Uroflowmetry – measurement of the flow rate of urine over time and the amount. The measurement of the flow of urine is the simplest urodynamic test which provides valuable information for the preliminary diagnosis and follow-up for diseases of the lower urinary tract.
Due to the fact, how it’s performed uroflowmetry (non-invasive, painless), this survey is completely safe for all patient groups, including pregnant women and children. The latter method is the gold standard in identifying functional and neurogenic disorders in the activity of the detrusor.
The purpose of the survey
Usually due to uroflowmetry can determine the slowing of urination or difficulty. The test also shows how functional the urinary tract and obturator urethral sphincters. Sphincter – a circular muscle that are Contracting, covers the output hole of the bladder and prevents leakage of urine.
The test reveal the obstruction to the normal urine. By measuring average and maximum speed of the jet, you can set the severity of the blockage and/or obstruction, contractility of urinary bladder, enlarged prostate.
One of the varieties of methods – radionuclide uroflowmetry, among other things, aimed at determination of residual urine, the bladder-ureteric and vesico-renal pelvis reflux, stenosis of the distal part of the urinary tract.
What can affect urination
Some conditions can directly or indirectly influence the nature and rate of urine flow:
- benign hypertrophy of the prostate, which can block the urethra;
- cancer of the detrusor;
- prostate cancer;
- neurogenic dysfunction or a violation of the nervous regulation in tumors or trauma of the spinal cord;
- frequent urinary tract infection.
The procedure of measurement
In contrast to conventional analysis of urine, in which the patient urinates into a container, if uroflowmetry there is no special disposable funnel device, a special urinal or toilet, which is a measuring instrument.
You need to urinate as this happens in normal conditions, not trying to manipulate the speed or force of the jet. Men can do it standing up, and women offer to sit on the apparatus or in a specially equipped chair.
Electronic uroflowmetry connected to the funnel or embedded into the toilet, measure the speed and volume of urine. Therefore, to begin the process of urination is necessary at the command of the technician when the machine is turned on.
Uroflowmetry records the amount of urine that the patient produces, the speed of flow in seconds and the period of time required for complete emptying of the bladder. The results are presented in chart form. In norm it is possible to see that at the beginning of the stream of urine is produced slowly, then accelerates and by the end of the process slowed down again. Any differences from the norm are clearly visible on the chart and help the doctor establish the diagnosis. Sometimes you may require a series of measurements over several days.
Uroflowmetry can be a fairly simple configuration or “expert” class
Earlier before the invention uroflowmetric used a manual measurement using a stopwatch and volumetric glassware. In the absence of the instrument, you can use this method. A stopwatch record the start and end of urination. Then measure the volume of urine released at a volumetric ware, and, dividing the volume in time calculate average speed.
In preparation for the examination
Before the study should not urinate for several hours, so the bladder was full, but not crowded. It is enough to drink 1 liter of water for half an hour before the test. The procedure itself is absolutely painless, and may cause except that the psychological discomfort.
Be sure before the test you should inform your doctor about the following points:
- established or suspected pregnancy;
- what medications and vitamins are taken;
- herbs, supplements.
Interpretation of results
The urine flow rate is volume flow rate during urination, increased amount of urine output after a certain period of time (per second or per minute). Use the letter “V” (for volume) and “Q” (the conventional symbol for the speed of the flow). Qmax indicates the maximum flow rate. It was on its value define the degree of obstruction of the urinary tract or the presence of obstacles in the current of urine.
The importance of standards
Indicators of uroflowmetry normal depend on age and sex. In men with age, the speed of the urine stream decreases in women these changes are less pronounced.
|4-7 years||The average consumption for males and females is 10 ml/sec|
|8-13 years||12 ml/sec||15 ml/sec|
|14-45 years||21 ml/sec||18 ml/sec|
|46-65 years||12 ml/sec||18 ml/sec|
|66-80 years||9 ml/sec||18 ml/sec|
The average rate of urination in both sexes exceed 10 ml / sec.
The length of time over which it reaches its maximum speed –4-9 seconds from the start of urination.
Reliable results it is fashionable to obtain if the study was conducted on the urine volume from 200 to 500ml, but, in extreme cases, you can consider the result obtained for 100 ml of urine.
In healthy people with a given amount of the entire act of urination that lasts about 20 seconds.
Reduced urine flow suggests the presence of a blockage or weak bladder muscles in men – BPH.
An increase in flow indicates a weakening of the muscles that control urination, which may be a sign of incontinence.
A – the normal curve; In – subvesical obstruction by increasing the side lobes of the adenoma ; C – narrowing of the urethra; D – the violation of the innervation of the bladder; E fluctuation of intra-abdominal pressure at maximum speed is the tension of the abdominal muscles
To evaluate the result of the study, after analyzing the graph of the curve of urination. Normally, as you can see, it has kolokolmorskiy form. When narrowing of the urethra that is more common in men, the curve after the initial set speed takes the form of a “plateau”.
If there is obstruction or weakening of the contractile ability of the bladder, the graph will show a decrease in peak flow rate. Detrusor hyperactivity will be recorded in the form of speed dial speed Qmax in the first second.
Decoding chart can contain a description of the nature of urination – obstructive, non-obstructive, ambiguous, rapid, intermittent. So, for example, intermittent diagram of urination is formed for strictures of the urethra, and is associated with the jerky contraction of the muscles of the abdominal wall. Thus, the stimulation of the emptying of the bladder due to the discharge of intra-abdominal pressure.
The advantages of the method
Uroflowmetry has a number of advantages as a diagnostic method:
- not associated with instrumental interference;
- there is no risk of infection during the procedure;
- can repeat and to give a picture of the treatment results in dynamics;
- the results are clear, fixed immediately;
- can be used in children and pregnant women.
Contraindications include the presence of a fistula (vesico-vaginal, or suprapubic vesico-rectal) and congenital anomalies formation of the bladder, such as bladder extrophy.