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Purpose: The ventral aspect of the penis in boys with hypospadias is composed of dysplastic tissue of the skin and the urethra. The aim of this study was to assess the pre-operative size and biomechanical properties of urethrae in boys with and without hypospadias using a more objective catheter-based system., Materials & Methods: In this non-blinded clinical observation study, the study population consisted of 19 boys with hypospadias-the case group (median age 13.9 months [range: 12.2-21.3])-and seven boys without hypospadias-the control group (median age 8.5 months [range: 3.8-18.1]). Modified measurements of impedance were used to assess the size, compliance and viscoelasticity of the urethrae under stepwise increased pressures (between 0, 40 and 60 cmH 2 O) using a customised Endolumenal Functional Lumen Imaging probe (EndoFLIP®)., Results: The sizes of the urethrae in boys with hypospadias are variable but tend towards being narrower and less compliant than those of the control subjects i.e. median diameter for meatus urethra was 3.2 mm (range: 2.98-3.92) in the hypospadias group compared with 3.64 (range: 3.22-4.44) in the control group at 40 cmH 2 O, and the median change in diameter at meatus urethra was 0.08 mm (range: -0.02 to 0.52) in the hypospadias group compared with 0.23 mm (range: -0.02 to 0.34) when the pressure was increased from 40 to 60 cmH 2 O. This biomechanical analysis found that there was no significant viscoelasticity of the urethral meatus in both the groups, whereas the remainder of the urethral structure generally had viscoelastic properties in the control group, seen as a creep on the time/diameter curves (Figure). In the group of boys with hypospadias, evaluations of the urethrae revealed varying viscoelastic abilities, ranging from abilities that were comparable with those of the control subjects to no sign of viscoelasticity at all., Conclusions: This study is the first to measure the biomechanical properties of the urethra in children, which might help to provide an understanding as to the structural and functional changes associated with hypospadias. The urethrae in the subjects with hypospadias were variable in diameter but tended to be narrower overall, especially in the distal portion of the urethra. Furthermore, the urethrae in boys with hypospadias were frequently less viscoelastic than those of controls., Clinical Relevance: The EndoFLIP® system may be a future way of objectively estimating the severity of a urethral obstruction and could potentially be included in the postoperative assessment of patients with signs of hampered voiding., (Copyright © 2018 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Introduction: Bladder capacity in children with nocturnal enuresis is assessed by maximal voided volumes (MVV) obtained through daytime frequency volume (FV) charts. Although a degree of association has been demonstrated, daytime MVV does not consistently correspond with the nocturnal bladder capacity (NBC) in monosymptomatic nocturnal enuresis (MNE). It was hypothesized that isolated reduced NBC is a common phenomenon in children with nocturnal enuresis, despite normal daytime bladder function., Objective: The aim of this study was to evaluate NBC in children with MNE and normal daytime voided volumes. Specifically, it aimed to determine the prevalence and degree of reduced NBC when using nocturnal urine production (NUP) during wet nights as a surrogate estimate of NBC. Furthermore, it aimed to investigate the relationship between NBC and desmopressin response., Materials and Methods: Data from 103 children aged 5-15 years consecutively treated for MNE in a tertiary referral centre and with normal MVV on daytime FV charts were collected for this cohort study. Home recordings were completed for 2 weeks at baseline and during desmopressin dose titration. Estimated nocturnal bladder capacity (eNBC) was assessed separately each night as the total NUP causing a wet night. If NUP during a wet night was less than MVV, it was considered to be reduced eNBC during that particular night., Results: Surprisingly, 82% (n = 84) of the children with MNE and normal daytime MVV experienced at least one wet night, with NUP below the daytime MVV indicative of a reduced eNBC. For 84 patients, mean percentage of wet nights with reduced eNBC (NUP below MVV) was 49% (SD ± 31). A total of 11% of children with frequently reduced eNBC (>40% of wet nights with reduced eNBC) responded to desmopressin (Summary Fig.). Of the children with frequently reduced NBC, 91% experienced wet nights, with NUP <65% of expected bladder capacity (EBC)., Conclusions: A significant proportion of children with MNE and normal MVV during the daytime frequently experienced wet nights, with a NUP well below their MVV and even <65% of EBC. This indicated that bladder reservoir dysfunction during sleep is relatively common in MNE. This abnormality was not reflected on daytime recordings, and thus nighttime data with NUP must be collected. This phenomenon may explain treatment failure to desmopressin, despite adequate antidiuretic response., (Copyright © 2017 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Conventional urodynamics (CU) is a highly standardized evaluation of lower urinary tract function. However, in pediatric patients there is concern that the reliability of measurements could be influenced by development effects and measurement variability, as well as by the unfamiliar clinical environment. Ambulatory urodynamics (AU) provides an alternative to this - it uses natural filling, is measured over a prolonged period, and is conducted in a child-friendly environment., Objective: The aim of this study was to conduct a comparative analysis of AU and CU to evaluate the consistency in voiding patterns obtained with these two methods of urodynamic testing., Study Design: Urodynamic parameters obtained by AU and CU methods in 50 pediatric patients aged >5 years were retrospectively analyzed. Voiding patterns were categorized into six types: coordinated contraction, detrusor after-contraction, fluctuated contraction, pre-void contraction, relief voiding, and weak or absent contraction. Voiding patterns were used to determine the repeatability within urodynamic tests and to identify consistency between AU and CU tests. Five urodynamic parameters were quantified and compared between AU and CU: voided volume, flow rate, maximum detrusor pressure, and detrusor pressure at peak flow rate. For inter-observer variation analysis, 100 voiding curves were randomly selected and categorized by two independent observers; inter-observer agreement was evaluated using the kappa statistic., Results: A single pattern of voiding was identified in five patients using AU and 37 using CU. Consistency of a single pattern between AU and CU was identified in three patients, and consistency between a predominant pattern with AU, defined by one type of voiding occurring >50% of one's voids, and a single pattern with CU was identified in 10 patients (summary table). Flow rates were similar between methods; however, higher maximum detrusor pressure and detrusor pressure at peak flow and lower voided volume were recorded with AU., Discussion: AU resulted in more diverse voiding patterns. Along with the differences in measured urodynamic parameters challenges the application of findings from one method to form a clinical diagnosis. Furthermore, CU may not be as sensitive as AU to the variability in lower urinary tract pathophysiology., Conclusions: More diverse voiding patterns were identified in AU compared with CU, with a lack of consistency in identified voiding pattern in both methods. Therefore, the urodynamic findings in children may have to be analyzed in more detail, taking the variations into account., (Copyright © 2016 Journal of Pediatric Urology Company. All rights reserved.)

Objective: To investigate the feasibility of robotically assisted retroperitoneoscopic upper pole heminephrectomy with the Da Vinci Surgical System., Patients and Methods: Fourteen girls (median age 4.9 years, range 0.5-20.2) underwent upper pole heminephrectomy using the retroperitoneal approach with the Da Vinci Surgical System. Prior to all procedures a ureteric catheter was placed. Using a modified access to the retroperitoneum the ureter to the upper pole and the vessels were dissected and ligated. The upper pole was removed by diathermy or ultrasonic scissors., Results: The median operative time was 176 min (range 120-360 min). In two patients, the procedure was converted to an open operation; in one case due to lack of progress, and in the other due to bleeding which could not be handled with the robotically assisted instruments. One patient had the ureteric stump removed due to recurrent infections. In all other patients the peri- and postoperative period was uneventful., Conclusion: The robotically assisted system is an excellent tool for minimally invasive surgery in the retroperitoneum, such as pyeloplasty, with its advantages of wrist-like movements of the instruments, magnified three-dimensional view, tremor control and improved ergonomics for the surgeon. Further development of the instruments is required before the resection of a non-functioning upper pole can be included in the spectrum of indications.