URODINAMYCS: a prime for the beginner by GIANCARLO VIGNOLI, MD Urodynamics and Urogynecological Unit Casa “Madre Fortunata Toniolo” Bologna
Urodynamics describes a group of physiological tests that are used in clinical practice to investigate abnormalities of lower urinary tract function. Contrary to popular belief, it is not an esoteric subject of limited applicability or difficult science. In fact, the principles underlying urodynamics are simple, and the techniques entirely logical in their application
History & Physical “ urodynamically – oriented”
Blaivas J, Lower Urinary Tract Physiology and Pathophysiology,FUUS 2008
Blaivas J ,Evaluation of Lower Uirnary Tract Dysfunction, FUUS 2009
Hosker G , Good Urodynamic Practice,ICS 2008
Kastgir J et a.Course on Urodynamics ,TTmed Urology,2010
As the bladder fills progressively, relaxation of the bladder (detrusor) muscle allows low pressure storage of urine, aided by inhibitory mechanisms within the spinal cord and pelvic ganglia. Concurrently, the complex system of sphincters that encircle the urethra start to contract in keeping with bladder filling in order to increase urethral resistance and maintain continence.
Micturition cycle: voiding
Conversely, voiding is a voluntary act that is associated with a lowering of urethral resistance by sphincter relaxation followed by a coordinated contraction of the detrusor muscle which leads to complete emptying of the stored urine.
Voluntary interruption of voiding
Strain ( Valsalva)
This combination of physiological and mechanical functions may be altered by various processes, and manifests in various ways, such as incontinence, detrusor muscle overactivity, voiding dysfunction, and so on.
Urodynamics in its purest sense is the study of the relationship between bladder pressure, volume and flow at the various stages of the micturition cycle.
It is important for the clinician to have a rudimentary understanding of the physiological processes involved and to endeavor to make a urodynamic diagnosis from the start, which is then confirmed or refuted by subsequent tests
By employing good basic clinical skills of detailed history-taking, physical examination and a selection of simple investigations, most problems may be diagnosed in the outpatients or office setting with a rather basic understanding of lower urinary tract physiology.
Patient clinical assessment
History including symptom score
Physical examination which includes:
- Digital rectal examination (DRE) for men
- Pelvic examination for women
- Focused neurological examination
Frequency volume chart/voiding diary
Urine dipstick analysis
Urine microscopy and culture
Post-void residual volume (bladder scan)
Patient Sheet Front Page
Patient : Ref :
Main symptom : *
Degree of bother: *
Previous surgery :
Incontinence Impact Questionnaire (IIQ)
Urogenital Distress Inventory (UDI)
International Prostate Symptom Score (IPSS)
Types of Bladder Diary
Micturition time chart
Frequency - volume chart
Complete Bladder diary ( including fluids,degree of urgency ,etc.)
Electronic Bladder Diary
Informations derived from Bladder Diary
It provides an objective record of symptoms (frequency, leakage episodes) and their severity
Maximum and average voided volumes, the “functional bladder capacity”
Distinguishes frequency from global polyuria (> 2.8 L urine output in 24 h)
Distinguishes between nocturia and nocturnal polyuria (nocturnal polyuria is > 30% of total 24-hour output occurring at night; it may reflect the presence of extraurinary tract pathology such as congestive cardiac failure, and abnormalities of antidiuretic or atrial natriuretic hormone secretion)
1-hour Pad Test ( positive > 5 gr)
1. Patient voids
2. Pre-weighed collecting device is put on and 1-h test begins
3. 0-15 min: subject drinks 500 mL of sodium-free liquid and sits/rests
4. 15-45 min: subject walks and climbs equivalent of one flight up and down stairs
5. 45-60 min: subject performs following activities: - standing up from sitting 10 times - coughing vigorously 10 times - running on the spot for 1 min - bending to pick up small objects off the floor five times - washing hands in running water for 1 minute
6. At the end of the 1-h test the collecting pad is removed and reweighed
7. If the test is thought to be representative, the subject voids and the volume is recorded
Vaginal Examination ( Inspection )
Vaginal Examination ( Stress Test )
POP-Q iuga simplified version
gh 3 cm
pb 2 cm
Tvl 10 cm
Ap 3 cm
Bp 3 cm
Source : Swift S , 2006
POP-Q ( gh : 3 cm )
POP-Q ( D : 10 cm )
POP-Q ( Aa : 3 cm )
POP-Q ( Ap : 3cm )
BARD Interactive Guide
Focused Neurological Examination
Anal reflex ( scratching the perineum makes the anus “wink”)
Anal sphincter tone & Voluntary control
Uroflowmetry is a simple, noninvasive technique which is easily performed in the outpatient setting and is often used as a screening test for voiding problems, or a means of selecting patients who require more complex urodynamic studies
Flow Curve Analysis
Qmax : Normal Ranges Males under 40 years: > 21 mL/sec Females under 50 years: > 25mL/sec Males 40-60 years: > 18 mL/sec Females over 50 years: > 18 mL/sec Males over 60 years: > 13 mL/sec
Male Free Flowmetry Predictive Value
Qmax < 10 mL/sec: 90% have bladder outflow obstruction
Qmax 10–14 mL/sec: 67% have bladder outflow obstruction
Qmax > 15 mL/sec: 30% have bladder outflow obstruction
Abdominal straining or Detrusor – Sphincter dyssinergia
Moving back and forth
Invasive Urodynamics Cystometry & Pressure/Flow study
The only absolute contraindication to urodynamics is a clinical urinary tract infection !
The best way to determine the presence of infection is to simply do a dipstick on the patient’s urine when they arrive and perform a uroflow
Patient’s with positive dips (nitrite) should be rescheduled and treated after catheterized urine is sent for analysis.
There are no urodynamic emergencies!
When unsure of the safety of the situation, always consider rescheduling .
Source : Life-Tech Introduction to Urodynamics
Patient's position (including children patients) can be gradually adjusted from lying to sitting position
bladder ( filling & recording)
Air-charged catheter ( Laborie Medical Technologies)
Micro-air charged balloon circumferentially placed around the catheter
Eliminate directional artifactual sensing
Particularly suitable for urethral pressure measurement
External strain gauges
Subtraction Cystometry pdet = pves-pabd
Calibration : pdet < 6 cm H20
Negative rectal pressure simulates a detrusor contraction
Types of EMG
Two types of information can be obtained from EMG:
a) a simple indication of muscle behavior
( the kinesiological EMG ) - the usual EMG in urodynamics
b) an electrical correlate of muscle pathology
( the neurophysiological EMG )
Patch (surface) EMG electrodes for females and males The kinesiological EMG
Source : Life-Tech Introduction to Urodynamics
Placement of wire electrodes in female The neurophysiological EMG
Source : Life-Tech Introduction to Urodynamics
Placement of wire electrodes in male The neurophysiological EMG
Source:Life-Tech Introduction to Urodynamics
Dyssinergic or Non-relaxing activity
Low amplitude activity*
* check neurophysiological study
Types of Dyssinergic activity
The procedure in 10 steps
1. Check transducers reference height: this is defined at the upper edge of the symphysis pubis, and is the level at which all external transducers must be placed for all the urodynamic pressures to have the same hydrostatic component.
2. Check patency of fluid lines by flushing
Check quality control of pressure signals: the resting values for the readings should be in a typical range and adequate subtraction should be evaluated by asking the patient to cough (there should be no more than a minor deflection, if at all, on pdet) .
4. Suggested filling rate : 50ml/min
During filling there should be continuous conversation between the examiner and the patient and every endeavor should be made to reproduce the symptoms. The patient should be instructed to tell the examiner when they first develop a sensation of bladder filling and when they have normal and strong sensations to void, as well as sensations of urgency and pain.
Coughs should be repeated regularly throughout the fill to check urodynamic stress incontinence
7 . At 200 ml of filling , patient is asked to cough and strain and VLPP is evaluated .
8 . Once the bladder is full, filling is stopped and the patient is asked to void into an uroflowmeter with the catheters in situ. This allows pressure-flow readings to be taken concurrently and examines the voiding phase.
9 . After voiding the patient should again be asked to cough to test that the catheters have not moved during micturition .
10. Failure to show equal pressure transmission after voiding would suggest that the voiding trace cannot be accurately interpreted.
Interpretation of traces
Assessment of Compliance
Bladder compliance describes the relationship between bladder volume and bladder pressure (dv /dp) and is expressed as increase in bladder volume per centimeter of water increase in bladder pressure (ml/cmH20)
In the normal bladder with a capacity of 400ml the change in pressure form empty to full should be less than 10 cm H20, giving a figure for normal compliance of 40 ml/cmH20
Values greater than 10 cmH20 or lower than 40ml/cmH20 at bladder capacity indicate a reduced compliance
Urgency Urodynamic Spectrum
Phasic contractions - Good sphincter control OAB - dry
Phasic contractions - Poor sphincter control OAB - wet
Terminal contractions - Poor brain control
Stress Urinary Incontinence
The role of urodynamics in stress urinary incontinence is a subject of ongoing debate.
NICE Guidelines does not recommend the routine use of preoperative urodynamics for women suffering with stress urinary incontinence
However,only 50% of women who report pure stress incontinence have pure urodynamic stress incontinence
There is some evidence that low urethral closure pressures may be associated with poorer outcomes.
There is some evidence that low amplitude DO have better outcomes after repair,while high amplitude DO do worse
Occult SUI is associated to POP in 15-30% of the patients.
Urodynamic stress incontinence
the involuntary leakage of urine during increased abdominal pressure, in the absence of a detrusor contraction .
Valsalva leak point pressure
Leak Point Pressure
Leak point information is obtained either by having the patient cough or valsalva.
The method that provides good leak pressure information utilizes Valsalva instead of cough.
Bladder filled at 200 ml
VLPP < 60cm H20 ISD
VLPP 60 to 90 cmH20 Equivocal
VLPP > 90 cm H20 Hypermobility
Source : Life-Tech Urodynamics
Mixed urinary incontinence
cough uncontrolled voiding reflex
There is a distinct lack of consensus relating to the use of urodynamic assessment in the interpretation of voiding dysfunction in women.
There are universally accepted nomograms for men with outflow obstruction but there remain various different urodynamic criteria for women.
Recent attempts have been made to simplify and clarify these, such as the nomogram proposed by Blaivas and Groutz in 2000, but standardization is still awaited.
Male bladder outlet obstruction
Loss of bladder line during voiding
The main urodynamic findings in men with LUTS include:
- Bladder outflow obstruction ( usually secondary to benign prostatic obstruction)
- Detrusor overactivity ( primary or secondary to obstruction)
- Dysfunctional voiding
- Detrusor underactivity ( primary or secondary to dysfunctional voiding)
PRESSURE/ FLOW ANALYSIS ICS Nomograms
BOO Index: pdetMax-2Qmax
BC Index: pdetMax+5Qmax
100-150 normal activity
Abrams P, 1999
Bladder outlet obstruction
The ICS has defined Dysfunctional voiding as an intermittent and / or fluctuating flow rate due to involuntary intermittent contractions of peri-urethral striated muscle during voiding in neurologically normal patients
Non-invasive BOO analysis
Non-invasive BOO analysis
Penile cuff test:
pressure interrupting flow is close to true isovolumetric pressure measured by conventional urodynamics
It is IMPERATIVE that clinicians performing studies on quadriplegics with a cervical spine injury at C-6 or above be prepared to recognize and treat Autonomic Dysreflexia .
Symptoms of Autonomic Dysreflexia
Rapid, increase in B/P of 20-40 mmHg or greater
Heavy sweating (usually above the level of the SCI)
Goose bumps (usually above the level of the SCI)
Tightness in the chest
Blurred or spotty vision
When doing urodynamics on a patient with potential risk for autonomic dysreflexia:
1. Monitor B/P and pulse continuously throug the procedure.
2 . Instill 2% xylocaine before catheterization.
3. Use body temperature fluids to fill the bladder.
4. Be prepared to:
Empty the bladder immediately if B/P elevating or episode imminent.
Raise the patient’s head if not already sitting.
Reduce sustained systolic B/P greater than 150mmHg pharmacologically with rapid acting antihypertensive agents, such as Nifedipine, immediate release – “bite and swallow”
5. Reverse symptomatic hypotension caused by sudden bladder decompression or meds. To do this:
Lower head and raise legs.
Administer IV fluids and anit-hypotensives.
6. Monitor the patients at least 2 hours after resolution of the episode. 7. Admit the patient to the hospital if there is poor response to treatment. 8. Document the episode according to recommended guidelines
Source : Life-Tech Introduction to Urodynamics
Videourodynamics ( VUDS ) adds a structural element to the functional study of standard urodynamics by enabling real-time visualization of the relevant anatomy with simultaneous pressure recordings, which makes it the most comprehensive urodynamic assessment possible.
VUDS is indicated when simultaneous anatomical information is required in addition to the functional data that a conventional urodynamic study provides .
Radiolucent toilet seat
Semilateral or oblique position
Neurogenic Bladder – Type 2 dyssinergia
Neurogenic bladder – Types 3 dyssinergia 4th degree reflux on the left
UPP is the recording of intraluminal pressure along the lenght of urethra
The study is performed during slow retraction ( 1 mm/s ) of a catheter with side holes
Bladder pressure should be measured simultaneously to exclude effects of an associated detrusor contraction
2- or 3-ways catheters
Types of Profilometry
Static urethral pressure profile ( at rest )
Dynamic urethral pressure profile ( during cough )
Micturational urethral pressure profile ( during voiding ).Rarely used
Patient in supine ( sometime standing ) position
After voiding the catheter is inserted into the bladder
The residual urine is drained and recorded
The catheter is conncted to the recording equipment and to an infusion pump.The manometer is zeroed to the air at the level of the upper edge of the symphisis
Start infusion pump (2ml/min of saline at 37°) and recorder
Start retraction of catheter ( 1 mm/s )
Urethral closure pressure ( ucp )
The effective pressure maintaining continence is not the urethral pressure,but the so-called closure pressure ( the urethral pressure minus vesical pressure )
If the intravesical pressure ever exceeds the urethral pressure the possibility of leakage obviously exist
MUCP Normal Values
Abrams P , Urodynamics ,
3° edition ,2006,p 104.
The maximum urethral pressure increase from infancy to the age of 25 years.
90 cm H20
Thereafter, the values decrease with increasing age
10 cm H20 by decade
Rud T ,Acta Obstet Gynecol Scand ,1980
The stress urethral profile
The concept of the “ stress” profile was introduced by Asmussen and Ulmsten in 1976
If the closure pressure become negative on coughing then leakage is likely to occur.
Closure pressure may be derived electronically by subtracting intravesical pressure from intraurethral pressure and this may be displayed on chart recorder
Pressure transmission lower than 90% in the proximal one-third of the urethra indicates a defect in urethral support
Ambulatory urodynamic monitoring (AUM) refers to functional tests of the lower urinary tract predominantly utilizing natural filling of the urinary tract and reproducing the subject’s normal activity.
Ambulatory studies seek to improve the correlation between urinary symptoms and clinical findings.
The indications for ambulatory urodynamic monitoring have been outlined in an ICS subcommittee report : - Lower urinary tract symptoms that conventional urodynamic fails to reproduce or explain - Situations in which conventional urodynamics may be unsuitable - Neurogenic lower urinary tract dysfunction - Evaluation of therapies for lower urinary tract dysfunction
Clinical sample : OAB Dry
Clinical sample : OAB Wet
The diagnostic software
The software is designed to develop a better understanding of urodynamics tracings
It does’nt make a “diagnosis”,something only a physician can do
It merely emphasizes a ”urodynamic diagnosis“according to current resources on urodynamic testing interpretation