The importance of the
urodynamic study is to identify if incontinence is of urethral cause, vesical or mixed and
classify the type of urethral urinary incontinence .
Cystometry That exam gives us information of the function of the bladder reservoir,
allowing to quantify the capacity and the vesical compliance. It gives us information as
to the existence of involuntary contractions of the detrusor (Fig. 1).
Abdominal leak point pressure (ALPP). The ALPP is defined as the vesical or abdominal
pressure which leads to urinary loss in the absence of contractions of the detrusor. This
exam confirms the diagnosis of urinary incontinence and in women it classifies the type of
incontinence. The way to do this exam has still not been standardized and the used
parameters. It is recommended that the patient do this exam standing.Several parameters
were described to classify Urinary Incontinence in women. McGuire2
uses the following values:
ALPP < 60cm H2O intrinsic sphincter deficiency.
ALPP > 61< 120 cm H2O urethral hypermobility.
Other authors recommend3:
ALPP < 90 cm H2O Intrinsic sphincter deficiency.
ALPP: 90 100 cm H2O ndefinite.
ALPP > 100 < 150cm H2O urethral hypermobility.
This classification takes into consideration the
physical characteristics of the patient, if she is obese or thin. The separation between
urethral hypermobility and intrinsic sphincter deficiency is not clear.
Videourodynamics Is the gold stand of urodynamic evaluation, allowing the
measurement of vesical and urethral pressure and visualization of the inferior urinary
tract. This exam must be used when you do not get a diagnosis through other ways.
When to make a urodynamic evaluation? In the cases of symptoms and a compatible physical
exam with stress Urinary Incontinence, test of positive effort and a normal urine test is
recommended to have a urodynamic study done. The urodynamic evaluation is a must before
any surgical treatment, in the cases of symptoms and atypical physical exams for stress
urinary incontinence, patients operated without success, recurrent urinary infection and
associated illnesses like Parkinson disease, cerebral vascular accidents, diabetes.
The treatment of SUI for IIS consists in the application of some techniques, like an
artificial sphincter, para-urethral injections and sling surgery, being the most used.
Using one of these techniques is it possible to dispense the urodynamic evaluation?
Theoretically, yes, because the sling technique may be used in SUI by hypermobility or
ISD. The main motive to continue making urodynamic studies is to evaluate the vesical
function, that is, if it presents instability of the detrusor. The instability of the
detrusor must not be treated through surgery, because only 33% of the patients with this
problem are cured the rest present an important worsening of the symptoms. The patients
with mixed Urinary Incontinence IUE + detrusor instability must be treated and many times
surgery is necessary. These patients must be warned of the possibility of persistence or
the symptoms worsening and signs of detrusor instability, which can be interpreted as non
therapeutic success by the patient.