What volume can a child normally store in the bladder at a safe pressure?

Bladder height to width ratio as a surrogate marker for non-physiological storage pressures in children with spinal dysraphism

INTRODUCTION

Spinal dysraphism is the most frequent cause of neurogenic bladder. Urodynamic study (UDS) is an important component of the follow-up of a child with neurogenic bladder. However, it suffers from a lack of widespread availability and is further hampered by technical difficulties and difficulty in its interpretation in children. A neurogenic bladder often appears vertically elongated; only limited and sparse literature is available regarding objectively defining the bladder shape and the urodynamic parameters in the cohort.

OBJECTIVES

This study aimed to investigate the usefulness of the bladder's height-to-width ratio (HWR) on cystogram as a screening tool for identifying "non-physiological" bladder pressures in children with spinal dysraphism. A prospective study was undertaken to evaluate children operated for spinal dysraphism. Cystogram, ultrasonography and UDS evaluation were performed. HWR was calculated by the ratio of the maximum height to the maximum bladder width at maximum cystometric capacity (MCC), where MCC was calculated using standard Koff's formula, given by (age in years + 2) *30 ml in children more than one year and weight *7 ml for infants. The children were categorised into groups based on maximum detrusor pressure (MDP) into two groups (MDP ≥ 30 cmH2O and MDP < 30 cmH2O). A receiver-operative characteristic curve was constructed to analyse the sensitivity and specificity of HWR in predicting the MDP.

RESULTS

A total of 53 children, operated for spinal dysraphism, met the study criteria during the study period, from March 2021 to September 2022. The median age of children was 4 years (IQR-3-5.5 years). The HWR ratio was compared between the two groups and was significantly higher for the non-physiological pressure bladders than for physiological pressure bladders (mean of 1.55 vs 1.26, p = 0.001). On evaluating the sensitivity and specificity of HWR for discerning children with non-physiological bladder pressures were 87.5% and 48.28%, respectively. The area under the curve (AUC) was 0.781, with a cut-off value of 1.3.

DISCUSSION

We attempted to evaluate the HWR based on bladder shape objectively. We demonstrated a moderate correlation between the bladder shape and the bladder pressures. An HWR of 1.3 or higher could be significant for identifying a non-physiological bladder storage pressure.

CONCLUSION

The height to width ratio of the bladder on cystogram is a useful tool as a surrogate marker for non-physiological storage pressures in bladders of children with spinal dysraphism.

Bladder capacity and growth in classic bladder exstrophy: A novel predictive tool

INTRODUCTION

Bladder capacity (BC) is an important metric in the management of patients with classic bladder exstrophy (CBE). BC is frequently used to determine eligibility for surgical continence procedures, such as bladder neck reconstruction (BNR), and is associated with the likelihood of achieving urinary continence.

OBJECTIVE

To use readily available parameters to develop a nomogram that could be used by patients and pediatric urologists to predict BC in patients with CBE.

STUDY DESIGN

An institutional database of CBE patients was reviewed for those who have undergone annual gravity cystogram 6 months after bladder closure. Candidate clinical predictors were used to model BC. Linear mixed effects models with random intercept and slope were used to construct models predicting log transformed BC and were compared with adjusted R2, Akaike Information Criterion (AIC), and cross-validated mean square error (MSE). Final model evaluated via K-fold cross-validation. Analyses were performed using R version 3.5.3 and the prediction tool was developed with ShinyR.

RESULTS

In total, 369 patients (107 female, 262 male) with CBE had at least one BC measurement after bladder closure. Patients had a median of 3 annual measurements (range 1-10). The final nomogram includes outcome of primary closure, sex, log-transformed age at successful closure, time from successful closure, and interaction between outcome of primary closure and log-transformed age at successful closure as the fixed effects with random effect for patient and random slope for time since successful closure (Extended Summary).

DISCUSSION

Using readily accessible patient and disease related information, the bladder capacity nomogram in this study provides a more accurate prediction of bladder capacity ahead of continence procedures when compared to the age-based Koff equation estimates. A multi-center study using this web-based CBE bladder growth nomogram (https://exstrophybladdergrowth.shinyapps.io/be_app/) will be needed for widespread application.

CONCLUSION

Bladder capacity in those with CBE, while known to be influenced by a broad swath of intrinsic and extrinsic factors, may be modeled by the sex, outcome of primary bladder closure, age at successful bladder closure and age at evaluation.

Home bladder pressure measurements correlate with urodynamic storage pressures and high-grade hydronephrosis in children with spina bifida

BACKGROUND

Patients with spina bifida are at risk for developing bladder and renal deterioration secondary to increased bladder storage pressures.

OBJECTIVES

To determine the association of home bladder volume and pressure measurements (home manometry) to: 1) detrusor storage pressures on urodynamics (UDS); and 2) the presence of Society of Fetal Urology (SFU) grades 3-4 hydronephrosis on renal bladder ultrasound in patients with spina bifida.

METHODS

Data were prospectively collected on patients with spina bifida and neurogenic bladder requiring clean intermittent catheterization. Patients used a ruler and typical catheterization equipment to measure bladder pressures and volumes at home. Home measurements were compared to UDS detrusor pressures and SFU hydronephrosis grade. Detrusor pressure <20 cm H₂O at 50% maximal cystometric capacity (MCC) on UDS was used as a measure of safe storage pressures on UDS; conversely, detrusor pressure >20 cm H₂O was used a measure to capture both unsafe storage pressures and those with potential for unsafe storage pressures. Receiver-operator characteristic curves and area under curve (AUC) were calculated to depict the association between home manometry variables with detrusor pressures on UDS and SFU grades 3-4 hydronephrosis.

RESULTS

Included were 52 patients with a median age of 10.3 years (interquartile range 6.3-14.4 years). Three home manometry measurements (maximum bladder pressure, bladder pressure at maximum catheterized volume, and mean bladder pressure) > 20 cm H₂O were sensitive for Pdet >20 cm H₂O at 50% MCC. Maximal bladder pressure >20 cm H₂O was the most sensitive among home manometry measures (sensitivity 100%, specificity 70%, AUC 0.92 for Pdet >20 cm H₂O at 50% MCC on UDS; sensitivity 100%, specificity 62%, AUC 0.89 for SFU grade 3-4 hydronephrosis). None of the patients who had maximum home bladder pressure <20 cm H₂O had SFU grades 3-4 hydronephrosis; conversely, individuals with maximal home bladder pressure >20 cm had a wide range of hydronephrosis grades.

CONCLUSION

None of the patients with maximal home bladder pressure <20 cm H₂O had grade 3-4 hydronephrosis. Home measurements of maximal bladder pressure, bladder pressure at maximum catheterized volume and mean bladder pressure of >20 cm H₂O were all sensitive for Pdet >20 cm H₂O at 50% MCC on UDS. Home manometry is an inexpensive and simple technique to identify patients at risk for and to monitor individuals at high risk of upper tract dilation, without incurring significant cost or morbidity.

Urologic Considerations in Pediatric Chronic Kidney Disease

Common causes of pediatric ESRD are distinct from those seen in the adult population. In the pediatric population, the most common are congenital anomalies of the kidney and urinary tract (CAKUT), affecting approximately 30% of children with CKD. These structural anomalies often require coordinated care with the pediatric urology team to address voiding issues, bladder involvement, and the potential need for surgical intervention. For pediatric nephrologists and urologists, common CAKUT that are encountered include antenatal hydronephrosis, obstructive uropathies (eg, posterior urethral valves), and vesicoureteral reflux. As more pediatric patients with CAKUT, CKD, and ESRD transition to adult care, it is important for receiving adult nephrologists to understand the clinical presentation, natural history, and prognosis for these diagnoses. This review outlines the diagnosis and potential interventions for these conditions, including strategies to address bladder dysfunction that is often seen in children with CAKUT. A discussion of these management decisions (including surgical intervention) for CAKUT, which are quite common to pediatric nephrology and urology practices, may provide unique learning opportunities for adult nephrologists who lack familiarity with these pediatric conditions.

Computational Tools for the Investigation of the Male Lower Urinary Tract Functionality in Health and Disease

Purpose

This paper aims to show the potentialities of computational bioengineering in the field of lower urinary tract pathophysiology. Engineering methods allow the investigation of urine flow in healthy and pathologic conditions and the analysis of urethral occlusion by means of artificial urinary sphincters.

Methods

Computational models of bladder and urethra were developed and exploited to investigate the lower urinary tract physiology in health and in disease. Average male morphometric configurations were assumed, together with typical properties of both biological tissues and fluids. The reliability of the models was assessed by the mutual comparison of results and the investigation of data from experimental and clinical activities.

Results

The developed models allowed to analyze typical situations, such as the micturition in health and in disease, and the lumen occlusion by external devices. The models provided information that clinical and experimental tests barely provide, as the occurrence of turbulent phenomena within urine flow, the shear stresses at the lumen wall, the external pressure that is strictly required to occlude the lumen.

Conclusions

The methods of bioengineering allow broadening and deepening the knowledge of the lower urinary tract functionality. More in detail, modeling techniques provide information that contributes to explain the occurrence of pathological situations, and allows to design and to optimize clinical-surgical procedures and devices.

Nonsecretory intestinocystoplasty: postoperative outcomes of 25 years

OBJECTIVE

The objective of bladder augmentation (BA) is to create a low-pressure reservoir with adequate capacity. Despite its benefits, the use of intestinal patches in bladder enlargement provides a high risk of developing complications and BA with demucosalised bowel represents a potential alternative. Therefore, this study evaluated urological parameters and long-term clinical follow-up of patients submitted to nonsecretory BA in a single center with 25 years of experience.

MATERIALS AND METHODS

Patients treated with BA underwent urological evaluation, which included history, physical examination and urodynamic study. The main urodynamic parameters (bladder capacity and bladder compliance) were assessed in the pre and postoperative moments, and compared by the Wilcoxon Signed Rank test. The main long-term complications were described.

RESULTS

269 patients (mean age 14±13 years, 47% male) underwent BA with the use of demucolised intestinal segments. Among the patients in the sample, 187 (69.52%) had neurogenic bladder, 68 (25.28%) had bladder exstrophy, nine had tuberculosis (3.34%), four had a posterior urethral valve (1.49%) and one with hypospadia (0.37%). After the surgical procedure, a significant increment in both urodynamic parameters was found, with a 222% increase in bladder capacity and 604% in bladder compliance (p < 0.001 in both analyzes). Mean follow-up time ranged from 2 to 358 months, with a median of 72 months (IQR 74-247). Among all patients, 5 presented spontaneous perforation.

CONCLUSION

The study showed statistically signifi cant increase in both compliance and bladder capacity after non-secretory BA, with a low rate of severe complications.

Filum Section for Urinary Incontinence in Children with Occult Tethered Cord Syndrome: A Randomized, Controlled Pilot Study

PURPOSE

Occult tethered cord syndrome, in which there is normal neuroanatomic imaging despite clinical and urodynamic evidence of neuropathic bladder behavior, is controversial. Several uncontrolled series describe improvement in bladder function following section of the filum terminale. We performed a pilot randomized, controlled study comparing medical treatment to surgical section of the filum plus medical treatment in children with occult tethered cord syndrome.

MATERIALS AND METHODS

Children refractory to standard medical management for 1 year or more with normal conus position on magnetic resonance imaging and abnormal urodynamics were randomized. Exclusion criteria included any neurological conditions, spinal dysraphism, bladder outlet obstruction and an atonic bladder. Patients were assessed at randomization and 1 year later with a standardized urodynamic score, the validated PEMQOL (Pediatric Enuresis Module on Quality of Life™) scale, and a validated bowel and bladder dysfunction score.

RESULTS

After 8 years we accrued 21 patients. The bowel and bladder dysfunction score improved in the surgical and medical arms (20% and 24%) and the urodynamic score improved slightly (6% and 4%, respectively). The PEMQOL Child and Family Impact Scales improved modestly in both groups. All differences were nonsignificant. Interim analysis indicated that more than 700 patients in each arm would be required to demonstrate a statistical difference with respect to urodynamic score based on our preliminary data.

CONCLUSIONS

There appears to be no objective difference in urological outcome between medical management plus or minus filum section for patients with occult tethered cord syndrome. These data challenge the existence of the concept of occult tethered cord syndrome, in which bowel and bladder dysfunction score is attributed to tethering by the filum despite a normally located conus.

Outcomes of living donor renal transplantation in children with lower urinary tract dysfunction: a comparative retrospective study

OBJECTIVES

To compare outcomes of renal transplantation (RTx) in children with end-stage renal disease (ESRD) resulting from lower urinary tract dysfunction (LUTD) vs other causes.

PATIENTS AND METHODS

A database of children (<18 years old) who underwent RTx between May 2008 and April 2012 was reviewed. Patients were divided into those with LUTD (group A, n = 29) and those with other causes of ESRD (group B, n = 74). RTx was performed after achieving low intravesical pressure (<30 cmH2 O) with adequate bladder capacity and drainage. The groups were compared using Student's t-test, Mann-Whitney, chi-squared or exact tests. Graft survival rates (GSRs) were evaluated using Kaplan-Meier curves and the log-rank test.

RESULTS

The mean ± sd (range) age of the study cohort was 5.05 ± 12.4 (2.2-18) years. Causes of LUTD were posterior urethral valve (PUV; 41.4%), vesico-ureteric reflux (VUR; 37.9%), neurogenic bladder (10.3%), prune belly syndrome (3.4%), obstructive megaureter (3.4%) and urethral stricture disease (3.4%). There was no significant difference in age, dialysis duration or donor type. In group A, 25 of the 29 patients (86.2%) underwent ≥1 surgery to optimize the urinary tract for allograft. Pretransplant nephrectomy was performed in 15 of the 29 patients (51.7%), PUV ablation in nine patients (31%) and ileocystoplasty in four patients (13.7%). The mean ± sd follow-up was 4.52 ± 1.55 and 4.07 ± 1.27 years in groups A and B, respectively. There was no significant difference in creatinine and eGFR between the groups at different points of follow-up. The GSRs at the end of the study were 93.1 and 91.1% in groups A and B, respectively (P = 1.00). According to Kaplan-Meier survival curves, there was no significant difference in the GSR between the groups using the log-rank test (P = 0.503). No graft was lost as a result of urological complications. In group B, one child died from septicaemia. The rate of urinary tract infections was 24 and 12% in groups A and B, respectively, but was not significant. No significant difference was found between the groups with regard to the incidence of post-transplantation hydronephrosis. Of the 22 patients who had hydronephrosis after transplantation, three were complicated by UTI. Injection of bulking agents was required in two patients for treatment of grade 3 VUR. In the third patient, augmentation cystoplasty was needed.

CONCLUSION

Acceptable graft function, survival and UTI rates can be achieved in children with ESRD attributable to LUTD. Thorough assessment and optimization of LUT, together with close follow-up, are key for successful RTx.

The Role of Genetically Modified Mesenchymal Stem Cells in Urinary Bladder Regeneration

Recent studies have demonstrated that mesenchymal stem cells (MSCs) combined with CD34⁺ hematopoietic/stem progenitor cells (HSPCs) can function as surrogate urinary bladder cells to synergistically promote multi-faceted bladder tissue regeneration. However, the molecular pathways governing these events are unknown. The pleiotropic effects of Wnt5a and Cyr61 are known to affect aspects of hematopoiesis, angiogenesis, and muscle and nerve regeneration. Within this study, the effects of Cyr61 and Wnt5a on bladder tissue regeneration were evaluated by grafting scaffolds containing modified human bone marrow derived MSCs. These cell lines were engineered to independently over-express Wnt5a or Cyr61, or to exhibit reduced expression of Cyr61 within the context of a nude rat bladder augmentation model. At 4 weeks post-surgery, data demonstrated increased vessel number (~250 vs ~109 vessels/mm²) and bladder smooth muscle content (~42% vs ~36%) in Cyr61OX (over-expressing) vs Cyr61KD (knock-down) groups. Muscle content decreased to ~25% at 10 weeks in Cyr61KD groups. Wnt5aOX resulted in high numbers of vessels and muscle content (~206 vessels/mm² and ~51%, respectively) at 4 weeks. Over-expressing cell constructs resulted in peripheral nerve regeneration while Cyr61KD animals were devoid of peripheral nerve regeneration at 4 weeks. At 10 weeks post-grafting, peripheral nerve regeneration was at a minimal level for both Cyr61OX and Wnt5aOX cell lines. Blood vessel and bladder functionality were evident at both time-points in all animals. Results from this study indicate that MSC-based Cyr61OX and Wnt5aOX cell lines play pivotal roles with regards to increasing the levels of functional vasculature, influencing muscle regeneration, and the regeneration of peripheral nerves in a model of bladder augmentation. Wnt5aOX constructs closely approximated the outcomes previously observed with the co-transplantation of MSCs with CD34⁺ HSPCs and may be specifically targeted as an alternate means to achieve functional bladder regeneration.

Predictors of urinary continence following tethered cord release in children with occult spinal dysraphism

OBJECTIVE

Children with occult spinal dysraphism represent a wide spectrum of patients. Previous studies assessing urologic outcomes have in part been deficient due to the inability to appropriately categorize these patients and gather long-term follow-up data. In this study, a uniform set of patients that had occult spinal dysraphism with magnetic resonance imaging findings of a fatty filum terminale (FF) and/or low-lying cord (LLC) was identified. Utilizing long-term follow-up data, predictors for achieving urinary continence following tethered cord release (TCR) were determined.

METHODS

A retrospective chart review of pediatric patients with a diagnosis of tethered cord who underwent TCR from 1995 to 2005 was performed. Analysis was limited to patients who had primary TCR by one of two neurosurgeons within our multidisciplinary spina bifida clinic, who had greater than 1-year follow-up, and who were old enough to have continence status assessed (age > 6 years unless definitively toilet trained earlier). Patients with other associated forms of spinal dysraphism (lipomyelomeningeocele, spinal lipomas, sacral agenesis), anorectal malformations, and genitourinary anomalies were excluded. Pre- and post-TCR urodynamics, radiographic studies, functional orthopedic status, and urologic outcomes were assessed. Urodynamic results were categorized by three blinded urologists into one of three urodynamic patterns: (1) normal, (2) indeterminate, and (3) high risk.

RESULTS

A total of 147 patients with FF and/or LLC that underwent TCR were reviewed. 51 patients were excluded because of another associated spinal dysraphism (15/51 patients) or an anorectal/genitourinary anomaly (36/51 patients). Fifty-nine of the remaining 96 patients had adequate long-term follow-up data to be included in the study. 20 patients were asymptomatic at the time of TCR while 39 presented with orthopedic and/or urologic symptoms. The average age at surgery was 59.3 months (range 2-277 months) with an average follow-up of 7.0 years (range 1-16 years). At latest follow-up, 47 (80%) patients were continent while 12 (20%) were either incontinent or utilizing clean intermittent catheterization (CIC). Statistical analysis revealed that age of untethering, type of cutaneous lesion, level of conus, presence of hydronephrosis, and high-grade vesicoureteral reflux (VUR) were not independent predictors of continence. In patients with a cutaneous lesion who were asymptomatic, 19/20 obtained continence post-TCR (*p = 0.036). In patients who were old enough to assess continence pre-TCR, 14/25 patients were continent pre-TCR and 11/25 were incontinent. Of the 14 who were continent pre-TCR, all remained continent post-TCR (*p = 0.002). Of the 11 who were incontinent pre-TCR, five (45%) eventually became continent post-TCR. Assessment of urodynamic data revealed that neither pre- nor post-TCR urodynamics predicted continence status.

CONCLUSION

Isolated cutaneous lesions and preoperative continence status are positive predictors for post-TCR continence. While pre- and post-TCR urodynamics do not predict continence status, their utility in preoperative work-up, monitoring for retethering, and long-term urologic follow-up requires further examination.

Onabotulinumtoxin A for treating overactive/poor compliant bladders in children and adolescents with neurogenic bladder secondary to myelomeningocele

This retrospective study was performed to verify the efficacy and safety of Onabotulinumtoxin A (BTX-A) in treating children with neurogenic bladder (NB) secondary to myelomeningocele (MMC) with detrusor overactivity/low compliance. From January 2002 to June 2011, 47 patients out of 68 with neuropathic bladder were selected (22 females, 25 males, age range 5–17 years; mean age 10.7 years at first injection). They presented overactive/poor compliant neurogenic bladders on clean intermittent catheterization, and were resistant or non compliant to pharmacological therapy. Ten patients presented second to fourth grade concomitant monolateral/bilateral vesicoureteral reflux (VUR). All patients were incontinent despite catheterization. In the majority of patients Botulinum-A toxin was administered under general/local anesthesia by the injection of 200 IU of toxin, without exceeding the dosage of 12IU/kg body weight, diluted in 20 cc of saline solution in 20 sites, except in the periureteral areas. Follow-up included clinical and ultrasound examination, urodynamics performed at 6, 12 and 24 weeks, and annually thereafter. Seven patients remained stable, 21 patients required a second injection after 6–9 months and 19 a third injection. VUR was corrected, when necessary, in the same session after the BT-A injection, by 1–3 cc of subureteral Deflux^®. Urodynamic parameters considered were leak point pressure (LPP), leak point volume (LPV) and specific volume at 20 cm H₂O pressure. The results were analyzed using the Wilcoxon test. All patients experienced a significant 66.45% average increase of LPV (Wilcoxon paired rank test = 7169 × 10 ⁻¹⁰) and a significant 118.57% average increase of SC 20 (Wilcoxon paired rank test = 2.466 × 10 ⁻¹²). The difference between preoperative and postoperative LPP resulted not significant (Wilcoxon paired rank test = 0.8858) No patient presented severe systemic complications; 38/47 patients presented slight hematuria for 2–3 days. Two patients had postoperative urinary tract infection. All patients were hospitalized for 24 h with catheterization. Thirty-eight out of 47 patients achieved dryness between CIC; nine patients improved their incontinence but still need pads. Ten patients have resumed anticholinergic agents. Our results suggest that the use of BTX-A is safe and effective in patients with MMC with a positive effect on their dryness and quality of life.

Urodynamic testing--is it a useful tool in the management of children with cutaneous stigmata of occult spinal dysraphism?

PURPOSE

Lumbar cutaneous stigmata in infants may be associated with occult spinal dysraphism and often prompt urological evaluation, including urodynamic testing. We examined whether urodynamic testing is useful in this population by evaluating the association between abnormal urodynamic test results and need for tethered cord release.

MATERIALS AND METHODS

We reviewed a historical cohort of children with cutaneous stigmata of spinal dysraphism referred to our hospital from 2002 to 2010. We evaluated patient characteristics, imaging, urodynamic studies and neurosurgical interventions. We analyzed the association between urodynamic testing and imaging studies, and neurosurgical intervention.

RESULTS

We retrospectively studied 123 patients with a median age of 11 months (IQR 6.5-15.5), including 112 nontoilet trained infants (91%). Of the patients 19% (23 of 123) had abnormal urodynamics, 85% (99 of 116) had abnormal spinal magnetic resonance imaging and 96% (98 of 102) had an abnormal spinal ultrasound. Tethered cord release was performed in 40 of 121 patients (33%). A significant association was found between abnormal urodynamics and neurosurgical intervention (p = 0.002). Abnormal spinal magnetic resonance imaging was also significantly associated with operative intervention (p = 0.05). Ultrasound of the spine (p = 1.0), ultrasound of the abdomen/pelvis (p = 0.68), history of urinary tract infections (p = 1.0) and constipation (p = 0.67) were not associated with intervention for tethered cord release.

CONCLUSIONS

Abnormal urodynamic studies in infants with cutaneous stigmata of spinal dysraphism are significantly associated with the requirement for neurosurgical intervention. Urodynamics are an important diagnostic modality aiding the neurosurgeon in determining the need for surgical intervention in this population.

Twelve-hour daytime observation of voiding pattern in newborns <4 weeks of age

AIM

To investigate the voiding pattern in <4-week-old newborns by 12-h daytime observation periods.

METHODS

Twenty-one healthy 1- to 28-day-old newborns were included (10 full term, 11 preterm). The 12-h free voiding parameters, including voiding frequency (VF), voiding volume (VV), post-voiding residual volumes (PRV) and status at voiding (awake/sleep), were recorded at day 1, 4, 7, 14 and 28 after birth.

RESULTS

Voiding was recorded 778 times. VF increased in the full-term and preterm newborns between day 4 and 7, decreased in preterms between day 14 and 28, but remained higher than in the full terms. VV increased twice in full terms and once in preterms during 28 days and PRV fluctuated. In contrast, VV was higher in the full term than in the preterms at days 4, 7, 14 and 28. PRV was higher at days 4 and 28. Interrupted voiding was less frequent in the full term than in the preterms.

CONCLUSION

Voiding pattern in the preterms differed in many ways from that of the full-term newborns. Frequent interrupted and incomplete voiding pattern in the preterm newborns indicates a disrupted coordination of the detrusor-sphincter and a delayed maturation of the neural micturition centre.

Evaluation of maximum voided volume in Korean children by use of a 48-h frequency volume chart

Study Type - Diagnostic (validating cohort). Level of Evidence 2a. What's known on the subject? and What does the study add? The relationship between the maximum voided volume followed a linear curve. The formula presented, bladder capacity (mL) = 12 ×[age (years) + 11], is thought to be a reasonable one for Korean children. Korean children have a smaller bladder capacity than that reported in previous Western studies.

OBJECTIVE

• To develop practical guidelines for the prediction of normal bladder capacity in Korean children measured by a frequency volume chart (FVC), maximum voided volume (MVV) is an important factor in the diagnosis of children with abnormal voiding function.

SUBJECTS AND METHODS

• In all, 298 children, aged 3-13 years, with no history of voiding disorders volunteered for the study. The MVV was determined in 219 subjects by use of a completely recorded FVC.

RESULTS

• Linear regression analysis was used to define the exact relationship between age and bladder capacity. An approximate formula related age to bladder capacity as follows: bladder capacity (mL) = 12 ×[age (years) + 11].

CONCLUSIONS

• The relationship between the MVV measured by a FVC by age (3-13 years) of Korean children followed a linear curve. • When applied to normal voiding patterns, the formula presented appears to be a reasonable one for Korean children.

Urodynamic studies are recommended in children with central nervous system tumors regardless of location

PURPOSE

Neurogenic bladder dysfunction is a frequent occurrence in association with neoplasms involving the central nervous system. We determine whether tumor location in children with central nervous system neoplasms correlates with specific patterns of urodynamic abnormalities, alleviating the need for urodynamic investigations in these patients.

MATERIALS AND METHODS

A total of 62 children with the diagnosis of a central nervous system neoplasm underwent urodynamic investigation after treatment between 1994 and 2004. Patient demographics, tumor location and etiology were assessed. Urodynamic variables recorded included bladder capacity, early and late compliance, voiding pressure and post-void residual volume. For comparative analysis patients were grouped according to central nervous system level of involvement. Statistical analysis was performed, with p<0.05 considered significant.

RESULTS

Mean±SD patient age at urodynamic evaluation was 10.6±7 years. Tumor was located intracranially in 21% of patients and in the spinal cord in 79% (cervical/thoracic in 27%, lumbar in 27%, sacral in 47%). There was no correlation between tumor location and any specific bladder dynamic parameter (p>0.05). Similarly there were no significant differences in urodynamic findings in patients with intracranial vs extracranial tumors, or in those with sacral vs suprasacral involvement.

CONCLUSIONS

Abnormalities in urodynamic parameters in children with a central nervous system tumor cannot be predicted based on the location of tumor involvement. Therefore, urodynamic evaluation is appropriate in all patients with neoplastic involvement of the central nervous system, regardless of the tumor location, for best management of lower urinary tract function.

The neurogenic bladder: medical treatment

Neurogenic bladder sphincter dysfunction (NBSD) can cause severe and irreversible renal damage and bladder-wall destruction years before incontinence becomes an issue. Therefore, the first step in adequate management is to recognize early the bladder at risk for upper- and lower-tract deterioration and to start adequate medical treatment proactively. Clean intermittent catheterization combined with anticholinergics (oral or intravesical) is the standard therapy for NBSD. Early institution of such treatment can prevent both renal damage and secondary bladder-wall changes, thereby potentially improving long-term outcomes. In children with severe side effects or with insufficient suppression of detrusor overactivity despite maximal dosage of oral oxybutynin, intravesical instillation is an effective alternative. Intravesical instillation eliminates systemic side effects by reducing the first-pass metabolism and, compared with oral oxybutynin, intravesical oxybutynin is a more potent and long-acting detrusor suppressor. There is growing evidence that with early adequate treatment, kidneys are saved and normal bladder growth can be achieved in children so they will no longer need surgical bladder augmentation to achieve safe urinary continence in adolescence and adulthood.

Development of an Objective Score to Quantify the Pediatric Cystometrogram

PURPOSE

We developed a reliable tool for quantitative assessment of the pediatric cystometrogram.

MATERIALS AND METHODS

Scores for expected capacity (EV), compliance (EV20), activity and sensation were developed according to established formulas for norms. Ordinal scores were derived by calculating observed over expected findings. Based on the derived percents scores of 1 to 5 were assigned. For EV--0 to 5 the formula used was EV = (age + 2) x 30 and for EV20--0 to 5 the formula used was EV20 = 17 x age + 55. Activity was determined as the volume of the first, total number and magnitude of involuntary contractions, each scored 0 to 5 and divided by 3. Sensation was scored as 0 to 3 according to volume at first sensation. A total of 87 blinded cystometrograms in 49 patients were independently scored twice by 3 pediatric urologists. The resultant 522 total and 2,088 component scores were assessed for reliability.

RESULTS

Intrarater reliability was strong with 80% of total scores (208 of 261) within +/- 1 point from initial to subsequent retest. Reliability component scores were stronger with 94% (983 of 1,044) within +/- 1 point from test to retest. Spearman's rank correlations for total score was 0.82 to 0.98, indicating a strong relationship between test and retest. Interrater reliability of components was strong with 89% of scores (1,851 of 2,088) between urologists within +/- 1 point. Correlation coefficients for total scores were 0.80 to 0.96, indicating a high degree of consistency between urologist assessments (p <0.05).

CONCLUSIONS

This score appears to reliably quantify the pediatric cystometrogram. Its application may be useful for the objective assessment of detrusor behavior before and after intervention. Further applications should allow refinement of this tool.

Voiding dysfunction in children. Pelvic-floor exercises or biofeedback therapy: a randomized study

Fifty-six patients 5.9-15.2 years old with dysfunctional elimination syndrome (DES) unimproved by previous therapies were randomly distributed into two voiding training programs: group 1 contained 26 patients submitted to 24 training sessions over a 3-month period; group 2 contained 30 patients submitted to 16 sessions over a 2-month period. Both groups adhered to a voiding and drinking schedule, received instruction on adequate toilet posture, were reinforced through the maintenance of voiding diaries, and went through proprioceptive and pelvic floor muscle training (Kegel exercises). Group 2 patients also received biofeedback therapy. Clinical evaluation was carried out before each program's initiation and 1, 6, and 12 months after each program's termination. All patients were submitted to renal ultrasonography and dynamic ultrasonography before and 6 months after each program's conclusion. Millivoltage recordings of pelvic floor muscles were compared before and after training. Urinary continence was improved after completion of either training program. Only those patients who received biofeedback training showed a significant decrease in postvoiding residual (PVR) urine as detected by dynamic ultrasonography. Our results show that either training regime can reduce episodic urinary incontinence and urinary tract infection but that further study is required to identify the optimal training duration.

The Role of Bladder Capacity in Antidiuretic and Anticholinergic Treatment for Nocturnal Enuresis

PURPOSE

We evaluated combination treatment with desmopressin and oxybutynin in patients with enuresis who did not respond to desmopressin monotherapy. Furthermore, we compared 2 methods of estimating bladder capacity and evaluated the ability of these methods to predict the response to desmopressin and oxybutynin.

MATERIALS AND METHODS

A total of 60 children with a mean age +/- SD of 10.6 +/- 3.0 years who had monosymptomatic nocturnal enuresis completed the study. After a 2-week observation period maximal voided volume during free access to fluid intake was determined by a 2-day frequency-volume chart and maximal voided volume after water load was determined on a separate day. Patients then received 20 mug desmopressin intranasally at bedtime during 2 weeks. In nonresponders to desmopressin with less than a 50% decrease in wet nights 5 mg oxybutynin twice daily was added for another 2 weeks.

RESULTS

Of the patients 41 (68%) showed more than 50% decrease in wet nights during the 2-week desmopressin treatment period (4.6 +/- 1.6 to 0.7 +/- 0.8, p <0.001). In desmopressin nonresponders combined treatment with desmopressin and oxybutynin resulted in a further decrease in wet nights (4.0 +/- 1.2 to 1.7 +/- 1.4, p <0.001). Maximal voided volume during free access to fluid intake was significantly higher in desmopressin responders than in nonresponders (244 +/- 111 vs 160 +/- 65 ml, p <0.001). In contrast, maximal voided volume after water load was not significantly different between desmopressin responders and nonresponders.

CONCLUSIONS

The study indicates a role for oxybutynin in combination with desmopressin in children who are not responding to desmopressin monotherapy. Maximal voided volume during free access to fluid intake is a clinically useful predictor of the response to desmopressin but not to oxybutynin.

Trying to predict 'dangerous' bladders in children: the area under the curve concept

OBJECTIVE

Children with neurological and non-neurological lower urinary tract dysfunction normally undergo video urodynamics. One reason is to try to diagnose 'dangerous' bladders. Currently, bladder compliance is used to predict 'dangerous' bladders; however, in children there are no standardized methods of measurement and thus no 'cut-off' values. Compliance may also be normal even though high-pressure detrusor overactivity waves may exist during the filling phase of urodynamics. We tried to determine whether measuring the area under the detrusor pressure curve (AUC) during the filling phase of urodynamics would be a useful parameter in predicting 'dangerous' bladders.

PATIENTS AND METHODS

Children referred to the urodynamics unit at Southmead Hospital, a tertiary referral centre, from 2000 to 2004 were investigated. Although 130 patients were identified, only 15 patients had raw data which were analysable using the available computer software.

RESULTS

There was no correlation between the AUC and predicting 'dangerous' bladders possibly due to limitations in the computer software.

CONCLUSION

Although the study did not reveal any correlation between the AUC and 'dangerous' bladders, it revealed the limitations of the available computer software in determining AUC, and highlighted the need for new standardized software and multinational, multi-centre trials to look into the concept of AUC. There is also a need for the International Continence Society to standardize methods and terminology in predicting 'dangerous' bladders.

[Urodynamic investigations in children]

Performing urodynamic investigations in children presents some difficulty due to the lack of any normogram, and due to the results that vary with age. Such investigation is therefore carried out only when clinical examination and radiological assessment fail to explain a voiding dysfunction. The procedure should be performed in a urodynamic unit that has paediatric expertise. A specific paediatric procedure is to be respected when performing uroflowmetry and cystometry in children. Assessing the urethral pressure profile is very difficult since moving a catheter along the urethra causes a reflex activity of the pelvic floor muscles. Main indications are: neuropathic bladders, voiding dysfunctions, urinary infections, anorectal malformations and pelvic tumours. As in adults, urodynamic investigations are useful when selecting a therapeutic strategy.

Renal transplantation in children with abnormal lower urinary tract

OBJECTIVE

This retrospective study reports the outcomes as well as pre- and posttransplant urologic treatments of renal transplantation for children with an abnormal lower urinary tract (LUT).

METHODS

Between March 1981 and December 2001, 195 children (< or =18 years of age) received live-donor kidney transplants. The 15 recipients (14 boys and 1 girl, mean age 13.5 +/- 3 years) who had lower urinary tract disorders included posterior urethral valves (PUV) with valve bladder (n=12) and neuropathic bladders secondary to meningomyelocele (n=3). These children were evaluated by voiding cystourethrogram, cystourethroscopy, and cystometry. The children with PUV were maintained on clean intermittent catheterization (CIC) and a detrusor relaxant at least 3 months before transplantation. Augmentation ileocystoplasty or continent cutaneous diversion were used in three patients. The graft and patient survivals as well as complications in this cohort was compared with a group of children with normal LUT, who underwent renal transplantation during the same period.

RESULTS

One child died in the early posttransplant period due to rupture of the external iliac artery. Follow-up ranged from 6 months to 16 years (mean=4.5 years). During the same period the graft and patient survival rates were comparable between the group of children with versus without abnormal LUT. Furthermore, mean serum creatinine and creatinine clearance values were also comparable. The group with an abnormal LUT showed a higher incidence of urinary fistula (3/14) and recurrent UTI and/or bacteremia (4/14).

CONCLUSIONS

Renal transplantation is feasible with good results for children with abnormal LUT. Pre- and posttransplant urologic management is critical for a successful outcome. However these children display a high incidence of urologic and infectious complications.

Measurement of bladder compliance can be standardized by a dimensionless number: clinical perspective

OBJECTIVE

To devise a new, practical and more accurate method for measuring bladder compliance, and to show that traditional estimates of compliance are impractical.

MATERIALS AND METHODS

Childhood bladder capacity varies greatly with age while detrusor pressure in a normal bladder does not. Consequently, traditional bladder compliance (DeltaV/DeltaP) increases with age, i.e. maturation. Therefore we devised a standard method that includes normal values of pressures and volumes to calculate and report bladder compliance in children, and that also applies to adults. A dimensionless number (NWahl(-1)) was computed for standardizing bladder compliance, comparing the normalized capacity to normalized pressure by the ratio (DeltaV/V(cap,NL))/(DeltaP/P(cap,NL)), where DeltaP is the pressure at bladder capacity, DeltaV the volume at bladder capacity, V(cap,NL) the volume at mean expected bladder capacity and P(cap,NL) the pressure at mean expected bladder capacity. V(cap,NL) is obtained from nomograms of published data.

RESULTS

The bladder compliance of patients undergoing urodynamic testing was calculated using NWahl(-1) and the traditional equation (DeltaV/DeltaP). NWahl(-1) provided a more accurate diagnosis and therefore was of more practical use.

CONCLUSIONS

Bladder compliance depends on patient age, sex and size; the new estimate used to standardize bladder compliance is based on these factors and is a dimensionless number. This may help when comparing patients and assessing outcomes.

SHOULD WARM INFUSION SOLUTION BE USED FOR URODYNAMIC STUDIES IN CHILDREN? A PROSPECTIVE RANDOMIZED STUDY

PURPOSE

We hypothesized that warm infusion solution should be used for urodynamic studies in children because it more closely simulates normal physiology. Thus, we conducted a prospective randomized study comparing consecutive room temperature (RT) and body temperature (BT) cystometrograms (CMG) in the same child.

MATERIALS AND METHODS

Subjects underwent identical CMGs using RT and BT saline in random order. Maximum cystometric bladder capacity (CBC), pressure at CBC, uninhibited detrusor contractions, detrusor leak point pressure, maximum flow rate, pressure at maximum flow, maximum voiding pressure, residual urine and pressure specific volumes below 20 and 30 cm water were compared. Data were analyzed using ANOVA, t test, and chi-square.

RESULTS

RT and BT CMGs in 44 males and 47 females with a mean age of 8.6 years were compared. Of the children 58 (64%) had spinal dysraphism, 8 (9%) had cerebral palsy, 5 (6%) had posterior urethral valves and 20 (21%) had recurrent urinary tract infection, daytime incontinence or frequency/urgency symptoms. Maximum CBC, pressure at CBC, and pressure specific volumes below 20 and 30 cm water were significantly lower (10% to 15%) during BT cystometry. Maximum flow rate was higher with BT saline. Detrusor leak point pressure, pressure at maximum flow, maximum voiding pressure, and residual urine did not differ. Uninhibited detrusor contractions were more frequent during RT infusions. No gender differences were found. The discrepancies between RT and BT cystometry were most prominent in infants, children with spinal dysraphism and children with large bladders.

CONCLUSIONS

There is a difference between cystometries performed using RT and BT saline. Capacity, storage variables and detrusor activity are diminished during BT cystometry. Although statistically significant differences were found between consecutive RT and BT CMGs, the magnitude of the difference may not be clinically relevant to change management. As such, we do not believe it is necessary to use warm infusion solution on a systematic basis for urodynamic studies in children. However, for children younger than 2 years when the magnitude was more relevant, the use of warm solution is recommended.

Measurement of bladder compliance can be standardized by a dimensionless number: theoretical perspective

OBJECTIVES

To: (i) calculate traditional compliance (CTrad) for a normal bladder by DeltaV/DeltaPdet, where DeltaV is the mean volumetric capacity and DeltaPdet is the detrusor pressure rise; (ii) assess its usefulness; (iii) identify the variables that are necessary for correctly assessing bladder compliance; and (iv) using these variables, report a method that, because it includes the effect of patient age, sex and size, correctly assesses compliance for management strategies.

METHODS

We obtained the mean volumetric capacity of a normal bladder (V(cap,NL)) and the mean detrusor pressure rise (P(cap,NL)) on filling a normal bladder to its volumetric capacity from our and other published work; (ii) calculated CTrad for a normal bladder; (ii) showed that the variables necessary for assessing compliance correctly are DeltaV, DeltaPdet, V(cap,NL), and P(cap,NL); and (iii) showed that the relationship among these is the dimensionless number, NWahl(-1), calculated as (DeltaV/V(cap,NL))/(DeltaPdet/P(cap,NL)). This value for individuals with a normal bladder was calculated, tabulated and graphed.

RESULTS

Because a normal individual's bladder capacity increases with age while the detrusor pressure increase does not, CTrad increases with age and therefore cannot be used for assessing compliance. Published data substantiate our result that CTrad for an individual with a normal bladder varies from 6.3 at 0.5 years old to 90 mL/cmH2O at 18 years old. NWahl(-1) correctly assesses bladder compliance because it is the same for all normal cases; consequently NWahl(-1) is more practical for clinical use.

CONCLUSIONS

Bladder compliance is standardized using DeltaV, DeltaPdet, V(cap,NL), and P(cap,NL) to give NWahl(-1), and bladder compliance is usefully reported using this value.

NONSECRETORY INTESTINOCYSTOPLASTY: A 10-YEAR EXPERIENCE

PURPOSE

We present long-term results on the use of demucosalized intestine for reconstructive surgery of the bladder.

MATERIALS AND METHODS

A total of 129 bladder augmentations with demucosalized intestine were performed in 123 patients (55% males and 45% females) 3 months to 53 years old during the last 10 years. Of the patients 82 presented with neurogenic bladder, 40 with bladder exstrophy, 3 each with tuberculosis and posterior urethral valves, and 1 with female hypospadias. Sigmoid was used in 104 cases and ileum in 25. In 105 cases a silicone balloon was left inside the augmented bladder for 2 weeks. In the remaining cases bladder mucosa was preserved and no mold was used. A silicone inflatable bladder neck cuff was implanted at the same time as augmentation in 32 patients.

RESULTS

Followup ranged from 3 to 135 months (median 51.0). There was a 329% increase in bladder capacity and compliance increased 7-fold. There were 13 (10.1%) cases considered failures, which were treated with reaugmentation using demucosalized ileum (6), different forms of augmentation (5) and no reaugmentation (2). There was no mucus formation, bladder perforation or neoplasia.

CONCLUSIONS

Based on our study we conclude that demucosalized intestine is a safe alternative for bladder augmentation and can be used for the same indications as total bowel segments.

Ureterocystoplasty: Indications for a Successful Augmentation

PURPOSE

We evaluate the outcome of ureterocystoplasty based on preoperative evaluations.

MATERIALS AND METHODS

We reviewed preoperative ultrasound, voiding cystourethrography and preoperative/postoperative urodynamic studies (UDS) in 64 patients undergoing ureterocystoplasty.

RESULTS

Augmentation was performed with the distal 5 to 8 cm of a single megaureter in 8 patients without and 16 with grade 4 to 5/5 reflux. Median gain or loss in capacity and compliance was +0.14-fold and -0.11-fold, respectively. Re-augmentation has occurred or is pending in 23 cases (92%). Augmentation was performed in 40 patients with either a complete single or double collecting system. In 9 patients without reflux the diameter of the augmenting system was directly related to success. None of 6 with a ureteral diameter of greater than 1.5 cm required re-augmentation (median increase in bladder capacity and compliance 6 and 50-fold, respectively). Ureterocystoplasty was inadequate in 3 patients with a ureteral diameter of less than 1.5 cm and re-augmentation was required. In 31 patients with reflux, preoperative UDS of the entire system was beneficial. If the system had either normal or mild noncompliance (greater than 20 ml/cm H2O) ureterocystoplasty improved compliance 1-fold (6 cases) and re-augmentation not required. If UDS showed moderately or severely noncompliant system (less than 20 ml/cm H2O, 26 cases) ureterocystoplasty increased capacity and compliance by 0.4-fold (40%) and 0.25-fold (25%), respectively. Re-augmentation has occurred or is pending in 21 of 26 cases (81%).

CONCLUSIONS

Ureterocystoplasty with any single or double collecting system is warranted in patients without reflux and a ureteral width greater than 1.5 cm, and in patients with reflux and mild noncompliance (greater than 20 ml/cm H2O) on UDS.

Low inferior vena caval catheters for hemodynamic and pulmonary function monitoring in pediatric critical care patients

OBJECTIVE

To assess the value of low inferior vena caval (LIVC) catheters for estimating central venous pressure in pediatric intensive care patients and to assess influences of intra-abdominal pressures and mean airway pressure on these measurements.

DESIGN

Prospective cohort of consecutive patients.

SETTING

Pediatric intensive care unit.

PATIENTS

Thirty patients ranging in age (18, 0-1 yrs; four, 1-3 yrs; four, 3-10 yrs; four, > or =10 yrs).

INTERVENTIONS

Interventions included catheterizations via internal jugular, subclavian, and common femoral veins, as well as direct right atrial catheterization during surgery; arterial catheter placement; airway pressure monitoring during mechanical ventilation; indirect intra-abdominal pressure monitoring via bladder catheter pressure readings; and arterial and central venous blood gas analysis. LIVC vein catheters were placed below the origin of the renal veins.

MEASUREMENTS AND MAIN RESULTS

LIVC pressure was highly correlated with central venous pressure (n=30, r2=.965, p=.0001). LIVC pressure did not correlate with intra-abdominal pressure (n=18, r2=.000). Mean airway pressure did not correlate with central venous pressure (n=11, r2=.106). The pH of LIVC blood was similar to that of central venous blood (n=18, r2=.941, p=.0001). PCO2 values of inferior vena cava and central venous blood correlated (r2=.945, p=.0001). However, agreement between inferior vena cava and central venous PO2 and oxyhemoglobin saturation was poor (PO2, r2=.066; oxyhemoglobin saturation, r2=.000).

CONCLUSIONS

LIVC catheters whose tips lie below the origin of the renal veins predict central venous pressure in pediatric intensive care unit patients. Intra-abdominal pressure and mean airway pressure do not affect this relationship, within the wide range of values for these variables included in this study. Blood samples drawn from femoral venous catheters can be used to monitor acid-base balance and partial pressure of carbon dioxide.

Long-term results of pediatric renal transplantation into a dysfunctional lower urinary tract

BACKGROUND

The authors reviewed their long-term experience with pediatric renal transplantation into a dysfunctional lower urinary tract to evaluate the results of contemporary lower urinary tract evaluation and management on graft survival and function.

METHODS

Between 1990 and 1996, 21 renal transplants were performed in 20 children with dysfunctional lower urinary tracts and 61 transplants were performed in 61 patients with normal lower urinary tracts. The minimum follow-up was 36 months (mean, 62.0 +/- 19.6 months). The cause of lower urinary tract dysfunction included posterior urethral valves (n=13), prune belly syndrome (n=4), meningomyelocele (n=2), and urogenital sinus abnormality (n=1). Urodynamics were performed on all children with dysfunctional lower urinary tracts. Using these perioperative assessments, lower tract management strategies were devised, including timed voiding alone (n=6), clean intermittent catheterization (n=8), bladder augmentation (n=4), and supravesical urinary diversion (n=2).

RESULTS

Overall 5-year actuarial patient and graft survival rates were 100% versus 95% (P=not significant [NS]) and 83% versus 69% in the dysfunctional and normal urinary tract groups (P=NS), respectively. Mean serum creatinine levels in dysfunctional and normal urinary tract patients with functioning grafts at 3 years were 1.3 +/- 0.5 and 1.3 +/- 0.7 mg/dL, respectively (P=NS). However, 35% of patients with a dysfunctional lower urinary tract experienced urologic complications.

CONCLUSIONS

Pediatric renal transplantation into a dysfunctional lower urinary tract yields outcomes comparable to transplantation into the normal lower urinary tract. Because of the high urologic complication rates, careful surveillance of lower urinary tract function by urodynamic evaluation is essential to optimize these outcomes.

What is the Variability Between 2 Consecutive Cystometries in the Same Child?

PURPOSE

We compared the results of 2 cystometrograms (CMGs) performed during a single session in the same child to determine the variability between consecutive cystometries.

MATERIALS AND METHODS

Subjects underwent 2 consecutive bladder fillings performed at the same rate and position. Maximum cystometric bladder capacity (CBC), pressure at CBC, leak point pressure, maximum flow rate, pressure at maximum flow, maximum voiding pressure, residual urine and pressure specific volumes (PSV) less than 20, 30 and 40 cm water were compared between studies. Uninhibited detrusor contractions (UICs), defined by the previous and new International Children's Continence Society definitions of UIC, were also compared. Data were analyzed using paired t test, chi-square and interclass correlation.

RESULTS

CMGs in 32 male and 34 female children were available for analysis. Mean subject age was 7.4 years (range 1 month to 18 years). Of the children 43 (65%) had spinal dysraphism, 4 (6%) had cerebral palsy, 5 (8%) had posterior urethral valves, and 14 (21%) had recurrent urinary tract infection, daytime incontinence and frequency/urgency symptoms. Maximum CBC, pressure at CBC, leak point pressure, maximum flow rate, pressure at maximum flow, maximum voiding pressure and residual urine did not differ between the 2 studies. PSVs less than 20, 30 and 40 cm water were highly correlated between the 2 CMGs (interclass correlation coefficients 0.795, 0.683 and 0.850, respectively). There were more UICs on the first than the second study (p = 0.02 and 0.03) as defined by the previous and new definitions of UIC. UIC threshold volume was less on the first CMG (p = 0.00 and 0.03). UICs were either present or absent on both studies in 56 of the 66 (85%) children by the previous UIC definition and in 51 (77%) by the new UIC definition.

CONCLUSIONS

There is no difference in CBC, PSV and pressure flow parameters when performing consecutive urodynamic studies in the same child. However, UICs are more frequent on the first study. We conclude that repeat cystometry is not indicated in the absence of UICs on the first study and suggest that the second consecutive CMG be used for clinical interpretation when repeat studies are performed in the same session.

Estimation of glomerular filtration rate and bladder capacity: the effect of maturation, ageing, gender and size

OBJECTIVE

To show that glomerular filtration rate (GFR) and bladder capacity (BC) develop isometrically, and to provide graphs for estimating GFR and BC for specific individuals of any age, sex, height and weight, for cystometric purposes.

MATERIALS AND METHODS

GFR and BC data were collected from published reports; graphs relating GFR and BC to age, sex, height and weight were obtained by using a computerized curve-fitting technique that minimizes the 1.1 power of the absolute error.

RESULTS

The plots show the GFR and BC for individuals of 10th, 50th and 90th percentile height and weight as a function of age and sex for different physiological conditions. GFR increases up to age 20 years and thereafter declines, whereas GFR per unit body surface area reaches a maximum at 3.25 years old and declines thereafter.

CONCLUSIONS

The clinical management strategy to preserve or enhance renal function in paediatric and adult nephrological disease should incorporate the present data on development, growth, ageing and deterioration of function. These data should be used when interpreting cystometrograms and evaluating compliance. The graphs are useful for clinically estimating GFR and BC, especially when estimating infusion rate and BC for individual patients. BC and GFR develop isometrically with a proportionality constant of 4.56 min, except from birth to 1.5 years of age. Accordingly, individuals with healthy urinary systems, irrespective of age, sex and size, in the same physiological conditions have, on average, the same time to reach BC, ranging from 7 h at a normal 1% GFR to 41 min at the maximum diuresis of 10% GFR.

Surgical management of the neurogenic bladder and bowel

Spina bifida and myelodysplasia are associated with neurogenic abnormalities of the bladder and bowel function. All children with myelodysplasia require an evaluation of their urinary tract with ultrasound and urodynamics to confirm normal bladder and kidney function. Patients with anatomical and functional abnormalities require treatment, the mainstay being intermittent catheterization and anticholinergic medication. The treatment goals for patients with a neurogenic bladder are the preservation of the upper urinary tract, bladder and bowel continence, independence, autonomy, and facilitation of self-esteem. A minority of children will not respond to conservative therapy and will ultimately require surgical intervention. This review will discuss the surgical options for bladder augmentation, bladder neck reconstruction and closure, as well as the methods for the creation of continent catheterizable stomas. The timing, indications, and description for each procedure will be addressed. Finally, the antegrade continence enema procedure will be described for the management of refractory fecal incontinence.

The role of imipramine therapy in bladder exstrophy after bladder neck reconstruction

OBJECTIVE

To assess the role of imipramine therapy after bladder neck reconstruction in patients with bladder exstrophy.

PATIENTS AND METHODS

Seventeen children with bladder exstrophy who achieved partial continence after bladder neck reconstruction received imipramine (1.5-2 mg/kg body weight) for a mean duration of 9.5 months. Assessment before and after therapy included an objective classification of the continence status and artificial slow-fill cystometry.

RESULTS

Eleven of the 17 patients had a good clinical response to imipramine, with an increase in the continent period to > 2 h, and in nocturnal continence. The urodynamic findings showed a significant improvement in the capacity, end-fill pressure, uninhibited contractions and '20 below' capacity. Only minor side-effects of the drug were reported.

CONCLUSION

Imipramine has a role in patients who achieve partial continence after reconstruction, and who have a moderately small capacity bladder with poor compliance and uninhibited contractions.

Dysfunction of the lower urinary and distal gastrointestinal tracts in pediatric patients with known spinal cord problems

Destruction of the urinary tract in children with elimination, storage, and holding dysfunction of the lower urinary and the distal GI tracts is caused primarily by high intravesical pressure. UTI accelerates this process. The LPP and the status of the urethral control mechanism and its relationship to the detrusor are the primary determinants of intravesical pressure. Intravesical pressures of more than 40 cm H2O are dangerous because they cause a pressure gradient that is transmitted proximally to the renal papillae, which results in the cessation of renal blood flow and a loss of renal function over time. Hydroureteronephrosis, VUR, UTI, urinary incontinence, and calculi formation also may occur. If these dangerously high intravesical pressures remain untreated, renal failure is likely to occur over time. These children then require dialysis or renal transplantation to survive, which is tragic and represents an enormous economic cost to society. Renal failure and upper urinary tract damage is nearly 100% preventable with early and appropriate evaluation and treatment. CIC is a crucial part of the management of these children and has been shown to be safe and effective, even in newborn boys. The use of the Credé maneuver (i.e., manual compression) to empty the bladder is obsolete and should be abandoned. The distal GI tract is inseparable from the lower urinary tract and must be treated simultaneously. Failure to treat the distal GI tract yields poor clinical results and much patient dissatisfaction and makes it difficult or impossible to treat the child's urinary tract problem successfully. Bowel-management programs must include daily high water and fiber intake, together with digital perianal stimulation or fecal extraction. Neuropathic bladder and bowel problems that are intractable to conservative medical and mechanical (i.e., CIC and digital perianal stimulation or fecal extraction, respectively) management almost always can be corrected surgically with high success rates in cooperative patients. Finally, neuropathic bladder and bowel problems can be extremely isolating and debilitating problems. Psychologic counseling and emotional support must be provided as needed. The care that these patients receive must be organized, comprehensive, and correlated with these patients' lifestyles. If these children are evaluated and treated early, they have the potential to live long, healthy, and productive lives.

Prototype system for enhancing cystometric analysis with special emphasis on the pediatric population

BACKGROUND AND PURPOSE

A urodynamic test system of improved accuracy and reliability was developed and implemented for enhancing cystometry. This system integrates known medical information, including the specialized problems of pediatric urodynamics, with the cystometric and imaging data.

METHODS

After the requirements for the ideal cystometrogram test unit were established, a system was constructed, calibrated, and implemented in clinical practice. The patient's age, size, and sex are used to produce a patient-specific pressure-volume template for the cystometrogram test.

RESULTS

This template showed the minimal and normal bladder capacities and the physiologically safe, equivocal, and dangerous pressure fields coded with symbolic colors. Different time averages of the pressure data were used to show bladder factors such as compliance and instability. The templates with data were presented automatically (therefore objectively) without operator intervention on monitors during testing and as printed copies on completion.

CONCLUSIONS

The presentation of data in an easily understood format facilitates effective communication between the urologist, referring physician, and patient. Some of the physiological and statistical problems in pediatric urodynamic testing are efficiently and accurately resolved by this system, resulting in better analysis and diagnostic capabilities.

Cystometric evaluation of reconstructed classical bladder exstrophy

OBJECTIVE

To evaluate the association of urodynamic variables with continence and upper tract status after reconstruction in patients with classical bladder exstrophy.

PATIENTS AND METHODS

Thirty-one patients with bladder exstrophy were assessed 1 year after a modified bladder neck reconstruction. The evaluation included a detailed history, radioisotope renography, voiding cysto-urethrography, ultrasonography and artificial slow-filling cystometry.

RESULTS

Fifteen of the 31 patients were satisfactorily continent; their maximum cystometric capacity was higher than that of the incontinent patients. The compliance, assessed as the maximum bladder capacity at a detrusor pressure of < 20 cmH2O, was significantly higher in the continent patients. There was a 45% incidence of unstable contractions in the 31 patients. Persistent sphincteric activity was detected on electromyography in 10 patients during voiding. Twenty-one patients could initiate a detrusor contraction during voiding. The residual volume was significant in nine of the 21 patients who attempted to void. Patients with a high end-fill pressure (> 40 cmH2O) had a significantly higher incidence of unobstructive hydronephrosis than had patients who had an end-fill pressure of < 40 cmH2O.

CONCLUSIONS

Bladder abnormalities are common after reconstruction of bladder exstrophy, with poor compliance, small capacity and unstable contractions. These factors hinder any increase in capacity and cause persistent incontinence. Hypocompliance and high end-fill pressure can lead to upper tract damage even in continent patients. Detailed urodynamic evaluation is vital to assess the results and to plan subsequent treatment.

Further experience with seromuscular colocystoplasty lined with urothelium

PURPOSE

We report our continuing experience with seromuscular colocystoplasty lined with urothelium. This procedure is designed to preserve the urothelium and potentially decrease the incidence of complications associated with standard bladder augmentation.

MATERIALS AND METHODS

We retrospectively reviewed the charts of 32 patients who underwent seromuscular colocystoplasty lined with urothelium between April 1994 and July 1999. Data were collected on patient demographics, surgical indications, previous and adjunctive surgical procedures, preoperative and postoperative urinary continence, upper urinary tract changes, urodynamic parameters, surgical complications and histological findings.

RESULTS

Mean patient age at surgery plus or minus standard deviation was 11.1 +/- 4.8 years. Mean followup was 1.6 +/- 1 years. A mean of 1.5 +/- 0.9 years postoperatively urodynamic studies available in 28 cases showed that total and safe bladder capacity increased by 1.8 and 2.4-fold, respectively. Continence was achieved in 71% of patients after the initial procedure, increasing to 81% after secondary procedures. Hourglass deformity developed in 7 cases (22%), augmentation failed in 4 (12.5%) and there were bladder calculi in 2 (6%). New onset or increased hydronephrosis and reflux were present in 6 of 62 (10%) and 9 of 60 (15%) evaluated renal units, respectively. Of the 7 interpretable biopsies 5 revealed various degrees of repeat colonic mucosal growth. There was no bladder perforation or metabolic abnormalities, and mucous production was not clinically significant.

CONCLUSIONS

Seromuscular colocystoplasty lined with urothelium is a viable alternative to standard bladder augmentation. The 2 procedures have a similar overall complication rate. Comparatively there appears to be a low incidence of bladder calculi, mucous production has not been clinically significant, metabolic disturbances have not developed and perforation has not occurred during short-term followup. We are enthusiastic about this technique and continue to apply it in select patients.

A new, unique and simple method for ureteral implantation in kidney recipients with small, defunctionalized bladders

BACKGROUND

Major, almost insurmountable, deterrents exist to the use of the small capacity, defunctionalized, nonneurogenic urinary bladder in renal transplantation, namely, the technical difficulty in performing a satisfactory ureteral implantation with conventional methods and the potential secondary problems with high grade ureteral reflux and obstruction. Alternatives are less than ideal and include transplantation into a bowel-augmented urinary bladder with intermittent self-catheterization, ileal conduit urinary diversion, or avoidance of transplantation and relegating the patient to life-long dialysis.

METHODS

Eight consecutive patients (ages 13 months to 29 years) with small, defunctionalized urinary bladders underwent a new method of intravesical implantation of the transplant ureter. The mean capacity of these bladders was 18.5+/-13.1 ml (range 6 to 45 ml), with the bladders defunctionalized for a mean 81.6+/-24.3% of the patients' total lifetime. The technique involved placement of the transplant ureter into a shallow, mucosa-denuded, rectangular trough extending from a superiorly placed ureteral hiatus distally to the trigone. We hypothesized that the mucosal margins on the two lateral aspects of the rectangular trough would grow over the anterior surface of the ureter until they met the advancing mucosal edges from the contralateral side to form a natural neosubmucosal tunnel.

RESULTS

Posttransplantation cystoscopic examination demonstrated bladder mucosal regeneration and growth over the ureter, confirming the spontaneous development of a good length neosubmucosal tunnel. All patients demonstrated no evidence of ureteral reflux or ureteral obstruction, whereas an immediate prior cohort of four consecutive patients with bladder capacities < or =30 ml showed that three of four had ureteral reflux (P=0.02) and four of four developed hydronephrosis (P=0.002). All urinary bladders in the present cohort enlarged to expected normal or nearnormal capacities. Serum creatinines were stable throughout the entire follow-up period, with the exception of one patient who had rejection episodes. Two patients had urinary tract infections posttransplantation, but there were no episodes of acute pyelonephritis.

CONCLUSIONS

This novel technique for ureteral implantation successfully capitalizes on the regenerative potential of the bladder mucosa, resulting in a physiological, anatomically natural, and very effective neosubmucosal tunnel. It appears to guarantee success against both ureteral reflux and obstruction, no matter how small the urinary bladder, and offers no hindrance to enlarging the bladder to near normal capacity posttransplantation. The implantation technique is simple and safe, and its use should eliminate the reluctance to use these bladders. Moreover, this procedure offers a major incentive for the successful rehabilitation of small, defunctionalized, nonneurogenic bladders after kidney transplantation.