Urological examinations —
Urine flow measurement
Bladder capacity and frequency of urination are important parameters for assessing bladder function. The capacity of the bladder in adults is between 600 and 1000 ml, though the sensation of a full bladder occurs before this (Ernst Mutschler et al: Mutschler Arzneimittelwirkungen, 9th edition, Wissenschaftliche Verlagsgesellschaft, 2008, p. 708). The average voiding volume, also known as functional bladder capacity, is around 300-400 ml (Lukacz E.S. et al, A healthy bladder: a consensus statement, International Journal of Clinical Practice, 2011, 65, 10, 1026-1036). These values may vary from person to person.
The number of daily urinations, also known as micturition frequency, depends on the individual bladder capacity and the amount of fluid ingested. The frequency of urination usually increases with age. With a maximum daily drinking volume of 2,000 ml, 4 to 7 urinations during the day and one at night are considered normal.
Urine flow measurement (uroflowmetry) is a diagnostic method used in urology to detect bladder emptying disorders. These disorders include frequent urination (pollakiuria), difficult urination (dysuria) and painful urination (alguria). The causes of such urination disorders can be enlargement of the prostate, narrowing of the urethra or problems with bladder function. Insufficient contraction of the bladder muscle can lead to a weakened urine stream and the formation of residual urine, which means that the bladder is not emptied completely.
Urine flow measurement (uroflowmetry) is a procedure in which the amount of urine passed per unit of time is measured. A uroflowmeter, which has a funnel to collect the urine, is used for this purpose. A sensor at the tip of the funnel measures the amount of urine and creates a curve that can be used to draw conclusions about possible disorders. For a meaningful uroflowmetry result, the bladder must be full and there must be a strong urge to urinate.
There should be at least 150 ml of urine in the bladder. During the measurement, the patient urinates into the funnel of the uroflowmeter until the bladder is completely empty. You should urinate without straining hard. Ultrasound is then used to check whether the bladder is completely empty (residual urine measurement).
Summary
Urine flow measurement (uroflowmetry) is a painless examination that measures the amount of urine per unit of time during bladder voiding. The most important parameter is the maximum urine flow, which is between 15 and 50 ml per second in adults. Values between 10 and 15 ml per second may indicate a more detailed examination, and values below 10 ml per second indicate an obstruction to bladder emptying. A delayed rise or fall in the curve may indicate prostate enlargement. The results of this examination help your doctor to diagnose the cause of the urination disorders and initiate appropriate treatment measures.