urodynamic study in urology

1. By Dr Sumit Gupta
Moderator: Prof. S.Rajendra Singh

3. NORMAL LUT TWO-PHASE
FUNCTION: Storage & Voiding

4. Physiology of Micturition

5. Physiology of Micturition
• Low bladder volumes: SNS is stimulated and PNS is
inhibited.
• Bladder full: PNS stimulated (bladder contracts) SNS
inhibited (internal sphincter relaxes).
• Intravesical pressure > resistance within the urethra: urine
flows.
• Pudendal nerve innervates external sphincter.

6. UDS
 Urodynamics describes a group of physiological tests that
are used in clinical practice to investigate abnormalities of
lower urinary tract function.
 Dynamic study of transport, storage & evacuation of
urine.
 Main goal of UDS: to reproduce pt.'s symptoms and
determine their cause by various tests.

7. UDS Armamentarium
 Cystometry(most important test), filling cystometry &
voiding cystometry
 Uroflowmetry
 Urethral pressure studies
 Pressure flow micturition studies
 Video-urodynamic studies
 Electromyography

8. INDICATIONS
 Incontinence:
-incontinence in whom surgery is planned.
-mixed ,urge & stress symptoms.
-associated voiding problems.
-pts. with neurologic disorders.

9. INDICATIONS (contd..)
 Outflow Obstruction:
-pt with LUTS, at least uroflow study.
 Neurogenic bladder:
-all neurologically impaired patients with
neurogenic bladder dysfunction.
 Children with voiding dysfunction:
-kids with daytime urgency and urge incontinence,
recurrent infection, reflux, or upper tract changes.

10. Clinical role
 Characterization of detrusor function.
 Evaluation of bladder outlet.
 Evaluation of voiding function.
 Diagnosis and characterization of neuropathy.

11. Three important rules before starting UDS
evaluation:
 1. Decide on questions to be answered before starting a
study.
 2. Design the study to answer these questions.
 3. Customize the study as necessary.

12. Terminology for Common Urodynamic Terms and Observations
According to the International Continence
Society Standardization Subcommittee
 The ICS has now defined the term urodynamic
observations to denote observations that occur during
and are measured by the urodynamics(UDS) test itself.
Two principal methods of urodynamic investigation
exist:
 Conventional urodynamic studies: normally take place
in the urodynamic laboratory involving artificial
bladder filling.
 Ambulatory urodynamic studies: a functional test of
the lower urinary tract using natural filling and
reproducing the subject’s everyday activities.

13.  The following are required of both types of studies:
 Intravesical pressure: the pressure within the bladder.
 Abdominal pressure: the pressure surrounding the bladder; currently it
is estimated from rectal, vaginal, or extraperitoneal pressure or a bowel
stoma.
 Detrusor pressure: the component of intravesical pressure created by
forces on the bladder wall that are both passive and active.
 Filling cystometry: the method by which the pressure and volume
relationship of the bladder is measured during bladder filling.
 Physiologic filling rate: a filling rate less than the predicted maximum.
Predicted maximum is the body weight in kilograms divided by 4 and
expressed as milliliters per minute.
 Nonphysiologic filling rate: a filling rate greater than the predicted
maximum.

14.  Urodynamic stress incontinence: noted during filling cystometry and
defined as the involuntary leakage of urine during increased abdominal
pressure in the absence of a detrusor contraction. This currently replaces
genuine stress incontinence.
 Urethral pressure measurements:
 Urethral pressure: the fluid pressure needed to just open a closed urethra.
 Urethral pressure profile: a graph indicating the intraluminal pressure along
the length of the urethra.
 Urethral closure pressure profile: the subtraction of intravesical pressure from
urethral pressure.
 Maximum urethral pressure: the maximum pressure of the measured profile.
 Maximum urethral closure pressure (MUCP): the maximum difference
between the urethral pressure and the intravesical pressure.
 Functional profile length: the length of the urethra along which the urethral
pressure exceeds intravesical pressure in women.

15.  Abdominal leak point pressure(ALPP): the
intravesical pressure at which urine leakage occurs
because of increased abdominal pressure in the
absence of a detrusor contraction.
 Detrusor leak point pressure(DLPP): the lowest
detrusor pressure at which urine leakage occurs in the
absence of either a detrusor contraction or increased
abdominal pressure.

16. CYSTOMETRY
 Measurement of intravesical bladder pressure during
bladder filling(measures volume-pressure relationships).
 Used to assess bladder sensation, capacity, compliance,
detrusor activity.
 Bladder access by transurethral catheter, or rarely by
percutaneous suprapubic tube.
 Filling medium either gas (CO2) or liquid (water, saline, or
contrast material at body temp).
 Liquid cystometry is more physiologic.
 Ideally, filling should be performed in standing position.

17. CYSTOMETRY(contd...)
 Bladder filling either by diuresis or filling through a catheter.
 Filling
 slow (up to 10 ml/min), physiologic
 medium (10 to 100 ml/min)
 fast (> 100 ml/min)
 Children and pts with known bladder hyperactivity require
slow fill rates.
 All systems should be zeroed to atmospheric pressure.
 No air bubbles.

18. Phases of cystometrogram

19.  Normal CMG:
- Capacity 350-600ml
- First desire to void between
150- 200 ml.
- Constant low pressure that
does not reach more than 6-
10 cm H2O above baseline
at the end of filling.
- Provocative
maneuvers(cough, fast fill
etc.) should not provoke a
bladder contraction
normally.
- No leakage on coughing .
- A voiding detrusor pressure
rise of < 70 cm H2O with a
peak flow rate of > 15 ml /
s for a volume > 150 ml.
- Residual urine of < 50 ml.

20. CYSTOMETRY(contd...)
 Single Vs multi-channel UDS:
-single: Pves only
-multi: Pves, Pdet, Pabd

21. CMG PARAMETERS
 Intravesical pressure(Pves): Total Pressure within the
bladder.
 Abdominal pressure(Pabd): Pressure surrounding the
bladder; currently estimated from rectal, vaginal, or
extraperitoneal pressure or a bowel stoma.
 Detrusor pressure(Pdet): Component of intravesical
pressure created by forces on the bladder wall, both
passive and active.
 True detrusor pressure = Intravesical pressure -
Intraabdominal pressure.(Pdet = Pves-Pabd)

22.  Physiologic filling rate: A filling rate < predicted maximum.
Predicted maximum = body weight in kg divided by 4 and
expressed as ml/min.
 Nonphysiologic filling rate: A filling rate > predicted
maximum.
 First sensation of bladder filling: Volume at which patient first
becomes aware of bladder filling.
 First desire to void: Feeling during filling cystometry that
would lead the patient to pass urine at the next convenient
moment.
 Strong desire to void: Persistent desire to void without fear of
leakage.

23.  Compliance:
- Relationship between change in bladder volume and
change in Pdet (Δvolume/Δpressure); measured in
ml/cm H2O.
- Normal bladder is highly compliant, and can hold
large volumes at low pressure.
- Normal pressure rise during the course of CMG in
normal bladder will be only 6-10 cm H2O.
- Decrease compliance < 20 ml/cm H2O, poorly
distensible bladder.

24. Impaired compliance is seen in:
 neurologic conditions: spinal cord injury/lesion, spina
bifida, usually results from increased outlet resistance
(e.g., detrusor external sphincter dyssynergia [DESD])
or decentralization in the case of lower motor neuron
lesions,
 Long-term BOO (e.g., from benign prostatic
obstruction),
 Structural changes- radiation cystitis or tuberculosis.
 Impaired compliance with prolonged elevated storage
pressures is a urodynamic risk factor and needs
treatment to prevent renal damage.

26.  Neurogenic detrusor overactivity: Overactivity
accompanied by a neurologic condition; also k/a
detrusor hyperreflexia.
 Idiopathic detrusor overactivity: Detrusor
overactivity without concurrent neurologic cause; also
k/a detrusor instability.

27.  Abdominal leak point pressure(ALPP): Intravesical
pressure at which urine leakage occurs because of
increased abdominal pressure in the absence of a
detrusor contraction.
 ALPP is a measure of sphincteric strength or ability
of the sphincter to resist changes in Pabd
 Applicable to stress incontinence; ALPP can be
demonstrated only in a patient with SUI.
 There is no normal ALPP, because patients without
stress incontinence will not leak at any physiologic
Pabd.
 Lower the ALPP, weaker is the sphincter.

28.  ALPP<60 cm H2O: significant ISD
 ALPP 60-90 cm H2O: equivocal
 ALPP>90 cm H2O: urethral hypermobility;
little or no ISD

29.  Detrusor leak point pressure(DLPP): Lowest
detrusor pressure at which urine leakage occurs in the
absence of either a detrusor contraction or increased
abdominal pressure (risk with > 40cm H2O).
 Its a measure of Pdet in a patient with decreased
bladder compliance.
 Higher the urethral resistance, higher the DLPP, the
more likely is upper tract damage as intravesical
pressure is transferred to the kidneys.

30. UROFLOMETRY
 Non invasive study.
 Measurement of the rate of urine flow over time.
 Estimate of effectiveness of the act of voiding along with PVR.
 Influenced by
 effectiveness of detrusor contraction
 completeness of sphincteric relaxation
 patency of the urethra
 3 methods used
 gravimetric
 rotating disk
 electronic dipstick

31. Recorded variables during UFM study:
 Voided volume (VV in milliliters)
• Flow rate (Q in milliliters per second)
• Maximum flow rate (Qmax in milliliters per second)
• Average flow rate (Qave in milliliters per second)
• Voiding time (total time during micturition in seconds)
• Flow time (the time during which flow occurred in seconds)
• Time to maximum flow (onset of flow to Qmax in seconds)

32. • Optimal voids 200 to 400cc.
• Voids < 150cc are difficult to interpret.
• Pt. should be well hydrated with full bladder, but
not overly distended bladder.
• Should be performed in privacy and pt.encouraged
to void in his normal fashion.
• Qmax & shape of curve- more reliable indicators of
BOO.
• Qmax- most reliable variable in detecting abnormal
voiding.

33. Normal uroflow curve is bell-shaped

34. Flattened pattern: Obstruction

35. Interrupted or straining pattern: Impaired bladder contractility,
obstruction, or voiding with/by abdominal straining.

36. "Box-pattern" : Urethral Stricture

37. Post Void Residual Urine
 Excellent assessment of bladder emptying.
 Performed by ultrasound (bladder scan) or
catheterization.
 Normally, it is < 0.5ml, but < 10% of voided volume
is considered insignificant.

38. Urethral pressure profilometry
 Urethral pressure profile (UPP): a graph indicating
intraluminal pressure along the length of urethra.
 Urethral pressure: fluid pressure needed to just open a
closed urethra.
 UPP is obtained by withdrawal of a pressure sensor
(catheter) along the length of urethra.

39. UPP Parameters:
 Urethral closure pressure profile is given by subtraction of
intravesical pressure from urethral pressure.
 Maximum urethral pressure is highest pressure measured
along the UPP.
• Maximum urethral closure pressure (MUCP) : maximum
difference between urethral pressure and intravesical
pressure.
 Functional profile length: length of urethra along which
urethral pressure exceeds intravesical pressure in women.

40.  In most continent women,
functional urethral length:approx.3 cm &
MUCP is 40 to 60 cm H2O.
 MUCP is not always indicative of severity of incontinence
hence not used commonly.

41. UPP

42. PRESSURE FLOW
MICTURITION STUDIES
 Simultaneous measurement of bladder pressure and
flow rate throughout the micturition cycle.
 Best method of quantitatively analyzing voiding
function.
 Access to bladder via transurethral or SPC 8F or less.
 Intra-abdominal pressure measured by balloon
catheter in rectum or vagina.
 Men should void in standing position, while women
seated on commode.

44.  Detrusor pressure at maximal flow(Pdet at Qmax):
Magnitude of micturition contraction at the time when
flow rate is at its maximum.
 Pressure <100 cm H2O indicate outlet obstruction
even if the flow rate is normal.
 Normal male generally voids with Pdet 40-60 cm H2O
and woman with lower pressure.
 Pdet more accurately measures bladder wall
contractions.

45.  Indications for pressure-flow studies:
- to differentiate between pts with a low Qmax sec. to
obstruction, from those sec.to poor contractility.
- Identify pt.with normal flow rates but high pressure
obstruction.
- LUTS in pt with hx of neurologic disease(CVA,
Parkinson’s).
- LUTS with normal flow rates (Qmax > 15cc/min).
younger men with LUTS.
- Men with little endoscopic evidence of prostate
occlusion

46. ICS provisional nomogram

47. VIDEO-URODYNAMICS
 UDS with simultaneous fluoroscopic image of lower
urinary tract.
 Equipment and technique:
- CMG + PFS same as before but the study is conducted
on a fluoroscopy table, and the filling medium is a
radiographic contrast agent.
 clinical applicability:
 complex BOO
 evaluation of VUR during storage &/or filling.
 neurogenic bladder dysfunction
 identification of associated pathology

48.  Primary BNO diagnosis & differentiation from
dysfunctional voiding in women: only on VUDS.

49. Video-urodynamics

50. ELECTROMYOGRAPHY
(EMG)
 Study of the electric potentials produced by depolarization of
muscle membranes.
 In case of UDS, EMG measurement of striated sphincteric
muscles of the perineum is done to evaluate possible
abnormalities of pelvic floor muscle function.
 EMG activity is measured during both filling and emptying.
 EMG is performed via electrodes placed in (needle
electrodes) or near (surface electrodes) the muscle to be
measured.

51.  Most important information obtained from sphincter EMG
is whether there is coordination or not between the
external sphincter and the bladder.
 EMG activity gradually increases during filling
cystometry (recruitment) and then cease and remains so
for the time of voiding.

52.  Failure of the sphincter to relax or stay completely relaxed
during micturition is abnormal.
 In pt with neurologic disease, this is called detrusor-
sphincter dyssenergia.
 In the absence of neurologic disease, it is called pelvic
floor hyperactivity,or dysfunctional voiding.

53. CYSTOMETROGRAPH

54. URODYNAMIC RISK FACTORS
 Following urodynamics findings are potentially dangerous and
usually require intervention to prevent upper and lower urinary
tract decompensation:
 1. Impaired compliance
 2. Detrusor external sphincter dyssynergia (DESD)
 3. Detrusor internal sphincter dyssynergia (DISD)
 4. High-pressure detrusor overactivity present throughout
filling
 5. Elevated detrusor leak point pressure (>40 cm H2O)
 6. Poor emptying with high storage pressures

55. Thank you