Use of uroflow parameters in diagnosing an overactive bladder-Back to the drawing board

The Use of Uroflowmetry as a Diagnostic Test

PURPOSE OF REVIEW

Uroflowmetry is widely used for initial non-invasive evaluation of lower urinary tract disorders. Current clinical use is mostly restricted to a scrutiny of the maximum flow rate and uroflow pattern recorded by a conventional flowmeter in a health care facility. There are several advancements in our understanding and in available technologies that promise to transform clinical utilization of this simple test.

RECENT FINDINGS

Several aspects of the uroflow test in addition to maximum flow rate and uroflow pattern show potential diagnostic utility. This includes flow acceleration, uroflow indices, uroflow-electromyography including lag time, stop uroflow test, and uroflow-based nomograms. There are initial attempts to use artificial intelligence in analysis. There is also new data with regard to factors influencing variability of uroflow testing that might influence the diagnostic value in as yet uncertain ways including diurnal variability, postural variability, locational variability, and operator variability. There are new technologies for uroflow testing in a home environment allowing for easy repetition. However, there are several challenges owing to a paucity of clinical data and standardization. There are also critical lacunae in terminology that need to be addressed. There are exciting new advancements in the field of uroflowmetry. However, there is need to standardize and validate the newer uroflow tracing analyses and technologies.

Over Active Bladder Index (OABI): A New Objective Tool Based on Uroflow Parameters for Diagnosis of Overactive Bladder in Children

AIMS

The aim of this study is to propose an objective uroflow based index for diagnosing over active bladder (OAB).

MATERIALS AND METHODS

Thirty patients with OAB and 30 controls were used in the pilot study. Three uroflow parameters: Uroflow index (UI = Qave/Qmax), voided volume ratio (VVR = voided volume/expected bladder capacity) and time to Q max (TQmax) were studied. Linear regression was performed for the three parameters with controls/OAB patients. Further 28 patients & 32 controls were recruited in a second validation study.

RESULTS

Mean (s.d) UI was 0.7 (0.1) in control while 0.4 (0.1) in OAB (p = 0.001). Mean (s.d) VVR was 0.7 (0.1) in control while 0.5 (0.1) in OAB (p = 0.01). Mean (s.d) TQmax was 5.2 (1.2) in control while 2.1 (1.8) in OAB (p = 0.001). Good correlation was noted with all parameters UI (r = 0.89); VVR (r = 0.87) and TQmax (r = 0.76); when all three were combined as an index the correlation was better (r = 0.95). Based on the beta coefficients an OAB Index [OABI = 8(UI)+9(VVR)+0.5(TQmax)] was proposed; ROC analysis revealed a cutoff of 12 (AUC 0.96). An OABI of <12 was proposed for diagnosing OAB, 12-15 for equivocal and >15 for normal children. In the validation study OABI had 93 % sensitivity; 100 % specificity; 100 % positive predictive value & 94 % negative predictive value. The overall accuracy was 97 %.

CONCLUSION

While current diagnosis of OAB is mainly subjective, the proposed OABI is an objective way of diagnosing OAB using uroflow parameters. OABI may also help to assess treatment response. Further larger studies are warranted.

Safety and short-term efficacy of mirabegron in children with valve bladder: a pilot study

AIMS

This pilot study aims to assess the short-term efficacy and safety of mirabegron in valve bladder, an important cause of persistent hydronephrosis after successful treatment of posterior urethral valves (PUV).

METHODS

Twenty-two patients with early valve bladder (no residual PUV; persistent hydronephrosis, wetting and urodynamic evidence of detrusor overactivity) were included. Three subjective parameters: frequency, wetting episodes; patient perception of bladder condition score (PPBC) and four objective parameters: uroflow index (UI = Qave/Qmax), voided volume (VV = voided volume/ expected bladder capacity), maximum filling pressure (P det-max) and society of fetal urology (SFU) hydronephrosis grading were analysed pre- and post-3-month treatment with mirabegron (0.5-1 mg/kg/day). All patients were observed for heart rate, BP, ECG changes during therapy.

RESULTS

There was significant reduction (p = 0.001) in mean frequency (pre 15; post 10), wetting episodes (pre 5; post 2) and PPBC (pre 4; post 3). There was significant improvement (p = 0.01) in mean UI (pre 0.3; post 0.5), VV (pre 0.54; post 0.72), Pdet-max (pre 42; post 25) and hydronephrosis grade (pre 3.5; post 2.2). There were no significant side effects.

CONCLUSION

This pilot study establishes short-term efficacy and safety of mirabegron in valve bladder with overactivity. Further larger long-term studies are warranted.

Clinical features of, and association of bladder ultrasound and uroflowmetry with, overactive bladder recovery period in children

BACKGROUND

Overactive bladder (OAB) is a symptomatic syndrome defined by urinary urgency, usually accompanied by increased urination frequency and nocturia, with or without urinary incontinence. The prevalence of pediatric OAB in 5-13 year olds is as high as 16.6%, but the pathophysiology and epidemiology have not been sufficiently elucidated.

METHODS

We retrospectively reviewed medical records in 117 children with OAB aged between 5 and 15 years during the years 2012-2016. At initial presentation, abdominal ultrasound and uroflowmetry were performed, and behavioral modifications, such as timed voiding, and constipation therapy were initiated. If there was no response after 4 weeks, antimuscarinic treatment was added. We evaluated the clinical features of OAB and factors related to the recovery period, which was defined as the period from the start of behavioral modifications to cure.

RESULTS

The average recovery period was 11.9 ± 9.73 months. There was no significant difference in the recovery period according to age, gender, percentage of urination frequency, nocturnal enuresis, or constipation. The recovery period was significantly shorter in the group with bladder wall thickness ≥5 mm than with bladder wall thickness <5 mm. Children with a tower-shaped curve on uroflowmetry had a significantly shorter recovery period than those with a bell-shaped curve.

CONCLUSIONS

Bladder wall thickness and uroflow curve shape are related to the recovery period of pediatric OAB.

How can we maximize the diagnostic utility of uroflow?: ICI-RS 2017

AIMS

To gauge the current level of diagnostic utility of uroflowmetry and to suggest areas needing research to improve this.

METHODS

A summary of the debate held at the 2017 meeting of the International Consultation on Incontinence Research Society, with subsequent analysis by the authors.

RESULTS

Limited diagnostic sensitivity and specificity exist for maximum flow rates, multiple uroflow measurements, and flow-volume nomograms. There is a lack of clarity in flow rate curve shape description and uroflow time measurement.

CONCLUSIONS

There is a need for research to combine uroflowmetry with other non-invasive indicators. Better standardizations of test technique, flow-volume nomograms, uroflow shape descriptions, and time measurements are required.

A comparison of normal and high post-void residual urine and urodynamic parameters in women with overactive bladder

Objective

To investigate voiding functions and assess the relationships of voiding parameters to overactive bladder symptoms and postvoiding residue volumes.

Materials and Methods

This is a retrospective study analyzing urodynamic parameters in patients who were diagnosed as having overactive in our urogynecology clinic between April 2014 and April 2016. A total of 290 women who met the selection criteria were included in the study. The patients were divided into two groups according to postvoiding residue volumes: group 1, postvoiding residue volumes <100 mL (n=135); group 2, postvoiding residue volumes ≥100 mL (n=155).

Results

A total of 290 women were included in the study; the mean age was 71.4 years. A total of 158 (54.5%) patients had detrusor over-activity during urodynamic testing. The mean maximum bladder capacity in elevated group 2 (postvoiding residue volumes ≥100 mL) was significantly higher than in group 1 (postvoiding residue volumes <100 mL) (p<0.01). Additionally, there was a significant difference between detrusor pressure at Q_max in both study groups (p<0.05). There were no significant differences in the first-sensation volume between the normal and elevated postvoiding residue volumes groups.

Conclusion

In conclusion, patients with overactive with elevated postvoiding residue volumes showed increased maximum bladder capacity, but detrusor over-activity was not more prevalent in these women compared with women with normal postvoiding residue volumes.

Stimulation of the pelvic nerve increases bladder capacity in the prostaglandin E2 rat model of overactive bladder

Overactive bladder (OAB) syndrome is a highly prevalent condition that may lead to medical complications and decreased quality of life. Emerging therapies focusing on selective electrical stimulation of peripheral nerves associated with lower urinary tract function may provide improved efficacy and reduced side effects compared with sacral neuromodulation for the treatment of OAB symptoms. Prior studies investigating the effects of pelvic nerve (PelN) stimulation on lower urinary tract function were focused on promoting bladder contractions, and it is unclear whether selective stimulation of the PelN would be beneficial for the treatment of OAB. Therefore our motivation was to test the hypothesis that PelN stimulation would increase bladder capacity in the prostaglandin E₂ (PGE₂) rat model of OAB. Cystometry experiments were conducted in 17 urethane-anesthetized female Sprague-Dawley rats. The effects of intravesical PGE₂ vs. vehicle and PelN stimulation after intravesical PGE₂ on cystometric parameters were quantified. Intravesical infusion of PGE₂ resulted in decreased bladder capacity and increased voiding efficiency without a change in bladder contraction area under the curve, maximum contraction pressure, or contraction duration. Bladder capacity was also significantly decreased compared with vehicle (1% ethanol in saline) confirming that the change in bladder capacity was mediated by PGE₂ PelN stimulation reversed the PGE₂-induced change in bladder capacity and increased the external urethral sphincter electromyogram activity at a specific stimulation condition (amplitude of 1.0 times threshold at 10 Hz). These results confirm that the urodynamic changes reported in conscious rats are also observed under urethane anesthesia and that PelN stimulation is a novel and promising approach for the treatment of the symptoms of OAB.

Use of free uroflowmetry vs pressure-flow studies in the diagnosis of overactive bladder syndrome in females

OBJECTIVES

To determine if pressure-flow study (PFS) parameters, including flow index (FI) calculated by dividing average urethral flow by maximal urethral flow, increase the accuracy of urodynamic studies in the diagnosis of overactive bladder (OAB).

STUDY DESIGN

Retrospective study to evaluate the medical history and urodynamic examination results of female patients diagnosed with lower urinary tract symptoms (LUTS) between January 2014 and December 2015. Patients were stratified into four groups depending on the type of LUTS: OAB; stress urinary incontinence (SUI); mixed urinary incontinence with predominant SUI symptoms (MUI-SUI); and mixed urinary incontinence with predominant OAB symptoms (MUI-OAB).

RESULTS

OAB was diagnosed in 26 (15%) patients, SUI was diagnosed in 93 (52%) patients, MUI-OAB was diagnosed in 43 (24%) patients, and MUI-SUI was diagnosed in 17 (9%) patients. FI calculated using free uroflowmetry (FI-free) was significantly lower in the OAB group compared with the other groups (p<0.01). Analysis revealed no difference in FI-free between the SUI, MUI-SUI and MUI-OAB groups. Significant differences were found between the study groups for most free uroflowmetric parameters, including maximal urethral flow, average urethral flow and micturition volume (p<0.05). Similar differences were not found in PFS parameters.

CONCLUSIONS

The decrease in the urethral lumen due to the presence of a transurethral catheter in patients with OAB, in contrast to women with SUI and MUI, was not found to influence FI calculated using free uroflowmetry or PFS. FI may serve as an important objective diagnostic tool for OAB, but only when calculated from free uroflowmetry parameters when assessing patients with LUTS.