Outline of 3,830 Male Patients Referred to Urodynamic Evaluation for Lower Urinary Tract Symptoms: How Common Is Infravesical Outlet Obstruction?

Introduction: The prevalence of bladder outlet obstruction in men has been overestimated leading to improper clinical results after transurethral resection of the prostate. Patients and Methods: 3,830 consecutive male cases submitted for urodynamic evaluation were prospectively analyzed using a Schaefer nomogram. The prevalence of detrusor overactivity and the occurrence of obstruction were prospectively studied using standardized urodynamic practice. Results: Infravesical obstruction was diagnosed in 44.8% of the studied population: 0.7% of the obstructed cases were obstructed at the sphincter zone and 7.9% showed obstruction as a high-pressure, high-flow-rate pattern. Detrusor overactivity was demonstrated in 73.9% of the obstructed cases and in 22% of the unobstructed. Older patients (>60 years) seemed more likely (odds ratio: 2.8) to present detrusor overactivity, but at the same time showed less frequent obstruction. The oldest subjects (>80 years) showed a lower prevalence of obstruction, although overactive bladder was a common finding. Conclusion: Infravesical obstruction is less frequent than previously stated. The common assumption that obstruction is the cause of lower urinary tract symptoms in older men is wrong. Older men are more likely to suffer from detrusor overactivity resulting from lower urinary tract symptoms rather than infravesical obstruction. Urodynamic studies seem to be crucial for a proper diagnosis in men considered candidates for surgical treatment.