Introduction. Uroflowmetry is being widely used in diagnostics of a very broad range of diseases.

Materials and methods. We have conducted a multi-centered randomized cohort study, which included 72 male and 9 female patients. In all patients, we measured the maximum speed of urine flow Qmax, the average speed Qave, and also the duration of urination (t).

Results. In men, the mean value of Qmax was 18.1±6.2 ml/s (from 6 to 53 ml/s) in standing position. Qave was 10.2±2.7 ml/s (ranging from 2.7 to 29.6 ml/s). The duration ofurination varied from 11 to 120 seconds (mean 30.5 s). For those in sitting position, Qmax was 17.3±3.5 ml/s (5.4 -48.0 ml/s), and а Qave - 10.6±2.9 ml/s (2.7 - 30.5 ml/s). The duration of urination varied from 10 to 109 seconds (mean 28.7 s). In sitting position, Qmax increased by 1 ml/s in 34.7% of men, and Qave - by 40.3%.

In women, the Qmax value was 30.2±4.2 ml/s (10.0 - 53 ml/s), Qave -13.2±1.8 ml/s (ranging from 6 to 21 ml/s) in standing position. For those in sitting position, the mean value of Qmax was 27.2±3.1 ml/ s (13.0 - 48.0 ml/s), Qave was 15.7±1.2 ml/s (9 - 27 ml/s). The mean duration of urination was 25.1 s (9-41 s) in standing position, and 22.8 s (9-53 s) in sitting position. Qmax increased by 1 ml/s in 55.6% of men, and Qave - by 44.4%.

Discussion. The literature data on the advantages of a certain body position during urination is controversial and is of opposite polarity. The process of urination depends on many factors, which accounts for the instability of the data from uroflowmetry tests; repeated measurements in the same position, which is comfortably for a patient, are required, and also in a condition of a strong urinary urge. Our results imply that, on average, the parameters of urination  did not significantly change in men and women after the changes in their positions. However, in every group there were patients, who have demonstrated significant changes in the speed of urine flow after the changes in body position.

Conclusions. Despite the fact that the mean values of the speed of urine flow and the duration of urination did not substantially change in the cohort in total, Qmax values were significantly higher during urination in sitting position in 34.7% of men, and Qave - in 40.3% of men.

Considering that the maximum and the mean speed of the urine flow is higher in every third male in sitting position, it is advisable to conduct uroflowmetry tests in different positions in order to formulate reasonable recommendations for bladder evacuation for a particular patient.

Authors declare lack of the possible conflicts of interests.