Home Uroflowmetry for the Evaluation of Boys with Urinary Incontinence

0022-5347/03/1694-1505/0 THE JOURNAL OF UROLOGY® Copyright © 2003 by AMERICAN UROLOGICAL ASSOCIATION

Vol. 169, 1505–1507, April 2003 Printed in U.S.A.

DOI: 10.1097/01.ju.0000054761.31086.46

HOME UROFLOWMETRY FOR THE EVALUATION OF BOYS WITH URINARY INCONTINENCE STEPHEN SHEI DEI YANG, CHUNG CHENG WANG*

AND

YUNG TAI CHEN

From the Department of Urology, En Chu Kong Hospital, School of Medicine, Taipei Medical University and National Taiwan University, Taipei, Taiwan

ABSTRACT

Purpose: We recorded uroflowmetry at home in boys with urinary incontinence and correlated the results with videourodynamics. Materials and Methods: Thirty-nine boys (mean age 8.4 ⫾ 2.0 years) with urinary incontinence underwent home uroflowmetry for 1 weekend. Artifactual spikes in 1 or more uroflow curves were present in 16 home uroflowmetry recordings. One patient, in whom none of the uroflow curves was interpretable, was excluded from the study. Of the remaining 38 boys 18 had monosymptomatic nocturnal enuresis, and 20 had nocturnal enuresis and diurnal voiding symptoms. Percentage expected bladder capacity is defined as functional/expected bladder capacity ⫻ 100%. Normal and obstructive home uroflowmetry levels are defined as functional bladder capacity at least 50% expected bladder capacity associated with multiple bell-shaped and obstructive uroflow curves, respectively. Small functional bladder capacity is defined as capacity less than 50% expected bladder capacity, regardless of uroflow patterns. Videourodynamics and cystoscopy were performed in 17 patients. Results: Normal home uroflowmetry was noted in 5 patients (13%), obstructive uropathy in 8 (21%) and small functional bladder capacity in 25 (66%). Urodynamically 3 boys with normal home uroflowmetry had normal voiding, and 6 with obstructive home uroflowmetry had bladder outlet obstruction (of whom 1 also had detrusor overactivity). In addition, of 8 boys with small functional bladder capacity 4 had detrusor overactivity, 3 had bladder outlet obstruction and 1 had both findings. Conclusions: Normal home uroflowmetry predicted normal voiding, and abnormal recordings implied abnormal voiding function in boys with incontinence. Bladder outlet obstruction and detrusor overactivity were frequently disclosed by obstructive home uroflowmetry and small functional bladder capacity. KEY WORDS: urodynamics, bladder, urinary incontinence

Because of noninvasiveness, uroflowmetry is suggested to be the perfect instrument for revealing voiding disorders in pediatric patients.1–3 The shape of the uroflow curve, rather than peak uroflow rate, is the most important factor in evaluating uroflow in a child. Importantly, voided volume less than 50 ml. is seldom considered relevant for interpreting uroflowmetry.3 Poor cooperation, agitation and/or anxiety in children can cause disturbances in standard urodynamic investigation, and probably also in uroflowmetry as reflected by frequent small voided volumes at the clinic.1–3 Small functional bladder capacity is a risk factor predicting poor outcome of conservative treatments for nocturnal enuresis.4 –7 Use of a frequency volume chart for 2 weekends provides reliable data regarding functional bladder capacity. However, there was a marked dropout rate (greater than 40%) in a study involving 4-day recording in women with urge incontinence and children with nocturnal enuresis.8, 9 We propose that recording uroflowmetry at home for 1 weekend may avoid these drawbacks, and provide multiple tracings for a reliable interpretation of uroflowmetry and a reasonable estimation of functional bladder capacity. In this series the results of home uroflowmetry were further correlated with videourodynamic study. Accepted for publication November 8, 2002. * Requests for reprints: Department of Urology, En Chu Kong Hospital, 399 Fushing Rd., Sanhsia Town, Taipei Hsien, Taiwan 237.

MATERIALS AND METHODS

Between 2000 and 2001, 39 consecutive male children (mean age 8.4 ⫾ 2.0 years) with urinary incontinence were asked to perform uroflowmetry at home for 1 weekend. All medications were stopped 1 week before the investigation. Using a home uroflowmeter (Dacapo, Dantec, Skovlunde, Denmark), patients were instructed to void when they had a “normal” desire to void.10 Successful home recording means more than 2 interpretable uroflow curves. Artifactual spikes in 1 or several uroflow curves of the same child were present in 16 home uroflowmetry recordings.10 One patient, in whom none of the uroflow curves was interpretable, was excluded from the study. Of the remaining 38 boys 18 had monosymptomatic nocturnal enuresis, and 20 had nocturnal enuresis and diurnal voiding symptoms (frequency/urgency in 10, diurnal enuresis in 9 and weak stream in 2). Expected bladder capacity is calculated as (age in years ⫹2) ⫻ 30 ml.11 The largest voided volume is defined as functional bladder capacity. Percentage expected bladder capacity is defined as functional/expected bladder capacity ⫻ 100%. Normal uroflow pattern is defined as a bell-shaped curve at a voided volume of at least 50% expected bladder capacity. Normal home uroflowmetry means all uroflow curves at a voided volume of at least 50% expected bladder capacity are bell-shaped. Obstructive uroflow pattern is defined as a constrictive, compressive or staccato curve at a voided volume of at least 50% expected bladder capacity.3, 10 Obstructive home uroflowmetry means multiple obstructive

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uroflow curves (fig. 1). Small functional bladder capacity means all voided volumes less than 50% expected bladder capacity, regardless of the shapes of uroflow curves (fig. 2). Videourodynamics and cystoscopy were performed in 17 patients. The remaining 21 boys/parents refused the examination because of invasiveness. Urodynamics done in this study conformed to standards recommended by the International Children’s Continence Society, except where specially noted.3 With the patients under intravenous anesthesia an 8Fr suprapubic catheter was inserted into the bladder. Urodynamics were performed 1 day later. The infused fluid is maintained at about 37C and at a pumping speed of 10% expected bladder capacity per minute. Primary bladder neck obstruction is defined as high detrusor pressure during voiding, low peak urinary flow rate, obstructive flow pattern and narrowing only at the bladder neck fluoroscopically.12 Dysfunctional voiding is defined as increased external sphincter electromyographic activity during voluntary voiding and segmental stenosis of the posterior urethra radiographically.3 Cobb’s collar (narrowing of the bulbar urethra) appears as a membranous lesion in the posterior urethra cystoscopically and as stenosis of the posterior urethra radiographically.13, 14 Detrusor overactivity is defined as unstable detrusor or small cystometric capacity without unstable detrusor contraction before voiding.3 In this series the results of home uroflowmetry and videourodynamics were interpreted independently and blinded to each other. RESULTS

Demographic data and results of home uroflowmetry are summarized in table 1. Mean number of uroflow recordings and voided volume greater than 50 ml. were 10.0 and 6.8, respectively. Mean recorded duration between first and last voiding was 27 hours. Mean functional and percentage expected bladder capacities were 142 ml. and 48%, respectively. Five patients (13%) had normal home uroflowmetry recordings. Twenty-five patients (66%) had small functional bladder capacity. Of these patients 23 had only bell-shaped tracings, and 2 had mixed bell-shaped and obstructive uroflow curves. Eight patients (21%) had obstructive home uroflowmetry recordings. Of these patients 7 had bell-shaped uroflowmetries at a voided volume between 50 ml. and 50% expected bladder capacity and obstructive patterns at a larger volume, and 1 had obstructive curves at small and large voided volumes. No child had mixed bell-shaped and obstructive uroflow patterns at a voided volume greater than 50% expected bladder capacity. Results of home uroflowmetry and videourodynamics are correlated in table 2. Three boys with normal home uroflowmetry had normal voiding urodynamically. Of 6 boys with

FIG. 1. Consecutive uroflowmetries show obstructive findings in 11.8-year-old boy with nocturnal enuresis and frequency. A and D, constrictive curves at volumes greater than 50% expected bladder capacity. B and C, curve becomes bell-shaped at small volumes. Subsequent videourodynamics disclosed primary bladder neck obstruction.

FIG. 2. Consecutive uroflowmetries reveal small functional bladder capacity in 9.8-year-old boy with monosymptomatic nocturnal enuresis. All voided volumes were less than 50% expected bladder capacity and uroflow curves were mixed with bell-shaped, equivocal and obstructive patterns. Subsequent videourodynamics disclosed dysfunctional voiding and unstable detrusor contraction.

TABLE 1. Demographic data and results for 38 boys evaluated by home uroflowmetry Parameter

Mean ⫾ SD

Range

Age (yrs.) No. wet nights/wk. No. uroflow recordings No. vol. greater than 50 ml. Recorded duration (hrs.) Functional bladder capacity (ml.) % Expected bladder capacity

8.4 ⫾ 2.0 5.9 ⫾ 1.8 10.0 ⫾ 5.0 6.8 ⫾ 3.7 27 ⫾ 12 142 ⫾ 65 48.0 ⫾ 18.0

5–12 1–7 3–21 0–18 11–58 48–294 10.6–92.0

obstructive home uroflowmetry 5 had bladder outlet obstruction, and 1 had obstruction and detrusor overactivity. Of 8 boys with small functional bladder capacity 4 had detrusor overactivity, 3 had bladder outlet obstruction and 1 had both findings. Primary bladder neck obstruction was observed in 4 patients, dysfunctional voiding in 3 and Cobb’s collar in 3. DISCUSSION

Home uroflowmetry recorded multiple uroflow curves and provided a better interpretation of voiding function in boys with incontinence. In normal young male volunteers home uroflowmetry disclosed almost no differences between ambulatory urodynamics in recorded voided volume and peak urinary flow rate.15 The frequent small voided volumes and artifactual spikes in home uroflowmetries may be due to detrusor overactivity, frequently detected in this study, or poor cooperation of the patients. Patients might rush to the toilet and incidentally kick the home uroflowmeter. Because of privacy and the intent not to disrupt volitional voiding, no one had the opportunity to eyewitness how the children voided or used the machine. However, only 1 home uroflowmetry recording was not interpretable. Another obstacle to obtaining adequate home uroflowmetry recordings is the variation of recorded duration of voiding. Some patients recorded a shorter duration, while others recorded a longer duration. With these limitations the successful recording rate in this study (98%) was still higher than that of the 4-day frequency volume recording in the children with nocturnal enuresis (50%) and women with urge incontinence (60%).8, 9 Uroflow patterns varied greatly at a voided volume between 50 ml. and 50% expected bladder capacity. A bellshaped uroflowmetry reading at a small voided volume may demonstrate an obstructive pattern at a larger volume. Thus, single uroflowmetry should be interpreted carefully, particularly at a voided volume of less than 50% expected bladder capacity. However, uroflow pattern was more consistent at a voided volume of greater than 50% expected bladder capacity. Multiple bell-shaped uroflow curves at a voided volume of

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HOME UROFLOWMETRY TO ASSESS URINARY INCONTINENCE IN BOYS TABLE 2. Results of home uroflowmetry in 17 boys with urinary incontinence and normal videourodynamics Detrusor Overactivity Home Uroflowmetry

Unstable Detrusor

Normal 3 Obstructive 0 Small functional bladder capacity 0 * Additional unstable destrusor was noted in 1 patient

Outlet Obstruction

Small Functional Bladder Capacity

0 1 3 in each group.

0 0 2

greater than 50% expected bladder capacity (normal home uroflowmetry) predicted normal voiding function, and multiple obstructive uroflow curves (obstructive home uroflowmetry) predicted some types of bladder outlet obstruction and occasionally detrusor overactivity. Although recording home uroflowmetry for 1 weekend may underestimate true functional bladder capacity, all voided volumes less than 50% expected bladder capacity did reflect a small functional bladder capacity, in which detrusor overactivity and/or bladder outlet obstruction was frequently disclosed urodynamically. In this study mean functional bladder capacity was 48% of expected bladder capacity, which is comparable to previous observations that mean functional bladder capacity in nonresponders to desmopressin is 52% to 56% expected bladder capacity.5–7 Currently there is no consensus regarding the definition of small functional bladder capacity. However, it seems reasonable and practical to use 50% expected bladder capacity as a cutoff. Using various formulas to calculate bladder capacity, some investigators have concluded that patients with a functional bladder capacity of 50% to 90% expected bladder capacity are more likely to benefit from desmopressin or other conservative therapies than are those with a bladder capacity below this range.4 –7, 11, 16 However, we were not certain why some boys with a small functional bladder capacity had only nocturnal symptoms.5–7 These patients might limit daytime drinking to avoid frequent voiding, as noted in some of our patients. Medical or surgical relief of bladder outlet obstruction has improved nocturnal enuresis/incontinence.13, 14, 17 In this series a daily dose of 0.5 to 1.0 mg. doxazosin was used in 3 boys with primary bladder neck obstruction, and transurethral incision of the bladder neck was performed in 1.12 Transurethral incision was performed in boys with Cobb’s collar, and biofeedback relaxation of the pelvic floor was used in those with dysfunctional voiding. Using these treatments, partial and complete responses of nocturnal enuresis were achieved in 5 patients each.3 Wet nights per week decreased from 5.4 ⫾ 2.2 to 0.8 ⫾ 1.2 (Student t test, p ⬍0.001). Maximum flow rate increased from 13.2 ⫾ 2.3 to 16.7 ⫾ 4.7 ml. per second (Student t test, p ⫽ 0.03), while mean voided volume was not significantly changed (210 ⫾ 92 versus 218 ⫾ 97 ml., Student t test, p ⫽ 0.42). In conclusion, normal home uroflowmetry recordings predicted normal voiding and abnormal recordings indicated abnormal voiding function in boys with urinary incontinence. Videourodynamics are recommended to disclose detrusor overactivity and/or bladder outlet obstruction in patients with small functional bladder capacity or obstructive home uroflowmetry. REFERENCES

1. Griffiths, D. J. and Scholtmeijer, R. J.: Place of the free flow curve in the urodynamic investigation of children. Br J Urol, 56: 474, 1984

Primary Bladder Neck Obstruction

Dysfunctional Voiding

Cobb’s Collar

Total

0 3 1

0 1* 2*

0 2 1

3 7 9

2. Hoebeke, P., Vande Walle, J., Everaert, K., Van Laecke, E. and Van Gool, J. D.: Assessment of lower urinary tract dysfunction in children with non-neuropathic bladder sphincter dysfunction. Eur Urol, 35: 57, 1999 3. Norgaard, J. P., van Gool, J. D., Hjalmas, K., Djurhuus, J. C. and Hellstrom, A. L.: Standardization and definitions in lower urinary tract dysfunction in children. International Children’s Continence Society. Br J Urol, suppl., 81: 1, 1998 4. Neve´ us, T., Tuvemo, T., La¨ ckgren, G. and Stenberg, A.: Bladder capacity and renal concentrating ability in enuresis pathogenic implications. J Urol, 165: 2022, 1999 5. Hamano, S., Yamanishi, T., Igarashi, T., Ito, H. and Murakami, S.: Functional bladder capacity as a predictor of response to desmopressin and retention control training in monosymptomatic nocturnal enuresis. Eur Urol, 37: 718, 2000 6. Rushton, H. G., Belman, A. B., Zoantz, M. R., Skoog, S. J. and Sihelnik, S.: The influence of small functional bladder capacity and other predictors on the response to desmopressin in the management of monosymptomatic nocturnal enuresis. J Urol, 156: 651, 1996 7. Eller, D. A., Austin, P. F., Tanguay, S. and Homsy, Y. L.: Daytime functional bladder capacity as a predictor of response to desmopressin in monosymptomatic nocturnal enuresis. Eur Urol, suppl., 33: 25, 1998 8. Hansen, M. N., Rittig, S., Siggaard, C., Kamperis, K., Hvistendahl, G., Schaumburg, H. L. et al: Intra-individual variability in nighttime urine production and functional bladder capacity estimated by home recordings in patients with nocturnal enuresis. J Urol, 166: 2452, 2001 9. van Melick, H. H., Gisolf, K. W., Eckhardt, M. D., van Venrooij, G. E. and Boon, T. A.: One 24-hour frequency-volume chart in a woman with objective urinary motor urge incontinence is sufficient. Urology, 58: 188, 2001 10. Schafer, W., Abrams, P., Liao, L., Mattiasson, A., Pesce, F., Sterling, A. M. et al: Good urodynamic practices: uroflowmetry, filling cystometry, and pressure-flow studies. Neurourol Urodyn, 21: 261, 2002 11. Koff, S. A.: Estimating bladder capacity in children. Urology, 21: 248, 1983 12. Yang, S. S. D., Wang, C. C., Hsieh, C. H. and Chen, Y. T.: ␣1-Adrenergic blockers in young men with primary bladder neck obstruction. J Urol, 168: 571, 2002 13. Yeung, C. K., Chiu, H. N. and Sit, F. K. Y.: Bladder dysfunction in children with refractory monosymptomatic primary nocturnal enuresis. J Urol, 162: 1049, 1999 14. Nonomura, K., Kanno, T., Kakizaki, H., Koyama, T., Yamashita, T. and Koyanagi, T.: Impact of congenital narrowing of the bulbar urethra (Cobb’s collar) and its transurethral incision in children. Eur Urol, 36: 144, 1999 15. Schmidt, F., Jorgensen, T. M. and Djurhuus, J. C.: Ambulatory urodynamics and home flowmetry, are there differences in the recorded data. Presented at annual meeting of International Continence Society, Seoul, Korea, September 18 –21, 2001 16. Hjalmas, K.: Urodynamics in normal infants and children. Scand J Urol Nephrol, suppl., 114: 20, 1988 17. Austin, P. F., Homsy, Y. L., Masel, J. L., Cain, M. P., Casale, A. J. and Rink, R. C.: ␣-Adrenergic blockade in children with neuropathic and nonneuropathic voiding dysfunction. J Urol, 162: 1064, 1999