STANDARDIZED ULTRASOUND METHOD FOR ASSESSING DETRUSOR MUSCLE THICKNESS IN CHILDREN

Effect of bladder volume and compliance on ultrasonographic measurement of bladder wall thickness in children with neurogenic bladder dysfunction

BACKGROUND

Spina bifida is the most common cause of neurogenic bladder dysfunction in children. Measurement of bladder wall thickness (BWT) is non-invasive, low-cost, and may be complementary to urodynamics in demonstrating bladder condition. It is still unknown the wall thickness response to volume change in bladders with different compliance states.

OBJECTIVE

To determine the most appropriate measurement technique by revealing the differences in measurements performed in different compliance and volume conditions in children with neurogenic bladder.

STUDY DESIGN

In the prospective study in 2022, patients with spina bifida who continued their urological follow-up in our spina bifida center were included. Patients with a diagnosis of the neurogenic bladder who performed clean intermittent catheterization at least 4-6 times a day and had a recent urodynamic result in the last 6 months were included in the study. According to urodynamic results, patients were divided into two groups normocompliant (NC) and low-compliant (LC) bladders. BWT measurements were made from the anterior, posterior, right lateral, and left lateral walls of the bladder 3 times as full, half-volume, and an empty bladder.

RESULTS

The study included 50 patients (NC group n:21, LC group n:29). The mean age of 24 female and 26 male patients was 6.45 ± 4.07 years. In all BWT measurements, a significant increase in wall thickness was observed with decreasing bladder volume. The best correlation between bladder volume and BWT was found in the anterior wall with a weak negative correlation (p = 0.049, r = -0.280). However, lateral wall measurements were significantly higher in low compliant patients compared to normocompliant patients when the bladder was full. The mean right lateral wall thickness was 1.58 ± 0.68 mm in the NC group and 2.18 ± 1.35 mm in the LC group (p = 0.044). Left lateral wall thickness was 1.45 ± 0.44 mm in the NC group and 2.02 ± 1.4 mm in the LC group (p = 0.033).

DISCUSSION

Although standardization has been tried to be achieved in BWT measurements, we understand from the studies in the literature that there is no unity in practice.

CONCLUSION

Lateral wall measurements were found to be significantly higher in LC patients compared to normocompliants in full bladder suggesting that more accurate BWT follow-up can be performed with lateral wall measurements in neurogenic bladder patients if bladder compliance is low. The present study seems to be the first study in the literature in which bladder compliance and ultrasonographic bladder wall thickness measurements were evaluated together in children with neurogenic bladder dysfunction.

Could urinary nerve growth factor and bladder wall thickness predict the treatment outcome of children with overactive bladder?

Objective:

Bladder wall thickness (BWTh) measurements and Nerve Growth Factor (NGF) /creatinine (Cr) values, as noninvasive tools, were found to predict daytime voiding problems in children with overactive bladder (OAB). The goal of this research was to examine if bladder wall thickness together with urine NGF/Cr could be a clinical utility in treatment outcome of OAB in children.

Patients and Methods:

A total of 60 children with OAB, (Group 1; n=40) and healthy normal controls (Group 2; n=20), aged 6-14 years old were involved in this prospective study. Children were evaluated with detailed history and physical examination, including neurologic examination, and were asked to complete a self-reported questionnaire and a 3-day bladder diary with the aid of their parents. Uroflowmetry was performed in all cases. Urinary nerve growth factor levels were measured by the ELISA and BWTh was measured trans-abdominally by one uro-radiologist specialized in pediatric ultrasonography. Urinary NGF levels were normalized by urinary creatinine levels and compared among all subgroups. Children with OAB received urotherapy as first line treatment at least for three months. 18 children refractory to urotherapy received anticholinergic therapy defined as group 3.

Results:

The median age of the study group was 10 (range 6 to 16). After urotherapy, 22 children had similar BWTh and NGF/Cr values compared to controls. (2.75 ± 1.15; 2.40 ± 1.00 mm; p=0.86 and 1.02 ± 0.10; 0.78 ± 0.15; p=0.12, respectively). After anticholinergic treatment, BWTh levels (2.25 ± 0.90; 2.40 ± 1.00 mm; p=0.94) and NGF/Cr values (0.95 ± 0.10; 0.78 ± 0.15; p=0.42, respectively) had no significantly difference compared to controls (Group 2).

In receiver operating characteristic analysis, bladder wall thickness was found to have sensitivity of 85% and specificity of 84.2% (3,20 AUC, 913; 95 %) and NGF/Cr had sensitivity of 90% and specificity of 92.1% (1,595; AUC, 947; 95 %) in predicting treatment outcome in children with OAB.

Conclusions:

Bladder wall thickness measurements and NGF/Cr values, as noninvasive tools, could guide outcomes in the treatment of children with overactive bladder.

Can ultrasound measurement of bladder wall thickness be a useful adjunct for regular urodynamics in children with spina bifida?

INTRODUCTION

Spina bifida is a major cause of neurologic bladder dysfunction among children. The goal of neurogenic bladder treatment is to preserve renal function. Close follow-up is essential, as lower urinary tract functions can change with patient growth. Presently, invasive urodynamics is the gold standard for precisely assessing lower urinary tract function. Ultrasound is a low-cost, non-invasive, uncomplicated examination that can be easily repeated. Bladder wall thickness (BWT) measurement by ultrasound has been proposed as a non-invasive alternative for identifying lower urinary tract dysfunctions.

OBJECTIVE

Currently there are few reports on BWT in children with spina bifida, and BWT assessment methodology has yet to be defined. The present study aim was to investigate whether BWT could be a useful adjunct for regular urodynamics in children with spina bifida. We especially focused on the precise bladder volume during BWT measurements that were simultaneously performed with urodynamics.

STUDY DESIGN

This prospective observational study investigated 33 patients with spina bifida who underwent video urodynamics. We assessed BWT measurements using ultrasound simultaneously performed with video urodynamics. BWT was calculated for the ventral and dorsal walls at 0%, 20%, 40%, 60%, 80%, and 100% of the expected bladder capacity.

RESULTS

Median of bladder capacity was 240 mL, and bladder compliance was 19.2 mL/cmH₂O. Detrusor overactivity was present in 66.7% and vesicoureteral reflux was present in 27.3% of the patients. BWT of the ventral wall was significantly lower than the dorsal wall. During increases in the bladder volume, both the ventral and dorsal walls exhibited proportional thinning (p < 0.05). There were no significant differences for BWT between males and females. Although there was a higher statistical tendency for detrusor overactivity versus without detrusor overactivity (p = 0.085), there were no significant differences found between patients with and without detrusor overactivity.

DISCUSSION

This is the first report where multiple BWT measurements points with video urodynamics were simultaneously performed. Selection of bladder volumes for BWT measurements is critical. Our current study measured six points for each patient during urodynamics. However, available data was not sufficient for detecting bladder function. Until now, there has been no valid standard condition defined for measuring BWT and thus, lack of a standardized method has resulted in discrepancies among studies.

CONCLUSION

Our measurement conditions showed BWT may not correlate with the degree of bladder detrusor dysfunction. As BWT ultrasound cannot identify bladder dysfunction of children with spina bifida, this cannot be used as a substitute for invasive urodynamics.

Prolonged Indwelling Urethral Catheterization as Minimally Invasive Approach for Definitive Treatment of Posterior Urethral Valves in Unstable Premature Babies

Premature newborns with posterior urethral valves (PUV) may present with medical conditions taking priority over definitive surgical care. We encountered three of such cases who underwent initial bladder decompression via transurethral catheterization and waited 2-3 weeks until they were fit enough for voiding cysto-urethrography to confirm PUV. An unexpected good urinary flow and negligible residual urine volume were documented during micturition, suggestive of valve disruption induced by insertion and prolonged duration of indwelling urethral catheter drainage. Cystoscopy documented non-obstructing remnant leaflets. Non-operative treatment may be considered as a viable alternative therapeutic option for PUV in tiny babies facing prolonged intensive care unit stay.

Interrater reliability of bladder ultrasound measurements in children

INTRODUCTION

Bladder ultrasound is becoming pivotal in the management and treatment of lower urinary tract dysfunction. There is a paucity of data regarding intra-observer and interobserver reliability of bladder ultrasound, especially in children. A previous study assessed interobserver agreement for both the postvoid residual volume and measurement of the bladder dimensions in adults showing excellent agreement.

OBJECTIVE

To examine the interobserver and intra-observer reliability of bladder wall thickness, bladder urinary and postvoid residual urinary volume using ultrasound evaluated by paediatricians having different training levels.

STUDY DESIGN

Four sonographers, 3 pediatric trainees and one experienced pediatric urologist measured the full bladder volume, the voiding residual volume, and the bladder wall thickness. Each sonographer made 3 measurements of each parameter. We assessed the interobserver and intra-observer variability by using intraclass correlations (ICCs). ICCs were calculated and tested with a significance level of 5%. The interrater ICC was calculated from the mean of the three measurements of each variable (full bladder volume, postvoid residual, bladder wall thickness). ICC ≥0.75 was considered excellent. Bland-Altman plots were also used to assess the interobserver agreement.

RESULTS

Sixty children were recruited (7.3 ± 1.1 years). The interobserver ICCs for bladder volume and voiding residual volume were 0.91 (confidence interval 0.85-0.95) for both. The interobserver ICCs for the bladder wall thickness was satisfactory 0.43, with a minimum detectable difference of 2 mm. The observed values for intra-observer analysis showed an excellent (ICC ≥ 0.90) agreement between the three measurements performed by each one of the sonographers. Bland-Altman plots showed that the bias (mean difference) was -0.35 and the limits of agreement were -3.43 and 2.73 for the bladder wall thickness measurements (Figure).

DISCUSSION

The interobserver reliability for both the postvoid residual volume and full bladder volume were excellent even in operators with different levels of training, pointing out the role of bladder ultrasound in the routine clinical practice. Weaker agreement was found for the bladder wall thickness measurement. The intra-observer agreement was excellent for all the measurements.

CONCLUSION

These results showed a good reliability of urinary bladder ultrasound in children aged 7.3 ± 1.1 years as far as bladder volume measurement is concerned. Given the variability of bladder wall thickness, a standardized methodology is desirable to increase its reliability.

Can we predict vesicoureteral reflux resolution in patients with non-neurogenic lower urinary tract dysfunction?

OBJECTIVE

To analyze factors influencing reflux resolution in patients with the coexistence of non-neurogenic lower urinary tract dysfunction and vesicoureteral reflux.

METHODS

The data of 153 children who were diagnosed with vesicoureteral reflux and accompanying non-neurogenic lower urinary tract dysfunction between 2010 and 2015 were retrospectively evaluated. Patients with neurogenic and anatomical malformations, monosymptomatic nocturnal enuresis, previous history of vesicoureteral reflux surgery, irregular and/or incomplete follow-up data were excluded. After exclusion of 55 patients, 98 patients were enrolled in this study. Patients were divided into two groups according to the presence of spontaneous vesicoureteral reflux resolution during the follow-up period. Group 1 consisted of 54 children with spontaneous vesicoureteral reflux resolution, whereas group 2 included 44 children without resolution. Medical history, physical examination, urinalysis, uroflowmetry combined with electromyography, ultrasonography, as well as the Dysfunctional Voiding and Incontinence Symptom Score questionnaire were also evaluated.

RESULTS

The mean age at presentation was 7.57 ± 0.23 years (range 5-13 years), and the mean follow-up period was 28.3 months. Significant differences were noted between the two groups in terms of dysfunctional voiding and incontinence symptom score, bladder wall thickness, and the post-void residual urine volumes. In addition, lower urinary tract symptoms, namely frequency, urgency and daytime incontinence, were found to be higher in group 2. In multivariate analysis, post-void residual urine volume and Dysfunctional Voiding and Incontinence Symptom Score were found to affect reflux resolution rates (P = 0.002, P = 0.002, respectively).

CONCLUSIONS

The absence of significant post-void residual urine volume, and a low Dysfunctional Voiding and Incontinence Symptom Score increase the likelihood of spontaneous resolution rates of vesicoureteral reflux in children with non-neurogenic lower urinary tract dysfunction.

Validation study of ultrasound bladder wall thickness measurements

INTRODUCTION AND HYPOTHESIS

The aim was to validate ultrasound bladder wall thickness measurements. We scanned at three frequencies (5 MHz, 7 MHz and 9 MHz), using two techniques described in clinical practice and compared them with direct micrometre calliper measurements.

METHODS

Bladder dome cadaver specimens were dissected from male and female cadavers. The direct micrometre calliper measurement under direct vision was used as the gold standard. We imaged using a Voluson E8 ultrasound scanner at three frequencies, using three probes: AB27D (2-7 MHz), RAB25D (2-5 MHz) and RIC50D (5-9 MHz). The specimens were scanned on two different occasions for intra-observer variability. A second operator, measured the samples again independently for the interobserver agreement. The specimens were gently placed onto a sheathed and gelled probe to avoid deformation. The method of scanning was the same for all the specimens, probes and operators.

RESULTS

Twenty-five bladder dome specimens were assessed. The correlation of the ultrasound measurement to the direct measurement improved at higher ultrasound frequencies. Measuring from the inside of the serosal hyperechogenicity also increased the accuracy correlation with the direct measurement for all the frequencies tested.

CONCLUSIONS

This is the first study validating BWT ultrasound measurements against cadaveric bladder wall calliper measurements. Technology and technique affect accuracy, which is important in clinical practice. The use of 5-MHz probes is not recommended. The most accurate measurement was obtained using high-frequency ultrasound, where the measurement did not include the serosal brightness. These data suggest that high-frequency ultrasound should be used to assess BWT.

Sonographic Reference Values for Bladder Wall Thickness, Detrusor Wall Thickness, and Bladder Weight in Apparently Healthy Adults in a Nigerian Population

The aim was to establish reference values of bladder wall thickness (BWT), detrusor wall thickness (DWT), and bladder weight (BW) in apparently healthy adults in a Nigerian population. Therefore, a cross-sectional study of healthy adult participants was conducted from May 2015 to April 2016. The urinary bladder was sonographically evaluated on a convenient sample of 384 adult participants. The BWT, DWT, and BW of the participants were measured and documented. The BW was estimated based on the surface area, thickness, and bladder muscle specific gravity. The mean BWT, DWT, and BW were 2.8 ± 0.3 mm, 1.3 ± 0.1 mm, and 23.3 ± 4.1 g, respectively. There was no statistically significant correlation between anthropometric variables with BWT, DWT, and BW except age, which had a weak positive correlation with BWT ( P = .05). This data set could be used for future research, in other parts of the country, for a possible nationwide nomogram.

Postvoidal residual urine is the most significant non-invasive diagnostic test to predict the treatment outcome in children with non-neurogenic lower urinary tract dysfunction

INTRODUCTION

Uroflowmetry (UF) alone is often inadequate or unreliable to diagnose lower urinary tract dysfunction (LUTD). Therefore, other non-invasive tests, such as ultrasound (US), post-voiding residual volume (PVR) assessment and symptom scales, are used as well for objective definition of the problem.

OBJECTIVE

The aim of this study was to investigate the possible predictive function of the non-invasive diagnostic tests for the response to treatment.

STUDY DESIGN

The prospective registry data of 240 patients with LUTD, from November 2006 to September 2013, were retrospectively analyzed. All patients were aged 5-14 years old. Patients with a previous diagnosis of vesicoureteral reflux (VUR), neurogenic bladder, monosymptomatic nocturnal enuresis (NE) were excluded from the study. Uroflowmetry, US, PVR and the Dysfunctional Voiding and Incontinence Symptom Scale (DVISS) were performed on every patient at their first visit and follow-ups. A DVISS <9 was considered as the DVISS response; parental opinion was based on International Continence Society criteria of clinical response. Time passed until clinical response was the last outcome parameter.

RESULTS

Mean age was 8.2 years. Median follow-up was 60.5 months. A total of 62% of patients had complete response, 28.1% had partial response, and 9.7% had no response. Demographic variables were not associated with clinical outcome. Co-existing enuresis nocturna, multiple pharmacotherapy, and increased DVISS were associated with longer time until clinical response. Post-voiding residual volume assessment was the only test to have a prognostic value.

DISCUSSION

Resolution rates of LUTD ranged from 40 to 90%. High resolution rate could be attributed to the long follow-up period, and the chance of spontaneous resolution. Treatment modalities and co-existing NE were associated with longer time until clinical response. Only PVR was associated with prognosis. This was the first study in literature to report such findings. It was seen that the normalization of pathologic patterns was a good sign for treatment success. The DVISS results showed significantly higher rates of incontinence compared to initial symptoms defined by the patients and/or their parents. This showed the importance of using scoring systems to better define the severity of symptoms. It was hard to establish a standardized cut-off value for bladder wall thickness on US. However, US was a good test for diagnosing additional pathologies.

CONCLUSION

Increased PVR was the single tool that was associated with prognosis and, therefore, should always be performed after UF. In addition, DVISS can help parents be counseled about their treatment expectations.

Pathophysiological and Therapeutic Considerations for Non-Neurogenic Lower Urinary Tract Dysfunction in Children

Non-neurogenic lower urinary tract dysfunction (LUTD) in children is very common in clinical practice and is important as an underlying cause of lower urinary tract symptoms, urinary tract infection and vesicoureteral reflux in affected children. LUTD in children is caused by multiple factors and might be related with a delay in functional maturation of the lower urinary tract. Behavioral and psychological problems often co-exist in children with LUTD and bowel dysfunction. Recent findings in functional brain imaging suggest that bladder bowel dysfunction and behavioral and psychiatric disorders in children might share common pathophysiological factors in the brain. Children with suspected LUTD should be evaluated properly by detailed history taking, validated questionnaire on voiding and defecation, voiding and bowel diary, urinalysis, screening ultrasound, uroflowmetry and post-void residual measurement. Invasive urodynamic study such as videourodynamics should be reserved for children in whom standard treatment fails. Initial treatment of non-neurogenic LUTD is standard urotherapy comprising education of the child and family, regular optimal voiding regimens and bowel programs. Pelvic floor muscle awareness, biofeedback and neuromodulation can be used as a supplementary purpose. Antimuscarinics and α-blockers are safely used for overactive bladder and dysfunctional voiding, respectively. For refractory cases, botulinum toxin A injection is a viable treatment option. Prudent use of urotherapy and pharmacotherapy for non-neurogenic LUTD should have a better chance to cure various problems and improve self-esteem and quality of life in affected children.

Potential Biomarkers Utilized to Define and Manage Overactive Bladder Syndrome

Clinical diagnosis of overactive bladder (OAB) syndrome has great variation and usually can only be based on subjective symptoms. Measurement of urgency severity score in adjunct with voiding diary may reflect the occurrence of OAB and incontinence severity in daily life. Urodynamic study can detect detrusor overactivity (DO), but not in all OAB patients. A more objective way and less invasive tool to diagnose and assess therapeutic outcome in OAB patients is needed. Recent investigations of the potential biomarkers for OAB include urinary and serum biomarkers and bladder wall thickness. Evidence has also shown that urinary proteins, such as nerve growth factor (NGF) and prostaglandin E2 (PGE2 ) levels increase in patients with OAB, bladder outlet obstruction (BOO) and DO. Patients with OAB have significantly higher urinary NGFlevels and urinary NGF levels decrease after antimuscarinic therapy and further decrease after detrusor botulinum toxin injections. However, the sensitivity of single urinary protein in the diagnosis of OAB is not high and several lower urinary tract diseases may also have elevated urinary NGF levels. Searching for a group of inflammatory biomarkers by microsphere-based array in urine might be a better method in differential diagnosis of OAB from interstitial cystitis, urinary tract infection (UTI) or urolithiasis. Bladder wall thickness has been widely investigated in the diagnosis of BOO and pediatric voiding dysfunction.The role of bladder wall thickness in the diagnosis of OAB, however, has not reach a consistent conclusion. We hereby review the latest medical advances in this field.

Can urinary nerve growth factor and bladder wall thickness correlation in children have a potential role to predict the outcome of non-monosymptomatic nocturnal enuresis?

INTRODUCTION

Measurement of bladder wall thickness (BWTh) by ultrasound has been introduced as a new and promising technique to assess bladder dysfunction, and increased levels of nerve growth factor have also been reported in the bladder tissue and urine of patients with sensory urgency and detrusor overactivity (DO).

OBJECTIVE

In this study we aimed to generate a clinically useful tool with urinary nerve growth factor levels and ultrasonographic BWTh to find possible pathogenetic clues and prognostic indicators as guides for the choice of therapy of non-monosymptomatic nocturnal enuresis.

METHODS

A total of 110 children, aged 6-16 years old, were involved in this prospective study. Group 1 consisted of children with non-monosymptomatic nocturnal enuresis (n = 40), Group 2 of children with monosymptomatic nocturnal enuresis (n = 40) and Group 3 of children with healthy normal controls (n = 30). Children were evaluated with detailed history and physical examination, including neurologic examination; they were asked to complete a self-reported questionnaire and a 3-day bladder diary with the aid of their parents. The number of wet nights, the number of voids per night, the presence of daytime voiding symptoms (urgency, urge incontinence, incontinence, holding maneuvers, frequency), fluid intake, and any history of urinary tract infections (UTIs) were recorded. Monosymptomatic nocturnal enuresis and non-monosymptomatic nocturnal enuresis diagnosis was made using the International Children's Continence Society definition. Urinary nerve growth factor levels were measured by enzyme-linked immunosorbent assay and BWTh was measured transabdominally by a uroradiologist who specialized in pediatric ultrasonography. Urinary nerve growth factor levels were normalized by urinary creatinine levels and compared in all subgroups.

RESULTS

The mean age of the study group was 9.6 (range 6-16) years. The mean BWTh was significantly increased in Group 1 compared with Group 2 (4.33 ± 1.12 mm, 2.33 ± 1.03 mm; p < 0.001) and healthy controls (4.33 ± 1.12 mm, 1.86 ± 0.57 mm; p < 0.001, respectively). Urinary levels of nerve growth factor corrected to urine creatinine (NGF/Cr) significantly increased in Group 1 with to Group 2 (2.75 ± 1.15 vs. 0.58 ± 0.15; p < 0.001) and controls (2.75 ± 1.15 vs.0.28 ± 0.10; p < 0.001, respectively). In receiver operating characteristic analysis, BWTh was found to have sensitivity of 95% and specificity of 85.7% (3.00 area under the curve [AUC] 0.937; 95%) and NGF/Cr had sensitivity of 97.5% and specificity of 98.6% (0.885; AUC, 999; 95%) in predicting lower urinary tract symptoms (LUTS) for non-monosymptomatic nocturnal enuresis (NMNE) (Figure).

DISCUSSION

In our study we have investigated that BWTh together with urinary NGF levels normalized to the concentration of urinary creatinine (NGF/Cr) may predict daytime voiding problems in children with primary nocturnal enuresis (PNE). The main basis of this study is previous findings which demonstrated that ultrasonography (US)-based measurement of BWTh is a useful diagnostic parameter for LUTS in children, and that increased levels of NGF in bladder tissue and urine such as sensory urgency, DO, and overactive bladder (OAB) was indicated by clinical and experimental studies. The present study demonstrated that urinary NGF/Cr levels and BWTh measurements were significantly increased in patients with NMNE with daytime urinary symptoms (urgency, urge-incontinence, incontinence, frequency) showing symptoms of an OAB than controls and MNE.

CONCLUSION

BWTh measurements and NGF/Cr values, as non-invasive tools, may guide therapy and improve outcomes in the treatment of children with NMNE. Further studies including a larger number of patients would be of great interest.

The significance of detrusor wall thickness as a prognostic factor in pediatric bladder outlet obstruction

PURPOSE

The purpose of this study is to determine detrusor thickness as a prognostic factor in posterior urethral valves.

METHODS

The medical information of 41 patients diagnosed with posterior urethral valves at our institute was retrospectively reviewed. The serum creatinine level after bladder decompression, results of ultrasonography, and voiding cystourethrography were compared between groups divided according to the final bladder and renal function. Detrusor thickness was measured using Müller's method.

RESULTS

The median detrusor thickness was 1.3 mm (0.4-2.5 mm). After median 45.6 months (7.2-96.0 months) of follow-up, impaired bladder function (IBF) was observed in 14 patients. In multivariate analysis, detrusor thickness greater than 1.3 mm (odds ratio, 32.6; 95% confidence interval, 3.1-340.6; P = .004) was the only independent risk factor for later IBF. Final renal function impairment developed in 24 patients (58.5%), and 3 patients (7.3%) were diagnosed with end-stage renal disease after median 66.0 months (32.4-133.2 months) of follow-up period. On multivariate analysis, age-specific elevated serum creatinine level at presentation (odds ratio, 11.1; 95% confidence interval, 1.1-112.5; P = .042) was an independent risk factor.

CONCLUSIONS

Detrusor thickness more than 1.3 mm on ultrasonography was an independent prognostic factor for later IBF.

Novel biomarkers for overactive bladder

Biomarkers constitute any objectively measurable indicator of a biological process. The classic biomarker used in the diagnosis of overactive bladder (OAB) has been detrusor overactivity, which is assessed urodynamically. In the search for a reliable, noninvasive alternative to urodynamics, interest has focused on genetic, imaging, and urinary factors. Along with other cytokines detectable in urine, prostaglandin E2 and nerve growth factor are indicators of low-grade inflammation. Although they correlate with OAB symptom severity, they have not been shown to have independent prognostic benefit. Imaging biomarkers have been investigated since the earliest days of video urodynamics. Despite extensive research on the ultrasonographic estimation of bladder wall thickness, further standardization of the technique is required before conclusions can be reached regarding diagnostic accuracy. Genetic factors contribute approximately half of the total risk for urgency incontinence. Functional polymorphisms of the cytochrome P450 IID6 gene significantly alter the metabolism of some commonly used anticholinergic drugs, but no genetic loci that influence risk of OAB have been definitively identified. The first genome-wide association studies for OAB are in progress, and should identify new susceptibility genes. Although current putative biomarkers correlate with OAB severity, much future work is required to assess their prognostic value, and establish their role in clinical practice.

Measurement of detrusor wall thickness in women with overactive bladder by transvaginal and transabdominal sonography

INTRODUCTION AND HYPOTHESIS

Women with overactive bladder (OAB) might have a greater detrusor wall thickness (DWT) suggestive of detrusor overactivity (DO).

METHODS

DWT was measured by transabdominal ultrasonography (TAU) and transvaginal ultrasonography (TVU) in normal and women with OAB-dry and OAB-wet. The subjects were further classified as normal, hypersensitive bladder, or DO by urodynamic results. DWT measured by TVU at empty bladder, and TAU at 250 ml and bladder capacity were compared among symptom and urodynamic subgroups.

RESULTS

TVU-measured DWT was significantly greater at the bladder neck than other sites of the bladder wall. No significant difference of TVU-measured DWT was noted among subgroups. No significant difference of TAU-measured DWT among subgroups at 250 ml, but DWT at bladder capacity was significantly greater in OAB-wet or DO than other subgroups.

CONCLUSIONS

A greater DWT at bladder capacity measured by TAU can be useful as biomarker for DO in patients with OAB.

Diagnosis and management of urinary incontinence and functional fecal incontinence (encopresis) in children

The ability to maintain normal continence for urine and stools is not achievable in all children by a certain age. Gaining control of urinary and fecal continence is a complex process, and not all steps and factors involved are fully understood. While normal development of anatomy and physiology are prerequisites to becoming fully continent, anatomic abnormalities, such as bladder exstrophy, epispadias, ectopic ureters, and neurogenic disturbances that can usually be recognized at birth and cause incontinence, will require specialist treatment, not only to restore continence but also to preserve renal function. Most forms of urinary incontinence are not caused by an anatomic or physiologic abnormality and, hence, are more difficult to diagnose and their management requires a sound knowledge of bladder and bowel function.

Non-invasive evaluation of voiding function in asymptomatic primary school children

This study aimed to evaluate the voiding characteristics of primary school children by using questionnaires and non-invasive diagnostic tools. The voiding characteristics of 212 healthy children in two primary schools were evaluated with ultrasound for bladder wall thickness (BWT) in association with the Pediatric Lower Urinary Tract Symptom Score (PLUTSS), familial questionnaire, uroflowmetry (UF) and urinalysis. Most of the children (70%) had achieved urinary and fecal continence between the ages of 18 months and 36 months. Twenty-five per cent of healthy children void fewer than four times or more than seven times per day. Ninety percent of children had a PLUTSS within normal ranges (< 9). Fifteen percent of patients had a uroflowmetric pattern other than bell-shaped. The peak and average flow rates were higher in girls. Enuresis nocturna was detected in 10% of children. None of the children had documented urinary tract infection. The average BWT from posterior wall at full bladder in healthy children was 1.1 mm. The anterior and posterior BWT measurements before and after micturition were found to be thicker in boys. Regarding the UF pattern, in post-voiding measurements in children with abnormal UF pattern, the bladder walls were thicker. Non-invasive tests in non-symptomatic children showed a range of variability, and these deviations should be kept in mind during the evaluation of voiding characteristics of a child. The symptom scoring system, with the high sensitivity and specificity rates it possesses, is one of the promising tools for this purpose.

Bladder Wall Thickness in Healthy School-Aged Children

OBJECTIVES

To evaluate the effectiveness of transabdominal ultrasonography for bladder volume and detrusor muscle thickness and to research the relationship of these measurements with age, height, and body mass index.

METHODS

We reviewed the records of 244 healthy, school-aged children from February to May 2003. After a complete urologic examination, the weight and height of all children were measured, and their body mass index was determined. Transabdominal ultrasonography with a high-frequency probe was performed to obtain the anterior, posterior, and lateral bladder wall thicknesses.

RESULTS

The mean age of the children was 10.7 +/- 3.6 years (range 7 to 15), and the mean bladder volume was 256 cm3 (range 78 to 790). The relationship between bladder volume and age was significant (P = 0.0001, r = 0.568). The mean anterior, posterior, and lateral detrusor thickness was 1.42 mm (range 0.8 to 2.8), 1.57 mm (range 0.7 to 3.1), and 1.49 mm (range 0.6 to 2.6), respectively. The relationships between increasing age and the anterior and posterior wall thicknesses were significant (P <0.05), but the relationship between age and the lateral wall thickness was not (P >0.05). The relationship between bladder volume and body mass index was significant (P = 0.0001, r = 0.2959). A strong positive and significant correlation was found between the anterior (P = 0.0001) and posterior (P = 0.001) wall thicknesses and body mass index, but the correlation between the lateral wall thickness and body mass index was not significant (P = 0.079, r = 0.113).

CONCLUSIONS

Strong, positive correlations were found between the anterior and posterior wall detrusor thicknesses and increased age and body mass index, but the same correlations for lateral wall detrusor thickness were not found.

Correlation between ultrasonographic bladder measurements and urodynamic findings in children with recurrent urinary tract infection

OBJECTIVE

To evaluate the role of bladder variables measured by ultrasonography (US) in assessing bladder dysfunction in children with urinary tract infections (UTIs).

PATIENTS AND METHODS

Children presenting with recurrent UTI (with or with no vesico-ureteric reflux) were prospectively recruited. At entry, each patient had US and both natural- filling (NFC) and conventional-filling (CFC) cystometry. Bladder volume and wall thickness index (BVWI) was calculated, and based on US studies and the bladder pattern on US, were classified as thick (BVWI <70), normal (70-130) and thin (>130) as previously reported. The criteria for diagnosing urodynamic patterns included normal, overactive and hypocontractile, as reported previously. The correlation between the US measured variables and urodynamic findings were then evaluated. Sixty-one children (38 boys and 23 girls; mean age 4.82 years, range 1-11) were selected for further evaluation.

RESULTS

Of the 61 children, 16 had a normal BVWI, 36 a 'thick' value and nine 'thin'. When the BVWI was correlated with the urodynamic findings, 14 of 16 with a normal BVWI had a normal bladder pattern, whereas 92% of the patients with a BVWI of <70 had overactive bladder (P < 0.001). Among children with a BVWI of >130, six of nine had a hypocontractile pattern. The mean (sd) bladder capacity (on CFC) compared to that expected for age was significantly lower, at 56.7 (32.3)% in 'thick' bladders, vs children with normal and thin bladders, at 91.3 (23.8)% and 98.7 (31.8)%, respectively (P < 0.001). A high voiding detrusor pressure was significantly associated with children who had a thick bladder rather than normal or thin bladder (P < 0.001).

CONCLUSIONS

This study further confirmed that the BVWI is a sensitive tool for diagnosing bladder dysfunction in children, and it can be used as a reliable guide for the appropriate choice of further invasive urodynamic studies.

Nomograms of total renal volume, urinary bladder volume and bladder wall thickness index in 3,376 children with a normal urinary tract

BACKGROUND

We have previously shown that urinary bladder volume index (BVI = length x width x depth of bladder) and bladder volume wall thickness index (BVWI = BVI at full bladder/average bladder wall thickness) are useful indicators of bladder dysfunction in children with enuresis and urinary tract infection. These indices show a good correlation with urodynamic studies. We have expanded the study to include normal paediatric subjects with a wide age range. We illustrate a simple sonography protocol with nomograms of different parameters, which provide useful references for functional assessment in children with urological abnormalities.

OBJECTIVE

To construct nomograms of total renal volume, maximum BVI and BVWI based on a Chinese paediatric population with age range from newborn to adolescence.

MATERIALS AND METHODS

Sonography was performed in consecutive children with normal urinary tracts on imaging, using a standardized protocol. Data were collected for construction of nomograms for different parameters.

RESULTS

Nomograms of total renal volume, BVI and BVWI were constructed based on 3,376 consecutive paediatric subjects. All parameters consistently increased with age.

CONCLUSION

Nomograms of total renal volume, BVI and BVWI could provide useful references for studying bladder dysfunction in children using noninvasive dynamic sonography.

Location of spina bifida occulta and ultrasonographic bladder abnormalities predict the outcome of treatment for primary nocturnal enuresis in children

OBJECTIVE

We examined whether the existence of spina bifida occulta or ultrasonographic bladder abnormalities was related to the outcome of treatment for primary nocturnal enuresis in children.

METHODS

Between April 1996 and September 2005, a total of 77 subjects (53 boys and 24 girls, aged 5-18 years; mean age, 9.9 years) with primary nocturnal enuresis were studied. Plain X-ray films of the spine and ultrasonographic bladder measurements (bladder wall thickness, bladder neck descent and bladder neck opening) were obtained and the correlations with the outcome of treatment using imipramine hydrochloride were assessed.

RESULTS

On plain X-ray films of the spine, spina bifida occulta (lumbar vertebrae in three, lumbosacral vertebrae in 19 and sacral vertebrae in 31) was recognized in 53 children (69%). Ultrasonographic bladder abnormalities were recognized in 40 children (52%). Children with lumbar and lumbosacral spina bifida occulta showed a higher rate of concomitant ultrasonographic bladder abnormalities (P = 0.006) and had a poorer response to treatment (P = 0.041) compared with the children who had sacral spina bifida occulta. Children with ultrasonographic bladder abnormalities had a worse response to treatment (P = 0.005) compared to the children without bladder abnormalities.

CONCLUSIONS

The presence of lumbar spina bifida occulta and ultrasonographic bladder abnormalities was related to the outcome of treatment for primary nocturnal enuresis in children, suggesting that spinal radiography and vesical ultrasonography may be useful predictive tests.

Ultrasound Assessment of Detrusor Thickness in Children and Young Adults with Myelomeningocele

PURPOSE

We determine by ultrasonography the range of dT in carefully treated and followed children with myelomeningocele, and evaluate the role of such measurements for the understanding of bladder abnormalities in these patients.

MATERIALS AND METHODS

We studied 66 children and young adults with MMC (34 males and 32 females, median age 8.1 years, range 1.1 to 20.1). Detrusor thickness was measured with a previously established ultrasonographic technique and the results were compared to those in normal children. The variation in detrusor thickness with degree of bladder dysfunction as well as with bladder wall trabeculation, kidney function and anticholinergic treatment was studied.

RESULTS

The detrusor of the ventral wall was slightly thinner in children with MMC compared to normal. No significant variation in dT was found for different degrees of bladder dysfunction, bladder wall trabeculation, kidney function or anticholinergic treatment. Boys had thicker detrusor of the ventral wall than girls.

CONCLUSIONS

Children with MMC, followed closely and treated according to international standards, do not acquire detrusor thickening as measured by ultrasonography. The detrusor thickness did not correlate with the degree of bladder dysfunction or renal function, or with anticholinergic treatment. Bladder wall trabeculation at VCU was not associated with bladder wall thickening on ultrasonography. We postulate that in a closely monitored and actively treated population of patients with MMC muscular hypertrophy and the development of connective tissue in the bladder wall is kept to a minimum.

Ultrasound measurement of detrusor wall thickness in healthy adults

AIMS

Measurements of detrusor wall thickness (DWT) are used to diagnose bladder outlet obstruction (BOO). No values of DWT exist in healthy adults so far. These values, however, are necessary to judge DWT in patients with suspected BOO correctly. The aim of this study was to determine DWT in healthy adults and to investigate if bladder filling, gender, age, or body-mass index (BMI) influences DWT.

MATERIALS AND METHODS

In 55 healthy adult volunteers between 15 and 40 years of age, DWT was measured at the anterior bladder wall with a 7.5 MHz ultrasound probe and with a full bladder. In nine of those volunteers, an urodynamic investigation was performed additionally during which DWT was measured in steps of 50 ml until 300 ml and in steps of 100 ml until the maximum bladder volume.

RESULTS

DWT decreases rapidly during the first 250 ml of bladder filling but, thereafter, remains almost stable until maximal bladder capacity. No statistical difference was found between DWT at 250 ml and DWT at a higher bladder filling. Men had a greater DWT compared to women (1.4 vs. 1.2 mm, P < 0.001). The age and BMI did not have a significant impact on DWT.

CONCLUSIONS

DWT remains stable at a bladder filling of 250 ml. At this state of bladder filling, DWT between different groups are comparable. Men have to be evaluated separately from women.

ULTRASOUND BLADDER MEASUREMENTS IN PATIENTS WITH PRIMARY NOCTURNAL ENURESIS: A URODYNAMIC AND TREATMENT OUTCOME CORRELATION

PURPOSE

Accurate assessment of bladder dysfunction associated with voiding dysfunctions often necessitates invasive urodynamic (UD) studies. We evaluate the use of a special ultrasound (US) protocol for the assessment of bladder dysfunction compared with urodynamic findings, and for prediction of treatment outcome in children with primary nocturnal enuresis (PNE).

MATERIALS AND METHODS

US measurements were performed on 514 children 5 to 18 years old (mean age 11.2) with PNE, and compared with those of 339 normal age matched children. A US protocol was specially designed for the evaluation of bladder parameters using bladder volume and wall thickness index (BVWI %), and expected percentage bladder volume index for kidney volume. Of the enuretic children 218 had severe enuretic symptoms with more than 3 wet nights a week. They underwent urodynamic studies for detailed assessment of any underlying bladder dysfunction. A standard 4-week course of desmopressin was given to these children after the US and UD studies. The US bladder parameters were then correlated with the UD findings and treatment response to desmopressin.

RESULTS

Comparing the BVWI in normal and enuretic children in correlation with functional bladder capacities we were able to delineate bladder wall thickness and capacity as BVWI less than 70-small capacity bladder with thick wall, BVWI 70 to 130-normal bladder capacity with normal wall thickness and BVWI greater than 130-large bladder capacity with thin wall. There were statistically significant correlations between BVWI and treatment response. In addition, there was a high predictive value of normal bladder function with a normal BVWI. Patients with good response to treatment had normal BVWI, whereas poor response to treatment was significantly associated with pathological bladder conditions, that is small bladder capacity with thick bladder wall or large bladder capacity with thin bladder wall (p <0.0001). Of note, abnormalities detected by UD correlated well with bladder abnormalities measured by US.

CONCLUSIONS

PNE comprises a diverse spectrum of conditions resulting in a mismatch of nocturnal urine production in excess of nocturnal functional bladder capacity, and underlying bladder dysfunction has an important role in the pathophysiology especially in refractory cases. This US protocol can provide useful predictive clues, which may be helpful to differentiate treatment subtypes, guide clinical management and minimize the need for invasive urodynamic studies.

Ultrasound assessment of detrusor muscle thickness in children with non-neuropathic bladder/sphincter dysfunction

OBJECTIVE

To measure detrusor muscle thickness in children with non-neuropathic bladder/sphincter dysfunction (NNBSD), and to evaluate the difference between children with various bladder dysfunctions and those with normal urodynamics.

MATERIALS AND METHODS

In 139 children the urodynamic study was performed, and the detrusor of the anterior bladder wall was measured using high-frequency ultrasonography (US). Children were categorized into five groups, according to urodynamic findings. Differences in detrusor thickness between groups were tested by one-way ANOVA with post hoc Scheffé test.

RESULTS

Forty-six children (33.1%) had normal urodynamics, and mean (+/-S.D.) detrusor thickness 1.3 +/- 0.5 mm (range 0.5-3.0). Fifty-two (37.4%) had urge syndrome, with detrusor thickness of 2 +/- 0.7 mm (1.0-3.6). Thirty-three (23.7%) had dysfunctional voiding, with detrusor thickness of 2.6 +/- 0.5 mm (1.5-3.6). Four (2.9%) had lazy bladder, with detrusor thickness of 0.9 +/- 0.1 mm (0.8-1.0), and four had anatomical infravesical obstruction, with detrusor thickness of 4.4 +/- 0.3 mm (4-4.6). The mean detrusor thickness in all children with NNBSD was 2.2 +/- 0.7 mm (range 0.8-3.6). Multiple comparisons showed significant difference between all groups, except between children with normal urodynamics and children with lazy bladder.

CONCLUSION

There is statistically significant difference in mean detrusor thickness between children with normal urodynamics and children with NNBSD. However, due to the overlap of measured values, it is not possible to determine the cut-off value that could be used to distinguish children with and without NNBSD.

Detrusor thickness in healthy children assessed by a standardized ultrasound method

PURPOSE

We determine the ultrasonographic detrusor thickness in healthy infants and children.

MATERIALS AND METHODS

We studied 150 healthy children, 79 boys and 71 girls, from newborns to 13 years old. The detrusor of the ventral and dorsal wall was measured with a previously established ultrasonographic technique, and the variation with age and bladder fullness was assessed.

RESULTS

Detrusor thickness varied significantly with the degree of bladder fullness (thinner at higher volumes). It also increased slightly with age. At bladder fullness of 10% or greater of expected bladder capacity (EBC), calculated using the formula EBC (ml.) = age (years) x 30 + 30, a practical upper limit for the detrusor thickness of the ventral wall at all ages was 2.0 mm. at a bladder fullness up to 50% of expected bladder capacity or 1.5 mm. at a higher degree of fullness. The detrusor of the ventral wall was slightly thicker in boys than in girls and also somewhat thicker than the detrusor of the dorsal wall.

CONCLUSIONS

The results indicate that ultrasonographic measurements of detrusor thickness in children may serve as a diagnostic tool and its usefulness in clinical as well as research work should be explored.

Dissolution of multicomponent microbubbles in the bloodstream: 1. Theory

The problem of dissolution of a bubble in the bloodstream is examined. The bubble is assumed to be filled with a mixture of a sparingly water-soluble gas (osmotic agent) and air. The dissolution of the bubble has three definite stages. In Stage 1, the bubble quickly swells in air. The swelling ratio depends on the surface tension, blood pressure, level of oxygen metabolism and initial mole fraction of osmotic agent in the bubble. In Stage 2, the osmotic agent slowly diffuses out of the bubble. The squared radius decreases nearly linearly with time, at a rate proportional to the Ostwald coefficient and diffusivity of the osmotic agent. In Stage 3, the partial pressure of the osmotic agent becomes so high that it condenses into a liquid. In order to prolong the lifetime of 5-micron bubbles in the bloodstream from < 1 s (as found with pure air), the osmotic agent must have a low Ostwald coefficient (< or = 10(-4)) and a relatively high saturated vapor pressure at body temperature (> or = 0.3 atm = 3 x 10(4) Pa).