Diagnostics of anatomical obstruction of the lower urinary tract using uroflowmetry with a pharmacourodynamic test

Abstract

Uroflowmetry is an effective, non-invasive method for detecting lower urinary tract obstruction. However, by the nature of the uroflowgram, it is impossible to distinguish between the anatomical and functional obstruction of the urethra. The aim of the study was to develop a screening non-invasive method for the diagnosis of anatomical urethral obstruction using uroflowmetry with a pharmacourodynamic test with selective alpha-1-blocker silodosin. The study involved 235 patients aged 66.2±1.8 years (from 30 to 76 years) with symptoms of the lower urinary tract (LUTS). Uroflowmetry was performed using a “Flow-K” uroflowmeter. Ultrasound examinations of the kidneys, prostate and bladder with determination of residual urine were performed using a HONDA HS-2000 ultrasound machine. All patients underwent a pharmacourodynamic test: repeated uroflowmetry 2.5-3 hours after a single dose of 8 mg of silodosin, taking into account the pharmacodynamics of the drug. During the pharmacourodynamic test, 15 patients with obstructive or obstructive-interrupted uroflowgram had no reaction to silodosin, which was considered a positive test for anatomical (mechanical) urethral obstruction. Аn increase the maximum and average volumetric flow rate of urine during urination by 25-30%, respectively from 9.02±0.24 ml/s up to 11.69±0.32 ml/s and from 5.64±0.21 ml/s to 7.03±0.25 ml/s, were noted in 220 patients with obstructive, obstructive-interrupted obstructive-intermittent or intermittent type of uroflowgram when conducting a pharmacaurodynamic test. Such results were considered negative for anatomical (mechanical) urethral obstruction. They testified to functional obstruction of the urethra, which was subsequently successfully corrected with prescribing selective alpha-1-blockers. Patients with a positive pharmacourodynamic test were prescribed further examination using such methods as ureteroscopy, urethrocystoscopy, retrograde urethrography, to confirm the violation of the patency of the urethra or bladder neck. Urethral stricture was diagnosed in 10 patients, a calculus of the posterior urethra in 2 patients, a median lobe of the prostate gland in 3 patients with BPH. In the presence of obstructive or obstructive-interrupted uroflowgram in patients with LUTS, the pharmacourodynamic test with silodosin can be used as a screening non-invasive test to detect anatomical obstruction of the lower urinary tract.