The document discusses the physiology of micturition, precautions for uroflowmetry measurements, and the interpretation of uroflowmetry parameters including flow patterns and EAU guidelines. It emphasizes the noninvasive nature of uroflowmetry as a key diagnostic tool for assessing lower urinary tract dysfunction, providing essential quantitative data on voiding dynamics. Additionally, it highlights the importance of proper protocol in uroflowmetry to ensure accuracy and reliability of results.

1. By
Omar Anwar Sayed
Urology specialist
Asyut university hospital
Supervised by
Dr Ahmed Abdel-
hameed Shahat
Associate Prof. of Urology
Asyut university hospital

2. 1. Physiology of micturition.
2. Precautions.
3. Uroflowmetry parameters.
i. Definitions.
ii. Flow Patterns.
4. EAU guidelines.
5. Take-home messages.

4.  During bladder filling:
the parasympathetic
innervation of the detrusor
is inhibited and the smooth
and striated parts of the
urethral sphincter are
activated, preventing
involuntary bladder
emptying. This process is
organized by urethral
reflexes known collectively
as the ‘guarding reflex’.

5.  Some input from the lateral
pons, which is also known as
the ‘L-region’ or the ‘pontine
storage centre’, might facilitate
sphincter reflexes or have a role
in involuntary sphincter
control.
 voluntary control of the bladder
and the urethra has two
important aspects, namely
registration of bladder filling
sensations and manipulation of
the firing of the voiding reflex.

6.  The PAG has a pivotal role in both. On one
hand, it receives and passes ascending bladder
signals to higher brain centres and into the
realm of conscious sensation. On the other
hand it receives projections from many higher
brain centres and also controls the primary
input to the PMC.

7.  During
Voiding: Animal
studies have shown
that reflex micturition
is mediated by a
spino-bulbo-spinal
pathway that passes
through the PMC in
the rostral brainstem.

8.  Excitation of the PMC
activates descending
pathways that cause
urethral relaxation and,
some seconds later,
activation of the sacral
parasympathetic outflow.
This results in contraction
of the bladder and an
increase in intravesical
pressure and the flow of
urine

9.  Relaxation of the urethral smooth
muscle is mediated by activation
of the parasympathetic pathway to
the urethra, which triggers the
release of NO, and by the removal
of adrenergic and somatic
cholinergic excitatory inputs.
 voluntary voiding in humans
implies interruption of the tonic
suppression (by the prefrontal
cortex) of PAG input to the PMC.
Fowler et al., 2008

10. 1. Physiology of micturition.
2. Precautions.
3. Uroflowmetry parameters.
i. Definitions.
ii. Flow Patterns.
4. EAU guidelines.
5. Take-home messages.

11. 1. Adequate privacy should be provided.
2. Patients should be asked to void when they feel
a ‘‘normal’’ desire to void.
3. Patients should be asked if their voiding was
representative of their usual voiding and their
view should be documented.

12. 4. Automated data analysis must be verified by
inspection of the flow curve, artifacts must be
excluded and verification must be documented.
5. The results from uroflowmetry should be
compared with the data from the patient’s own
recording on a frequency/volume chart.
6. Sonographic estimation of post-void residual
volume completes the noninvasive assessment
of voiding function.
Schäfer et al., 2002

13. 7. Uroflowmetry parameters should preferably be
evaluated with voided volume > 150 mL. as Qmax
is prone to within-subject variation (eau guidelines
2019).
8. For childhood and adolescent:
 The voided volume should not be less than 50 cc or
50% of expected bladder capacity (EBC) for age as
the flow rates and curve may be misleading (Van
Batavia and Combs 2018).
 When Bladder capacity (VV+PVR) are > 115% of
EBC, the uroflow rates and curves may not be
accurate (Franco et al., 2015)
 EBC=(age+1)×30

14. 1. Physiology of micturition.
2. Precautions.
3. Uroflowmetry parameters.
i. Definitions.
ii. Flow Patterns.
4. EAU guidelines of uroflowmetry.
5. Take-home messages.

15.  is a noninvasive test to study the dynamics of
urine flow.
 Therefore, it is an indispensable, first-line
screening test for most patients with suspected
LUT dysfunction.
 Objective and quantitative information, which
helps one to understand both storage and
voiding symptoms, are provided by this simple
urodynamic measurement.
Schäfer et al., 2002

16.  Voided volume: the
total volume expelled
via the urethra.
 Maximum flow rate
(Qmax): the maximum
measured value of the
flow rate.
Blavias et al.,2008

17.  Average flow
rate(Qave): voided
volume divided by
flow time. The
calculation of average
flow rate is only
meaningful if flow is
continuous and
without terminal
dribbling.
Blavias et al.,2008

18.  Flow time (TQ): the
time over which
measurable flow
actually occurs.
 Time to maximum
flow (TQmax): the
elapsed time from
onset of flow to
maximum flow.
Blavias et al.,2008

19.  Voiding time: total
duration of
micturition including
interruptions. When
voiding is completed
without interruption,
voiding time is equal
to flow time.

20.  Qmax is the one of the most important data
obtained with urinary flowmetry but only
second in order of importance to the urinary
flowmetry curve profile.
 Qmax is considered normal for > 15 ml/sec.,
however, BOO could not be excluded.
 Liverpool nomogram can be used for
providing easily interpreted normal reference
ranges of Qmax for both sexes in adults.

23.  For childhood and adolescent:
 A suggested rule of thumb
is that if the square of the
Qmax [(mL/s)2] is equal to or
bigger than the voided
volume, then the recorded
Qmax is very likely to be
normal.
 Miskolc nomogram can also
be used for diagnosing
lower urinary tract
disturbances (either through
Qmax or Qave) in children
over a wide range of body
size and voided volumes.

27.  VOID report should be listed as follows: max flow
rate (Qmax)/voided volume(VV)/post-void
residual (PVR).
 Maximum (smoothed) urine flow rate should be
rounded to the nearest whole number (a recording
of 10.25 ml/s would be recorded as 10 ml/s).
 Voided volume and post void residual volume
should be rounded to the nearest 10 ml (a
recording of a voided volume of 342 ml would be
recorded as 340 ml).
Schäfer et al., 2002

28.  It is either continous or interrupted.

29.  Normal shape:
1. The normal shape is a bell
shape
2. Qmax is reached in the
first 30% of the curve
(five seconds from the
start).
3. The shape of the curve
can vary, for the same
patient depending on the
volume voided, but the
first and the last leg of the
curve will have similar
shapes.

30.  Bladder outlet obstruction (BOO)
 Qmax and Qave are smaller (Qave > Qmax/2)
 Qmax is reached relatively fast and is followed by a
long descending slope that ends in terminal
dribbling.
 Two patterns can be recognized

31.  Compressive BOO BPH

32.  Constrictive BOO Urethral stricture

33.  Detrusor
hypocontractility
 Qmax is low and is
reached late in the
second part of the
curve.
 Pressure/flow study
only can establish a
diagnosis.

34.  Other forms
1. Tower flow curve: an
almost immediate and
rapid rise to peak
uroflow rate shortly after
onset of voiding with
rapid decrease consistent
with an explosive
voiding contraction;
suggestive of detrusor
overactivity (OAB or
IDOD).  Tower-shaped curve in a
10-year-old boy
(Qmax/VV/PVR =
27.9/58.7/3.8).

35. 2. Staccato flow curve:
fluctuating and irregular
flow curve with multiple
peaks and valleys but that
never reaches zero during
the void and is still
continuous; by ICCS
definition to qualify as
staccato the fluctuations
need to be larger than the
square root of the maximum
flow rate; suggestive of an
active external sphincter
during voiding (i.e.,
Dysfunctional voiding but
can be seen in other LUT
conditions)
 Staccato curve in an 11-
year-old girl
(Qmax/VV/PVR =
17.3/95.0/1.8).

36.  Staccato flow pattern (Qmax 38 ml/sec.)

37. A. Qmax= 2ml/s,
Qave= 2ml/s.
B. Qmax= 10ml/s,
Qave= 2 ml/s.

38. 1. Physiology of micturition.
2. Precautions.
3. Uroflowmetry parameters.
i. Definitions.
ii. Flow Patterns.
4. EAU guidelines.
5. Take-home messages.

39.  The diagnostic accuracy of uroflowmetry for
detecting BOO varies considerably and is
substantially influenced by threshold values.
 A threshold Qmax of 10 mL/s has a specificity of
70%, a PPV of 70% and a sensitivity of 47% for
BOO.
 The specificity using a threshold Qmax of 15 mL/s
was 38%, the PPV 67% and the sensitivity 82%. If
Qmax is > 15 mL/s, physiological compensatory
processes mean that BOO cannot be excluded.
 Low Qmax can arise as a consequence of BOO,
DUA or an under-filled bladder .

40.  Therefore, it is limited as a diagnostic test as it
is unable to discriminate between the
underlying mechanisms.
 Specificity can be improved by repeated flow
rate testing. Uroflowmetry can be used for
monitoring treatment outcomes and correlating
symptoms with objective findings.

44.  In children with neurogenic bladder, uroflowmetry
can rarely be used since most affected patients do
not void spontaneously. In those with cerebral
palsy, non-neurogenic-neurogenic bladder or other
neurological conditions allowing active voiding it
may be a practical tool.
 It provides an objective way of assessing the
efficiency of voiding, while recording of pelvic
floor activity with electromyography (EMG) can be
used to evaluate synergy between detrusor and the
sphincter. The post-void residual urine is
measured by US. The main limitation of
uroflowmetry is a compliant child to follow
instructions

45. 1. Physiology of micturition.
2. Precautions.
3. Uroflowmetry parameters.
i. Definitions.
ii. Flow Patterns.
4. EAU guidelines.
5. Take-home messages.

46.  Excitation of the PMC relaxation of the
urethra. Seconds later, activation of the sacral
parasympathetic outflow bladder
contraction & ↑ urine flow.
 Precautions should be considered during uroflow
testing.
 VOID report should be listed as follows: max flow
rate (Qmax)/voided volume(VV)/post-void residual
(PVR).
 If Qmax is > 15 mL/s, physiological compensatory
processes mean that BOO cannot be excluded.
 Low Qmax can arise as a consequence of BOO, DUA
or an under-filled bladder .
 Flow patterns are either bell-shaped, plateau, tower-
shaped, staccato or interrupted pattern.

48. Uroflow Mohamed, Fathy
Gender:
Date of birth:
Investigation age:
Patient number:
Male
11/11/1940
79
Investigation date:
Investigation nr:
Hospital:
Investigator:
Referred by:
11/12/2019
01
ASSIUT UNIVERSTY
Mohamed Osama
00:10 00:20 00:30 00:40 00:50
0
1000 1
Miction command
0
50
ml
Vmic
ml/s
Qura
Time
0 100 200 300 400 500
5
10
15
20
25
100 200 300 400 500
+1
mean 0
-1
-2
-3
Average flow rate
mean 0
-1
-2
-3
Peak flow rate SD
Qura 30
(ml/s)
Bladder volume: 199 ml Average flow rate: 5 ml/s
Volume (ml)
Peak flow rate: 11 ml/s
Siroky nomogram
Uroflow results
VOID
Peak flow rate
Time to peak flow
Voided volume
Flow time
Voiding time
Delay time
Average flow rate
Corrected Qmax
Miction index
11 / 200 / -
10.7
7
199
38
40
10
5.2
14
-
ml/s
s
ml
s
s
s
ml/s
sqrt ml
-
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