Overactive Bladder Workup

Updated: Dec 09, 2016
  • Author: Pamela I Ellsworth, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Workup

Approach Considerations

A few simple office and laboratory tests, in conjunction with the history and physical examination, usually suffice for a diagnosis of overactive bladder (OAB). A urinalysis and culture (if urinary tract infection [UTI] is suspected) is indicated in patients being evaluated for OAB. In select individuals, further testing such as an assessment of postvoid residual may be indicated.

Guidelines for diagnosis of OAB by the American Urological Association (AUA)/Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) include the following [2, 3] :

  • A thorough history, physical examination, and urinalysis should be done initially
  • If necessary, a urine culture, or postvoid residual assessment, or both, can be done, along with use of bladder diaries or symptom questionnaires
  • Urodynamic study, cystoscopy, and diagnostic renal and bladder ultrasonography are not necessary in the initial workup of uncomplicated cases and should be reserved for refractory or otherwise complicated cases
  • Urine cytology is not recommended in the absence of hematuria when the patient responds to therapy
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Urine Studies

Urinalysis is used to exclude microhematuria, pyuria, urinary tract infection, and glucosuria. In those individuals with microhematuria, further evaluation including a urine cytology is recommended. In individuals at risk for bladder cancer, a cytology even in the absence of microhematuria may be indicated.

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Postvoid Residual Testing

Postvoid residual testing is not indicated in all patients. It is helpful in men with both obstructive and OAB symptoms, in women who have undergone prior pelvic surgery (eg, prior incontinence surgery), and those with significant pelvic organ prolapse.

Postvoid residual volume is assessed by means of urethral catheterization or ultrasonography. No definitive upper level of normal for postvoid residual has been established, but many would argue that postvoid residuals greater than 150-200 mL are indicative of incomplete bladder emptying and may warrant further evaluation.

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Cystometry

Cystometry is a simple method for testing the bladder’s storage function and provides information on bladder capacity, the extent of accommodation or compliance, the ability to sense bladder filling, and temperature; it can also help assess for detrusor overactivity during bladder filling.

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Urodynamic Study

Urodynamic study is not indicated as part of the first-line evaluation of patients with OAB unless a neurologic etiology is suspected. It is most commonly performed in individuals in whom first-line therapies for OAB fail and/or in whom a neurogenic etiology is suspected.

A urodynamic study consists of cystometrography (CMG) and uroflow/electromyelography. CMG assesses the storage phase of bladder function, which includes the following:

  • Bladder capacity
  • Bladder compliance
  • Detrusor overactivity
  • Sensation of filling

Uroflow/electromyelography assesses the voiding phase, which includes the following:

  • Detrusor pressure during voiding
  • Relaxation of the pelvic floor muscles during voiding
  • The nature of the flow pattern (ie, bell-shaped curve, staccato)
  • Presence or absence of Valsalva voiding

Intravesical pressure is a combination of intra-abdominal pressure and detrusor pressure. To determine the detrusor pressure, the intra-abdominal pressure is measured with a rectal catheter; this pressure is subtracted from the total intravesical pressure (measured with the bladder catheter). In males, a nomogram is available, the pressure/flow study, whereby detrusor pressure is plotted against flow rate, and this is used to assess for bladder outlet obstruction.

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