(1)
Functional Urology Unit, Casa Madre Fortunata Toniolo, Bologna, Italy
There are several standardized validated questionnaire to aid the clinician in evaluating lower urinary tract symptoms, degree of bother, and quality of life including:
Urogenital Distress Inventory Short Form (UDI-6)
ICI Questionnaire Short Form on Urinary Incontinence (ICIQ-UI)
AUA Symptom Score (AUASS)
International Prostate Severity Score (IPSS)
Validated questionnaires are helpful in structuring history taking and providing checklists for gathering data.
However, the proper interpretation of urodynamics starts from the knowledge of the mechanisms beyond the symptoms of the lower urinary tract since UDS study should be customized for each individual to maximize the utility of the test.
In other words, when you run a test, from simple uroflowmetry to more complex multichannel pressure/flow study, you should have exactly in mind what you are looking for. A precise algorithm should enable you to navigate easily among the patient’s symptoms reducing unnecessary testing and accelerating the diagnostic process.
The key symptoms of lower urinary tract are divided according to micturition cycle in:
Storage symptoms
Voiding symptoms
2.1 Storage Symptoms
Storage symptoms include:
Increased daytime frequency
Urgency
Nocturia
Urinary incontinence
Nocturnal enuresis in children
Painful bladder
2.2 Increased Daytime Frequency
Increased daytime frequency is the need to void too often by day.
The normal diurnal frequency is between three and seven times a day.
Increased frequency is seldom the patient’s only complaint. It is usually associated with other symptoms, most frequently urgency.
Frequency can occur as a result of reduced functional bladder capacity or incomplete bladder emptying or both. In addition, it may be caused by anxiety or by patient (mostly females) adaptation to avoid urine leakage by maintaining a relatively low urinary volume in the bladder (coping mechanism). Also a fear of urinary retention, especially in older males, may be compensated by a frequent voiding.
The assessment of functional bladder capacity through a voiding diary is the first step in the evaluation of symptom.
Box 2.1: Definition of Bladder Capacity
Bladder capacity may be defined in three contexts:
Functional bladder capacity
Cystometric bladder capacity
Anatomic bladder capacity
Functional bladder capacity is defined as the volume of urine accumulated in the bladder prior to voluntary micturition; it is typically evaluated by measuring the maximum, mean, or median voided volume (MVV) recorded on a bladder diary. Functional bladder capacity is about 300 ml in females, 400 ml in males, and 120 ml in children. Its value tends to be smaller than cystometric capacity.
Cystometric capacity is defined as the intravesical volume at the end of the filling of CMG, when the patient experiences a strong desire to void or is granted to micturate by the examiner. Usually its value is higher than functional bladder capacity.
Anatomic bladder capacity or maximum anesthetic bladder capacity is defined as the volume that can be infused into the bladder during a cystoscopic procedure while the patient is under anesthesia. This maneuver can be used to evaluate bladder wall compliance in specific clinical conditions (painful bladder, actinic cystitis). Since it is measured under spinal or general anesthesia, it tends to be significantly greater than both functional and cystometric capacity.
If functional bladder capacity is normal, increased frequency is a consequence of an increased output of urine. This condition may depend on:
Increased intake of fluid (occasionally psychotic)
Osmotic diuresis (diabetes mellitus)
Excessive production of antidiuretic hormone (diabetes insipidus)
If functional bladder capacity is reduced, frequency may be related to:
Detrusor dysfunction (OAB, reduced compliance, hypersensitive bladder)
Voiding dysfunction with post-void residual urine
Free flowmetry with assessment of post-void residual urine may be a reasonable approach to exclude a voiding problem.
Filling cystometry remains the most suitable test to evaluate a detrusor dysfunction.
Conventional urodynamics may be necessary in some cases (e.g., interrupted flow curve) to highlight a detrusor underactivity or a dysfunctional voiding.
For increased daytime frequency simplified algorithm, see Fig. 2.1.
Figure 2.1
Simplified algorithm of increased daytime frequency
2.3 Urgency
Urgency is the complaint of a sudden, compelling desire to void which is difficult to defer.
Box 2.2
In literature the terms urge and urgency are often interchanged.
Urge is a strong desire of voiding in physiological conditions.
Urgency is a pathological compelling desire of voiding beyond full-bladder capacity that is perceived as a negative sensory experience (see Chap. 7).
Although urgency is the distinctive feature of overactive bladder (OAB), it remains imprecisely characterized and incompletely understood with respect to underlying pathophysiology. There are at least three key components in what the patient perceives as urinary urgency:
Peripheral factors that generate the sensation of urgency (first of all detrusor overactivity but also abnormal bladder sensation and inflammation)
The processes by which the sensation is transmitted to the brain (A-delta myelinated fibers or C fibers)
Bladder sensation is normally carried out by A-delta myelinated fibers. In pathologic conditions (i.e., spinal cord injury, inflammation, obstruction), C fibers are recruited to form new synaptic connections. The result is a lower threshold of micturition reflex.
The manner in which the brain interprets and controls the sensation.
In normal conditions, with near-empty bladder, the situation during much of the daily life, the cortical areas which modulate the perception of urge are not detectably activated, but activation in the midbrain of periaqueductal gray area (PAG) indicates an unconscious monitoring of ascending bladder signals.
At full-bladder capacity, strong voiding sensation is accompanied by an activation of the right insula, dorsal anterior cingulate cortex, and supplementary motor area and by a deactivation of the frontal cortex, which seems responsible of symptom control. In patients with OAB, weaker insula activity is typically observed at low volumes and stronger activity at high volumes, suggesting a sudden and dramatic sensation of urgency. In addition, a reduced deactivation of frontal cortex is typically seen.
In elderly the lost of control is a consequence of white matter damage which may disrupt the connecting pathways of the brain-bladder control network decreasing ability to postpone voiding and increasing urgency.
There is no consensus about the best way to measure this symptom. Some clinicians prefer the voiding diary; others support the use of scales used to assess pain. None of the two methods take into account the compelling desire to void, i.e., the reduction in warning time that precedes the need to void.
In patient complaining urgency, infection and urological malignancy should be ruled out.
Historically, urodynamics has not been recommended in the initial evaluation of OAB, since it is defined primarily by clinical symptoms. As the pathophysiology of the OAB has become more clearly elucidated, UDS has again gained an important role since it can provide objective data to reflect these new findings.
Filling cystometry is the most suitable urodynamic test to assess urgency.
Three findings can be observed:
Phasic detrusor overactivity
Terminal detrusor overactivity
Hypersensitive bladder (see Chap. 7)
2.4 Nocturia
Nocturia is the complaint of interruption of sleep one or more times because of the need to micturate. Each void is preceded and followed by sleep.
Normal subject does not get up in the night to urinate. However over 65 years for men and 75 for women, it is normal to get up once a night.
Historically nocturia has been considered as a secondary consequence of an underlying urological disease, i.e., BPH or detrusor overactivity.
In fact, nocturia can be related to four distinct mechanisms:
An overall increase of urine production (global polyuria)
An increase in urine production only at night (nocturnal polyuria)
Reduced bladder capacity
Sleep disorder
The term global polyuria indicates an overall urine volume greater than 40 ml/kg in adults. It is usually seen in individuals with diabetes mellitus, diabetes insipidus, primary polydipsia, voluntary excessive fluid intake, hypercalcemia, or intake of particular drugs (mostly diuretics).
Nocturnal polyuria is defined by the ICS as a nocturnal urine volume (NUV) greater than 20–33 % of total 24-h urine volume. This proportion is called nocturnal polyuria index (NPi) and its value varies from 14 % in young adults to 34 % in people over 65 years.
Nocturnal polyuria is one of the most frequent causes of nocturia in adults, especially in elderly age group. Nocturnal polyuria occurs in consequence of several factors including:
Modification of the circadian rhythm of production of arginine vasopressin (AVP) hormone (water diuresis)
Excess production of atrial natriuretic peptide occurring in chronic heart failure with nighttime evacuation of daytime fluid sequestration with peripheral edema (solute diuresis)
A combination of both
Water diuresis is represented by high FWC and low osmolarity at night. For solute diuresis the driving force seems to be increased sodium clearance at night.
Nocturnal polyuria can also occur in consequence of sleep apnea which may produce an excess of atrial natriuretic peptide and medications (diuretics).
Reduced bladder capacity includes all the conditions associated with storage symptoms, in particular overactive bladder and bladder outlet obstruction. Nocturia occurs when the nocturnal bladder capacity (NBC) is overcome by the amount of urine entering the bladder during the night. Hence, even without exceeding production of urine at night, the bladder cannot assume the NUV storage. This concept is expressed by the NBC index (NBCi), which corresponds to the actual number of voids minus the predicted number of voids. The predicted number of voids is obtained by subtracting one from Ni. Hence, NBCi >0 means that voids at night occur below the maximum single voided volume at day (MVV), indicating that the bladder itself cannot store the amount of urine produced at night.
Even insomnia can cause nocturia in the elderly.
This classification facilitates appropriate treatment; it is, therefore, essential to conduct a complete and structured assessment of the symptom to avoid subsequent failures.
Box 2.3: Terminology of Nocturia Based on Voiding Diary
NUV (nocturnal urinary volume) = the amount of urine passed at night including the first voided volume in the morning.
Ni (nocturia index) = nocturnal urine volume/maximum single voided volume.
NPi (nocturnal polyuria index) nocturnal urine volume/24-h urine volume. It should be <1.
MVV (maximum voided volume) = maximum single voided volume during the day.
PNV (predicted number of nightly voids) = nocturia index-1.
NBCi (nocturnal bladder capacity index) = actual number of nocturnal voids – predicted number of nocturnal voids.
2.5 Urinary Incontinence
Urinary incontinence is the complaint of any involuntary leakage of urine.
There are three main types of incontinence:
- 1.
Stress incontinence
- 2.
Urge incontinence
- 3.
Mixed incontinence
2.5.1 Stress Incontinence
Stress incontinence is the complaint of involuntary loss of urine on effort or physical exertion, e.g., sporting activities, or on coughing or sneezing. It can be defined also as an “activity-related incontinence” to avoid confusion with psychological stress.
In female, there are two mechanisms underlying the disorder:
- 1.
Defect in the urethral support for a weakening of the muscles of the floor pelvic or ligament injury support (hypermobility of the urethra).
- 2.
Lack of urethral tone (intrinsic sphincter deficiency). In most of the women, the mechanisms coexist.
The primary aim of clinical assessment is to distinguish between:
Uncomplicated SUI
Complicated SUI
Urodynamic testing is not necessary when conservative treatment is planned and even before anti-incontinence surgery (mid-urethral sling) in presence of uncomplicated SUI.
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