Urodynamic methods of examination. A non-invasive procedure for diagnosing pathologies of the genitourinary system - uroflowmetry: what it is, how to prepare and how to pass the test Urine flow rate measurement uroflowmetry

Urodynamic methods of examination are a method of dynamic assessment of the accumulative and evacuation functions of the bladder and are designed to reproduce the symptoms of lower urinary tract, establishing their cause, quantitative assessment of urodynamic parameters, and, as a result, to confirm the clinical or formulation of the urodynamic diagnosis.

All urodynamic examination methods can be divided into non-invasive and invasive.

Non-invasive methods:

1. Urination diary.

2. Uroflowmetry.

3. Determination of the volume of residual urine.

4. Pad test (test with pads).

5. Electromyography with skin electrodes.

Invasive methods:

1. Cystometry.

2. Determination of the pressure of urine loss.

3. Urethral profilometry.

4. Pad test with standardized bladder volume.

5. Pressure/flow study.

6. Determination of the volume of residual urine (catheterization).

7. EMG with needle or mushroom electrodes.

Considering that the use of invasive methods is associated with urinary tract catheterization, and, consequently, with its accompanying complications, such as infection, hematuria, and urinary retention, it is necessary to carefully determine the indications for urodynamic examination and its diagnostic value in each specific case. Urodynamic evaluation of patients should in without fail start with non-invasive methods. In some cases, this is enough to establish a clinical diagnosis and start treatment.

Among the non-invasive methods, the most reliable is filling out a urination diary in simple (time of urge to urinate, volume of urine output) and expanded (time of urge to urinate, volume of urine output, daily intake fluids, episodes of urgency and incontinence, degree of activity during the day, and number of pads used) options.

Uroflowmetry and determination of the volume of residual urine allows for a total assessment of the evacuation function of the lower urinary tract. Electromyography with skin electrodes and Pad-test (test with pads) are used mainly in patients with urinary retention disorders.

Diary of urination

The urination diary is a specific urodynamic study recording the time and volume of urine excreted for each urination for several days. The urination diary is filled in by the patient himself and can be just notes on paper. Recently, specially prepared tables with empty lines that are convenient for use and understandable to patients have appeared, which the patient fills out for, as a rule, 3 days, recording the time of urge and the volume of urine excreted. In addition, these diaries record daily fluid intake, episodes of urgency and urinary incontinence, activity levels during the day, and number of pads used. Completing a voiding diary and performing a Pad test is a model for performing ambulatory urodynamics.

The urination diary is the most important part of the outpatient examination of patients with urination disorders, since only with its help you can find out the following data:

1. Diuresis

2. Typical bladder emptying habits

3. The ability to visit the toilet in a timely manner

Completing a urination diary should always precede the decision to perform invasive urodynamic examination methods and prescribe any conservative therapy (drug treatment, change in habitual urination stereotypes, biofeedback treatment - biofeedback therapy).

The amount of urine formed at night in healthy people is less than 30% of the total daily diuresis, and the volume of urine produced during sleep (morning urine) is approximately 50% more than the volume of urine released during daytime urination. As practice shows, self-filling of the diary by patients allows obtaining sufficiently accurate volumes of urine excreted. When comparing urination diaries filled out on an outpatient basis and tests for natural daily diuresis conducted in a clinic, the difference in certain volumes did not exceed 7%.

Daily diuresis and average volumes of urine excreted per urination are less in older people (over 70 years old) than in young people, as well as in women compared to men. In patients with hyperactive bladder and urge incontinence, the average volume of urine excreted per urination is less than about half compared with healthy people. The number of urination per day in such patients almost doubles, despite the fact that daily urine output remains almost unchanged. In children, the functional capacity of the bladder is determined by the formula 30 + (30 × age in years).

Subjective assessment of urinary incontinence.

Ways to subjectively assess urinary incontinence are the use of a visual analog scale, a non-visual analog scale, and a scale clinical assessment.

Visual analog scale (VAS) . This method of subjective assessment of urinary incontinence consists in asking the patient to mark a dot on a 10 cm long non-graded line that corresponds to the degree of overall quality of life disorder caused by urinary incontinence. The left border of the line corresponds to the definition of "does not bother", the right one "the worst that can be imagined." Unfortunately, we have noticed that the vast majority of patients determine the degree of quality of life disorders on this scale in the middle of the line.
Non-visual analogue scale. oral form assessment of the degree of violation of the quality of life on a digital scale from 0 to 10.
Scale of clinical assessment (ordinate scale). With this type of subjective assessment, the patient must choose one of the proposed answers to the question about the degree of influence of urinary incontinence on quality of life. An example would be a “slightly” response from such a line of questions (none, insignificant, moderate, significant, extreme) An alternative questionnaire could include next questions related to episodes of urinary incontinence (none, rarely, often, constantly)

Quantification of urine loss (Pad-test)

Quantification of urine loss is based on the measurement of the weight of absorbent pads during the test period.

Weighing used pads must be accurate to ± 1 gram. Gaskets should not be "overfilled". For this purpose, either large pads are used that can absorb a significant amount of liquid, or a change of pads is necessary. To ensure proper Pad test accuracy, used pads are stored in a sealed plastic bag to prevent them from drying out and reducing weight.

The test period can be short (20-120 minutes) or extended (day, several days). A short type of test is usually performed in a clinic. In this case, in order to standardize the test, it is possible to perform it with a known bladder volume (filling before starting the test). The 24-hour Pad test is performed during the patient's normal physical activity.

The amount of liquid drunk. It is appropriate to recall that one liter of pure water in healthy (normally hydrating) people is excreted within about two hours. The same volume of water containing sodium and chlorine will be excreted in about 24 hours. Therefore, if a short Pad test is planned in the clinic, it is not recommended to drink mineral or soda water.

The following is a methodology for performing an hourly pad test (ICS standards):

1. Pre-weighing the pad

2. Drink within 15 minutes pure water(not mineral and not soda) in a volume of 500 ml.

3. Walking for 30 minutes (up and down one floor)

4. Physical activity within 15 minutes

a) sit down and stand up several times within 10 minutes

b) cough a few times for 10 minutes

c) running in place for 1 minute

d) lift several times within 5 minutes small items off the floor

e) washing hands under running water for 1 minute

5. Gasket is removed and weighed

6. Emptying the bladder (uroflowmetry) and measuring the amount of urine excreted

Obviously, modifications of the test procedure depending on the physical condition of the patient are acceptable.

One-hour pad test with standardized bladder volume.

The recommended ICS pad test can be modified by filling the bladder to 50% or 75% of the cystometric capacity or the capacity known from the voiding diary. Naturally, there is no need to drink liquid and the test period can be reduced to 20 minutes. The sensitivity of the test increases if bladder filled to a volume approaching the maximum value of urine output indicated in the diary of urination. Differences in the amount of urine lost when the bladder is filled up to 50% or 75% are not significant. The advantages of modifying the Pad test with a known bladder volume are higher sensitivity and reliability. However, this method requires bladder catheterization.

Pad test on an outpatient basis

The duration of this test is 24 or 48 hours. There was no significant increase in the sensitivity and reliability of the 48 hour test in relation to the daily test. The patient during the test is engaged in the usual daily work. standard scheme test run does not exist. During the test, the pads are replaced if necessary and put into a sealed plastic bag. At the end of the study, they are brought and weighed in the clinic, compared with the known weight of the dry pad.

table

Limit values ​​and reliability of the Pad-test.

	Hour Pad Test	24-48 hour pad test
Limit value for urinary incontinence	1 gram in 60 minutes	8 grams per day
False negative result	14 - 42 %	4 - 10 %
False positive result	1 - 5 %	1 %
Representativeness	30 - 88 %	61 - 94 %

Interpretation and Validity of the Pad Test

It is clear that normally there should be no loss of urine. However, not a large number of Loss of urine during the Pad test is observed in people who do not believe that they have involuntary loss of urine - a false positive result. On the other hand, with a mild degree of urinary incontinence, when conducting a standard Pad test, changes in the weight of the pads may not be determined - a false negative result.

Mistakes

The pad may become “full” or wet due to excessive sweating, vaginal discharge, or menstruation. A small amount of urine in the bladder leads to a decrease in the reliability of the Pad test.

Uroflowmetry

Uroflowmetry is the measurement of urine flow rate by determining the amount of urine excreted per unit of time. Urinary flow rate reflects the end result of a voiding cycle consisting of adequate detrusor function, opening of the bladder neck, and patency of the urethra. A decrease in urine flow rate indicates a violation of the emptying of the bladder, but does not allow to accurately localize the level of this violation. Uroflowmetry is a non-invasive method of urodynamic study. To obtain representative results, uroflowmetry should be performed in a separate room, in the absence of medical personnel and unauthorized persons, and also before instrumental endourethral interventions and catheterization. Therefore, a urodynamic study, as a rule, begins with the performance of uroflowmetry.

If necessary, uroflowmetry can be combined with simultaneous recording of intravesical and intra-abdominal pressure, electromyography of the pelvic floor muscles and cystography (video urodynamics). The ideal is to determine the volume of residual urine after uroflowmetry (by direct catheterization with subsequent cystometry or ultrasound in cases where uroflowmetry is performed as the only method of urodynamic study).

Before uroflowmetry, the patient should have a normal (normal) desire to empty the bladder. The study is carried out in the usual position for the patient to empty the bladder (sitting or standing). It is necessary to warn the patient that during the study it is necessary to relax the muscles of the perineum, not to strain the muscles of the anterior abdominal wall and do not squeeze the urethra.

Drawing. Uroflowmetric curve

Characteristics of uroflowmetry and its clinical interpretation

a) delay time

c) maximum urine flow rate

e) the volume of urine excreted

g) average urine flow rate

a) delay time

Delay time - is the time interval from the urge to urinate to the start of the actual process of emptying the bladder, or the time from the episode of urgent urge to the start of emptying. Typically, the delay time does not exceed 10 seconds. In cases of infravesical obstruction or psychological factors having a "braking" effect on the onset of urination during uroflowmetry (unusual environment, the presence of strangers, etc.), the delay time may be lengthened.

b) the rise of the curve, and the time to reach the maximum flow rate of urine

The curve should rise "steeply". A slow rise in the curve indicates a slow opening of the bladder neck (functional or organic) or insufficient detrusor contractility. The time to reach the maximum flow rate depends on both the volume of urine excreted and the maximum flow rate. The normal values ​​of this indicator have not been established. However, the time to reach the maximum urine flow rate should not exceed the time of the first third of the total urine flow time.

c) maximum urine flow rate (Qmax)

The maximum urine flow rate is the maximum flow rate measured by uroflowmetry. Qmax is the main uroflowmetric parameter. When interpreting, it is necessary to compare the values ​​of the maximum urine flow rate with the type of uroflowmetric curve, the excreted volume of urine, age and gender.

Drawing. Interrupted type of uroflowmetric curve

In men border normal values the maximum urine flow rate is considered to be ≥ 15 ml / s, which with 70-90% certainty indicates the absence of bladder outlet obstruction. However, an increase in ejection pressure may lead to an increase in maximum urinary flow rate. This type of bladder emptying occurs in young men with bladder outlet obstruction (IVO with high pressure expulsion and maximum urine flow).

Drawing. The figure shows the prognostic value of the maximum urine flow rate in patients with hyperplasia prostate subjected to surgical treatment.

Maximum urine flow rate ≤ 10 ml/sec. indicates the presence of infravesical obstruction (90% confidence). Insufficient (less than 120 ml) volume of excreted urine and violations of the contractility of the detrusor lead to a decrease in the maximum flow rate of urine.

The maximum flow rate of urine decreases with increasing age. It is not considered as any pathology. It is believed that after 40 years, Qmax decreases by 2 ml / s. for 10 years - Figure 10.

Drawing. Dependence of the maximum urine flow rate on age in men with no complaints of urination disorders.

In women, it is traditionally accepted that 20 ml / s is the lower limit of the normal maximum flow rate of urine. However, it must be remembered that in women, due to insignificant urethral resistance, it is not necessary to achieve high values ​​​​of the maximum urine flow rate for adequate emptying of the bladder. High values ​​of Qmax (40-50 ml/sec.) indicate a decrease in urethral resistance, which is often observed in women who complain of urinary incontinence.

d) type of uroflowmetric curve

Normally, the uroflumetric curve has the shape of a bell with even and smooth ascending and descending components. Various disorders of the function of the lower urinary tract lead to a change in the normal nature of the uroflowmetric curve. However, a change in the form of the urflowmetric curve indicates only the presence of dysfunction, but not as a type of this dysfunction. The significance of the maximum urine flow rate is only apparent with the correct type of curve. With an interrupted or intermittent type of uroflowmetric curve, a change in the maximum flow rate of urine may indicate the presence of bladder outlet obstruction. However, an interrupted curve type may be due to detrusor weakness, abdominal emptying of the bladder, urethral kink due to pelvic organ prolapse, increased sphincter activity, or psychological factors. At pathological form curve, it is necessary to conduct a serial uroflowmetric study or uroflowmetric monitoring within 2-3 days. The interrupted appearance of the curve can also be due to hardware artifacts.

The figures show different kinds uroflowmetric curves.

Normal appearance of the uroflowmetric curve in a healthy male.

Asymmetric appearance of the uroflowmetric curve, characteristic of a slight infravesical obstruction.

Prolongation of the time required to achieve the maximum flow rate of urine and a decrease in Q max due to sclerosis of the bladder neck.

The "boxed" view of the uroflowmetric curve is typical for patients with urethral strictures.

Not right kind uroflowmetric curve (combination of detrusor contraction with muscle tension of the anterior abdominal wall and periodic infravesical obstruction) during bladder emptying in a patient with a cystocele.

"Jerky" type of uroflowmetric curve due to contractions of the external sphincter in a patient with detrusor-sphincter dyssynergy.

Discontinuous type of uroflowmetric curve due to tension of the muscles of the anterior abdominal wall and the absence of detrusor contraction in a patient with impaired innervation of the bladder (urination using the Crede maneuver - squeezing urine)

Very high maximum urinary flow rate in a patient with sphincter urinary incontinence.

e) the volume of urine excreted

In the absence of bladder outlet obstruction, the maximum urinary flow rate will increase in a parabolic fashion with respect to the increase in urine output. With a large volume of urine excreted, the maximum flow rate decreases. With infravesical obstruction, the maximum flow rate of urine increases only to certain values, depending on the degree of obstruction.

Drawing. Dependence of the maximum urine flow rate on the allocated volume. The highest reliability of Q max values ​​is observed when the volume of urine excreted is 200-400 ml. The decrease in the maximum flow rate of urine with an excreted volume of less than 100 ml is not significant.

f) urine flow time and urination time

In the intermittent type of urination, the time of urine flow and the time of urination will be different. At the same time, the maximum urine flow rate decreases and depends on the volume of individual portions of urine per urination. Urine instillation at the end of micturition reflected in the uroflowmetric curve indicates infravesical obstruction (predictive value 90%). Occasionally, terminal drip of urine occurs in men in the absence of obstruction due to rhythmic contraction of the bulbocavernosus muscles or when urine is squeezed out of the urethra by hand.

g) average urine flow rate (Q aver)

The average urine flow rate is calculated by dividing the excreted volume of urine by the time of urination.

Errors and artifacts encountered in uroflowmetry

The appearance of unreliable data during uroflowmetry may be associated with psychological discomfort and inhibition of the urge to urinate due to inappropriate conditions for the study (unauthorized persons or a large number of medical personnel in the office), an unusual position for emptying the bladder, insufficient urge to urinate, small or too large volume of accumulated urine, acute infection urinary tract, performing a study after instrumental interventions on the urethra). In addition, the appearance of the uroflowmetric curve and the maximum flow rate of urine are influenced by the tension of the muscles of the anterior abdominal wall, the compression of the urethra by hand, which is practiced by some men at the beginning of the act of urination. The unreliability of the maximum urine flow rate data is also associated with hardware errors (for example, in a uroflowmeter based on the weight measurement of urine flow rate, the error can reach 10%)

Artifacts of Wobble manifest as sudden peaks and dips in the uroflowmetric curve and are associated with a change in the direction of the urine stream falling on the walls of the uroflowmetric funnel. Dips in the uroflowmetric curve appear with contractions of the external sphincter.

Drawing. Artifacts of fluctuation. Peaks and dips at the beginning and end of uroflowmetry are associated with a change in the direction of urine flow to the walls of the uroflowmetric funnel.

Drawing. An artifact of a high maximum urinary flow rate in a man due to hand compression of the urethra at the start of urination. The compression resulted in urinary retention at the level of the distal urethra with a good opening of the bladder neck and a high maximum flow rate at the onset of micturition.

Residual urine volume

Definition

Residual urine is the volume of fluid remaining in the bladder immediately after urination is complete.

Necessary conditions for measuring the volume of residual urine

Prior to the determination of residual urine, urination should be carried out with a normal urge to urinate, in acceptable conditions, in an optimal and familiar position for urination.

Residual urine measurement

Direct bladder catheterization or ultrasound may be used to determine residual urine volume.

Catheterization is an invasive procedure and should therefore be used if there are other indications for it (eg subsequent urodynamics). It must be remembered that in order to completely empty the bladder through the catheter, it must be advanced back and forth. When inserting a thin urodynamic catheter, moderate hand pressure on the bladder area is necessary to ensure complete emptying. If a Foley catheter is used to determine the volume of residual urine in patients with a cystostomy, it must be taken into account that in the presence of a balloon catheter, some urine always remains in the bladder.

In cases where bladder catheterization is not required, transabdominal ultrasound is the non-invasive method of choice for determining residual urine volume. The estimate of residual urine volume is based on calculations using various mathematical formulas(e.g., 0.5 × width × height × length of the echographic "shadow" of the bladder)

When measuring the volume of residual urine, the obtained data must be compared with the volume of excreted urine.

Reliability

The accuracy of measuring the volume of residual urine by ultrasound is ± 33%, regardless of the measurement formula.

Mistakes

Most common cause False-positive data on large volumes of residual urine is the delay between urination and the start of measurement of residual urine. For example, if a patient is advised to drink a large amount of liquid before uroflowmetry and ultrasound, diuresis can age up to 10 ml per minute. In this case, the measurement of the volume of residual urine 10 minutes after urination will show that the volume of residual urine was 100 ml. Other causes of erroneous residual urine volume data include overfilling of the bladder, vesicoureteral reflux, bladder diverticula, and a bladder shape that does not allow for determination of all dimensions needed to calculate its volume.

Normal values

The bladder should empty completely. The limit value for children (except newborns) and adults is 10 ml. This does not mean that more high values are an indication for treatment without taking into account other parameters of urodynamics. In older people (men and women), the volume of residual urine can reach values ​​​​of 50 ml or more in the absence of any complaints. Moreover, in the same patient, the difference in the values ​​of the volume of residual urine in different days may exceed 100%. As a rule, residual urine is more in the morning. Usually data on the volume of residual urine are given as a separate indicator. We believe that more valuable information about the completeness of the emptying of the bladder is the percentage of the volume of residual urine to the volume of urine excreted or bladder capacity, which is known from the diary of urination.

Causes of residual urine and urodynamic features

The causes of residual urine are violations of the function of the detrusor. They may be associated with either insufficient contraction force (myogenic detrusor decompensation) or, more commonly, insufficient contraction force throughout the emptying phase (sufficient at the beginning and decrease at the end). Detrusor contractility disorders may be primary (idiopathic causes) or more often secondary to bladder outlet obstruction or neurogenic disorders of lower urinary tract function.

Most often, with uroflowmetry in patients with a significant volume of residual urine, a “flattening” of the uroflowmetric curve is observed, or its intermittent appearance. Detrusor pressure may be normal, increased, or decreased, but there is always a decrease or complete absence before the completion of bladder emptying. The threshold of sensitivity is often raised. The volume of the first and imperative urge is reduced. However, in general, there is a weak correlation between the sensitivity threshold data, the volume of the first and imperative urge and the amount of residual urine.

Clinical significance of residual urine.

Residual urine is of clinical significance only if it results in deterioration of upper urinary tract function or causes associated symptoms of impaired bladder emptying. Most often these symptoms are frequent urges to urination, poor urine stream, interruption of the urine stream, urinary retention, urinary incontinence and recurrent urinary tract infection.

In patients with infravesical obstruction and normal or high detrusor pressure, in the absence of adequate treatment, there is a high risk of developing retention changes in the upper urinary tract and reduced renal function. With the timely elimination of obstruction, normal urination is restored, and obstructive symptoms disappear. Low detrusor pressure in the emptying phase is a poor prognostic factor in terms of the restoration of adequate emptying of the bladder after removal of bladder outlet obstruction. On the other hand, low detrusor pressure lowers the risk of worsening upper urinary tract function.

Determination of the pressure of urine loss.

Figure. Determination of urinary loss pressure in a woman with stress urinary incontinence.

The bladder during the previous cystometry is filled up to 250 ml. Next, the patient was asked to cough. The beginning of urine loss coincided with the value of intravesical pressure equal to 30 cm of water column, the maximum value of intra-abdominal pressure was 138 cm of water column. Urodynamic conclusion: stress urinary incontinence.

Urine loss pressure is the pressure at which urine loss occurs during a urodynamic study. Urine loss can be assessed visually or with a uroflowmeter. Urine loss pressure can be measured in the bladder and in the rectum (abdominal pressure threshold).

Determination of urinary loss pressure is used in the diagnostic algorithm for examining patients with stress urinary incontinence and determining the risk of deterioration in the function of the upper urinary tract in patients with infravesical obstruction (detrusor-sphincter dyssynergy or less often in patients with prostatic hyperplasia).

Intra-abdominal pressure of urine loss (abdominal pressure threshold) or stress pressure of urine loss. Valsalva pressure of loss of urine, pressure of loss of urine on coughing.

These urodynamic research methods are used in women with stress urinary incontinence and in men with complaints of urinary incontinence after surgical treatment (TUR, adenomectomy, prostatectomy, urethrotomy).

Research methodology

1. The bladder is catheterized, the residual urine is evacuated. A balloon catheter is inserted into the rectum to measure the abdominal pressure threshold.

2. The study can be done lying down, sitting or standing. The external opening of the urethra must be clearly visualized to determine the moment of loss of urine. A visual assessment of urine loss can be replaced by the use of a uroflowmeter, video urodynamics, a special diaper with an electrical sensor that reacts to urine loss.

3. The urodynamic system is calibrated, the values ​​are reset, the pressure measurement sensors are at the level of the upper edge of the pubic symphysis.

4. The bladder is filled with physiological saline t-37º C (contrast solution for video urodynamics) to a volume that causes the urge to urinate 100-300 ml

5. The patient is asked to push with increasing force (Valsalva maneuver) and to cough with varying force (cough test) until loss of urine is noticed.

6. The pressure at which urine loss is recorded is recorded and measured. The minimum pressure values ​​during the Valsalva test and cough test will be the values ​​of the pressure of urine loss.

Grade

Normally, an increase in intravesical and intra-abdominal pressure to any value does not cause uncontrolled loss of urine. Confirmation of stress urinary incontinence is the coincidence of urine loss with an increase in intra-abdominal pressure. In women, loss of urine with abdominal pressure ≥ 90 cm of water. is regarded as stress urinary incontinence associated with hypermobility of the urethra, and loss of urine at a pressure of ≤ 60 cm of water. like sphincter urinary incontinence. In general, urine loss pressure values ​​are lower with the Valsalva maneuver than with the cough test.

There is no clear correlation between urinary loss pressure and other urodynamic parameters and the Pad test.

Reliability

With repeated determinations of urinary loss pressure, the 95% confidence interval approaches values ​​of ± 30%.

Mistakes

Patients with a large cystocele may have false positive high urinary loss pressures due to partial obstruction of the urethra or because the cystocele "accepts" a large amount of intra-abdominal pressure that is often transmitted to this area. Artifacts with high pressure loss of urine are associated with simultaneous contraction of the external sphincter with an increase in intra-abdominal pressure. The values ​​of the stress pressure of urine loss are not reliable in patients with detrusor overactivity arising in response to provocative tests(Valsalva and cough tests) and in patients with low elasticity of the bladder wall. The urodynamic catheter creates some degree of obstruction, which affects the pressure values ​​of the loss of urine.

Intravesical pressure of urine loss. Detrusor pressure of urine loss.

Evaluation of intravesical and detrusor pressure of urine loss is necessary in patients with neurogenic disorders of the lower urinary tract (detrusor-sphincter dyssynergy) and in children with dysfunctional urination to determine the possible risk of damage to the upper urinary tract (vesicoureteral reflux). In some cases, the indications for this study is a significant amount of residual urine in patients with prostatic hyperplasia.

Methodology.

1. The study will be carried out lying down

2. The bladder is catheterized with a urodynamic catheter, residual urine is evacuated, the urodynamic system is calibrated, pressure sensors are at the level of the upper edge of the pubic symphysis.

3. The bladder is filled with sterile saline t-37º at a rate of 10-100 ml / min

4. Minimum intravesical and detrusor pressures at which urine loss occurs are recorded and measured

Grade.

Patients with intravesical pressure > 40 cm of water have a high risk of complications from the upper urinary tract. The volume of the bladder, at which the detrusor pressure is below 40 cm of water. can be considered relatively "safe". The urinary loss detrusor pressure is not a measure of sphincter function and stress urinary incontinence.

Pressure-flow study.

The pressure/flow study is a simultaneous recording of bladder pressure and urine flow rate. During the study, intravesical pressure is recorded through a urodynamic catheter, intra-abdominal pressure with a special balloon catheter, and detrusor pressure is automatically calculated by subtracting intravesical pressure and intra-abdominal pressure (Pdet = Pves-Pabd). Often during a pressure/flow study there is a need to determine sphincter activity by means of electromyography (EMG). Thus, this method of urodynamic research gives sufficient full information on the function of the detrusor and urethra during the emptying phase of the bladder. If the study is complemented by EMG, then it is possible to assess how coordinated detrusor function and sphincter activity are. The pressure/flow study allows a detailed assessment of urinary disorders. Using this method, it is possible to establish the presence of infravesical obstruction, a violation of the contractility of the detrusor, and various variants of neurogenic dysfunction of the lower urinary tract.

A pressure/flow study is usually performed as a follow-up to a filling cystometry. In addition, emptying cystometry can be combined with simultaneous x-ray examination(video urodynamics) or ultrasound.

Indications for performing a pressure/flow study

1. In patients with impaired evacuation function of the bladder, when using non-invasive examination methods (uroflowmetry, determining the volume of residual urine) it is not possible to differentiate between infravesical obstruction and detrusor contractility disorder (or their combination), especially when deciding on the surgical treatment of patients with prostatic hyperplasia.

2. In cases where the establishment of an accurate urodynamic diagnosis is of prognostic value.

3. Scientific research

View of the urodynamic system during a pressure/flow study

The figure shows the scheme for conducting a pressure/flow study with simultaneous EMG. A double-lumen catheter 6 F was installed in the bladder along the urethra, and a balloon-catheter 8 F with a surface electrode for EMG was installed in the rectum. The bladder is filled with saline at room temperature using a special pump from a plastic bag. With the help of special pressure sensors and EMG sensors, changes in intravesical, intra-abdominal pressure and sphincter activity are recorded. The flow rate of urine is recorded by a uroflowmeter. The urodynamic system screen records various parameters during a pressure/flow study. This figure shows a study of a 64-year-old man with complaints of persistent frequent urination and the occurrence of an imperative urge to urinate after undergoing transurethral resection of the prostate 12 weeks ago. During the examination, the patient is in a standing position. The first part of this study is filling cystometry. The first urge to urinate occurred when the volume of injected fluid was 120 ml. With a volume of injected fluid of 332 ml, involuntary contractions of the detrusor occurred, which caused the onset of the emptying phase of the bladder. During this phase, the maximum urine flow rate was 9.3 ml/sec, the detrusor pressure was 75 cm of water.

Conclusion: detrusor hyperactivity, residual infravesical obstruction.

How to Perform a Pressure/Flow Study

І. A sterile double-lumen urodynamic catheter 6 F is inserted into the bladder through the urethra without prior anesthesia, since the use of anesthetic gels can distort the results of uroflowmetry. (coughing, straining).

There are some features associated with the presence of a urodynamic catheter during a pressure/flow study:

1. In women and men (without compression of the urethra by an enlarged prostate or urethral stricture), the presence of a catheter does not significantly affect the flow of urine

2. A significant increase in intravesical pressure during urination in men with bladder outlet obstruction may cause the catheter to move from the bladder into the urethra.

3. In rare cases (urethral stricture, young children, severe prostate enlargement), it is reasonable to perform a suprapubic bladder puncture with a small diameter catheter to perform a pressure/flow study. Contraindications to this method are a decrease in bladder capacity, severe obesity.

ΙΙ. The balloon-catheter 8 F is inserted as high as possible into the rectum. This position of the catheter makes it possible to accurately measure intra-abdominal pressure fluctuations, since this zone is located above the fixation of the peritoneum to the rectum. The catheter is fixed and connected to a pressure transducer. The catheter balloon is filled to a volume at which the difference between intra-abdominal and intravesical pressure is zero. Through coughing, the adequacy of pressure transfer from the balloon catheter to the recording device is determined (pressure peaks on the monitor of the urodynamic system).

ΙΙΙ. Registration of detrusor pressure occurs by means of automatic subtraction of intra-abdominal pressure from intravesical and is reflected on the monitor as a record of a separate channel. Coughing and tension of the anterior abdominal wall is necessary in order to be sure that the increase in intra-abdominal and intravesical pressure occurs equally and is not accompanied by an increase in detrusor pressure values ​​(equal to zero).

ΙΥ. Simultaneous recording of sphincter activity. Electromyography is covered in a separate chapter.

Characteristics of the study pressure / flow - EMG and their clinical interpretation.

Interpretation of the pressure/flow study consists of both a general assessment of the obtained record of various curves, and individual parameters of the study (intravesical pressure, intra-abdominal pressure, urine flow rate).

The figure shows a diagram of a pressure/flow study with symbols corresponding to the ICS nomenclature.

A. Uroflowmetry curve and maximum urine flow rate (Q max).

On average, the values ​​of the maximum urine flow rate in this study are somewhat lower than in standard (free) uroflowmetry.

B. Intravesical pressure (P ves).

As mentioned earlier, intravesical pressure depends on detrusor and intra-abdominal pressure. General value intravesical pressure reflects the force of "expulsion" of the bladder.

B. Intra-abdominal pressure (P abd).

Quite often there is a slight decrease in intra-abdominal pressure during urination. Although an increase in intra-abdominal pressure should not be observed during bladder emptying, some healthy subjects experience an initial and terminal increase in Pabd. In addition, in some patients, the tension of the anterior abdominal wall and an increase in intra-abdominal pressure leads to an increase in the maximum urine flow rate, while in others, Q max decreases. In women, an increase in intra-abdominal pressure during emptying of the bladder can occur without violations of the contractile function of the detrusor.

D. Detrusor pressure (P det).

The contraction of the detrusor should be sufficient in strength and duration until the bladder is completely empty. A normally functioning detrusor adapts to an increase in urethral resistance by increasing the force of contractions, which is manifested in the study by an increase in detrusor pressure. In the presence of obstruction at the level of the bladder neck, contractions increase with maximum force (isometric contraction of pism), with an open neck, the force of contractions is weaker (isotonic contraction of pist). Therefore, the relationship between detrusor pressure and urine flow rate allows a deeper understanding of the dynamics of urination and its disorders. The presence of infravesical obstruction is confirmed by a chart reflecting the ratio of the maximum flow rate of urine and detrusor pressure.

The table shows the formula for calculating urethral resistance (infravesical obstruction).

URETHRAL RESISTANCE
Normal if: Doubtful if: Obstructive if	pdet.Qmax - 2 Qmax< 20 20 ≤ pdet.Qmax - 2 Qmax ≤ 40 pdet.Qmax - 2 Qmax > 40
The pressure is expressed in cm of water, and the flow rate of urine in ml / sec.

Drawing. ICS proposed method for determining bladder outlet obstruction in men.

The formula for determining the contractility of the detrusor is presented in the table.

CONTRACTILITY OF THE DETRUSOR

Reduced if pdetQmax + 5 Qmax< 100

Normal if 100 ≤ pdetQmax + 5 Qmax ≤ 150

Very good if pdet Qmax + 5 Qmax > 150

The figure shows a chart for assessing the contractility of the detrusor. Maximum isometric contraction force is referred to as a "stop test" when recording a pressure/flow study. During this test, the patient is asked to strongly contract the external sphincter (perineal muscles) while urinating. The degree of increase in detrusor pressure is marked on the diagram. However, contraction of the muscles of the perineum reflexively leads to inhibition of urination and a decrease in detrusor pressure. Detrusor contraction by the end of micturition is considered a normal urodynamic phenomenon.

D. Electromyography of the external sphincter.

External sphincter activity during urination (detrusor contraction) should not be recorded on an EMG. However, in patients with detrusor-sphincter dyssynergy due to spinal injury, pathological activity of the external sphincter is noted, coinciding with detrusor contraction. Sphincter activity decreases when the force of the detrusor contraction decreases, allowing the bladder to empty to some extent. In patients with no neurological disease dysfunctional urination or detrusor-sphincter discoordination is caused by a “flash” of sphincter activity (rising the EMG channel curve) during urination. Voluntary or involuntary contractions of the urethral sphincters cause the flow of urine to stop during urination. The contraction of the sphincters is accompanied by an increase in intravesical and detrusor pressure.

The figure shows a diagram of a pressure/flow study in a woman with stress urinary incontinence. During the study, a "stop test" was carried out. The bladder is filled up to 162 ml of fluid at body temperature (37°). Detrusor function during the filling phase is stable. The patient then began to urinate. When the urine flow rate reached its maximum, the patient was asked to stop urination by contracting the muscles of the perineum until the detrusor pressure reached its maximum. The uroflowmetry curve in the middle part (a) is suddenly interrupted due to the voluntary contraction of the muscles of the perineum and stopping the flow of urine. With a volume of 153 ml, the maximum urine flow rate was 27.5 ml/sec. The detrusor pressure curve (b) shows a gradual increase in the force of contractions up to 47 cm of water. during urination and up to 115 cm of water. with contraction of the muscles of the perineum. The intravesical pressure curve (c) is similar to the detrusor pressure curve, since isolated contraction of the perineal muscles is not accompanied by an increase in intra-abdominal pressure (d).

When the muscles of the anterior abdominal wall are tense, an increase in sphincter activity is sometimes noted due to the transmitted excitation from other muscle groups.

E. Retention of the flow of urine.

This urodynamic parameter is the time between a change (increase) in bladder pressure and a corresponding change in urine flow rate. Urinary retention is partly due to physiological reasons(urethra length and flow velocity) partly hardware reasons (distance to measuring device)

The figure shows a pressure/flow study on a 64-year-old man. The arrow indicates the interval corresponding to the delay time of urine flow.

Typically, the delay time for the flow of urine is 0.5-1 sec. This indicator must be taken into account when determining the pressure/flow relationship, especially with rapid changes in pressure values ​​and the maximum flow rate of urine.

G. Opening pressure (pves.open, pdet.open).

Intravesical and detrusor pressure at the beginning of micturition reflect the degree of resistance to the opening of the bladder neck. Detrusor opening pressure exceeding 80 cm of water. indicates the presence of obstructive urination. Tension of the anterior abdominal wall and, accordingly, an increase in intra-abdominal pressure at the beginning of urination is typical for patients with infravesical obstruction, but is not a mandatory sign of lower urinary tract dysfunction.

H. Maximum pressure (pves.max, pdet.max, pabd.max)

The maximum values ​​of intravesical, intra-abdominal, detrusor pressure are the most high performance pressure during a pressure/flow study. They can be recorded at times when the urine flow rate is zero.

I. Closing pressure (pves.clos, pdet.clos, pabd.clos).

The closing pressure is the pressure values ​​corresponding to the end of the urine stream.

K. Pressure at maximum urine flow (pves.Qmax, pdet.Qmax, pabd.Qmax)

The pressure at maximum urine flow is the pressure that is recorded at the moment when the urine flow rate has reached its maximum. If the uroflowmetric curve has a discontinuous appearance, the pressure at maximum urine flow is determined at the point of maximum flow, where the detrusor pressure has lower values ​​at this urine flow rate. Similarly, intravesical and intra-abdominal pressure is determined.

L. Dependence of detrusor pressure on urine flow rate.

When urinating, there is a definite relationship between detrusor pressure and urine flow rate. At zero values ​​of the urine flow velocity at the beginning of urination, the detrusor pressure reaches its maximum values ​​(piso). With an increase in the flow rate of urine, the detrusor pressure gradually decreases to zero values.

The figure shows the function of the detrusor depending on the rate of urine flow.

M. Urethral resistance.

Urethral resistance to urine flow during urination is expressed as the relationship between urine flow rate and detrusor pressure. Relationship between Qmax and Pdet. can be obtained by plotting the x-axis for urine flow velocity and the y-axis for detrusor pressure. In most modern urodynamic systems software allows you to automatically get such a diagram.

H. Passive urethral resistance

Passive urethral resistance is defined as the lowest value of urethral resistance. This means that the detrusor pressure is smallest values at any rate of urine flow, which corresponds to the maximum opening of the urethra during urination.

The figure shows a diagram of urethral resistance. in green the ascending part of the uroflowmetric curve is indicated, and its descending part is marked in red. Passive urethral resistance is indicated by a purple line.

Classification of urethral resistance during the bladder emptying phase.

The function of the urethra during urination is defined as 1) normal or 2) obstructive.

The term obstruction is used when the urethral resistance to urine flow increases. The obstructive nature of urination can be associated with both inappropriate activity of the urethral sphincters (hyperactivity) and anatomical changes (prostate enlargement, urethral stricture). Hyperactivity of the internal and external sphincters results in a discontinuous type of urethral resistance curve. Passive urethral resistance depends on the elasticity and stretchability of the urethral tube and its sphincters.

Quantification of urethral resistance.

A sufficiently large number of methods for assessing urethral resistance have been proposed. All of them are based on the relationship between detrusor pressure and urine flow rate. The most popular method for quantifying urethral resistance is the Abrams/Griffiths formula, AG= pdet.Qmax - 2 Qmax.

Classification of the contractility of the detrusor in the phase of bladder emptying.

During urination, the detrusor is defined as 1) acontractile, 2) reduced detrusor activity, 3) normal detrusor contractility.

Acontractile detrusor- no detrusor contractions during the pressure/flow study.

Decreased detrusor activity- detrusor contractions are not adequate in strength and duration in the absence of infravesical obstruction, which leads to incomplete emptying of the bladder.

Normal detrusor contractility- contractions of the detrusor in the absence of infravesical obstruction, ending with complete emptying of the bladder.

Detrusor contractility is assessed using a pressure/flow study chart. High detrusor pressure and urinary flow rate indicate a strong detrusor contraction. To assess the contractility of the detrusor, the most common nomogram proposed by Schäfer W.

Using Abrams/Griffiths nomograms ( AG= pdet.Qmax - 2 Qmax) and Schäfer ( pdet Qmax + 5 Qmax) Based on the results of the pressure/flow study, a urodynamic conclusion can be made about detrusor contractility (degree of dysfunction) and bladder outlet obstruction.

RELIABILITY OF THE STUDY PRESSURE/FLOW.

1. Repeated measurements during the same study

With repeated measurements during the same study, there is a consistent decrease in urethral resistance and the strength of detrusor contractions, as well as a tendency to increase the excreted urine volume. The 95% confidence limit for the reduction in pdet.Qmax is 4-10% and 10-16%, respectively, between the first and second and first and third measurements. The average values ​​of differences in repeated measurements are: pdet.Qmax - 3 ± 10 cm H 2 O, pdet.open and pdet.close - 7 ± 15 cm. H 2 O, Qmax - 0.5 ± 3 ml / s., The allocated volume and the volume of residual urine - 15 ± 90 ml. Mean values ​​of differences in repeated measurements during one study for Qmax< 2 мл/сек., и для pdet.Qmax < 15 cm. H 2 O наблюдаются у 80% пациентов.

2. Reliability of repeated studies.

It is estimated that 10-15% of patients change the classification of the type of voiding dysfunction on pQ nomograms on repeated pressure/flow studies.

3. Concordance between the results of the pressure/flow study in healthy people and patients with complaints of urinary disorders.

It is noted that in approximately half of men over 50 years of age in the study of pressure / flow, the obtained data will correspond to a questionable or obstructive zone. In one third of patients with lower urinary tract symptoms due to prostatic enlargement, a pressure/flow study does not confirm bladder outlet obstruction. The results of surgical treatment in this group of patients are worse than in patients with proven urodynamic infravesical obstruction. However, drug treatment can be equally effective in patients of both groups.

bugs and artifacts.

The presence of air bubbles in the connecting tubes or pressure sensors, "blockage" of the lumen and incorrect position of the urodynamic catheter, uneven transmission pressure on the bladder (discrepancy between the increase in pves and pabd) leads to erroneous measurement data.

The figures below show clinical examples pressure/flow studies.

Drawing. Pressure-flow study and detrusor/urine flow diagram in a woman with stress urinary incontinence. The study started with filling cystometry. The patient began to urinate from the moment the first urge appeared. The uroflowmetry curve as a whole has the correct form, however, due to the fact that the allocated volume was only 75 ml, the urination rate (Qmax) is 15 ml/sec. The graph of pressure values ​​shows the absence of tension in the anterior abdominal wall and even a decrease in intra-abdominal pressure during urination. The force of contraction of the detrusor during emptying of the bladder reached 20 cm of water. The detrusor/flow diagram shows non-obstructive voiding. Urodynamic diagnosis - detrusor hyperactivity, adequate detrusor contractile function in the emptying phase, absence of infravesical obstruction.

Drawing. Pressure/flow study and detrusor/flow diagram in a patient with urination, which is carried out by tension of the anterior abdominal wall. Complaints of stress urinary incontinence. With cystometry, stable detrusor function, with normal elasticity and a maximum cystometric capacity of 365 ml. This example shows a rather unusual type of bladder emptying for women - due to the tension of the anterior abdominal wall. The indication for a pressure/flow study was "fractional" bladder emptying and a low maximum urinary flow rate on uroflowmetry, with a residual urine volume of 35 ml. According to the results of the study, there is no data for infravesical obstruction, as well as any detrusor activity during emptying of the bladder. Obviously, surgery stress urinary incontinence in this patient can lead to poor bladder emptying and residual urine.

V urological practice several ways to study the work of the urinary organs. Uroflowmetry or miciometry is not the most common, but very informative for assessing the activity of the bladder and its sphincter during urination (miction).

Research methodology

Miction disorders occur both in organic pathology and functional. Therefore, it is not always possible to detect a problem using ultrasound, MRI or X-ray contrast studies. Uroflowmetry (UFM) comes to the rescue.

This diagnostic method allows you to see on graphic image, which he issues as a final document, the average and maximum speed of micturition and the amount of urine released. The results will show:

• patency of the urethra;
• patency of the vesicourethral part;
• contractile activity of the muscle that releases urine.

Uroflowmetry is available, physiological, does not require intervention in the body. The patient urinates into a container with a tube, and the device fixes. In addition, uroflowmetry will be used to track the dynamics of the treatment.

Indications for uroflowmetry

Prescribed for any problems with urination:

• sharp and chronic cystitis in women and men;
• violation of periodicity;
• change in the volume of urine;
• jet change;
• if you have to strain to urinate;
• incontinence.

How to prepare for uroflowmetry?

Special preparation is not needed. Just take care of filling the bladder by the time of diagnosis. To do this, drink 0.5 liters of water 40-60 minutes before the scheduled examination time.

Some need to tune in psychologically, but this is not difficult, since during uroflowmetry the patient is alone in the room.

If you are taking medications that affect the urinary system (diuretics, antihypertensive drugs, herbs), then warn your doctor about this.

How is the research done?

Diagnostics is carried out in a specially designated, voiding room. The patient is introduced to the apparatus and shown the button to be pressed at the beginning of the micturition and 5 seconds after it ends. The subject is then left alone. The device will record the urination produced in the funnel, which is connected to the device. For women, there is a voiding chair in the office, while men urinate standing up. The process is recorded automatically. The patient is then sent to the office. ultrasound diagnostics, where the amount of residual urine is determined (normally, it should not exceed 30 ml). A catheter is also used for this purpose, but the method loses before, as it is considered invasive.

Normal indicators and interpretation of the results

Normally, the urine stream is initially weak, then it gains strength, then the speed decreases. The process, recorded on paper, will show the doctor about the problems, if any. The doctor evaluates the indicators, taking into account the age of the patient, the volume of urine in the bladder and the type of pathology.

UFM indicators include:

1. Maximum and average speed of urination. Depends on gender, age, detrusor tone and internal sphincter of the bladder, the state of the vesicourethral segment. In men, with a urine volume of up to 200 ml, the maximum rate is 20 ml / s, more than 200 ml - 30 ml / s. In women - 20-25 ml / sec. The average speed rate is 10-15 ml / sec.
2. Time. Depends on the patency of the vesicourethral segment and the urethra. Normal is 20 seconds. With intermittent micturition, the time that urine was excreted from the urethra is summarized.
3. Volume. The most reliable results are obtained if the amount of urine is at least 50 ml.
4. Waiting time for urination. The norm is 30-40 seconds. When the muscle that releases urine is affected, it is much larger. With prostatic hyperplasia, it can reach several minutes.

In the event of pathologies of the urinary tract, an examination should be carried out. It is important to know in advance how uroflowmetry is performed, since only the most comfortable conditions for the patient during the diagnosis guarantee an accurate result. This type of examination allows you to identify a number of urological disorders, but you need to be prepared for it not only physically, but also mentally.

Method features

For the patient, this method looks like normal urination into a specific container.

Uroflowmetry - diagnostic method genitourinary system, the determining indicator of which is the speed of the urine stream during urination. It is carried out using special equipment or an ordinary stopwatch. In the second case, it is especially important not to be shy, since any changes in the state during urination can significantly change the result. The result will be a misdiagnosis.

The procedure is carried out quickly, without disturbing the natural integument of the body. Before the study, you need to consult a doctor, clarify all the details of the procedure, the presence of side effects. If the patient uses any medication, the doctor must be notified. In the process of diagnosis, it is important for the patient to relax and not move. To create favorable conditions, the measurement sensor is installed in a separate room, and the doctor receives data on a computer monitor remotely. This method determines the volume of urine excreted, the speed of the jet and the time for which a certain volume is excreted.

Indications for holding

Urinary incontinence is the uncontrolled flow of urine through the urethra.

This type of research is most important for the diagnosis of prostate adenoma. In addition, the procedure is carried out in the case of:

• enuresis;
• the presence of symptoms of bladder cancer;
• uncontrolled urination;
• functional changes in the bladder;
• urethral obstruction (impaired patency);
• chronic inflammation of the bladder (cystitis);
• infectious lesions of the urinary tract.

Study preparation

Preparation for uroflowmetry concerns not only the physical condition of the patient, but also the psychological one. In order for the urea to be filled enough for the procedure, 1 liter of liquid must be drunk 1 hour before. Therefore, the next urination is possible only as part of the diagnosis, not earlier. Any questions of interest should be asked to the doctor in advance so that there are no misunderstandings during the diagnosis. Depending on the existing pathologies, the patient may need to independently measure the time of urination and volume at home, and the results should be recorded and provided to the doctor before the study.

To obtain an accurate result, uroflowmetry is carried out as a matter of priority.

If the patient was previously prescribed drugs that stimulate the bladder and urethra, then before uroflowmetry, you should stop using them, as well as taking any medicines and even vitamin supplements. Pregnant women should inform the doctor about their condition. Urination during the diagnosis is carried out in the usual position for a person: men - standing, women - sitting. Though necessary equipment is installed in a separate room, it is important to mentally tune in advance. Any changes in the state of a person, even stress and anxiety, affect the results.

How is uroflowmetry performed in children and adults?

Decryption of received data

During uroflowmetry, numerous data are displayed on the monitor. Only a doctor can understand all the subtleties, draw up a single picture and make a diagnosis based on the results obtained. However, the patient recognizes some of the data himself:

• T is the time of urination. Period from onset to cessation of urination. Reflected by a long curve on the x-axis. It should be noted that the period of urination does not apply here. If the jet was interrupted, then these indicators will be different.
• Q max - the maximum speed of the urine stream. Talks about the volume produced for a specific period of time. With deviations from the norm, the presence of pathology is not necessary. In this case, the gender and age of the patient play an important role.
• Q mid - average jet speed. It characterizes urination in general and shows the ratio of the allocated volume to the time spent on the process.
• Tq max - the acquisition of the maximum speed from the moment the jet appeared. At healthy person the uroflowogram rises, and this parameter occupies 1/3 of the graph. In the presence of pathologies, the graph rises slightly, and TQ max increases.
• V is the total volume of excreted urine. For successful diagnostics, this coefficient should exceed 50 ml. Ideally - 200-600 ml.
• Tw is the waiting period for the appearance of a stream of urine.

The method of research is the measurement of the volume of urine excreted and the time spent on it.

A characteristic symptom of prostatitis is a violation of urination. Not only the frequency, but also the rate of urine output changes. One way to determine the pathology is uroflowmetry. In men, when sent for examination, the question arises - what is it? Urometry means a type of diagnostics aimed at measuring the outflow rate and volume of urine. Deviation of the indicator from the norm indicates a deterioration in the tone of the bladder and impaired patency urethra. Uroflowmetry allows you to confirm or refute the presence of inflammation and tumors in the prostate gland.

When is uroflowmetry necessary?

With age, the condition of the internal organs worsens in a man. The urinary system is no exception. The bladder and urethra are depleted, atrophied, which leads to deterioration of urination.

Apart from age-related changes, the reason for the deterioration of urination is infravesical obstruction. In other words, the narrowing of the urethra under the bladder. Infravesical obstruction is characteristic of following changes and diseases:

• prostatitis in various forms;
• stricture urinary canal- narrowing;
• sclerosis of the neck of the bladder;
• benign prostatic hyperplasia;
• neoplasms of various etiologies;
• injury, inflammation, and so on.

Diseases are accompanied by impaired urination, and uroflowmetry makes it possible to detect pathology even at an early stage.

In the USA and European countries, the diagnostic method is used for the initial visit to a urologist or andrologist. In Russia, the situation is different: uroflowmetry serves as an auxiliary method of instrumental examination. Not all clinics have the opportunity to do this kind of analysis.

How uroflowmetry is performed - general information

There is nothing complicated in the methodology. To conduct a simplified uroflowmetry, a measuring cup and a stopwatch are sufficient. The method is available for use at home, but gives approximate results. It is necessary to fix the duration of urination with a stopwatch and the volume of urine with a measuring cup. To find out the rate of urine outflow, divide the volume of fluid by seconds. You will get an approximate speed. Knowing normal performance uroflowmetry - you can understand the presence or absence of pathology in the body.

More accurate readings are obtained using a uroflowmeter (see photo). The device consists of a container for collecting urine, branch pipes, and a stand. The device is connected to a personal computer, uroflowmetry data is transmitted to it. The result of the analysis is displayed by the program in the form of graphs that can be printed on a printer. This facilitates the interpretation of the results and allows you to accurately determine the pathology.

Read also: Blood test indicators for prostatitis

Modern uroflowmeters allow you to find out the following indicators:

1. Volume and time of urination.
2. Average and maximum flow rate of urine.
3. Waiting time for urination.
4. Uroflowmetric index.
5. The nature of the uroflowmetric curve.

For the patient, the diagnosis is painless, does not cause moral inconvenience.

If there are no pathologies in the body of a man, the outflow of urine is slow at the initial stage, accelerates towards the middle of the process, and decreases towards the end. The device captures the urodynamics of the entire process, then gives the overall result. When making a preliminary diagnosis, the doctor takes into account the age and gender of the patient, general clinical picture, history data.

Uroflowmetry indicators may have an error. To get an accurate result, the diagnosis is carried out in different time days for 2-3 days. This approach allows you to identify changes in urination and get a reliable picture of a possible pathology.

Preparing for uroflowmetry - what you need to know

Diagnosis is extremely simple, so no special preparation is required. Before uroflowmetry, drugs that stimulate the muscles of the bladder and urethra should not be taken - this will distort the indicators. An hour before the examination, you need to drink a liter of water to fill your bladder. Immediately before uroflowmetry, you can not relieve a small need.

An important factor is psychological preparation. To do this, the doctor explains to the patient the essence of the method, tells what needs to be done. Urination is carried out in the usual position for a man - standing. Stress, anxiety, anxiety affect the rate of urination, which is reflected in the indicators.

Uroflowmetry parameters in normal and pathological conditions

To identify infravesical obstruction using uroflowmetry, you need to know the indicators are normal. See the table for average values ​​for men.

Uroflowmetry is a diagnostic method that measures the rate of urination. This is a relatively simple diagnostic method that is used for various.

Indications for research:

How is uroflowmetry performed:

• Use of a special apparatus (uroflowmeter). At the same time, the patient is asked to enter the tank of the apparatus, which analyzes important indicators and gives fairly accurate numbers. The study should be carried out in conditions that are comfortable for the patient, and if necessary, the diagnosis is repeated several times to obtain the most objective data. It should be remembered that diagnostics should be carried out at, but its overflow is highly undesirable.
• Use of measuring utensils and a stopwatch. With this option, the patient detects the time of the beginning and end of urination and fixes the volume of urine. Then the resulting volume is divided by the time and get the average speed of urination. The use of this method is shown in the absence of a uroflowmeter. Naturally, unlike hardware method, the use of a stopwatch does not allow you to get all the necessary indicators of the flow.

Uroflowmetry parameters are normal:

• The maximum rate of urination - the norm for men is 15 ml / sec or more; for women - 20 ml/s and more.
• The average rate of urination - normally exceeds 10 ml / sec.
• The time to reach maximum speed is normally within 4-9 seconds.
• Total urination time - estimated by the doctor in accordance with the allocated volume.
• Volume of urine excreted: ideally, the study is considered objective if the total volume is between 200 and 500 ml. The minimum volume at which the results of uroflowmetry can be taken into account is 100 ml.
• The period of time required to start micturition usually does not exceed 10 seconds. However, one should take into account the psychological component that prevents some people from adequately urinating in uncomfortable conditions.

How to prepare for uroflowmetry:

• 30-60 minutes before the study, you need to drink 0.5-1 liter of water.
• The patient waits for the urge to urinate and informs the doctor about it.
• A study is being carried out, during which it is necessary to create comfortable conditions for the patient. If necessary, open a water tap to enhance the conditioned reflex.
• In some cases, to obtain objective data, it is necessary to conduct several studies.

Examples of uroflowmetry results:
	Norm
	Minor bladder outlet obstruction