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Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation
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Journal of Pediatric Urology (2016) xx, 1.e1e1.e5
Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation R. Babu, S. Hariharasudhan, C. Ramesh Department of Pediatric Urology, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, India Correspondence to: R. Babu, Pediatric Urology Unit, Sri Ramachandra Medical College and Research Institute, Porur, Chennai 600116, India, Tel.: þ91 9840359062 [email protected] (R. Babu) Keywords Posterior urethral valve; Voiding cystourethrogram; Stricture; Residual valve; PUV ablation; Children Received 9 February 2016 Accepted 21 April 2016 Available online xxx
Summary Introduction There are conflicting reports on the criteria with which to determine success following posterior urethral valve (PUV) ablation. The aims of this study were to assess the value of the posterior urethra: anterior urethra ratio (PAR) in predicting successful PUV ablation. Materials and Methods All neonates and infants with confirmed PUV on voiding cystourethrogram (VCUG) were included. Initial PAR was computed by dividing maximum posterior urethral diameter by anterior urethral diameter. Distances were measured by an on-screen distance measurement tool in the Radiology department, to avoid error. Only oblique images with good voiding phases were used for assessment. All patients underwent cystoscopy and PUV ablation using cold knife. Postoperative VCUG and cystoscopy were performed at 3 months follow-up. Success was defined as cystoscopic resolution of obstruction, in addition to biochemical and radiological improvement, and this was compared with PAR findings. An equal number of age-matched control patients who
had a normal VCUG (as a part of evaluation of antenatal hydronephrosis) were also analyzed. Results A total of 56 patients (median age 15 days, range 3e250 days) were analyzed between 2013 and 2016. The mean PAR was 1.5 (0.42) in controls and 3.42 (0.75) in those with PUV at diagnosis (P Z 0.001). In those with successful PUV ablation (n Z 51) the mean PAR was 1.8 (0.21), and in those with residual PUV/stricture (n Z 5) the mean PAR was 3.16 (0.54). The difference between these two groups was statistically significant (P Z 0.0001). Applying the value of mean þ 2 SD of successful PUV ablation, an upper limit of PAR >2.2 was proposed to predict failure. Using this cut-off, 4/7 with PAR >2.2 had confirmed failure, while 48/49 with PAR <2.2 had successful resolution (P Z 0.001) Conclusion Whenever the posterior urethra is more than 2.2 times the diameter of the anterior urethra (PAR >2.2) on repeat VCUG following a PUV ablation, a cystoscopy check is essential to rule out residual PUV/stricture.
http://dx.doi.org/10.1016/j.jpurol.2016.04.041 1477-5131/ª 2016 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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R. Babu et al.
Figure The posterior urethra: anterior urethra ratio (PAR) was computed by dividing the maximum posterior urethral diameter by the anterior urethral diameter (in mm). Distances were measured by an on-screen distance measurement tool in the Radiology department, to avoid error. a) Normal VCUG e control: PAR Z 6.02/4.85 Z 1.24; b) PUV at the time of diagnosis: PAR Z 12.7/ 3.3 Z 3.84; c) successful PUV ablation: PAR Z 5.32/4.62 Z 1.15; d) persistent obstruction due to stricture or residual valve: PAR Z 7.11/1.94 Z 3.66.
Introduction Posterior urethral valve (PUV) is an important cause of obstructive uropathy in boys, and can lead to severe lifethreatening complications like end-stage renal disease [1,2]. Primary valve ablation is the widely accepted treatment modality for newborns with PUV. The incidence of recurrent obstruction following PUV ablation due to residual valve or stricture has been reported to be around 10e20% [3,4]. Some surgeons subject all patients to a routine repeat cystoscopy around 3 months after PUV ablation, while others repeat a VCUG before embarking on a repeat cystoscopy, which warrants a general anesthesia [5e11]. There are conflicting reports in the literature on the criterion to determine success following PUV ablation [12e18]. The aims of the present study were to assess the
changes in the posterior urethra: anterior urethra (PU: AU) ratio (PAR) after ablation, and correlate them with cystoscopic findings. It was hypothesized that PAR could be used as an objective tool with which to predict success or failure following PUV ablation.
Materials and methods All neonates and infants with confirmed PUV on VCUG between 2013 and 2016 were prospectively studied. A fixed protocol was used, wherein all patients were initially stabilized with catheterization, intravenous fluids and antibiotics until biochemical parameters/hydration were normalized. A single surgeon performed PUV ablation using 8.5/9 F resectoscope and cold knife at 5, 7, and 12 o’clock positions, as described previously [7]. Per-urethral drainage was kept for 48e72 h post operation.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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MODEL
PU AU ratio in evaluation of success following PUV ablation
1.e3
Initial PAR was computed by dividing maximum posterior urethral diameter by anterior urethral diameter. Distances were measured by an on-screen distance measurement tool (Medsynapse (R) Medsynaptic Pvt Ltd, Pune, India) in the Radiology department by the same person (RB), to avoid error. Only oblique images with good voiding phases were used for assessment. Postoperative VCUG and PAR assessment were performed at 3 months follow-up. Figure describes the technique of PAR assessment and its calculation. All patients who underwent PUV ablation underwent repeat cystoscopy after 3-month VCUG. In addition, sonographic and biochemical resolution were also assessed. Success was defined as cystoscopic resolution of obstruction in addition to biochemical and radiological improvement, and this was correlated with the PAR findings. Urodynamic study, nuclear imaging and long-term outcomes were not included as a part of this study. The PAR values were expressed as mean (SD). An equal number of control patients who had a normal VCUG (as a part of evaluation of antenatal hydronephrosis) were also analyzed. Statistical analysis was performed using student’s t-test and Chi-squared test. A difference with P-value <0.05 was considered statistically significant. Institutional ethical clearance was obtained for this study.
In those with successful PUV ablation (n Z 51) the mean PAR was 1.8 (0.21), while in those with residual PUV/ stricture (n Z 5) the mean PAR was 3.16 (0.54). The difference between these two groups (Fig. 1) was statistically significant (P Z 0.0001, student’s t-test). Applying the value of mean þ 2 SD of successful PUV ablation, an upper limit of PAR >2.2 was proposed to predict failure. Using this cut off, 4/7 with PAR >2.2 had confirmed failure at cystoscopy. All of them underwent repeat ablation and were stable at follow-up. The remaining 3/7 with PAR >2.2 did not have residual obstruction at cystoscopy. The VCUG probably showed persistent non-obstructive PU dilatation, as these patients did not have any associated biochemical or sonological deterioration. In those with PAR <2.2, 48/49 had successful resolution on cystoscopy with a corresponding biochemical/sonological improvement (P Z 0.0005, Fishers exact test) (Table 1). One patient in this group, despite resolution of PU dilatation (PAR <2.2), continued to have sonological deterioration (persistent SFU grade 4 hydronephrosis and >50% post-void residual urine), which was possibly due to valve bladder. This patient did not have evidence of obstruction at cystoscopy.
Results A total of 56 patients with PUV were analyzed in the study between 2013 and 2016. Patient age range included in the study was 3e250 days, with a median age of 15 days. An equal number of controls that had a normal VCUG (no VUR or PU dilatation) and resolution of hydronephrosis at followup ultrasound (n Z 56, median age 18 days, range 5e98 days) were analyzed. The mean PAR was 1.5 (0.42) in controls, while 3.42 (0.75) in those with PUV at diagnosis (P Z 0.0001, student’s t-test). A total of 51/56 (91.1%) were considered to have successful resolution of PUV based on cystoscopic assessment and corresponding improvement in hydroureteronephrosis on ultrasonogram and renal function (SFU grade improved from Grade 3e4 pre ablation to grade 1e2 post ablation; post-void residual volume improved from 40e50% to 15e25% of pre-void volume after ablation; nadir creatinine improved from 1.68 (0.8e5.2) to 0.82 (0.5e1.6) mg/dl). In five patients, there was evidence of persistent hydronephrosis (SFU grade 3e4) and elevated post-void residual volume (40e50%) on ultrasound, and this was associated with persistent obstruction on cystoscopy (three stricture; two residual valve). All these patients underwent repeat PUV ablation. Table 1 Contingency table showing outcomes based on a cut-off posterior urethra: anterior urethra ratio (PAR) value of 2.2. 4/7 with PAR >2.2 had failure confirmed on check cystoscopy, while 48/49 with PAR <2.2 had successful resolution (P Z 0.0001). PAR >2.2 PAR <2.2 Total
Success
Failure
Total
3 48 51
4 1 5
7 49 56
Discussion Endoscopic valve ablation has been described as the best initial management modality for children with PUV [1e4]. VCUG is considered as the reference radiological study with which to visualize the urethra and, hence, diagnose PUV in children [5,6]. Several authors have reported sensitivity rates ranging between 80 and 90% for the initial diagnosis of PUV [7,8]. Shopfner and Hutch [9] studied the normal urethra on VCUG and described its radiological and anatomical features. Popek [10] analyzed the histological and pathological changes in the urethra with obstruction, and felt posterior urethra stretches due to its anatomic and histological characteristics compared with the anterior urethra.
Figure 1 Bars represent mean posterior urethra: anterior urethra ratio (PAR). Compared with the controls (1.5) the mean PAR was significantly higher in those with PUV pre-op (3.42). In the postoperative VCUG, compared with the group with successful resolution (1.8), the mean PAR was significantly higher in those with persistent obstruction (3.16).
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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1.e4 Assessment, on the operating table, of adequacy of valve ablation based on a good urine stream post ablation is highly subjective. An uroflowmetry to assess the outcome at followup is next to impossible in neonates and infants. Improvement in creatinine may not be consistent in all patients with resolved PUV as this could be impacted by congenital renal dysplasia and recurrent pyelonephritis/scarring in some patients. Persistent hydronephrosis in those with resolved PUV could be due to bladder dysfunction or VUR. Post-void residual assessment is not a foolproof method in neonates who do not void on command. In addition, incomplete voiding can be due to immature detrusor sphincter coordination mechanism. A repeat VCUG has been widely used to assess the success following PUV ablation [11]. A varying degree of posterior urethral dilatation often persists, even after a successful PUV ablation and without objective measurement of diameter; it can be difficult for the surgeon to decide on the further course of action. VCUG being a dynamic study, some authors [12] have questioned the wisdom in calculating the urethral ratio and considered cystoscopy to be the ideal way to exclude obstruction. However, a routine repeat cystoscopy to assess success of PUV ablation can be overkill, as it warrants general anesthesia. Schober [13] reported that 52 out of 66 patients with endoscopic findings of PUV had clear evidence of valves on VCUG, while the remaining 21% had inconclusive VCUG. De Jong [14] demonstrated that fair agreement exists among urologists when judging cystoscopy results. Smeulders [15] reported that combining VCUG and cystoscopy could more accurately predict the resolution of obstruction. Oktar [16] preferred analyzing clinicoradiological data before making a decision to repeat cystoscopy. Gupta [17] described a PAR of 1.7 in controls, 4.9 in those with PUV, and 2.14 in those with successful ablation. Bani hani [18] described a PAR of 2.6 in normal children, 8.8 in those with PUV, and 3.1 with successful ablation. Menon [19] reported a more acceptable PAR of 1.04 in controls, 7.8 in those with PUV, and suggested that a PAR of >1.92 should alert to persistent obstruction due to residual valve or stricture. The gross discrepancy in their values is probably related to the ways of computing the ratio. The authors did not mention use of online radiology tools to accurately measure PAR. Also, timing of measurement post PUV ablation was not uniform in the above studies. In many of the above studies, a repeat cystoscopy was not used to decide on success, in addition to clinical/radiological improvement. The present study subjected all patients to repeat cystoscopy. A drawback of the present study was the small number of participants. The impact of bladder function on the urinary stream, and the role of persistent VUR in masking the posterior urethral dilation were not addressed in this study. In addition, a multivariate analysis comparing biochemical and radiological improvements with PAR findings was not performed. This study focused on a single hypothesis: whether PAR could be used as an objective tool with which to predict success or failure following PUV ablation, and the findings support its use. Based on these findings, a PAR >2.2 on VCUG, as a cut off for repeat cystoscopy to rule out persistent obstruction, is proposed. In those with a PAR <2.2, an invasive repeat cystoscopy under general anesthesia could be avoided if radiological
R. Babu et al. improvement is associated with clinical and biochemical improvement. Further larger studies are warranted to support or negate the evidence.
Conflict of interest No conflict of interest.
Funding No funding. RB designed and conceived the study.
References [1] Lo ´pez Pereira P, Martinez Urrutia MJ, Jaureguizar E. Initial and long-term management of posterior urethral valves. World J Urol 2004;22(6):418e24. [2] Chatterjee SK, Banerjee S, Basak D, Basu AK, Chakravarti AK, Chatterjee US, et al. Posterior urethral valves: the scenario in a developing center. Pediatr Surg Int 2001;17(1):2e7. [3] Karmarkar SJ. Long-term results of surgery for posterior urethral valves: a review. Pediatr Surg Int 2001;17(1):8e10. [4] Sudarsanan B, Nasir AA, Puzhankara R, Kedari PM, Unnithan GR, Damisetti KR. Posterior urethral valves: a single center experience over 7 years. Pediatr Surg Int 2009;25(3): 283e7. [5] Sarhan O, El-Ghoneimi A, Hafez A, Dawaba M, Ghali A, Ibrahiem el-H. Surgical complications of posterior urethral valve ablation: 20 years experience. J Pediatr Surg 2010; 45(11):2222e6. [6] Close CE, Carr MC, Burns MW, Mitchell ME. Lower urinary tract changes after early valve ablation in neonates and infants: is early diversion warranted? J Urol 1997;157(3):984e8. [7] Babu R, Kumar R. Early outcome following diathermy versus cold knife ablation of posterior urethral valves. J Pediatr Urol 2013;9(1):7e10. [8] Ditchfield MR, Grattan-Smith JD, de Campo JF, Hutson JM. Voiding cystourethrography in boys: does the presence of the catheter obscure the diagnosis of posterior urethral valves? AJR Am J Roentgenol 1995;164(5):1233e5. [9] Shopfner CE, Hutch JA. The normal urethrogram. Radiol Clin North Am 1968;6(2):165e89. [10] Popek EJ, Tyson RW, Miller GJ, Caldwell SA. Prostate development in prune belly syndrome and posterior urethral valves: etiology of prune belly syndrome e lower urinary tract obstruction or primary mesenchymal defect? Pediatr Pathol 1991;11(1):1e29. [11] Lal R, Bhatnagar V, Mitra DK. Urethral strictures after fulguration of posterior urethral valves. J Pediatr Surg 1998;33(3): 518e9. [12] de Kort LM, Uiterwaal CS, Beek EJ, Jan Nievelstein RA, Klijn AJ, de Jong TP. Reliability of voiding cystourethrography to detect urethral obstruction in boys. Urology 2004;63(5): 967e71. discussion 971e2. [13] Schober JM, Dulabon LM, Woodhouse CR. Outcome of valve ablation in late-presenting posterior urethral valves. BJU Int 2004;94(4):616e9. [14] de Jong TP, Radmayr C, Dik P, Chrzan R, Klijn AJ, de Kort L. Posterior urethral valves: search for a diagnostic reference standard. Urology 2008;72(5):1022e5. [15] Smeulders N, Makin E, Desai D, Duffy PG, Healy C, Cuckow PM, et al. The predictive value of a repeat micturating cystourethrogram for remnant leaflets after primary endoscopic ablation of posterior urethral valves. J Pediatr Urol 2011;7(2): 203e8.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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PU AU ratio in evaluation of success following PUV ablation [16] Oktar T, Salabas E, Acar O, Atar A, Nane I, Ander H, et al. Residual valve and stricture after posterior urethral valve ablation: how to evaluate? J Pediatr Urol 2013;9(2):184e7. [17] Gupta RK, Shah HS, Jadhav V, Gupta A, Prakash A, Sanghvi B, et al. Urethral ratio on voiding cystourethrogram: a comparative method to assess success of posterior urethral valve ablation. J Pediatr Urol 2010;6(1):32e6.
1.e5 [18] Bani Hani O, Prelog K, Smith GH. A method to assess posterior urethral valve ablation. J Urol 2006;176(1):303e5. [19] Prema Menon KLN, Rao S, Vijaymahantesh RP, Kanojia R, Samujh YK, Batra KS, et al. Posterior urethral valves: morphological normalization of posterior urethra after ablation is a significant factor in prognosis. J Indian Assoc Pediatr Surg 2010;15(3):80e6.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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Journal of Pediatric Urology (2016) xx, 1.e1e1.e5
Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation R. Babu, S. Hariharasudhan, C. Ramesh Department of Pediatric Urology, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, India Correspondence to: R. Babu, Pediatric Urology Unit, Sri Ramachandra Medical College and Research Institute, Porur, Chennai 600116, India, Tel.: þ91 9840359062 [email protected] (R. Babu) Keywords Posterior urethral valve; Voiding cystourethrogram; Stricture; Residual valve; PUV ablation; Children Received 9 February 2016 Accepted 21 April 2016 Available online xxx
Summary Introduction There are conflicting reports on the criteria with which to determine success following posterior urethral valve (PUV) ablation. The aims of this study were to assess the value of the posterior urethra: anterior urethra ratio (PAR) in predicting successful PUV ablation. Materials and Methods All neonates and infants with confirmed PUV on voiding cystourethrogram (VCUG) were included. Initial PAR was computed by dividing maximum posterior urethral diameter by anterior urethral diameter. Distances were measured by an on-screen distance measurement tool in the Radiology department, to avoid error. Only oblique images with good voiding phases were used for assessment. All patients underwent cystoscopy and PUV ablation using cold knife. Postoperative VCUG and cystoscopy were performed at 3 months follow-up. Success was defined as cystoscopic resolution of obstruction, in addition to biochemical and radiological improvement, and this was compared with PAR findings. An equal number of age-matched control patients who
had a normal VCUG (as a part of evaluation of antenatal hydronephrosis) were also analyzed. Results A total of 56 patients (median age 15 days, range 3e250 days) were analyzed between 2013 and 2016. The mean PAR was 1.5 (0.42) in controls and 3.42 (0.75) in those with PUV at diagnosis (P Z 0.001). In those with successful PUV ablation (n Z 51) the mean PAR was 1.8 (0.21), and in those with residual PUV/stricture (n Z 5) the mean PAR was 3.16 (0.54). The difference between these two groups was statistically significant (P Z 0.0001). Applying the value of mean þ 2 SD of successful PUV ablation, an upper limit of PAR >2.2 was proposed to predict failure. Using this cut-off, 4/7 with PAR >2.2 had confirmed failure, while 48/49 with PAR <2.2 had successful resolution (P Z 0.001) Conclusion Whenever the posterior urethra is more than 2.2 times the diameter of the anterior urethra (PAR >2.2) on repeat VCUG following a PUV ablation, a cystoscopy check is essential to rule out residual PUV/stricture.
http://dx.doi.org/10.1016/j.jpurol.2016.04.041 1477-5131/ª 2016 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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Figure The posterior urethra: anterior urethra ratio (PAR) was computed by dividing the maximum posterior urethral diameter by the anterior urethral diameter (in mm). Distances were measured by an on-screen distance measurement tool in the Radiology department, to avoid error. a) Normal VCUG e control: PAR Z 6.02/4.85 Z 1.24; b) PUV at the time of diagnosis: PAR Z 12.7/ 3.3 Z 3.84; c) successful PUV ablation: PAR Z 5.32/4.62 Z 1.15; d) persistent obstruction due to stricture or residual valve: PAR Z 7.11/1.94 Z 3.66.
Introduction Posterior urethral valve (PUV) is an important cause of obstructive uropathy in boys, and can lead to severe lifethreatening complications like end-stage renal disease [1,2]. Primary valve ablation is the widely accepted treatment modality for newborns with PUV. The incidence of recurrent obstruction following PUV ablation due to residual valve or stricture has been reported to be around 10e20% [3,4]. Some surgeons subject all patients to a routine repeat cystoscopy around 3 months after PUV ablation, while others repeat a VCUG before embarking on a repeat cystoscopy, which warrants a general anesthesia [5e11]. There are conflicting reports in the literature on the criterion to determine success following PUV ablation [12e18]. The aims of the present study were to assess the
changes in the posterior urethra: anterior urethra (PU: AU) ratio (PAR) after ablation, and correlate them with cystoscopic findings. It was hypothesized that PAR could be used as an objective tool with which to predict success or failure following PUV ablation.
Materials and methods All neonates and infants with confirmed PUV on VCUG between 2013 and 2016 were prospectively studied. A fixed protocol was used, wherein all patients were initially stabilized with catheterization, intravenous fluids and antibiotics until biochemical parameters/hydration were normalized. A single surgeon performed PUV ablation using 8.5/9 F resectoscope and cold knife at 5, 7, and 12 o’clock positions, as described previously [7]. Per-urethral drainage was kept for 48e72 h post operation.
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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PU AU ratio in evaluation of success following PUV ablation
1.e3
Initial PAR was computed by dividing maximum posterior urethral diameter by anterior urethral diameter. Distances were measured by an on-screen distance measurement tool (Medsynapse (R) Medsynaptic Pvt Ltd, Pune, India) in the Radiology department by the same person (RB), to avoid error. Only oblique images with good voiding phases were used for assessment. Postoperative VCUG and PAR assessment were performed at 3 months follow-up. Figure describes the technique of PAR assessment and its calculation. All patients who underwent PUV ablation underwent repeat cystoscopy after 3-month VCUG. In addition, sonographic and biochemical resolution were also assessed. Success was defined as cystoscopic resolution of obstruction in addition to biochemical and radiological improvement, and this was correlated with the PAR findings. Urodynamic study, nuclear imaging and long-term outcomes were not included as a part of this study. The PAR values were expressed as mean (SD). An equal number of control patients who had a normal VCUG (as a part of evaluation of antenatal hydronephrosis) were also analyzed. Statistical analysis was performed using student’s t-test and Chi-squared test. A difference with P-value <0.05 was considered statistically significant. Institutional ethical clearance was obtained for this study.
In those with successful PUV ablation (n Z 51) the mean PAR was 1.8 (0.21), while in those with residual PUV/ stricture (n Z 5) the mean PAR was 3.16 (0.54). The difference between these two groups (Fig. 1) was statistically significant (P Z 0.0001, student’s t-test). Applying the value of mean þ 2 SD of successful PUV ablation, an upper limit of PAR >2.2 was proposed to predict failure. Using this cut off, 4/7 with PAR >2.2 had confirmed failure at cystoscopy. All of them underwent repeat ablation and were stable at follow-up. The remaining 3/7 with PAR >2.2 did not have residual obstruction at cystoscopy. The VCUG probably showed persistent non-obstructive PU dilatation, as these patients did not have any associated biochemical or sonological deterioration. In those with PAR <2.2, 48/49 had successful resolution on cystoscopy with a corresponding biochemical/sonological improvement (P Z 0.0005, Fishers exact test) (Table 1). One patient in this group, despite resolution of PU dilatation (PAR <2.2), continued to have sonological deterioration (persistent SFU grade 4 hydronephrosis and >50% post-void residual urine), which was possibly due to valve bladder. This patient did not have evidence of obstruction at cystoscopy.
Results A total of 56 patients with PUV were analyzed in the study between 2013 and 2016. Patient age range included in the study was 3e250 days, with a median age of 15 days. An equal number of controls that had a normal VCUG (no VUR or PU dilatation) and resolution of hydronephrosis at followup ultrasound (n Z 56, median age 18 days, range 5e98 days) were analyzed. The mean PAR was 1.5 (0.42) in controls, while 3.42 (0.75) in those with PUV at diagnosis (P Z 0.0001, student’s t-test). A total of 51/56 (91.1%) were considered to have successful resolution of PUV based on cystoscopic assessment and corresponding improvement in hydroureteronephrosis on ultrasonogram and renal function (SFU grade improved from Grade 3e4 pre ablation to grade 1e2 post ablation; post-void residual volume improved from 40e50% to 15e25% of pre-void volume after ablation; nadir creatinine improved from 1.68 (0.8e5.2) to 0.82 (0.5e1.6) mg/dl). In five patients, there was evidence of persistent hydronephrosis (SFU grade 3e4) and elevated post-void residual volume (40e50%) on ultrasound, and this was associated with persistent obstruction on cystoscopy (three stricture; two residual valve). All these patients underwent repeat PUV ablation. Table 1 Contingency table showing outcomes based on a cut-off posterior urethra: anterior urethra ratio (PAR) value of 2.2. 4/7 with PAR >2.2 had failure confirmed on check cystoscopy, while 48/49 with PAR <2.2 had successful resolution (P Z 0.0001). PAR >2.2 PAR <2.2 Total
Success
Failure
Total
3 48 51
4 1 5
7 49 56
Discussion Endoscopic valve ablation has been described as the best initial management modality for children with PUV [1e4]. VCUG is considered as the reference radiological study with which to visualize the urethra and, hence, diagnose PUV in children [5,6]. Several authors have reported sensitivity rates ranging between 80 and 90% for the initial diagnosis of PUV [7,8]. Shopfner and Hutch [9] studied the normal urethra on VCUG and described its radiological and anatomical features. Popek [10] analyzed the histological and pathological changes in the urethra with obstruction, and felt posterior urethra stretches due to its anatomic and histological characteristics compared with the anterior urethra.
Figure 1 Bars represent mean posterior urethra: anterior urethra ratio (PAR). Compared with the controls (1.5) the mean PAR was significantly higher in those with PUV pre-op (3.42). In the postoperative VCUG, compared with the group with successful resolution (1.8), the mean PAR was significantly higher in those with persistent obstruction (3.16).
Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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1.e4 Assessment, on the operating table, of adequacy of valve ablation based on a good urine stream post ablation is highly subjective. An uroflowmetry to assess the outcome at followup is next to impossible in neonates and infants. Improvement in creatinine may not be consistent in all patients with resolved PUV as this could be impacted by congenital renal dysplasia and recurrent pyelonephritis/scarring in some patients. Persistent hydronephrosis in those with resolved PUV could be due to bladder dysfunction or VUR. Post-void residual assessment is not a foolproof method in neonates who do not void on command. In addition, incomplete voiding can be due to immature detrusor sphincter coordination mechanism. A repeat VCUG has been widely used to assess the success following PUV ablation [11]. A varying degree of posterior urethral dilatation often persists, even after a successful PUV ablation and without objective measurement of diameter; it can be difficult for the surgeon to decide on the further course of action. VCUG being a dynamic study, some authors [12] have questioned the wisdom in calculating the urethral ratio and considered cystoscopy to be the ideal way to exclude obstruction. However, a routine repeat cystoscopy to assess success of PUV ablation can be overkill, as it warrants general anesthesia. Schober [13] reported that 52 out of 66 patients with endoscopic findings of PUV had clear evidence of valves on VCUG, while the remaining 21% had inconclusive VCUG. De Jong [14] demonstrated that fair agreement exists among urologists when judging cystoscopy results. Smeulders [15] reported that combining VCUG and cystoscopy could more accurately predict the resolution of obstruction. Oktar [16] preferred analyzing clinicoradiological data before making a decision to repeat cystoscopy. Gupta [17] described a PAR of 1.7 in controls, 4.9 in those with PUV, and 2.14 in those with successful ablation. Bani hani [18] described a PAR of 2.6 in normal children, 8.8 in those with PUV, and 3.1 with successful ablation. Menon [19] reported a more acceptable PAR of 1.04 in controls, 7.8 in those with PUV, and suggested that a PAR of >1.92 should alert to persistent obstruction due to residual valve or stricture. The gross discrepancy in their values is probably related to the ways of computing the ratio. The authors did not mention use of online radiology tools to accurately measure PAR. Also, timing of measurement post PUV ablation was not uniform in the above studies. In many of the above studies, a repeat cystoscopy was not used to decide on success, in addition to clinical/radiological improvement. The present study subjected all patients to repeat cystoscopy. A drawback of the present study was the small number of participants. The impact of bladder function on the urinary stream, and the role of persistent VUR in masking the posterior urethral dilation were not addressed in this study. In addition, a multivariate analysis comparing biochemical and radiological improvements with PAR findings was not performed. This study focused on a single hypothesis: whether PAR could be used as an objective tool with which to predict success or failure following PUV ablation, and the findings support its use. Based on these findings, a PAR >2.2 on VCUG, as a cut off for repeat cystoscopy to rule out persistent obstruction, is proposed. In those with a PAR <2.2, an invasive repeat cystoscopy under general anesthesia could be avoided if radiological
R. Babu et al. improvement is associated with clinical and biochemical improvement. Further larger studies are warranted to support or negate the evidence.
Conflict of interest No conflict of interest.
Funding No funding. RB designed and conceived the study.
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Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041
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PU AU ratio in evaluation of success following PUV ablation [16] Oktar T, Salabas E, Acar O, Atar A, Nane I, Ander H, et al. Residual valve and stricture after posterior urethral valve ablation: how to evaluate? J Pediatr Urol 2013;9(2):184e7. [17] Gupta RK, Shah HS, Jadhav V, Gupta A, Prakash A, Sanghvi B, et al. Urethral ratio on voiding cystourethrogram: a comparative method to assess success of posterior urethral valve ablation. J Pediatr Urol 2010;6(1):32e6.
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Please cite this article in press as: Babu R, et al., Posterior urethra: Anterior urethra ratio in the evaluation of success following PUV ablation, Journal of Pediatric Urology (2016), http://dx.doi.org/10.1016/j.jpurol.2016.04.041