Early, accurate diagnosis of bladder outlet obstruction in men with lower urinary tract symptoms may reduce the need for invasive testing (ie, catheter placement, urodynamics), and prompt early treatment to provide symptomatic relief and avoid complications.
To systematically review the evidence on (1) the diagnostic accuracy of office-based tests for bladder outlet obstruction in men with lower urinary tract symptoms; and (2) the accuracy of the bladder scan as a measure of urine volume because management decisions rely on measuring postvoid bladder residual volumes.
Data Sources and Study Selection
MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (1950-March 2014), along with reference lists from retrieved articles were searched to identify studies of diagnostic test accuracy among males with lower urinary tract symptoms due to bladder outlet obstruction. MEDLINE, EMBASE, CINAHL, and the Cochrane Library (1950-March 2014) were searched to identify studies of urine volumes measured with a bladder scanner vs those measured with bladder catheterization. Prospective studies were selected if they compared 1 or more office-based, noninvasive diagnostic test with the reference test or were invasive urodynamic studies, and if urine volumes were measured with a bladder scanner and bladder catheterization.
Data Extraction and Synthesis
For the bladder outlet obstruction objective, 8628 unique citations were identified. Ten studies (1262 patients among 9 unique cohorts) met inclusion criteria. For the bladder scan objective, 2254 unique citations were identified. Twenty studies (n = 1397 patients) met inclusion criteria.
Main Outcomes and Measures
The first main outcome and measure was the diagnostic accuracy of individual symptoms and questionnaires compared with the reference standard (urodynamic studies) for the diagnosis of bladder outlet obstruction in males with lower urinary tract symptoms. The second was the correlation between urine volumes measured with a bladder scanner and those measured with bladder catheterization.
Among males with lower urinary tract symptoms, the likelihood ratios (LRs) of individual symptoms and questionnaires for diagnosing bladder outlet obstruction from the highest quality studies had 95% CIs that included 1.0, suggesting they are not significantly associated with one another. An International Prostate Symptom Score cutoff of 20 or greater increased the likelihood of bladder outlet obstruction (positive LR, 1.5; 95% CI, 1.1-2.0), whereas scores of less than 20 had an LR that included 1.0 in the 95% CI (negative LR, 0.82; 95% CI, 0.67-1.00). We found no data on the accuracy of physical examination findings to predict bladder outlet obstruction. Urine volumes measured by a bladder scanner correlated highly with urine volumes measured by bladder catheterization (summary correlation coefficient, 0.93; 95% CI, 0.91-0.95).
Conclusions and Relevance
In patients with lower urinary tract symptoms, the symptoms alone are not enough to adequately diagnose bladder outlet obstruction. A bladder scan for urine volume should be performed to assess patients with suspected large postvoid residual volumes.