The Role of Non-invasive Testing in Evaluation and Diagnosis of Pediatric Lower Urinary Tract Dysfunction

Who needs an ultrasound? Using patient symptom questionnaire & UTI history to determine when to obtain an RBUS in children with non-neurogenic lower urinary tract dysfunction

INTRODUCTION

Non-neurogenic lower urinary tract dysfunction (LUTD) is one of the most common reasons for presentation to a pediatric urologist, affecting up to 20% of children. Predicting who will benefit from RBUS as part of their work-up is challenging as the majority will have normal imaging.

OBJECTIVE

Our objective was to assess the utility of using the Dysfunctional Voiding and Incontinence Scoring System (DVISS) and urinary tract infection (UTI) history to predict which LUTD patients were most likely to have an abnormal RBUS as well as determine a DVISS cutoff to aid in making this prediction. We hypothesized that higher DVISS scores and a positive urinary tract infection (UTI) history would be associated with increased likelihood of RBUS abnormality.

STUDY DESIGN

We retrospectively reviewed outpatients seen for LUTD from 5/2014-1/2016 who received an RBUS. Association between prior UTI, DVISS score, gender, and race and RBUS abnormality were evaluated using logistic regression analysis. Receiver operating characteristic (ROC) curves were created to evaluate the predictive model and a Youden index calculated to determine the optimal cutoff for DVISS score to predict abnormal RBUS.

RESULTS

15 of 333 patients (4.5%) had a clinically significant RBUS abnormality. Significantly more patients with abnormal RBUS had a positive UTI history and median DVISS was higher. UTI history and DVISS score were associated with RBUS abnormality whereas neither gender nor race were. A DVISS score cutoff of 12 was determined to be ideal for predicting abnormal imaging. Using DVISS≥12 and positive UTI history, patients with both risk factors were significantly more likely to have an abnormal RBUS than those with zero or one risk factor (Figure).

DISCUSSION

To the best of our knowledge this is the first study to try to identify risk factors associated with RBUS abnormality in pediatric LUTD patients and create an evidence-based approach to imaging these patients. We found both DVISS cutoff ≥12 and positive UTI history to be useful to risk stratify LUTD patients' likelihood of abnormal RBUS. Limitations include the study's retrospective nature as well as the fact the population was drawn from a tertiary care pediatric hospital with a large referral population and the fact that the decision to order an RBUS was based on individual clinician preference and decision making.

CONCLUSIONS

We found that DVISS score≥12 and UTI history are useful in guiding the decision to obtain RBUS in pediatric LUTD patients.

Is it time to reconsider how we document pediatric uroflow studies?: A study from the SPU Voiding Dysfunction task force

BACKGROUND

Uroflowmetry is a non-invasive study used in the diagnosis and monitoring of treatment response for lower urinary tract disorders. For optimal clinical utility, uroflow studies rely on careful clinical interpretation by a trained provider, but currently there is a lack of accepted standardized normal values for the measured uroflow parameters in children. The International Children's Continence Society proposed standardizing the terminology for uroflow curve shapes. However, the patterning of curves is largely at the physician's subjective discretion.

OBJECTIVES

The aims of this study were to understand inter-rater reliability in interpreting uroflow curves and to define characteristics of uroflow curves that could be used to provide definitive criteria for uroflowmetry parameters.

METHODS

All members of the SPU Voiding dysfunction Task Force were invited to contribute deidentified uroflows to a centralized HIPAA complaint receiving database. All studies were then distributed to all raters for review. Each observer's findings were recorded according to ICCS criteria (ICCS), additional readings were done using a previously reported system which defined curves as smooth or fractionated (SF) and whether the shape resembled a bell, tower, or plateau (BTP). Flow indexes (Qact/Qest) (FI) for Qmax and Qavg were generated using formulas previously reported for children 4-12 and for patients≥12 years.

RESULTS

A total of 119 uroflow studies were read by 7 raters and curves were contributed from 5 sites. Kappa scores for the 5 readers from different institutions were 0.34 and 0.28 for the ICCS and BTP methods, respectively (both considered fair agreement). Kappa for smooth and fractionated curves was 0.70 (for each; considered substantial agreement), which were the two highest agreement scores obtained throughout the study. Discriminant analysis (DA) revealed that the FI Qmax was the dominant vector, and that the ICCS uroflow parameters have a total of 42.8% prediction rate in the training sample. Using DA of a smooth/fractionated system, the total prediction rates were 72% and 65.5% for smooth and fractionated, respectively.

DISCUSSION

Given the poor inter-rater agreement for analyzing uroflow curve pattern based on ICCS criteria in this study and others, one may find it reasonable to consider alternative approaches to describing and characterizing uroflow curves. Our study is limited by lack of EMG and post-void residual data.

CONCLUSIONS

For a more objective uroflow interpretation and comparison of studies among different centers, we recommend using our proposed system (based on FI, and smooth vs. fractionated curve pattern), which is more reliable.

Assessment of lower urinary tract function in pediatrics using ultrasonography

Ultrasound imaging is a less invasive imaging modality without radiation exposure and is available for repeated tests. It is the gold standard examination for diagnosing and managing disorders of the urinary tract, including lower urinary tract dysfunction (LUTD) in pediatric urology. Ultrasound imaging is effective for screening underlying diseases and determining treatment strategies. Ultrasound examination at the bedside should focus on post-voided residual urine (PVR), bladder wall thickening, renal morphology, and rectal diameter. Since PVR must be tested immediately after voiding, examining infants who cannot complain of the urge to void is difficult. PVR measurement combined with a 4-h voiding observation or alarm system activated by urine is recommended for these infants. Early diagnosis is important because LUTD is associated with the risk of morbid residual urine and high voiding pressure, which can result in renal deterioration, urinary leakage, and febrile urinary tract infection.

Is there a unique symptom in lower urinary tract dysfunction in children?

OBJECTIVES

Lower urinary tract symptoms (LUTS), particularly urgency, incontinence and intermittency are common in children and it is suggested that the specific symptoms may be used for definite diagnosis for LUT dysfunction (LUTD). This study was performed to investigate the relationship between each LUTD and its associated symptoms, using uroflowmetry/electromyography (UF/EMG) as a diagnostic tool.

METHODS

Each patient was categorized into one of four LUT conditions which were overactive bladder (OAB), dysfunctional voiding (DV), underactive bladder and primary bladder neck dysfunction (PBND), according to UF/EMG results. Patients' complaints and findings were documented by using voiding dysfunction symptom score, bladder diary, urine analysis and ultrasonography. In addition, a detailed history of bowel habits (including use of Rome III criteria) was obtained.

RESULTS

There were 189 children of which 106 were female. The OAB was the largest group including 91 patients, followed by the DV group which had 61 patients. The symptoms specific to any LUTD group were constipation and hesitancy (P < .05). Hesitancy was present in 89.4% with PBND and constipation was present in 78.6% of patients with DV. None of other symptoms were able to differentiate any LUTD group from the other.

CONCLUSIONS

While certain symptoms are often presumed by clinicians to imply specific diagnoses, the main outcome of this study is that there is a generally weak correlation between the specificity of symptoms and LUTD. Symptoms-based approach may lead to misdiagnosis in LUTD. Thus, it may be essential to focus on the underlying pathologies and UF/EMG test may help this.

Validity and reliability of a home-based, guardian-conducted video voiding test for voiding evaluation after hypospadias surgery

Purpose

To investigate the validity and reliability of a home-based, guardian-conducted video voiding test for assessing postoperative voiding function after hypospadias surgery.

Materials and Methods

In a single center, patients who had undergone urethroplasty by a single surgeon and postoperative uroflowmetry and video voiding tests conducted between 2008 and 2016 were retrospectively reviewed. Urinary stream was categorized into five grades by three pediatric urologists in a blinded manner. The primary outcome was statistical correlation across raters as measured by Spearman correlation coefficient to validate the interpretation of the video voiding test. The secondary outcome was the reliability of the voiding video test compared with maximum urinary flow rate assessed by uroflowmetry.

Results

Thirty-one patients with hypospadias were enrolled. The patients' average ages were 12.3±3.2 months (range, 8–21 months) and 42.8±3.9 months (range, 35–48 months) at the time of surgery and voiding video tests, respectively. Hypospadias was anterior, penile, and proximal in 1 (3.2%), 18 (58.1%), and 12 (38.7%) patients, respectively. The number of patients with each voiding stream grade was as follows: very poor, 4; poor, 4; fair, 13; good, 4; and very good, 6. All intraclass correlation coefficients of the stream grade among the three observers were >0.95. Correlation between the maximum flow rate obtained by use of conventional uroflowmetry and the video voiding stream grade was validated (rho 0.778, p<0.001).

Conclusions

The home-based guardian-conducted video voiding test is easy to perform and the present results demonstrate its validity and reliability for assessing patients' post-urethroplasty voiding pattern.

Does small voided volume influence uroflowmetry curve patterns in Japanese children with daytime urinary incontinence?

BACKGROUND

A voided volume (VV) of <50% of the expected bladder capacity for age is considered small VV. It was recommended that a VV ≥50% of expected bladder capacity for age is required to assess uroflowmetry (UFM) curves because a small VV causes changes in UFM curve characteristics. However, no clear consensus has been reached on the criterion for evaluating UFM curve patterns.

OBJECTIVE

The aim of the study was to evaluate the reproducibility and characteristics of UFM curve patterns in children with daytime urinary incontinence (DUI) and with a variety of VVs.

METHODS

This study investigated 119 children (79 boys and 40 girls) with primary DUI who underwent UFM 3 times on the same day and were classified into two groups: small VV (<50% of expected bladder capacity for age) in 0-1 of the 3 UFM measurements (group 1; normal VV) or in 2-3 of the 3 UFM measurements (group 2; small VV). The authors then evaluated the agreement of UFM curve patterns among the 3 measurements, classifying complete, partial, or no agreement according to the number of identical curve patterns. The authors also evaluated the most characteristic patterns of UFM curve patterns for each group.

RESULTS

Group 1 comprised 45 children, and group 2 comprised 74 children. Rates of complete agreement (group 1, 24/45; group 2, 30/74), partial agreement (group 1, 19/45; group 2, 35/74), and no agreement (group 1, 2/45; group 2, 9/74) did not differ significantly between groups (p = 0.226). Bell curve patterns were significantly more common in group 1 than in group 2 (p = 0.025). Frequency of the tower pattern was significantly higher in group 2 than in group 1 (p = 0.006) (Summary table).

DISCUSSION

No differences in agreement rates of UFM curve patterns were seen between two groups (small and normal VV). The authors thus suggest that UFM curve patterns can be validly assessed in children with DUI and with small VV. It was found that the bell pattern was significantly more common among children with normal VV, whereas the tower pattern was significantly more common among children with small VV. The tower pattern reflects an overactive bladder. The present results suggest that some children have DUI that is not attributable to urgency.

CONCLUSION

Reproducibility of UFM curve patterns might be properly assessed even in children with DUI and with small VV. This result suggests the presence of various pathological conditions other than the conditions with urgency underlying DUI.

Diagnosis and Management of Bladder Dysfunction in Neurologically Normal Children

Normal bladder and urethral sphincter development as well as neural/volitional control over bladder-sphincter function are essential steps for regular lower urinary tract function. These maturational sequences are clinically evident by the age of 5 years. However, in 17-22% of children, symptoms persist beyond that age, characterizing lower urinary tract dysfunction (LUTD). The clinical spectrum is wide and includes overactive bladder, voiding postponement, underactive bladder, infrequent voiding, extraordinary daytime only urinary frequency, vaginal reflux, bladder neck dysfunction, and giggle incontinence. LUTD may lead to vesicoureteral reflux and recurrent urinary tract infections, increasing the likelihood of renal scarring. LUTD is often associated with constipation and emotional/behavioral disorders such as anxiety, depression, aggressiveness, and social isolation, making diagnosis, and treatment imperative. Diagnosis of LUTD is essentially based on clinical history, investigation of bladder storage, voiding symptoms (urinary frequency, daytime incontinence, enuresis, urgency) and constipation. Dysfunctional Voiding Score System (DVSS) is a helpful tool. Physical examination focuses on the abdomen to investigate a distended bladder or palpable fecal mass, the lumbosacral spine, and reflex testing. Bladder diaries are important for recording urinary frequency and water balance, while uroflowmetry is used to assess voided volume, maximum flow, and curve patterns. Bladder ultrasonography to measure post-void residual urine volume and urodynamics are used as supplemental tests. Current first line treatment is urotherapy, a combination of behavioral measures to avoid postponing micturition, and a restricted diet for at least 2 months. Anticholinergics, β3 agonists and neuromodulation are alternative therapies to manage refractory overactive bladder. Cure rates, at around 40%, are considered satisfactory, with daytime symptoms improving in 32% of cases. Furthermore, children who are also constipated need treatment, preferentially with polyethylene glycol at doses of 1-1.5 g/kg in the 1st 3 days and 0.25-0.5 g/kg thereafter until the 2-month period of behavioral therapy is complete. If urotherapy fails in cases of dysfunctional voiding, the next step is biofeedback to teach the child how to relax the external urethral sphincter during micturition. Success rate is around 80%. Children with underactive bladder usually need a combination of clean intermittent catheterization, alpha-blockers, biofeedback and neuromodulation; however, cure rates are uncertain.