Post-Fulguration Outcomes of Upper Urinary Tract Dilatation in Children with Posterior Urethral Valves: A Prospective Analytical Evaluation

Posterior urethral valves (PUV) represent the most common cause of congenital lower urinary tract obstruction in male children and remain a major contributor to long-term renal morbidity. The obstruction caused by abnormal membranous folds in the posterior urethra leads to increased intravesical pressures, secondary bladder dysfunction, vesicoureteral reflux (VUR), hydronephrosis, and progressive upper urinary tract dilatation. Early diagnosis and timely fulguration of valves are essential to relieve obstruction and preserve renal function; however, upper urinary tract dilatation may persist, regress, or worsen even after technically successful valve ablation. This variability underscores a complex interplay between bladder function, severity of initial obstruction, renal dysplasia, associated reflux, and timing of intervention.

Antenatal ultrasonography has improved the early detection of urinary tract dilation, but only a small proportion of PUV cases are identified prenatally. Postnatally, children may present with poor urinary stream, recurrent urinary tract infections, failure to thrive, or renal insufficiency. After confirmation by voiding cystourethrogram (VCUG), primary valve fulguration remains the standard of care. Although relief of obstruction typically improves urinary drainage, the structural and functional recovery of the upper urinary tract is not uniform. Persistent hydronephrosis or hydroureter may indicate inadequate valve ablation, persistent bladder dysfunction (“valve bladder syndrome”), ongoing VUR, or irreversible renal dysplasia

Several studies have highlighted that renal outcomes in PUV depend not only on surgical adequacy but also on the degree of renal dysplasia, nadir serum creatinine, presence of VUR, bladder compliance, and detrusor overactivity. et al.(20)[1] described the anatomical basis and spectrum of upper tract changes in obstructive uropathy, emphasizing the importance of early decompression. et al.(20)[2] highlighted “valve bladder syndrome,” wherein persistent bladder dysfunction after fulguration contributes to continued upper tract deterioration. et al.(20)[3] demonstrated that long-term renal dysfunction is common in PUV patients, particularly in those with severe preoperative obstruction. et al.(20)[4] identified prognostic indicators linked to persistent upper tract dilation, including high-grade VUR and impaired bladder dynamics. Further, et al.(20)[5] showed that ultrasonographic monitoring of hydronephrosis can predict renal outcomes following valve ablation.

Aim

To evaluate post-fulguration outcomes of upper urinary tract dilatation in children with posterior urethral valves.

Objectives

To compare pre- and post-fulguration ultrasonographic changes in renal pelvis and ureteric dilatation.

1.        To identify etiological factors associated with persistent or worsening upper urinary tract dilatation after valve ablation.

2.     To assess the role and effectiveness of adjuvant therapies and additional interventions in improving upper tract outcomes.

Table 1: Baseline Profile and Overall Post-Fulguration Outcomes (N = 100)

Table 1 presents the baseline characteristics and overall post-fulguration outcomes among the 100 children included in the study. The mean age at fulguration was 2.10 ± 2.30 years, which did not significantly differ from the reference value of 2 years (t = 0.43, p = 0.668), and the mean duration since the last fulguration was 18.70 ± 6.20 months, also showing no statistical deviation from the expected 18-month interval (t = 1.13, p = 0.262). At the 24-month follow-up, 73% of children demonstrated improvement in upper urinary tract dilatation, which was significantly higher than the 50% reference proportion (z = 4.60, 95% CI: 64.3%-81.7%, p < 0.001). Among specific outcome categories, complete resolution occurred in 39% and partial improvement in 34% of children, while persistent significant dilatation and worsening were observed in 18% and 9%, respectively. Analysis of renal pelvis dimensions showed a significant reduction in the pooled anteroposterior (AP) diameter, declining from 17.9 ± 9.4 mm at baseline to 14.9 ± 7.1 mm at 24 months. The mean difference of -3.0 mm was statistically significant (t = -4.84, 95% CI: -4.23 to -1.77, p < 0.001).

Table 2: Comparison of Pre- and Post-Fulguration Ultrasonographic Changes (N = 100)

Table 2 compares pre- and post-fulguration ultrasonographic changes over a 12-month period. The mean right renal pelvis AP diameter significantly reduced from 18.1 ± 9.3 mm at baseline to 14.5 ± 7.0 mm at 12 months, with a mean change of -3.6 mm (t = -5.20, 95% CI: -4.9 to -2.3, p < 0.001). Similarly, the left renal pelvis AP diameter decreased from 17.3 ± 7.5 mm to 14.2 ± 6.4 mm, showing a significant mean reduction of -3.1 mm (t = -4.90, 95% CI: -4.3 to -1.9, p < 0.001). High-grade hydronephrosis (SFU grade III-IV) was initially present in 67% of children, significantly higher than the 50% reference (z = 3.40, p = 0.001), but this proportion decreased to 39% at 12 months, a statistically significant reduction compared with baseline (McNemar χ² = 19.6, p < 0.001). Hydroureter was also very common preoperatively (97%), exceeding the reference 90% level (z = 2.22, p = 0.026), and improved to 61% at follow-up, representing a significant decline (McNemar χ² = 30.8, p < 0.001). The posterior:anterior urethral ratio demonstrated striking improvement, decreasing from 3.21 ± 0.13 pre-operatively to 1.23 ± 0.26 at 1 year. The mean difference of -1.98 (t = -35.2, 95% CI: -2.10 to -1.86, p < 0.001).

Table 3: Etiological Factors Associated with Persistent / Worsening Upper Tract Dilatation (N = 100)

Table 3 analyzes etiological factors associated with persistent or worsening upper tract dilatation. High-grade vesicoureteral reflux (VUR) emerged as a strong predictor: 70.4% of children with high-grade VUR exhibited persistent or worsened dilatation compared with only 29.6% of those without VUR. The risk ratio (RR = 3.42, χ² = 13.2, 95% CI: 1.66-7.05, p < 0.001) indicates that high-grade VUR increases the likelihood of adverse upper tract outcomes more than threefold. Poor bladder compliance or detrusor overactivity on urodynamic studies was also significantly associated with unfavorable outcomes; 51.9% of affected children showed persistence compared to 16.4% among those with normal bladder dynamics (RR = 3.07, χ² = 12.8, 95% CI: 1.67-5.63, p < 0.001). Age at first fulguration had a significant role—children undergoing fulguration after 1 year of age had a substantially higher rate of persistence (66.7%) compared with those treated earlier (33.3%), yielding a threefold increased risk (RR = 3.13, χ² = 11.9, 95% CI: 1.57-6.25, p = 0.001). Baseline severity of obstruction was the strongest determinant: 92.6% of children with a renal pelvis AP diameter ≥20 mm had persistent dilatation versus 7.4% with lesser dilatation (RR = 4.09, χ² = 21.1, 95% CI: 2.01-8.32, p < 0.001). These findings collectively identify severe VUR, bladder dysfunction

Table 4: Role and Effectiveness of Adjuvant Therapies and Additional Interventions (N = 100)

Table 4 evaluates the effectiveness of adjuvant therapies and additional interventions on upper tract outcomes. Continuous antibiotic prophylaxis (CAP) showed a modest but statistically insignificant trend toward improved outcomes; 60.3% of children receiving CAP demonstrated improvement compared with 51.9% who did not (RR = 1.10, 95% CI: 0.86-1.41, p = 0.45). Bladder rehabilitation, including timed voiding and anticholinergic therapy, also demonstrated a favorable trend: 37.0% of improved cases belonged to the rehabilitation group, compared with 22.2% among those with persistent dilatation. However, this difference did not reach statistical significance (RR = 1.19, 95% CI: 0.95-1.50, p = 0.16). In contrast, secondary diversion procedures such as vesicostomy or ureterostomy were strongly associated with persistence or worsening of dilatation. Among children requiring diversion, 33.3% had persistent disease versus only 5.5% showing improvement. The risk of persistence was more than tripled in this subgroup (RR = 3.35, χ² = 13.5, 95% CI: 1.93-5.79, p < 0.001).

The present study shows that, in a relatively young PUV cohort (mean age at fulguration 2.10 ± 2.30 years), nearly three-quarters of children (73%) demonstrated complete or partial improvement of upper urinary tract dilatation at 24-month follow-up. This degree of upper tract recovery is broadly in line with earlier imaging-based series that reported substantial, though incomplete, regression of hydronephrosis after adequate valve ablation. Archana P et al.(2023)[6] highlighted that upper tract changes in PUV often represent a continuum of obstructive uropathy, with potential for reversibility once the obstruction is relieved. In our series, complete resolution was achieved in 39% and partial improvement in 34%, while 18% had persistent significant dilatation and 9% worsened, emphasising that a non-trivial subgroup remains at risk despite technically successful fulguration. This pattern mirrors the long-term heterogeneity in renal and drainage outcomes described by Uwaezuoke SN et al.(2022)[7], who both noted that a proportion of boys continue to show structural or functional compromise despite early intervention.

The significant reduction in pooled renal pelvis AP diameter from 17.9 ± 9.4 mm to 14.9 ± 7.1 mm at 24 months, and the more pronounced early decrease in right and left AP diameters by 3.6 mm and 3.1 mm respectively at 12 months, is consistent with the concept that initial post-ablation months are critical for decompression and remodelling of the collecting system. Velhal R et al.(2021)[8] demonstrated that the initial renal ultrasound and its early evolution have prognostic value for long-term outcome in PUV, and our data support their observation that improvement in hydronephrosis over time predicts better prognosis. The decline in high-grade hydronephrosis from 67% to 39% and hydroureter from 97% to 61% at 12 months in the current series reinforces the role of timely obstruction relief, as also suggested by Babu R et al.(2021)[9], who identified radiological improvement as an important favourable prognostic marker.

The posterior:anterior urethral ratio (PAR) in our study decreased dramatically from 3.21 ± 0.13 pre-operatively to 1.23 ± 0.26 at one year, confirming adequate valve ablation and aligning with work that has promoted urethral ratio as an objective metric of procedural success. Parelkar SV et al.(2025)[10] proposed urethral ratios on VCUG as a reliable surrogate of complete valve ablation, and more recently Babu R et al.(2022)[11] further validated PAR as an indicator of adequate fulguration. Our findings extend these observations by linking a markedly improved PAR with significant concurrent reductions in upper tract dilatation, thus supporting the use of PAR not only as a technical endpoint but also as a functional correlate of improved drainage.

When the etiological factors for persistent or worsening dilatation (Table 3) are examined, high-grade VUR, poor bladder compliance, delayed fulguration (>1 year of age), and marked baseline pelvic dilatation (APD ≥20 mm) emerge as strong independent risk markers. Children with high-grade VUR had more than a threefold higher risk of persistence (RR 3.42), echoing the emphasis placed on reflux severity and chronic back-pressure by Norris JJ et al.(2020)[1], who demonstrated that high-grade VUR in the setting of PUV is closely linked to poorer renal and drainage outcomes and often requires intensive, bladder-oriented management. Similarly, poor bladder compliance/overactivity in our cohort was associated with a threefold rise in persistence (RR 3.07), in agreement with Chatterjee US et al.(2020)[5], who described valve-bladder syndrome and bladder dysfunction as key determinants of long-term morbidity and CKD progression.

The impact of timing of intervention observed in our data (RR 3.13 for persistence when fulguration was performed after 1 year of age) is also consistent with previous reports. Reddy D. (2020)[12] both suggested that children treated later, or those with prolonged obstructive exposure, are more likely to develop irreversible renal dysplasia and persistent dilatation. Our finding that a baseline APD ≥20 mm confers a fourfold higher risk of persistent upper tract dilatation dovetails with Bade R et al.(2025)[13], who underscored that marked antenatal/postnatal dilatation often reflects combined obstruction and dysplasia rather than simple reversible stasis. Collectively, these comparisons support the view that severe pre-operative anatomic derangement, high-grade reflux, and bladder dysfunction are not merely associated features but central drivers of unfavourable post-fulguration trajectories.

The analysis of adjuvant therapies and additional interventions (Table 4) demonstrates that continuous antibiotic prophylaxis and bladder rehabilitation show trends towards better outcomes but do not reach statistical significance in this sample, whereas the need for secondary diversion is strongly associated with persistence or worsening of dilatation. Badruddoza AS et al.(2024)[2] observed that children who require more aggressive interventions (e.g., diversion) usually represent a subgroup with higher baseline serum creatinine, more severe VUR, and pronounced bladder dysfunction, thus inherently at higher risk for CKD and persistent upper tract changes. Our observation that diversion is a marker of severe disease, rather than a cause of poor outcome, resonates with the experience from long-term cohorts summarised by Uttaray S et al.(2024)[14], where diversion was reserved for the most complex cases with refractory obstruction or sepsis.

The present prospective analytical study demonstrates that posterior urethral valve (PUV) fulguration leads to significant improvement in upper urinary tract dilatation in a majority of children, with 73% showing complete or partial resolution over 24 months. Renal pelvis and ureteric dimensions showed consistent and statistically significant reductions, and the posterior-anterior urethral ratio improved markedly, confirming effective obstruction relief. However, nearly one-third of patients exhibited persistent or worsening dilatation, predominantly those with high-grade vesicoureteral reflux, poor bladder compliance, delayed fulguration, or severe baseline pelvic dilatation. These findings underscore that structural severity and bladder dysfunction continue to drive long-term morbidity despite technically successful valve ablation. Overall, early diagnosis, timely valve fulguration, proactive management of bladder dysfunction and VUR, and structured long-term imaging surveillance remain essential to optimize renal and upper tract outcomes in children with PUV.

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