Uroflowmetry is one of common methods for the evaluation of lower urinary tract symptoms. However, these examinations in an outpatient setting are psychologically burdensome for some patients and often affect the examination results. By using the portable urinary flowmeter, we can solve this problem and easily perform repeated examinations. The purpose of this study was to compare the portable urinary flowmeter Freeflow® with other urinary flowmeters Flowsky® and validate the accuracy of the measured values.

A prospective study was performed on five patients. Uroflowmetry was a simple method of examining urinary function in an outpatient setting. We used the portable urinary flowmeter Freeflow® and provided urinary flowmeter Flowsky®. The measurement principle of the Freeflow® was that a change in the rotation speed of the impeller due to urination was converted into a urinary flow rate and urination volume by a pulse number measuring device via an optical sensor. The measurement principle of the Flowsky® was that a change of water level in the toilet bowl due to urination was converted into a urination volume by a water level sensor. Endpoints were urination volume, maximum urinary flow rate, average urinary flow rate, urination time and time to reach maximum urinary flow rate in uroflowmetry. Freeflow® was urinated in a sitting or standing position, and the waste liquid was dropped into Flowsky®, and urinary flow was measured at the same time.

The median values of urination volume, maximum urinary flow rate, average urinary flow rate, urination time and time to reach maximum urinary flow rate are 158.2 ml (13.9-257 ml), 13.8 ml/second (2.4-19.6 ml/second), 8.4 ml/second (1.2-11.3 ml/second), 17 seconds (6-26 seconds), 9 seconds (3-15 seconds) for Freeflow®, respectively, and 156.2 ml (14.1-261.4 ml), 13.5 ml/second (2.3-18.6 ml/second), 8.4 ml/second (1.8-12.0 ml/second), 18.6 seconds (4.9-25.8 seconds), 9.2 Seconds (2.5-16.6 seconds) for Flowsky®, respectively. Compare the two groups, the variability of the measured values were 4.1 ml (0.2-5.7 ml), 0.2 ml/second (0-1.0 ml/second), 0.6 ml/second (0-0.9 ml/second), 0.6 seconds (0.2-1.6 seconds) and 0.5 seconds (0-1.6 seconds) in absolute value, respectively (P= 0.9862, 0.9453, 0.8722, 0.9836 and 0.8874, respectively).

It was suggested that the measured values of Freeflow® were almost the same as those of Flowsky®. There was no statistically significant difference between the two groups.

This study was the first to evaluate the accuracy of the measured values by using Freeflow®. We can use the portable urinary flowmeter positively in our daily outpatient care.