Functional obstruction may be caused by detrusor-sphincter dyssynergia (DSD), either at the level of the smooth muscle or rhabdosphincter; primary bladder neck obstruction, which may be functional and anatomic in character; or due to dysfunctional voiding, associated with learned voiding disorders or pelvic floor dysfunction associated with pain syndromes.
Anatomic obstruction in men results most commonly from benign prostatic enlargement (BPH) or urethral stricture.
Examination of historical and physical evidence of both onset and magnitude and severity of symptoms is critical in the primary evaluation of these patients. In men, benign prostatic obstruction (BPO) is the most common cause of BOO and stems from a variety of etiologies. Other causes of BOO include urethral stricture disease, dysfunctional voiding, neurogenic-based detrusor-sphincter dyssynergia (DSD), and primary bladder neck obstruction.
A
normal flow rate in men does not preclude the possibility of obstruction.
Concomitant analysis of flow rates and residual volumes is important to avoid
misinterpretation of isolated data. Urodynamics, alternative radiologic
procedures, or cystoscopy is recommended in the case of failed presumptive
therapy, a complex presentation scenario, or when a diagnosis is in doubt. Formal
urodynamic evaluation is usually reserved for complicated cases and is often
performed in conjunction with a pressure flow evaluation.
