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Make the Diagnosis: Bladder Outlet Obstruction

Prior Probability of Bladder Outlet Obstruction

When compared with a diagnostic standard of urodynamic studies, 64% (95% CI, 52%-74%) of men in clinical research studies have bladder outlet obstruction.

Population for Whom Bladder Outlet Obstruction Should Be Considered

Bladder outlet obstruction in men should be considered when lower urinary tract symptoms are present. The most common cause is benign prostatic hypertrophy (BPH), with 90% of men aged 81-90y having BPH.1,2 However, a variety of conditions can cause bladder outlet obstruction that can exist without the presence of urinary symptoms (see Box 97-1).3,4

Box 97-1. Causes of Lower Urinary Tract Symptoms Other Than Bladder Outlet Obstruction Secondary to Benign Prostatic Hyperplasia

  • Urethral stricture

  • Primary bladder neck obstruction

  • Bladder neck contracture

  • Meatal stenosis

  • Bladder dysfunction (ie, overactive bladder)

  • Urinary tract infections

  • Malignancies (ie, bladder cancer, prostate cancer)

  • Chronic pelvic pain conditions (ie, prostatitis, interstitial cystitis)

  • Medications (ie, diuretics)

  • General medical conditions (ie, congestive heart failure)

  • Nervous system dysfunction

  • Stroke

  • Parkinson disease

  • Adapted from Abrams et al,6 2013, and Abrams et al,7 2002.

Assessing the Likelihood of Bladder Outlet Obstruction

The data for assessing bladder outlet obstruction come from symptomatic men clinically suspected of having BPH, primarily in the absence of other underlying conditions known to cause obstruction. Individual lower urinary tract symptoms (eg, intermittent stream) are not diagnostically useful, with CIs including 1. The most commonly used combination of symptoms is the American Urological Association Symptom Index, also known as the International Prostate Symptom Score.5 While this widely used questionnaire does a good job of quantifying the severity of symptoms, the combination of symptoms does not do well in predicting those with bladder outlet obstruction when compared with a urodynamic reference standard (see Table 97-1).

Table 97-1.Assessing the Likelihood of Bladder Outlet Obstruction in Men With Lower Urinary Tract Symptoms

For very practical reasons, most physicians use the bladder scan as a less invasive alternative to bladder catheterization to determine if there is retained urine after urination (the postvoid residual). There are no diagnostic accuracy studies of the bladder scan compared with a universally accepted threshold value of urine retention. However, there is good correlation between the bladder scan and postvoid residual from catheter placement (r = 0.93). Below the commonly accepted threshold value of 200 ml for postvoid residual, the difference between the bladder scan estimate and the catheter result tend to be smaller ...

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