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18062

The Bladder of Willful Infrequent Voiders: Underactive or Underutilized?

Saturday, October 20, 2012
Grand Ballroom A/B (Hilton Riverside)
Angela M. Fast, B.S., Andrew J. Combs, RPA-C, Jason P. Van Batavia, M.D. and Kenneth I. Glassberg, M.D., FAAP, Division of Pediatric Urology, Department of Urology, Columbia University College of Physicians and Surgeons, Morgan Stanley Children's Hospital of New York-Presbyterian, New York, NY

Purpose:   Detrusor underutilization disorder (DUD) has previously been described as a lower urinary tract (LUT) condition characterized by chronic or episodic willful deferment of voiding. This underutilization results in expanded bladder capacity and can lead to infections from prolonged periods of stasis or urgency +/- incontinence provoked by over-distension. Voiding is otherwise normal and the pelvic floor quiet on uroflow/electromyography (uroflow/EMG). We further characterized DUD patients based on LUT symptoms and uroflow/EMG findings before and after treatment.

Methods:   We reviewed our database to identify neurologically and anatomically normal children diagnosed with DUD on uroflow/EMG testing with all tests performed when patient expressed a sense of fullness. Only patients with an initial bladder capacity greater than 1.25 times expected bladder capacity (EBC) were included, with %EBC = [actual bladder capacity]/[EBC]. LUT symptoms, uroflow/EMG and urodynamic study (UDS) findings were analyzed.  Patients were treated with timed voiding every 3-4 hours. Treatment outcomes were analyzed in patients with follow-up studies.

Results:   Fifty-five children (mean age 10.5 years, range 3.7-20.2; 34 female, 19 male) were diagnosed with DUD.  Infrequent voiding (70.9%), UTI history (49.1.9%) and incontinence (49.1%) were the most common LUT symptoms (Table 1). Table 2 reports uroflow/EMG findings.  Seven patients also had UDS; none had evidence of detrusor underactivity. Twenty-three patients had follow-up (mean treatment length: 8.4 months), with 3 patients reporting treatment non-compliance. Of the 20 compliant patients, 17 (85%) reported improvement in their LUT symptoms, none had a UTI and bladder capacity decreased 49.7% (p<0.001). Non-compliant patients denied symptomatic improvement and had a 23% further increase in bladder capacity.

Conclusion: DUD patients with their expansive bladder capacities typically present with a history of infrequent voiding, UTIs and incontinence. While willful infrequent voiders are often referred to as having an "underactive bladder," no patient who underwent UDS showed any evidence of detrusor underactivity and only 1 (1.8%) had a strain/interrupted flow pattern generally believed associated with that condition. With increased bladder utilization, these patients improved symptomatically, stopped wetting, stayed infection free and experienced normalization of bladder capacity, demonstrating the efficacy of therapy and likelihood that "underactive bladder" is an incorrect characterization. 

Table 1.  LUT symptoms in DUD patients (n=55)

Symptom

No. patients (%)

Infrequent voiding

39 (70.9)

UTI

27 (49.1)

     Febrile UTI

10 (18.2)

Incontinence

27 (49.1)

     Daytime incontinence

14 (25.5)

Urgency

23 (41.8)

Frequency

1 (1.8)

Bowel dysfunction

  6 (10.9)

Straining

1 (1.8)

Table 2.  Uroflow/EMG findings pre- and post- treatment with timed voiding

All (n=55)

Pre (n=20)

Post (n=20)

Paired P-value

Mean Qmax (ml/sec)

32.7

35.3

31.8

0.02

Mean Qave (ml/sec)

21.9

19.5

19.3

0.84

Mean PVR (cc)

19.5

13.9

7.4

0.03

Mean % EBC

1.72

1.72

1.19

<0.001

Mean Lag time (sec)

6.9

7.5

4.5

0.65

Strain/interrupted flow pattern

1

0

0