual urine volume

•In some, bladder augmentation may be needed

•Over the last 30 years, the prognosis of children with PUV has steadily improved.

•Today, the mortality of patients with PUVs is less than 3 %. This is attributed to several factors including:

–Early prenatal diagnosis

–Prompt resolution of bladder obstruction

–Aggressive treatment of bladder dysfunction

–Improved surgical techniques

–Improved dialysis and transplantation techniques

•Approximately one third of patients with PUVs progress to renal insufficiency in their lifetimes.

•An interesting group of patients are those with vesicoureteral reflux dysplasia (VURD) syndrome.

–In these patients, one kidney is hydronephrotic, nonfunctioning, and has highgrade vesicoureteral reflux.

–The high-grade reflux is thought to act as a pop-off valve, leading to reduced overall bladder pressures and preservation of contralateral renal function.

–In the past, these patients were thought to have a better outcome due to preserved renal function in one kidney at the sacrifice of the other.

–These patients however, may suffer longterm adverse renal function with hypertension, proteinuria, and renal failure.

19.10 Long-Term Outcomes

•The presence of bladder outflow obstruction as a result of PUV will result in an increase in the intravesical pressure.

•This raised intraluminal pressure will be transmitted to the developing kidney leading to:

–Renal parenchymal apoptosis

–Abnormal cellular differentiation

–Glomerular changes

•The extent of these early changes will determine the renal function in later life.

•The degree of obstruction is important in this regard.

•In cases where the obstruction is less severe or declares itself later in pregnancy, the effects of obstruction tend to be more on the bladder and

renal effects are limited to dilatation of the collecting system with minimal disruption of normal nephrogenesis.

•An alternative theory propose that renal dysplasia seen in conjunction with posterior urethral valves is secondary to abnormal position of the ureteric bud and implantation into the metanephric blastema.

•Renal dysfunction seen in patients with posterior urethral valve appears to be the result of varying degrees of inherent dysplasia and the effects of bladder outflow obstruction.

•In post-natal life these changes can be further exaggerated by:

–Urinary tract infections

–VUR

–Bladder dysfunction

•A significant loss of nephrons will lead to hyperfiltration of existing functional nephrons as a result of vasodilatation of the afferent arterioles (glomerular capillary hypertension).

•This compensatory mechanism will decompensates over time.

•The end result is:

–Glomerulosclerosis

–Proteinuria

–Hypertension

–Reduced glomerular filtration rate

–Damage to the distal nephron impairs the concentrating ability of the kidney resulting in polyuria and polydipsia (nephrogenic diabetes insipidus)

–End stage renal failure

19.10.1 Vesico-ureteric Reflux

•At presentation, approximately 50 % of patients with PUV have vesico-ureteric reflux (VUR) on the initial MCUG.

•VUR in these patients is secondary to the bladder outflow obstruction and co-existent bladder dysfunction.

•Approximately 15 % of patients with PUV will have unilateral high grade VUR with ipsilateral non-functioning kidney.

•Following valve ablation the severity of VUR may decrease or resolve completely in

25–50 % of cases, and this improvement is more likely in those presenting as neonates or during infancy.

•Persistent VUR, especially high grade and bilateral, after successful valve ablation is associated with poor long-term renal outcome.

•Anti-reflux procedures in boys with PUV is no longer recommended as this is associated with a high failure rate.

•Patients with high grade VUR and poor function of the ipsilateral kidney are treated with nephrectomy of the non-functioning ipsilateral kidney and bladder augmentation using the dilated ureter.

•A refluxing ureterostomy as a form of urinary diversion can be used also.

•The distal ureter has been used as a Mitrofanoff channel with or without an associated antireflux procedure.

•Persistent high grade VUR are treated surgically prior to renal transplant. These are known to be risk factor for recurrent urinary tract infection which has a negative impact on a transplanted kidney.

19.10.2 Hydro-ureteronephrosis

•The majority of neonates presenting with posterior urethral valves will have bilateral hydro-ureteronephrosis.

•Some of these cases will worsen as a result of functional obstruction at the level of uretro-vesical junction which usually resolves within 48–72 h. This is attributed to the thickened trabeculated bladder wall that collapses, pinching off the ureteric orifices following decompression of the urinary bladder. The obstruction is usually followed by post-obstructive diuresis and do not require internal JJ stenting or placement of nephrostomies.

•Other cases of hydro-ureteronephrosis may improve following catheterization.

•Ureteric re-implantation with or without tapering is no longer performed in cases of hydro-ureteronephrosis secondary to PUV.

19.10.3 Bladder Dysfunction

•The importance of bladder dysfunction and its impact outcome on both urinary continence and renal function in boys with posterior urethral valves was recognized.

•This is secondary to in-utero changes in response to outflow obstruction and/or the result of urinary diversion.

•Others believe that urinary diversion does not adversely affect the bladder function but may improve it.

•The ‘valve bladder syndrome’:

–This was introduced to encompass several features seen in patients with PUV and include:

•The abnormal voiding patterns and symptoms of voiding dysfunction

•The persistent thick walled bladder

•Incomplete bladder emptying

•Associated upper urinary tract dilatation

–Three dominant urodynamic patterns were found in these patients:

•The hyper-reflexic bladder

•The hypo-compliant bladder

•The acontractile bladder

•Overlap between these patterns may be seen

•Urodynamic abnormalities were observed in 80 % of the overall patient group with PUVs.

•Bladder dysfunction is an important key to long term renal function outcomes.

•Bladder instability and poor compliance correlate with a poor renal functional outcome.

•It was shown that patients with the following features are more likely to progress to end stage renal disease:

–Severe bladder dysfunction, defined as low compliance with end filling pressure >40 cm of H2O

–Post-void residual volume >30 %

–Underactive detrusor

–Patients in need for clean intermittent catheterization (CIC)

19.10.4 Renal Transplantation

•A significant number of boys with PUV progress to end-stage renal failure.

•These patients will need renal transplantation.

•Urinary bladder assessment is an important part of the pre-transplant work-up of these patients.

•A high pressure, poorly compliant, low bladder capacity may risk the transplanted kidney with the possibility of graft loss.

•These patients are managed with bladder augmentation which can be performed prior to or after renal transplantation.

–Bladder augmentation cystoplasty with/ without a catheterisable conduit performed prior to renal transplant allows postoperative healing without immunosuppression but risks a ‘dry cystoplasty’ which must be managed by bladder cycling and lavages.

–Bladder augmentation cystoplasty can be performed after renal transplantation and in these, it is important that immunosuppression requirements have been stabilized and the improved renal function offers clear advantages. The transplanted ureter may be reimplanted into the native bladder or brought out as a cutaneous ureterostomy.

–The 5 year renal graft survival rates in the PUV have improved over the last two decades from 40 % in the 1980s to near 70 % in the 1990s.

19.10.5 Fertility

•The following factors influence the efficacy of ejaculation in patients with posterior urethral valves:

–Persisting dilatation of the posterior urethra

–Damage to tissues around the verumontanum

–Secondary urethral strictures resulting from previous surgery

•Erectile dysfunction is seen more commonly in patients with chronic kidney disease and those on dialysis.

•The majority of these patients however, will have a semen analysis that is considered within the normal range.