Simultaneous primary posterior urethral valves ablation and bladder neck incision may decrease kidney and bladder failure in long-term follow-up in patients with bladder neck hypertrophy and poor bladder function at presentation: report of 301 cases

Abstract

Objectives

To investigate the effects of bladder neck incision (BNI) and primary valves ablation on long-term kidney and bladder function in children with posterior urethral valves (PUV) and bladder neck hypertrophy (BNH).

Patients and methods

From 1997 to 2016, a total of 1381 children with PUV were referred to our tertiary hospital. Of these patients, 301 PUV patients with bladder neck hypertrophy need concurrent BNI and valve ablation. All patients were followed up every 3–6 months on regular basis in first 2 post-surgical years and annually then after. The paired t-test and chi-square test were used to perform statistical analysis with p value < 0.05 defined as the level of significance.

Results

Mean age at diagnosis was 7.22 ± 2.45 months (ranging from 7 days to 15 months) with a mean follow-up of 5.12 ± 2.80 years. The incidence of hydronephrosis was decreased from 266 (88.3%) at the baseline to 73 (24.3%) patients in long-term follow-up. At baseline, 188 (62.5%) patients were diagnosed with VUR, which decreased to 20 (6.6%) individuals at the end of follow-up. Bladder and renal function were improved in follow-ups following concomitant PUV ablation and BNI. No Myogenic failure was depicted in all patients with BNH. No ureteric reimplantation was needed during the two decades follow-up.

Conclusion

Simultaneous valve ablation with BNI may present further profits in children with PUV and BNH particularly cases of BNH with poor bladder function at the time of presentation. This method can improve the results of urodynamic and imaging studies after the surgery. We hypothesize every child with PUV presentation who has concurrent vesicoureteral reflux, CKD or persistent hydrourethronephrosis may suffer from secondary bladder neck obstruction. This secondary bladder outlet obstruction must be managed through BNI as the surgical relief.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-024-01546-0.

Introduction

The posterior urethral valve (PUV) is considered the most common cause of congenital urethral obstruction in male infants, which leading to end-stage renal disease (ESRD) and progressive renal damage. This obstructive anomaly’s incidence in the general population is estimated at 1 in 5000 to 8000 male infants [1, 2]. The North American Pediatric Renal Transplant Cooperative Group reported that PUV accounts for 16.8% of renal damage in children with ESRD [3].

Bladder dysfunction (BD), bilateral vesicoureteral reflux (BVUR), bilateral severe hydroureteronephrosis (BHUN), congenital renal dysplasia (CRD), and recurrent urinary tract infections (UTIs) are among the factors leading to progressive deterioration of renal function in PUV patients. Urinary voiding problems are the significant risk factors in terms of myogenic failure, detrusor hyperreflexia, and poor bladder compliance with improved resistance to filling [4]. Myogenic decompensation might appear following increased persistent detrusor pressure, leading to poor bladder emptying and greater post-void residual (PVR) urine volume [5].

The role of bladder dysfunction secondary to the obstructive effect, the so-called “Valve bladder”, as first characterized by Mitchell, came to be understood as the critical aspect of the ongoing bladder deterioration and renal function after valve ablation [6]. The persistent obstructive process in a few patients might be due to bladder neck dyskinesia [7], as some previous studies reported hypertrophic semi-closed bladder necks in PUV patients by endoscopic evidence [7]. Thus, the complete and accurate treatment of lower urinary tract obstruction (primary or secondary events) in PUV requires more interventions besides valve ablation.

Several adjuvant curative interventions are recommended to accomplish treatment aims in PUV patients. Primary endoscopic valve incision (PEVI) was believed to be effective in managing the anatomical obstruction and dilation of the upper urinary tract; nevertheless, the sequelae can persist in the bladder and kidneys even after PEVI during infancy and childhood and generally through adolescence [8]. Approximately 75–80% of boys are verified to be affected with bladder dysfunction in urodynamic examinations after PUV ablation, which may lead to renal failure in one-third of these patients [9]. Administration of alpha-adrenergic/anticholinergic medicine, initiation of clean intermittent catheterization (CIC), injection of Botulinum toxin, and Desmopressin are presented with some minor/temporary effects in PUV patients [10].

The most effective surgical procedure in the management of primary bladder neck obstruction (PBNO) compared to other adjuvant therapeutic modalities [11, 12] is bladder neck incision in selected patients with high ride hypertrophied fibrotic bladder neck. Concomitant valve ablation and BNI are proposed to diminish the risk of bladder hypercontractility as well as a dramatic decrease in voiding pressure and decompression of the secondary dilated ureter and VUR and prevent its progression toward myogenic failure [13]. Additionally, these techniques may decrease the need for further adherence to anticholinergic therapy combined with CIC and enhance short-term urodynamic outcomes [9]. The usage of the BNI technique alone is limited mainly due to possible retrograde ejaculation after the operation in children with PUV; however, according to the results of our previous study, we verified that the concurrent PUV ablation and BNI was not associated with additional risk of urinary incontinence and dry ejaculation in early adulthood with preserved antegrade ejaculation [14].

Following our first randomized clinical trial of concomitant BNI and PUV ablation [9], we found the bladder outlet complex obstruction rather than a tiny urethral membrane; the bladder neck hypertrophy may play a significant role in the bladder function. The voiding cystourethrogram (VCUG) depicts a narrow bladder neck, and the video-urodynamic findings confirm the high lag time and very high voiding pressure (more than 300 cm H₂O) before and after valve ablation. The video-urethrocystoscopy confirms a pale tight ring shape and high ride bladder neck.

At our referral center, all pediatric cases with PUV will be managed by endoscopic PUV valve ablation surgery. No vesicostomy will be indicated in the presence of 4.6 Fr. tip neonatal urethrocystoscope with 3 Fr. working channel. The working channel negotiates the Bagbee electrode and Holmium Yage 200–400 µM laser fiber.

The promising outcomes of our previous study prompted us to assess the long-term outcomes of concomitant BNI and primary valve ablation in patients with PUV, with particular emphasis on urodynamic and imaging assessments, as well as bladder and renal function at puberty.

Patients and methods

Patients’ selection and baseline data

The current retrospective study was approved by the institutional review board at the Tehran University of Medical Sciences (IR.TUMS.MEDICINE.REC.1398.400). A review of the PUV patients who were candidates for concurrent BNI and valve ablation database from September 1997 to August 2016 identified 1381 patients for whom data were available regarding urodynamic and imaging findings following the operation.

The exclusion criteria in this study were patients with simultaneous PUV and urogenital anomalies including duplicated urethra, anterior urethral valve (AUV), anterior urethral diverticulum (AUD) vertebral anomalies, megaureter as well as patients who lost follow-up or had history of previous endoscopic or open surgical intervention prior to have been referring to the senior author’s (AMK) clinic in the tertiary pediatric center. These prior surgical interventions were categorized into lower urinary diversion (lower ureterostomy or vesicostomy), upper urinary diversion (upper ureterostomy or pyelostomy), and previously reimplanted bladder in missed PUV cases. The inclusion criteria of the study were typical PUV on VCUG as well as fibrotic high ride and hypertrophied bladder neck on video urethrocystoscopy, urodynamic evaluations before and after surgery, presence of regularly based follow-ups on urinary tract ultrasonography, serum biochemical assessments, urinalysis, and urine culture. Of the 1381 children with PUV, 1080 cases were excluded from the study (876 cases due to a history of previous endoscopic or open surgical intervention prior to referral and 204 cases due to concurrent other urogenital anomalies) and 301 were included in the study. All patients underwent concomitant BNI and primary valve ablation by a senior author (AMK).

All children underwent comprehensive urological evaluations, including postnatal urinary tract ultrasound, voiding cystourethrogram, isotope scan, natural fill urodynamic study, and blood biochemistry measurements. After performing the aforementioned investigations, following circumcision and suprapubic catheter insertion, VCUG study was performed in the presence of an intact urethra (virgin urethra). After stabilization of the patient’s hemodynamics, the patient was taken to the theater for endoscopic surgery. Under general anesthesia, the urine jet per urethra was recorded with gentle pressure on the bladder dome. Direct video-urethroscopy was performed to see the type of urethral valves and proceed to the bladder neck to depict the bladder neck hypertrophy as a pale high-ride bladder neck ring. Then, a video-cystoscopy was done to see the configuration of the ureteric orifices and the degree of bladder trabeculation.

Surgical technique

In all patients, the valves were fulgurated using a blunt-tipped flexible Bagbee™ fulgurating electrode with electrocoagulation of a proper-sized neonate urethrocystoscope (4.5–6 Fr. tip with 3 Fr. working channel) (Richard Wolf® Company). All patients underwent valve ablation along with BNI via a single deep incision at the 6 o’clock position proximal to the verumontanum precisely to prevent damage to the prostate capsule; the verumontanum (located in the posterior aspect of the prostatic urethra) remained untouched. This procedure was performed with vigilance to leave the adventitia undamaged. The valve fulguration was done with electrocoagulation with minimal electric current (Supplementary videos 1 and 2). Video-endoscopic valve fulguration was performed with 10–15% electric energy of the cautery transferred by 3 Fr. Bagbee/metal stylet and follower of 3 Fr. JJ stent (supplementary video 3, 4). The bladder neck incision technique by coagulation mood is presented in the supplementary video 5.

Outcome measurement

All the patients included in this study had regular post-operative follow-ups including every 3 months in the first year of post-operation, every 6 months in the second post-operative year, and then every year. If in-person follow-up visits were not possible, the remote follow-up visits occurred via phone interviews. Moreover, in the case of patients who were unable to perform their in-person post-surgical follow-ups. They referred to the pediatric urologists/nephrologists of their province of residence and the study’s co-authors were informed of the post-surgical follow-up findings, to decrease the number of patients with loss of post-surgical follow-ups. Urinary tract ultrasonographic studies and renal function tests were also performed according to patients’ history. Chronic renal failure was defined as an absolute increase in serum creatinine of 2 mg/dL or, according to the CKD classification and end-stage renal disease (ESRD), was defined as the need for renal replacement therapy (dialysis and kidney transplantation) in the follow-up period due to a significant decrease in renal function to the point that the kidneys can no longer work on their own [15]. Ultrasound was used to evaluate the severity of hydronephrosis, which was graded according to the SFU guidelines [16].

The images were randomly reviewed and graded by pediatric radiologists specializing in this field. A senior pediatric urologist randomly selected and assessed final reports to ensure the evaluation quality.

We performed a standard slow-fill urodynamic study in all toilet-trained children through a 7 Fr. double lumen urethral catheter for the assessment of detrusor overactivity urine leakage or urinary incontinence, and Pdet Max and Qmax were also determined during voiding in all patients. Detrusor overactivity was considered a phasic detrusor contraction of more than 15 cm H₂O that the child could not restrain during filling cystometry with or without urinary incontinence. Bladder hypercontractility was defined as detrusor uninhibited contractions and a maximum voiding detrusor pressure (Pdet max) ≥ 90 cmH₂O. PVR urine volume was considered significant if exceeding 10% of expected bladder capacity. Myogenic bladder failure, also known as over-distended bladder, was mentioned as an intrinsic detrusor dysfunction or partial bladder emptying following un-sustained detrusor contraction without any sign of obstruction. Considerable residual volume is more than 10% of the estimated bladder capacity (EBC). The simplified formula of EBC (ml) is defined as the weight of infants (Kg) × 7 to give a reliable estimate of the expected bladder capacity independent of age [17].

Statistical analysis

SPSS®, v23 (IBM SPSS Statistics, IBM Corporation. Chicago, IL, USA) was applied for statistical analysis. The paired t-test was performed to evaluate parametric data during the follow-up period, and the chi-square test was also conducted to assess the relationship between treatment and the number of included patients. Data are presented as mean ± SD, and p values < 0.05‍ were considered statistically significant.

Results

A total of 301 patients were included in this retrospective study. The mean ± SD age of patients at the time of diagnosis was 7.22 ± 2.45 months with a range of 7 days to 15 months with the mean follow-up of 5.12 ± 2.80 years. The most frequent presenting complaints of patients at the time of diagnosis were febrile urinary tract infection (FUTI) in 195 (65.0%), Intrauterine growth retardation (IUGR) in 165 (55.0%), voiding difficulties in 135 (45.0%), urinary tract infection (UTI) in 105 (35.0%), and abdominal mass which represents the severe hydronephrosis and palpable bladder in 75 (25.0%) patients.

The urine culture was positive in 165 patients (55.0%), including E. coli (N = 155), Pseudomonas aeruginosa (N = 25), Klebsiella Pneumonia (N = 15), and Enterobacter (N = 10) before referral. All patients had a history of FUTI after their first month of life. VCUG before the ablation and post-ablation is shown for two patients in Fig. 1.

Fig. 1.

a, c Voiding cystourethrogram (VCUG) prior to the ablation; and b, d VCUG post-ablation in two patients

The distribution of hydronephrosis and vesicoureteral reflux (VUR) in patients at the baseline and after simultaneous BNI and valve ablation are shown in Table 1. The incidence of hydronephrosis decreased from 266 (88.3%) at baseline to 73 (24.3%) patients in long-term follow-up. At the baseline, 188 (62.5%) patients were diagnosed with VUR, which decreased to 20 (6.6%) individuals at the end of follow-up. At the end of the follow‐up, none of the patients required ureteral reimplantation.

Table 1.

Degrees of hydronephrosis and vesicoureteral reflux (pre and post-surgery)

	Baseline, n (%)	follow-up, n (%)	P-value
HUN	266 (88.3)	73 (24.3)	< 0.001
Mild	26 (8.6)	39 (13.0)
Moderate	85 (28.2)	24 (8.0)
Severe	155 (51.5)	10 (3.3)
VUR	188 (62.5)	20 (6.6)	< 0.001

The most essential urodynamic parameters are also depicted in Table 2. The presence of myogenic failure in the baseline was reported in 16 (5.3%) patients in patients with delayed diagnosis up to school age. In contrast, none of our patients had signs of myogenic failure in long-term post-operative assessments. Considerable residual volume was observed in 15 (5.0%) cases at baseline and 9 (3.0%) patients in long-term follow-ups. In the baseline study, we depicted detrusor overactivity in 189 (62.8%) patients, which decreased to 17 (5.6%) children after the surgery. Bladder hyper-contractility was detected at baseline in 263 (87.4%) patients pre-operatively which significantly decreased to 15 (5.0%) patients after long-term follow-ups. Pdet max also reduced from 288.66 ± 42.31 to 46.74 ± 22.41 during the follow-up period.

Table 2.

Parameters of urodynamic study

	Baseline	Follow-up	P-value
PDETMAX (cmH20)	288.66 ± 42.31	46.74 ± 22.41	< 0.001
Bladder Hypercontractility	263 (87.4%)	15 (5.0%)	< 0.001
Myogenic failure	16 (5.3%)	0	0.003
Significant Residual volume	15 (5.0%)	9 (3.0%)	< 0.001
Detrusor overactivity	189 (62.8%)	17 (5.6%)	0.001

Discussion

The results of the current study demonstrate improvement in bladder and renal function after valve ablation and BNI in PUV patients, supporting the bladder valve complex hypothesis. Congenital anomalies of the kidney and urinary tract (CAKUT) include approximately 20 to 30% of prenatal anomalies varied as posterior urethral valve and prune belly syndrome, horseshoe kidney, obstructive renal dysplasia, ureteropelvic junction obstruction, ureteral duplications, non-motile ciliopathies and several syndromes associated with renal malformations (Meckel–Joubert, short rib, Bardet–Biedl, asplenia/polysplenia, hereditary renal dysplasia, Zellweger, trisomies, VACTER-L, Potter, caudal dysplasia, and sirenomelia), as well as ADPK, and ARPK [18]. PUV is considered the most common cause of CAKUT in male fetuses and infants [19].

Urinary tract obstruction should be managed as early as possible in gestation [20]. Regardless of substantial progress in the identification and management of children with PUV, debates remain regarding the optimal therapeutic approach. Most children with PUV are susceptible to progression toward ESRD. Hypertrophy of the bladder wall and bladder neck increases the severity of hydroureteronephrosis, which leads to more renal parenchymal damage and subsequent need for renal replacement therapy. As summarized in Table 3, according to the literature, the prevalence of progression toward ESRD in PUV patients varies between 7 and 67%.

Table 3.

Rate of progression to renal failure in patients with posterior urethral valve

First author	Country	Year of publication	Study period	Sample size	Follow-up	% ESRD	Conclusion
Chatterjee [21]	India	2020	2005–2016	272	7.8 years (range 3–14 years)	45 (16.54%)	Rhabdosphincter spasm underneath actually renders bladder outlet obstruction, and cusps of PUV, particularly in neonates, amplify the obstruction, following that bladder outlet obstruction cascades detrusor hypertrophy
Bhadoo [22]	India	2014	1992–2013	152	5 years (range: 2–18 years)	42.7%	High prognostic significance of initial serum creatinine, PRA levels and GFR in cases with PUV
Kibar [23]	Turkey	2011	1994–2008	52	7.2 years (range 15 months-14 years)	32.69%	Diagnosis after 1 year of age is associated with a lower risk of developing renal insufficiency on long-term follow up.
Ansari [24]	India	2018	2000–2010	270	8.5 years (range 5–15)	59 (21.8%)	In a well performed UDS, BCI may be a useful tool for early detection of boys with PUV who are likely to progress to CKD stage IIIB or more.
Tambo [1]	Africa	2018	2005–2016	18	34.56 ± 21.47 months	12 (66.8%)	There is the need to counsel parents/guardians on the importance of long-term follow up after relief of obstruction.
Lundar [25]	Norway	2019	2001–2016	60		21 (35%)	Prenatal decompression of the bladder and upper tract is beneficial in patients with PUV, which is relevant to the discussion of prenatal intervention in these fetuses.
Uthup [26]	India	2010	2006–2007	30	7.78 years (ranged from 5–16 years)	10 (33%)	The presence of vescicoureteral reflux was not a risk factor for decline in GFR in our study.
Nasir [27]	Nigeria	2019	2012–2016	29	5 months	13.8%	There was significant improvement in RF after initial catheter drainage. The incidence of IRF at follow-up was 13.8%. Long-term follow-up is necessary to identify patients at risk of end-stage renal disease.
Kajbafzadeh [28]	Iran	2015	2000–2012	38	1–8 years	1 (2.63%)	Concomitant anterior and posterior valves seem to be more prevalent than previously assumed, and might be missed on initial assessment. Oblique view voiding cystourethrography with full-length delineation of the urethra is of paramount diagnostic importance when obstruction is suspected.
Okafor [29]	Nigeria	2013	2008–2009	31	12.6 months (range 3–22 months)	4 (12.9%)	The poor outcome may be related to delayed diagnosis, poor renal function at presentation and poor renal support. Improving time to diagnosis and renal support may lead to better outcome.
Emir [30]	Turkey	2002	-	26	12.6 months (range: 2 days ± 8 years)	8 (30.77%)	All patients with PUV had pathological urodynamic findings that could change with age, and early relief of the infravesical obstruction could have an improving effect on bladder function. Urodynamic investigations may help us to design the proper treatment according to the bladder function.
Lemmens [31]	Belgium	2014	2001–2011	39	-	7 (19%)	The introduction of PUV disease specific reference Scr centiles may be helpful to facilitate earlier prediction and guide counseling, but necessitates external validation.
Celakil [32]	Turkey	2019	1996–2018	113	70 months (60.00–216.00)	7 (10.9%)	PUV has a considerable risk for CKD development. Antenatal diagnosis, management of proteinuria and hypertension may modify this progression.
Herbst [33]	United states	2019	1992–2006	685	7 years (IQR, 2–14 years)	36 (7%)	Patients in this multicenter cohort with posterior urethral valves had a 5% risk of death, and were most likely to die during their initial hospitalization. Risk of death was higher with a diagnosis of pulmonary hypoplasia. Kidney dysplasia was associated with a higher risk of need for dialysis/transplant.
Alsaywid [34]	Saudi Arabia	2021	1998–2008	39	5.5 years	18%	A child with PUV who has a risk factor does have an increased potential of developing CKD, knowing that the type of intervention offered to treat PUV has no impact on the outcome.
Rickard [35]	Canada	2020	2000–2017	22	86 ± 76 months	12 (54%)	Patients with early PUV diagnoses who develop symptomatic UTI may benefit from early creation of a Mitrofanoffcathetherizable channel, which is associated with delayed ESRD progression and need for dialysis.
Odeh [36]	Canada	2016	2003–2013	75		16 (21.33%)	Estimates of renal parenchyma quantity (total renal parenchymal area) and quality (corticomedullary differentiation and renal echogenicity) measured on initial postnatal ultrasound carry prognostic value in determining future risk of stage 5 chronic kidney disease in patients with posterior urethral valves.
Odetunde [37]	Nigeria	2012	1997–2009	21		8 (36%)	ate presentation is common in our setting. This is associated with high morbidity and mortality rates. Efforts at improving awareness and early diagnosis among the health team should be made to stem the tide.
Mirshemirani [38]	Iran	2013	2007–2012	98	3.4 ± 1.2 years	ARF in 45 (46%) Mortality in 5 (5.1%)	Urinary drainage by feeding tube in early days of infancy, followed by valve ablation is the best treatment in PUV, and urinary diversion improves the outcome. VCUG is still the gold-standard imaging modality for documenting PUVs. The factors like renal dysplasia and UTI have their role in final outcome.
Abdel-Salam [39]	Egypt	2020	2005–2016	30	6.7 ± 3.8 years	14 (46.7%)	Nadir creatinine and vesicoureteral reflux have high prognostic value for late renal functions, and antenatal diagnosis is associated with better renal functions in patients with posterior urethral valves. Increasing family awareness, antenatal care facilities, and referral to tertiary care centers are priorities for promoting the antenatal diagnosis and management in developing countries. Facilities and training for prenatal intervention should be encouraged

The clinical consequences of congenital urethral obstruction include impaired compliance, connective tissue changes in the obstructed bladder, increased Procollagen III gene expression, increased connective tissue mass (Collagen I, III, IV), elevated level of Elastin and decreased Collagenase activity in the obstructed bladder [40].

Renal dysplasia, bilateral VUR, early onset of manifestations, and recurrent UTI are among the main factors affecting long-term results of renal function in patients with PUV. However, bladder dysfunction is mentioned as the leading risk factor for renal failure in patients with PUV [41]. According to our results, detrusor overactivity, poor compliance, and bladder hypercontractility are the most common urodynamic patterns in patients with PUV. Ghanem et al. reported poor bladder compliance and detrusor overactivity as significant causes of renal dysfunction in PUV [42].

Primary valve ablation has been applied in our center as the principal treatment approach for PUV. Valve reoperation may not be considered a curative option due to the confirmed persistence of symptoms post-operatively. Therefore, several adjuvant therapies have been proposed for the management of bladder dysfunction and to prevent further ESRD in patients with PUV [11, 43]. According to the study by Misseri et al., early anticholinergic medications and time-voided regimens are effective strategies for regaining bladder control and preventing bladder instability [44]. However, the risk of myogenic failure may be enhanced following increased bladder capacity and reduced voiding detrusor pressure. Previous studies verified that superficial valve ablation is not efficient for the management of bladder dysfunction in children with PUV. In case of poor adherence to anticholinergic therapy to reduce low compliance competently, CIC should be utilized before augmentation surgery. Nocturnal catheter evacuation, repeated evacuation, and oral desmopressin treatment [11] instead of CIC are also suggested by previous reports.

The BNI technique has been recognized as a straightforward and successful surgical approach for the management of secondary bladder neck obstruction; however, there was a great concern regarding incontinence and retrograde ejaculation post-operatively, which limited the application of this technique [9, 45]. Nevertheless, several studies proved that retrograde ejaculation can be expected complications following BNI, which can be significantly reduced by using modified techniques, especially Concomitant BNI, and valve ablation is proposed to diminish the risk of bladder hypercontractility as well as a dramatic decrease in voiding pressure and decompression of the secondary dilated ureter and VUR and prevent its progression toward myogenic failure during adulthood [46]. There is no single report in the literature regarding retrograde ejaculation following BNI in children with a history of PUV during the adulthood period. Some of the patients in this study have been followed long-term in case of urinary continence and ejaculation; as reported in our previous research, there was no incontinence and dry ejaculation, and all of them considered their ejaculation normal [14].

There was also a concept regarding the length and depth of incision, which is crucial in increasing the risk of incontinence. It was recently confirmed that a solitary incision at 6 o’clock was unrelated to the development of any complications in children following BNI, which was in line with the findings of the current study; however, they did not demonstrate noteworthy profits regarding the results of urodynamic measures post-operatively [4].

The bladder neck has been recognized as the predominant cause of bladder outlet obstruction in patients with PUV, which may lead to decompensation.; however, reports by Glassberg [47] and Waterhouse [48] mainly disputed this concept and argued against bladder neck narrowing, which may result in bladder neck contracture. Recently, it has been authenticated that some PUV patients are presented with a gradual urinary obstructive process following bladder neck dyskinesia. Gennaro et al. recommended that chronic increased detrusor pressure may lead to myogenic decompensation in younger patients [49]. The gradual deterioration of bladder function and larger PVRs might be secondary to bladder neck obstruction [5]. According to one study in 2005, major hypertrophic semi-closed bladder necks were shown by endoscopic evidence in patients with myogenic decompensation and PUV. They theorized that voiding under the abovementioned conditions may cause bladder neck obstruction, leading to detrusor insufficiency by long-term bladder outlet resistance [7]. Moreover, alpha-blockers are effective for developing voiding dysfunction and upper urinary tract dilation through reduced bladder outlet resistance and intravesical pressure [47].

According to our results, CKD was detected in 24 patients (8.0%) during the last follow-up, and it progressed toward end-stage renal disease in 11 patients (3.7%). PUV is the most common cause of progression toward CKD and ESRD in children. However, our study’s rate of progression toward ESRD was considerably low compared with previous reports with the use of valve ablation or anticholinergic drugs only [39]. We suggest carefully scanning the posterior urethral region whenever signs suggest obstruction at the urethral level of the urinary tract. The following diagram demonstrates the approach to diagnosing PUV patients and neonates with symptoms of urethral obstruction (Fig. 2).

Fig. 2.

The approach to diagnosed PUV patients and neonates with symptoms of urethral obstruction

This study by evaluating the long-term follow-ups of pre- and post-surgical urodynamic and imaging study findings in 301 patients who underwent BNI and valve ablation could have limitations due to the retrospective design. Whereas cases with previously performed vesicostomy and urinary diversions, multiple valve ablations, and concurrent urogenital anomalies especially concomitant other urethral anomalies, concomitant vertebral anomalies which can affect the urodynamic findings are excluded to evaluate the net effect of BNI and valve ablation on post-surgical urodynamics and imaging findings in pediatric patients with varying degrees of SFU grade hydronephrosis due to infra-vesical obstructions. Recommending future studies with prospective cohorts or randomized clinical trials evaluating and comparing the post-surgical urodynamic findings in the concomitant BNI and valve ablation with valve ablation alone groups off note.

There have been limited studies regarding the application of simultaneous valve ablation and BNI in diagnosed PUV patients as bladder valve complex hypotheses during the past decades. Our results showed promising improvement in urodynamic parameters after simultaneous valve ablation and BNI in long-term follow-up in PUV children. The degree of VUR and hydronephrosis was also significantly reduced in these patients. Moreover, this method notably diminished further economic burden following complications of adjuvant therapies in PUV patients.

Conclusion

This single-surgeon supervised study of 301 cases of PUV treated with the combination of BNI and valve ablation demonstrates that valve destruction with BNI can be considered a simple and valuable treatment for PUV. This method effectively improved bladder and renal function compared to superficial valve ablation. We propose that this approach will delay the progression of urodynamic parameters, which may culminate in the development of chronic renal failure or ESRD in patients with PUV.

Authors’ contributions

AMK: Idea development, surgery, AR: Data analysis, PH: Assistance in surgery, HA: Assistance in surgery, SS: Idea development, Manuscript drafting. All authors read and approved the final manuscript.

Funding

There were no funding sources for this study.

Availability of data and materials

The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The institutional review board at the Tehran University of Medical Sciences approved the current retrospective study. All experiments followed relevant guidelines and regulations and the Declaration of Helsinki (IR.TUMS.MEDICINE.REC.1398.400). A written informed consent was obtained from all patients and their parents.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.