Predicting the Need for CIC and Its Effect on Renal Replacement Therapy in Posterior Urethral Valves
By: Daryl McLeod, MD; Brian VanderBrink, MD | Posted on: 01 Jun 2021
Posterior urethral valves (PUVs) are a leading cause of pediatric end-stage kidney disease (ESKD) and renal transplantation in children. The eventual fate of the kidneys is a cumulative result of a multitude of factors, which include decreased nephron mass at birth, lower urinary tract dysfunction (LUTD) and recurrent infection. A proposed serum surrogate of nephron mass for young PUV patients is the serum nadir creatinine in the first year of life (SNC1).1,2 In a multicenter cohort of early diagnosis and treatment of PUV, all boys with a SNC1 ≥1 mg/dl required renal replacement therapy (RRT) by 8 years of age, while no child with a SNC1 <0.4 mg/dl progressed to RRT with median age at followup of 6 years.2 This was in sharp contrast to the variable course of kidney disease progression in those children with SNC1 0.4–0.99 mg/dl. Accordingly, in patients with PUV in the SNC1 range of 0.4–0.99 mg/dl, there may exist greater potential to modify disease course and prevent or delay a tenuous kidney homeostasis from progressing.
LUTD is prevalent in PUV.3 Typical bladder patterns in pediatric PUV patients range from a decreased compliance with detrusor overactivity in infancy to a high capacity and poorly emptying bladder in adolescence. This phenomenon has been described as the valve bladder.4 Multiple strategies to combat this LUTD in PUV patients have been utilized ranging from timed and double voiding to pharmacotherapies such as antimuscarinics and/or alpha blockers. Implementation of clean intermittent catheterization (CIC) with or without nighttime bladder emptying (NBE) is also often initiated due to concerns for significant LUTD and/or polyuria, with the goal of preserving bladder and kidney function.4,5 Furthermore, introduction of CIC may provide urinary continence in these children, which can have psychosocial benefit. Evidence suggests that both CIC and NBE are feasible and have potential benefit in patients with PUV. Introduction of catheterization of any type in patients with PUV, especially in older children, can be challenging given their sensate urethra. CIC introduced early can circumvent this issue, as can a surgically created abdominal catheterizable channel (ie Mitrofanoff).6
The ESKD observed in PUV patients is due to a combination of unmodifiable factors such as renal hypoplasia/dysplasia and potentially modifiable factors such as urinary tract infection and LUTD. While numerous retrospective studies have shown that CIC can ameliorate LUTD, there exists conflicting evidence demonstrating that CIC unequivocally delays chronic kidney disease (CKD) progression or ESKD incidence.5 These mixed results may in part be due to patient selection where CIC is preferentially implemented in children with more severe disease who are less likely to show kidney benefit from the intervention. This highlights the importance of individualized treatment plans based on risk stratification.
Determining which child would ultimately benefit from initiation of CIC or NBE as a method to impede progression of CKD is a particularly challenging aspect of PUV management. Holmdahl proposed, and we agree, the easiest age to start CIC is during year 1 when there is less expectation of pain or fear of catheterization.5 However, variability exists between providers across the management spectrum of PUV, including indications to initiate CIC or NBE. On an internal audit of provider practice patterns within our Pediatric Urology Midwest Alliance we found initiation of bladder drainage ranged from 5% to 54% depending on institution. This variation in provider practice, even among academic pediatric urologists within a similar geographic region highlights a significant barrier in retrospective outcomes data. This exemplifies the importance of standardized management and prospective data collection so that care and subsequently outcomes can be optimized.
Unfortunately, with reviewing current retrospective data, it is difficult to definitively comment on the potential impact on kidney outcomes from starting CIC in the pediatric patient with PUV. Acknowledging the high risk of progression to ESKD in the PUV population, all avenues of potential disease mitigation must continue to be explored. Optimization of LUTD in these high risk children is worthwhile as any ability to delay, or perhaps prevent altogether, the need for RRT can be of immeasurable clinical benefit.
- Merguerian PA, McLorie GA, Churchill BM et al: Radiographic and serologic correlates of azotemia in patients with posterior urethral valves. J Urol 1992; 148: 1499.
- McLeod DJ, Szymanski KM, Gong E et al: Renal replacement therapy and intermittent catheterization risk in posterior urethral valves. Pediatrics 2019; 143: e20182656.
- Holmdahl G, Sillén U, Hanson E et al: Bladder dysfunction in boys with posterior urethral valves before and after puberty. J Urol 1996; 155: 694.
- Koff SA, Mutabagani KH and Jayanthi VR: The valve bladder syndrome: pathophysiology and treatment with nocturnal bladder emptying. J Urol 2002; 167: 291.
- Holmdahl G, Sillén U, Hellström A-L et al: Does treatment with clean intermittent catheterization in boys with posterior urethral valves affect bladder and renal function? J Urol 2003; 170: 1681.
- King T, Coleman R and Parashar K: Mitrofanoff for valve bladder syndrome: effect on urinary tract and renal function. J Urol, suppl., 2014; 191: 1517.