Comparison of accuracy of functional measurements of the urethra in transperineal vs. endovaginal ultrasound in incontinent women
Original article by
ALEKSANDRA STANKIEWICZ (*) - ANDRZEJ P. WIECZOREK (*) - MAGDALENA M.WOZNIAK (*)
MICHAL BOGUSIEWICZ (**), KONRAD FUTYMA (**) TOMASZ RECHBERGER (**)
GIULIO A. SANTORO (***)
(*) Pediatric Radiology Department, Children's Hospital, Medical University of Lublin, ul Chodzki 2, 20-093 Lublin - Poland
(**) 2nd Gynecology Department, Teaching Hospital, Medical University of Lublin, ul.Jaczewskiego 8, 20-090 Lublin - Poland
(***) 3rd Division of General Surgery, Regional Hospital, Treviso - Italy
Key words:Dynamic transperineal ultrasound; Endovaginal ultrasound; Stress urinary incontinence; Pelvic Organ Prolapse.
INTRODUCTION
Female urinary incontinence (UI) and pelvic organ prolapse
(POP) are conditions with severe economic and psychosocial
impact affecting millions of women. It is estimated
that almost 30% of women older than 35 years suffer from
POP and/or UI.1 The etiology of PFD is multifactorial and
includes surgical interventions, number and type of deliveries,
hormones' profile, aging, obesity.1-3 The diagnosis of
these conditions is based on physical examination and imaging,
mostly on ultrasound examination. Transperineal ultrasound
(TPUS: Fig. 3, 4) 
and
endovaginal ultrasound (EVUS: Fig. 5, 6) ,
which are widely used, give only general information on anatomy,
anatomical relationships and mobility of pelvic floor structures,
but are insufficient to give a highly detailed assessment.
Recently introduced high resolution three-dimensional (3D)
EVUS seems to be a very promising modality to improve the
imaging of female pelvic floor dysfunctions.
Aim of this study was to compare the diagnostics methods
TPUS and EVUS in the assessment of urethral mobility in
female patients suffering from stress urinary incontinence.
MATERIALS AND METHODS
Twenty-five females suffering from stress urinary incontinence
(SUI) were enrolled in this study (median age: 56 years,
range: 28-76 years) and underwent TPUS and 3D-EVUS
examinations. Transperineal US was performed with a 6 MHz
convex transducer (tape 8802, B-K Medical, Herlev, Denmark),
while EVUS was performed with a 6.5-9 MHz multiplanar
transducer (tape 8848, B-K Medical, Herlev, Denmark)
with perpendicular and transverse beam formation to the
urethra and 3-D acquisition system. All the examinations
were performed using the same ultrasound scanner (ProFocus
2202, B-K Medical, Herlev, Denmark). Three-D application
was used for the assessment of the morphology of the urethra
and surrounding structures. Transperineal US was performed
by positioning the transducer tenderly onto the perineum, in
midsagittal line, to visualize pubic symphysis, urethra and
bladder, vagina and anal canal (Fig.
1) .
Endovaginal US was
performed by inserting the transducer into vagina in a neutral
position with no compression on the urethral complex
and surrounding structures. It was mandatory to visualize
the pubic symphysis and entire urethra from bladder neck to
external meatus (Fig.
2) .
We divided females in two groups: patients suffering only
from SUI (first group: 10 patients - 40%) and patients with
SUI and coexisting POP (second group: 15 patients - 60%;
7 cystocele, 8 recto/enterocele). Mobility of the urethra was
evaluated by measuring the bladder-symphysis distance (BSD
- distance from bladder neck to the lowest margin of the pubic
symphysis) and the length of urethral complex. These measurements
were taken at rest, during Valsalva manoeuvre and
squeeze. For each patient 12 measurements were taken: urethral
length and BSD at rest, during Valsalva and squeeze
manoeuvre by using both TPUS and EVUS. For the statistical
analysis the mean values, standard deviation (SD) and t-Student test were used.
Five percent inference error was assumed as statistically significant (p < 0.05).
RESULTS
Mean values of the measurements taken in the first group
of patients are presented in table 1
, whilst the measurements
obtained in the second group of patients are presented in
table 2.
In the first group of 10 (40%) incontinent patients
with no coexisting anatomical disturbances there were no
statistical differences in the length of urethral complex at
rest and during Valsalva manoeuvre and squeeze between
TPUS and EVUS. The values of BSD taken at rest and
during Valsalva manoeuvre were also similar. In the second
group of 15 (60%) incontinent patients suffering from POP
the measurements of the length of urethral complex taken by
TPUS and EVUS differed significantly in all three tests (p
< 0.001). Measurements of BSD at rest and during squeezing
were also significantly different (p < 0.01 at rest and p <
0.05 during squeezing). The values of BSD during Valsalva
manoeuvre varied between TPUS and EVUS although the
difference was not statistical.
DISCUSSION
Transperineal ultrasound is a cheap, available and relatively
easy to perform technique for the assessment of
urethral morphology and relationship of the urethra with
bladder and pubic symphysis. The lowest margin of pubic
symphysis represented the point of reference for measurements.
A huge disadvantage of TPUS is the inaccurate urethral
assessment due to an extensive compression of the
transducer onto the perineum. Moreover, this examination
is not adequately precise in the evaluation of the urethra
because it is not possible to distinguish the layers of the urethral
wall or to visualize the urethral support. This could be
due to the use of the low frequency convex transducer routinely
used for abdominal ultrasound which is not dedicated
for the assessment of pelvic floor. However, TPUS allows
an easily assessment of urethral mobility during dynamic
tests.3 Transperineal ultrasound is reliable in the diagnostics
of POP,5 being accordant with ICS-POPQ scale, as confirmed
by the study of 140 patients with POP performed by
Dietz and al.4
Endovaginal ultrasound with novel high frequency transducer
(9-16 MHz) as well as 3-dimensional data acquisition
represents a more precise method in the assessment of
urethra as well as other pelvic floor structures. This transducer
was initially used in proctology for the evaluation of
the anal canal, morphology of the anal sphincters, fistulas
and staging of the rectal cancer,9, 10 as well as in urology
for prostate brachytherapy. The biplane transducer with perpendicular
and transverse beam formation allows visualization
of the structures on the axial plane, as well as on the
sagittal plane, and 3D data acquisition allows their reconstruction
on the coronal plane. Untill now it was achievable
only by CT or MRI not by ultrasound. To perform EVUS
correctly, it is extremely important to insert the transducer
into the vagina in a neutral position and not to compress extensively on the urethra, the anal canal or the surrounding
structures. Only the neutral position allows the most reliable
evaluation of the morphology and anatomical relations and
offers the possibility to detect potential disturbances.
In the diagnosis of urinary incontinence it is very important
to assess precisely the location of the urethra and its
morphology, to distinguish the layers of the urethral wall,
to depict the striated sphincter and to assess the bladder
neck at rest and during dynamic tests. The location of the
urethra was until now described by the values of different
angles observed on the sagittal plane during TPUS.8 However, the measurements obtained only in one plane
could not give the whole information about the diagnosed
disturbances and should not be considered as prognostic
factors. Thus, 3D-EVUS, giving an opportunity of the
assessment of the urethral angulations on three different
planes, seems to be a very promising alternative method to
TPUS. Moreover 3D-EVUS provides very precise assessment
of anatomy and morphology of female pelvic floor
structures and can improve our knowledge on etiology of
their disorders.
This study shows that in females suffering from SUI and
coexisting pelvic organ prolapse the endovaginal examination
is not reliable in the assessment of the urethral mobility
due to alterations of anatomical relations resulted from
introduction of the transducer into the vagina. Additionally,
in all patients the transducer inserted into vagina makes
squeeze test impossible to perform appropriately. However,
in the measurements of the length of urethral complex and
BSD at rest and during Valsalva manoeuvre in incontinent
patients with no coexisting anatomical disturbances both
TPUS and EVUS methods have the same accuracy.
CONCLUSIONS
In incontinent women with no coexisting anatomical disturbances
both ultrasound methods (TPUS and EVUS) have
the same accuracy in the measurements of urethra complex
and BSD at rest and during Valsalva manoeuvre. Measurements
taken by EVUS during squeezing and measurements
in incontinent women additionally suffering from pelvic
organ prolapse appears to be inaccurate due to the introduction
of the transducer into the vagina, which alters the anatomical
relationships of the pelvic structures.
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Correspondence to:
Dr. ALEKSANDRA STANKIEWICZ
E-mail: o.fragola@gmail.com