Flowmetry

Uroflowmetry, or uroflowmetry, is a diagnostic test performed in the office for patients experiencing difficulty urinating. It is also routinely performed on patients undergoing prostate exams to assess urination strength and control.

Urinary flow rate is defined as the amount of urine volume eliminated per unit of time. It is expressed in cubic centimeters or milliliters per second. Urinary flow rate is not constant but varies throughout urination, resulting in characteristic flow curves. This test measures the amount of urine the patient's bladder is able to expel per second, the duration of urination, and observes whether any interruptions occur during urination.

After uroflowmetry, it is important to measure the residual urine in the bladder, that is, the amount of urine remaining in the bladder after urination. Post-void residual urine is generally estimated using ultrasound.

The main parameters measured in flowmetry are:

Maximum flow (Qmax): maximum value reached by the urinary flow during urination.
Urinary volume: Total amount of urine eliminated.
Flow time: This is the total duration of urination.
Urination time: The time elapsed from when the patient starts urinating until it ends. This time coincides with the flow time as long as there is no interruption of the urinary stream.
Average flow rate: This is obtained by dividing the voiding volume by the flow time.

The procedure for performing a uroflowmetry test is very simple: The patient urinates into a device that measures the force of the urinary stream in a quiet environment. They will have all the time they need to urinate, in privacy and without interruption. The results of this test are printed as a graph with the values of the parameters mentioned above.