applications of ultrasonography in female lower urinary tract symptoms diagnosis and intervention

■ REVIEW ARTICLE ■

APPLICATIONS OF ULTRASONOGRAPHY IN FEMALE LOWER
URINARY TRACT SYMPTOMS: DIAGNOSIS AND INTERVENTION
Wen-Chen Huang, Jenn-Ming Yang1,2*, Shwu-Huey Yang2
1

Department of Obstetrics and Gynecology, Cathay General Hospital, Division of Urogynecology, Department of
2
Obstetrics and Gynecology, Mackay Memorial Hospital, and Taipei Medical University, Taipei, Taiwan.

SUMMARY
Lower urinary tract symptoms (LUTS) are a common health problem causing considerable inconvenience to
many women. Moreover, they are non-specific and can be caused by a large number of disorders. A thorough
evaluation, including physical examination, imaging studies, and urodynamic investigation of the lower urinary
tract, is crucial for appropriate management of bothersome symptoms. Ultrasonography has the advantages
of non-invasiveness, reproducibility, no radiation exposure, and low cost. With the use of a high-resolution
transducer, pelvic organs can be demonstrated clearly on ultrasonography. In addition, three-dimensional
sonography provides a clear demonstration of the spatial orientation of the female lower urinary tract. Both
color and power Doppler scanning can not only reveal the vascular flow in pelvic organs, but also demonstrate
urinary flow. Ultrasonography has dual functions in the management of female LUTS: diagnosis and intervention.
It may help physicians to recognize the anatomic characteristics of specific pelvic floor disorders, to explore
the pathophysiologic mechanism responsible for pelvic floor dysfunction, and to assist in the surgical
management of LUTS with minimal invasion. Since female LUTS may originate from gynecologic or nongynecologic conditions, it is more convenient and helpful to obtain transvaginal and introital sonograms at
the same time by using an endovaginal probe. [Taiwanese J Obstet Gynecol 2004;43(3):125–135]
Key Words: color Doppler, detrusor overactivity, interventional ultrasonography, lower urinary tract
symptoms, stress urinary incontinence, voiding dysfunction

Introduction
Lower urinary tract symptoms (LUTS) are a common
health problem causing considerable inconvenience for

many women. LUTS consists of irritative and obstructive symptoms, which are non-specific and can be caused
by a large number of disorders. A thorough evaluation,
including physical examination, imaging studies, and
urodynamic investigation of the lower urinary tract, is

*Correspondence to: Dr. Jenn-Ming Yang, Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay
Memorial Hospital, 92 Chung-Shan North Road, Section 2,
Taipei 104, Taiwan.
E-mail:
Received: March 4, 2004
Revised: March 23, 2004
Accepted: March 23, 2004

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3

crucial for appropriate management of bothersome
symptoms.
Since the introduction of real-time technology in the
1980s [1], ultrasound has been widely applied and has
replaced radiography in the evaluation of pelvic floor
disorders [2–4]. It has the advantages of non-invasiveness, reproducibility, no radiation exposure, and low
cost. With the use of a high-resolution transducer,
pelvic organs can be demonstrated clearly. Moreover,
three-dimensional technology with simultaneous axial,
transverse, and coronal views of pelvic floor organs
clearly displays the spatial orientation of the female
lower urinary tract [5]. Both color and power Doppler
scanning can not only reveal the vascular flow in pelvic
organs, but also demonstrate urinary flow. Color Doppler ultrasound analyzes the frequency shift of flow
velocity information, while power Doppler technology

uses the amplitude component of received signals to

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quantify the number of moving particles.

Basic Procedure
Many approaches have been proposed for the ultrasound evaluation of the lower urinary tract. These include transabdominal [1], transvaginal [6], transrectal [7], perineal (or translabial) [8], and introital approaches [9,10]. As the lower urinary tract can be
shaded by the acoustic shadow of the pubic symphysis,
the transabdominal approach is rarely used except for
measurement of bladder volume [10]. For dynamic
assessment, the transvaginal approach may exert a
compressive effect on the lower urinary tract [11,12].
Therefore, in order to prevent the distortion of the
anatomy of the lower urinary tract by probes, the
perineal or introital approaches are currently widely
used. The differences between perineal and introital
approaches are the site where the transducer is placed
and the probe used in scanning: perineal ultrasound
uses a linear- or curved-array convex probe with frequency between 3.5 and 5 MHz [13], while introital
ultrasound uses a sector endovaginal probe with frequency between 5 and 7.5 MHz [9,10]. The transducer
is placed on the perineum in the perineal approach, and
is positioned between the labia minora just underneath
the external urethral orifice in the introital approach
[14]. Both of these approaches have been proved to be
devoid of potential morphologic artifacts resulting from
the distortion of the bladder neck or urethra [2].

It has been suggested that the information obtained
during ultrasonographic evaluation of the female lower
urinary tract should include the patient’s position, bladder volume, liquid used for bladder filling, method of
bladder filling (spontaneous or retrograde filling),
simultaneous pressure measurement (cystometry,
urethral pressure profile, or voiding study), size of ultrasound transducer, ultrasound machine (type and
manufacturer), ultrasound frequency, picture orientation, and approach (introital, perineal, vaginal, rectal,
or abdominal) [10,15]. There is disagreement regarding the optimal orientation of images. Some authors
prefer an orientation as on conventional transvaginal
ultrasound [16]. However, others recommend showing
superior structures above, inferior structures below,
anterior structures on the right, and posterior structures on the left [10].
The examination can be performed in a dorsal lithotomy, semireclining, or standing position [16,17].
There are no significant differences in the dynamic assessment of the bladder neck between the semireclining
and standing positions [17]. The ultrasonographic evalu-

126

ation of the lower urinary tract begins with the midsagittal plane. This results in an image including the symphysis pubis, urethra, bladder neck, vagina, cervix,
rectum, and anal canal (Figure 1). By moving the transducer to the left or to the right, additional areas of
periurethral structures can be assessed [17]. The pressure exerted by the transducer should be kept as low as
possible, while being sufficient to obtain good images
with high resolution. The presence of a full rectum may
impair diagnostic accuracy, and sometimes, necessitates a repeat assessment after defecation [16].
The bladder volume should be fixed on examination:
300 mL for the evaluation of dynamic changes in the
bladder neck, and less than 50 mL for the assessment of
bladder wall thickness [10,17,18]. The bladder volume
can be estimated by either a transabdominal or transvaginal approach, although the accuracy is not reliable
for bladder volumes less than 50 mL. In the transabdominal approach, three parameters, including height

(H), depth (D), and width (W), are obtained from two
perpendicular planes (sagittal and transverse). In sagittal scanning, height and depth correspond to the greatest superior–inferior measurement and the greatest
anterior–posterior measurement, respectively. Thus,
the bladder volume can be calculated from the formula:
bladder volume (mL) = H = D = W = 0.7, where 0.7 is a
correction factor for the non-spherical shape of a full
bladder. The approximate error rate of the above formula is 21%. Transvaginal ultrasound has also been
recommended to measure bladder volumes of 2 mL to
300 mL. Horizontal height (H) and vertical depth (D)
are obtained from sagittal scanning, and the bladder
volume can be estimated according to the formula:
bladder volume (mL) = H = D = 5.9 – 14.6 (95%
confidence limits around ( 37 mL) [19].

Figure 1. Pelvic floor scan using introital ultrasonography.
Ut = uterine corpus; BL = bladder; sp = symphysis pubis;
u = urethra; v = vagina; A = anus; r = rectum; cx = cervix.

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3


Ultrasonography in Female Lower Urinary Tract Symptoms

Normal Images of the Female Lower
Urinary Tract
On ultrasonography, the symphysis pubis is displayed
as an ovoid-shaped structure with a homogeneous hyperechogenic nature. Without signs of infection, the
bladder content is uniformly echolucent. The bladder
wall is smooth and intact. The normal bladder wall is no
more than 6 mm thick [20] and can be divided into two

layers: the outer endopelvic fascia and the inner bladder
mucosa. The former is more echogenic than the latter.
The thickness of the endopelvic fascia is fixed regardless
of bladder volume; however, the thickness of the bladder mucosa varies with the degree of bladder distension.
While scanning is a little deviated to the right or left
parasagittal plane, two tiny nodules – the ureter papilla
– located at the junction of the trigone and bladder can
be visualized with peristalsis. The position of the ureteral
orifice can be identified by urinary flow from the ureter
orifice (ureter jet phenomenon) displayed on color and
power Doppler scanning. The urethra is a tubular structure with a central echolucent area and surrounding
echogenic sphincters [21]. Color and power Doppler
ultrasonography can reveal blood supply signals within
and around the urethra, whereas scanty vascular signals
are noted in the bladder wall. Less bladder neck hypermobility and no bladder neck funneling are noted in
normal continent women compared with those with
stress urinary incontinence (SUI) and pelvic organ prolapse [9,17]. The normal range of bladder neck motion
has not been defined and there is a wide range of overlap
between normal and abnormal values. In addition,
measurements of bladder neck position are reported to
be influenced by bladder filling, patient position, and
catheterization [22,23]. Using the introital approach,
Yang and Huang found that in healthy continent patients,
the angles between the bladder neck and the midline of
the symphysis pubis are 81 ( 15$ at rest, and 113 ( 27$
during straining, with a rotational angle of 30 ( 20$;
the distances between the bladder neck and the midline
of the symphysis pubis are 25.7 ( 4.9 mm at rest and
22.9 ( 3.3 mm during straining [9]. Bader et al reported
that in women without SUI and prolapse, the posterior

urethrovesical angle is 96.8$ at rest and 108.1$ during
stress [24].

Ultrasonographic Characteristics of
Pelvic Floor Disorders
Without infection, urine is anechoic in nature, occasionally with some free-floating particles on ultrasonography. With infection, the echogenicity of the urine in-

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3

creases or even forms a fluid-debris level. The bladder
wall is focal or generally thickened. Intravesical blood
clots, which are echogenic in nature, may be demonstrated in some rare conditions, such as surgical damage to the lower urinary tract, postoperative bladder
bleeding, or hemorrhagic cystitis. Hemorrhagic cystitis
is defined as gross hematuria associated with bladder
inflammation, and may be caused by infection, medication, chemical toxins, or pelvic irradiation [25]. A thickened and hypervascular bladder wall with either active
bleeding from the bladder wall or formation of intravesical blood clots, or both, are the usual findings on
color or power Doppler ultrasonography [25,26]. The
detection of distal ureteral calculi or bladder stones by
sonography appears promising [27–29]. However, excretory urography is still helpful because not all urolithiasis can be detected by ultrasonography. The
sonographic characteristics of a distal ureteral calculus
include unilateral dilatation of the ureter, which is invisible in normal conditions [30], and the existence of a
hyperechogenic stone within the ureter accompanied
by a strong acoustic shadow and surrounding edematous tissue [31]. Bladder calculi account for 5% of urolithiasis and usually occur as a result of foreign objects,
obstruction, or infection [32]. In the situation of bladder calculi secondary to a suture from a bladder neck
suspension, hyperechoic suture material and bladder
stones can be clearly demonstrated on ultrasonography
[29,33]; however, radiography and cystoscopy may fail
to identify the underlying pathogenesis of the stone
[29].
Abnormalities of the bladder wall include focal or

generalized thickening, loss of integrity, and abnormal
vascularity. In addition to infection, pelvic radiation,
pelvic surgery, bladder outlet obstruction, and neoplasm may also cause bladder wall thickening [20,34].
In patients with bladder outlet obstruction, a thickened
bladder wall with trabeculation, or even formation of
diverticulum, and high post-void residual urine volume
may be displayed on ultrasonography. Transvaginal
ultrasonography has been suggested as a useful tool in
the detection of bladder wall invasion by cervical cancer
[35]. The mobility of the bladder wall can be assessed by
the ability of the bladder to slide along the uterine cervix
when the probe is pushed up against the bladder from
the anterior fornix. Mobility is considered to indicate
an intact bladder wall [35]. With further invasion of
cervical cancer into the bladder, the relationship of free
mobility between the cervix and bladder is lost, the integrity of the endopelvic fascia is broken, and a tumor
nodule may be formed and protrude into the bladder
cavity. Transvaginal ultrasonography has been reported
to have 95% accuracy in detecting bladder wall invasion

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by cervical cancer [35].
Ultrasonography is also a useful diagnostic modality for screening and detecting bladder tumors [36]. On
ultrasonography, bladder tumors can be polypoid, sessile, or plaque-like, with a regular or irregular surface
and with or without calcified foci [36]. Color and power
Doppler ultrasonography may demonstrate neovascularization within the tumor, with a low resistance

index in the tumor vessels (Figure 2). Vesicovaginal
fistula and vesicouterine fistula can be displayed by
transvaginal ultrasonography. Factors aiding the visualization of vesicovaginal fistula are edematous changes
in the bladder and vaginal walls, accumulation of urine
inside the vagina, and urine flow induced by coughing or
the Valsalva maneuver [37–39]. Reverse urine flow from
the fistula into the bladder may be induced by increased
intravaginal pressure secondary to reflex pelvic floor
contraction or the inward motion of the vaginal probe

A

B

during coughing [38]. This should be differentiated
from the urinary stream coming from the ureter orifice
(ureter jet phenomenon).
Thirteen percent of cases with bladder outlet obstruction are secondary to urethral stricture [40], which
appears as distortion of the central hypoechoic urethral
mucosa on ultrasonography [41]. Better delineation
of a urethral stricture can be achieved by increased abdominal pressure on a full bladder, permitting pseudoantegrade filling of the proximal urethra [42]. A hyperechoic structure around the urethral mucosa on ultrasonography indicates a fibrotic and nondistensible urethral segment [43], which is histologically consistent
with spongiofibrosis [43,44], and is visible even in the
presence of extensive stenosis. It is closely related to the
ultimate prognosis of urethral stricture [43,44]. Urethral diverticulum is an uncommon cause of female
LUTS. The reported incidence of female urethral diverticulum is 1% to 6% [45]. Transvaginal ultrasound
is effective in the evaluation of suspected urethral diverticulum [45], which is demonstrated as single or
multiple cystic lesions with hypo- or mixed echogenicity surrounding the urethra (Figure 3).
Ultrasound is useful in detecting retroperitoneal
hematoma following retropubic urethropexy, especially
in patients with postoperative febrile and micturition

problems [46]. Retropubic hematoma is displayed as
an echolucent cyst between the symphysis pubis and
the urethra and bladder. The size and progression of
the hematoma can be determined by ultrasound, allowing timely and sufficient management to alleviate
symptoms.
Ultrasound can identify different compartmental
defects of the pelvic floor. Pelvic organ prolapse has
been quantified using translabial ultrasound [2]. Enteroceles are often difficult to recognize on clinical
examination, but are easily detected by perineal or
introital ultrasound. Disadvantages of these methods
are incomplete imaging of the cervix and vault with
large rectoceles, and the possible underestimation of
extensive pelvic floor relaxation because of the limited
field of view depth of the transducer.

Pathophysiologic Changes in Pelvic Floor
Dysfunction
Detrusor overactivity

Figure 2. Bladder cancer: (A) cystoscopic and (B) threedimensional sonographic examination revealing a polypoid
mass protruding from the bladder wall.

128

A well-known sonographic finding in patients with
unstable bladder is wavelike detrusor contractions
accompanied by bladder neck opening [2]. Khullar et
al and Soligo et al reported that an increase in mean
bladder wall thickness is unique to detrusor overactivity

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3


Ultrasonography in Female Lower Urinary Tract Symptoms

A

B

Figure 3. (A) Proximal and (B) distal urethral diverticulum.
Transvaginal sonography shows the urethral diverticulum (d),
an echolucent cystic mass surrounding the proximal urethra
(A) or deviating the distal urethra toward the symphysis pubis
(B). bl = bladder; u = urethra; eu = external urethral meatus.

[47,48]. With a cutoff value of 5 mm, bladder wall thickness together with symptoms of overactive bladder
have sensitivity of 84% and specificity of 89% for detecting detrusor overactivity [47,48]. These authors speculated that the increased bladder wall thickness in this disorder was secondary to detrusor hypertrophy associated
with increased isometric detrusor contraction, urethral
sphincter volume, and urethral closure pressure [47,
48]. Robinson et al reported that in patients without
evidence of genuine stress incontinence on laboratory
studies, a cutoff of 6 mm was highly suggestive of detrusor instability [4]. However, Yang and Huang reported
that a thickened bladder wall was a common finding in
female LUTS, except in hypersensitive bladder [18].
Age, resting bladder neck angle, urethral mobility, and
maximum urethral closure pressure are significantly
associated with bladder wall thickness at the trigone
and dome. Demographic, anatomic, and urodynamic
factors may affect the bladder wall thickness at the
trigone, dome, or both [18].

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3

Stress urinary incontinence
Ultrasonography is not used for differential diagnosis of
SUI. Instead, together with clinical examination and
urodynamic data, it has been utilized to detect anatomic
alterations associated with SUI, to select appropriate
therapy, and to evaluate surgical outcomes and postoperative complications [2]. Ultrasonographic studies
for SUI should provide quantitative measurements and
qualitative descriptions of the lower urinary tract [10].
The German Association of Urogynecology recommends
both posterior urethrovesical angle and bladder neck
position as quantitative parameters in ultrasonographic
study [10]. There are three methods for the measurement
of bladder neck position: from one distance and one
angle (Figure 4A) or two distances (Figure 4B), or from
the height of the bladder neck with reference to a horizontal line drawn at the lower border of the symphysis
pubis (Figure 4C). The first two methods use the symphysis pubis with its central line and inferior border as
references, and have good reproducibility, whereas the
third method is reliable only when a stable transducer
position at rest and during straining is guaranteed.
The differences between resting and stress bladder
neck angles yield the rotational angle, which represents
urethral or bladder neck mobility [9], in a similar way
to the Q-tip test. There are no definite values of normal
bladder neck descent or urethral mobility, possibly because of the methodologic variations such as patient
position, bladder filling, quality of the Valsalva maneuver,
and measurements of bladder neck position. Although
the positions of the bladder neck in patients with SUI are

lower than those of continent women [9,11], there is an
overlap between these two groups. Urethral mobility is
reportedly related to incontinence grade [49,50]. On
ultrasonography, the qualitative analysis of the female
lower urinary tract consists of observation of bladder
neck funneling [9,14,16,51–53] and bladder neck descent during stress [2,9]. The occurrence of bladder
neck funneling suggests poor urethral closure pressure
[52,53]. In addition to SUI, bladder neck funneling may
also be found in urge-incontinent women [3,53], but it
does not occur in normal continent women unless the
bladder is full [17,52]. On some occasions, the opening
of the bladder neck may be followed by egress of urine,
which is manifested as hyperechoic flow from the bladder through the urethra on real-time scanning. This can
be confirmed by color or power Doppler ultrasonography. During straining, the bladder neck may move in
a semicircular fashion with the tip of the symphysis
pubis as the center (rotational descent), or move downward along the urethral axis (sliding descent) [2,9].
Although the exact pathophysiology of SUI is
unknown, the great majority of women with primary

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SUI have urethral hypermobility [9,52,54,55]. Open
Burch colposuspension is a well-accepted procedure
for treating SUI secondary to urethral hypermobility
without intrinsic sphincter deficiency [55–57], and is
the reference standard against which other procedures
are compared [55–57]. Burch colposuspension elevates

and stabilizes the bladder neck and proximal urethra in
a high retropubic position. On ultrasound, higher bladder neck position, smaller bladder neck angle at rest and
during straining, and less rotational angle can be observed after both open and laparoscopic Burch colposuspension [58–61]. Other reported ultrasonographic
findings after open colposuspension include decreased
posterior urethrovesical angle, ventrocranial displace-

A

ment of the bladder neck, and reduced incidence of
bladder neck funneling and bladder hypermobility [58–
61]. Successful colposuspension is associated with a
more anterior, although not necessarily more elevated, urethrovesical position [2,58–61]. However, a trend
that urethral support decreases with time has been
noted on ultrasound in patients who have undergone
either open or laparoscopic Burch colposuspension
[58,60]. In patients developing posterior bladder suspension defect, cystocele and enterocele may be detected on ultrasound.
Despite a high success rate of around 70% to 90%,
urinary retention and late voiding difficulty occur after
up to 20% of colposuspensions. One of the precipitat-

C
cx

Bladder
Bladder
SP

`
H

R

`

Urethra

a
SP

U

V

_

A
Horizontal line

B
Bladder
Dx
SP

`
Dy
Urethra

130

Lower border of SP

Figure 4. Three methods for the measurement of bladder neck
position recommended by the German Urogynecologic
Association. (A) One distance and one angle. The schematic
drawing shows measurement of the posterior urethrovesical
angle (`) and the bladder neck position by measuring the
distance between the bladder neck and the inferior border of
the symphysis (a) and the angle between this line and the
central line of the symphysis pubis (_). A = anus; R = rectum;
cx = cervix; V = vagina; U = urethra; SP = symphysis pubis.
(B) Two distances. A rectangular coordinate system is set up
with the origin at the lower border of the symphysis pubis (SP).
The x-axis is determined by the central line of the SP, which runs
between its lower and upper borders. The y-axis is constructed
perpendicular to the x-axis at the lower SP border. Dx is defined
as the distance between the y-axis and the bladder neck, and Dy
is defined as the distance between the x-axis and the bladder
neck. For precise localization of the bladder neck, the upper
and ventral point of the urethral wall at the immediate transition
into the bladder is used. (C) Bladder neck height. A horizontal
line is drawn at the lower border of the symphysis pubis (SP).
The height (H) of the bladder neck is determined as the
distance between the bladder neck and this horizontal line. For
reliable measurements at rest and during the Valsalva maneuver
and pelvic floor contractions, the position of the transducer
may not be changed.

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3

.

Ultrasonography in Female Lower Urinary Tract Symptoms

ing factors is bladder neck overcorrection with undue
elevation and fixation of the bladder neck [59–61].
Viereck et al have shown that differences between the
pre- and postoperative vertical height of the bladder
neck are associated with postoperative voiding complaints, for example, urgency, de novo urge incontinence,
or voiding difficulty [59,60].
The tension-free vaginal tape (TVT) procedure is
becoming common for the treatment of female SUI and
has the advantage of being minimally invasive. TVT is
highly echogenic and easily identified posterior to the
urethra on ultrasound [62–71]. On ultrasound, bladder neck mobility remains unchanged after TVT. Urethral angulation and ventrocaudal movement of the
tape towards the symphysis pubis have been described
during straining in patients who have received TVT [63].
The mode of action seems to be associated with dynamic kinking of the urethra during straining or compression of the urethra against the posterior surface
of the symphysis pubis, or both (Figure 5) [63–66].
However, studies have reported variable effects of the
TVT procedure on voiding function [63,67]. After the
TVT procedure, the incidence of urinary retention or
obstructive voiding symptoms is reported to be around
2.3% to 14% [68], and postvoid residual urine is increased postoperatively [69]. Profound angulation of
the midurethra at rest suggests over-lift of the urethra by the tape [63,70], while acute narrowing of
the central echolucent area of the urethra at rest implies voiding dysfunction postoperatively [71].

Voiding dysfunction
The cause of voiding dysfunction may relate to the
bladder or urethra, or both. Bladder factors include detrusor underactivity or areflexia; urethral causes consist of functional or mechanical obstruction, which can

further be categorized as compressive or constrictive.
On sonography, the urethra is shown as a tubular structure with a hypoechoic center representing the urethra
mucosa (Figure 1). The hypoechoic nature remains even
when the urethral mucosa is prolapsed [72].
Voiding dysfunction may result from distortion of
the anechoic urethral mucosa by an intraluminal lesion
(i.e. urethral stricture) [41] or from extramural factors
such as an over-lifted TVT [71]. The pathophysiologic
mechanism of voiding dysfunction secondary to an impacted pelvic mass such as a retroverted gravid uterus or
a fibroid in the posterior uterine wall is different from
those for dysfunction secondary to over-elevation in the
bladder neck suspension procedure or to genitourinary
prolapse [29,60,61,73]. Voiding dysfunction in cases of
an impacted pelvic mass is caused by a displaced cervix
compressing the lower bladder, obstructing the internal

Taiwanese J Obstet Gynecol • September 2004 • Vol 43 • No 3

A

B

Figure 5. Dynamic changes in the lower urinary tract after the
tension-free vaginal tape (TVT) procedure. Introital sonography
shows dynamic kinking of the urethra with compression of the
urethra against the posterior surface of the symphysis pubis
during stress. With reference to the midline of the symphysis
pubis, the bladder neck–pubic symphyseal angles are 118$ and
171$ at rest (A) and during stress (B), respectively. The dotted
line is drawn horizontally at the lower border of the symphysis

pubis (sp). The TVT is hyperechogenic and located posterior to
the midurethra (oblique arrows).

urethral orifice [74,75]. The urethra itself is not compressed or distorted.

Interventional Application
Minimally invasive methods are the current trend in
health care. Transvaginal ultrasound provides highresolution imaging of the lower urinary tract, and may
serve as an aid in the management of lower urinary tract
disorders with minimal invasion. With the combination
of ultrasonography and flexible cystoscopy, percutaneous suprapubic cystostomy may be performed via a
stab technique with minimal risk to the surrounding
pelvic organs [76]. In the procedure of urethral dilation

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for urethral stricture, transvaginal ultrasound is helpful
in preventing urethral perforation and creation of a false
passage, a possible sequel to blind dilation. Even in the
presence of extensive stenosis, the urethral mucosa
appears as a hypoechoic area on ultrasonography. Thus,
under ultrasonographic guidance, advance of the dilator
exactly through the echolucent part of the urethra ensures
penetration of dilators into the correct tissue [39].
Vesicovaginal fistula will cause social inconvenience
and have a psychologic impact on women. The treatment of a vesicovaginal fistula includes bladder drainage and surgery, depending on the size and location of
the fistula. Adequate and undisturbed drainage results

in closure of a small posthysterectomy fistula in 12% to
80% of cases, but the outcome is unpredictable. If the
fistula does not close, then it must be repaired surgically.
The timing of surgical intervention is most important
and is best determined by periodic evaluation of the
tissue. Transvaginal sonography offers serial, non-invasive assessment of the condition of the bladder wall and
fistula, and helps in determining the timing of surgical
repair [39].
After a major procedure in which surgical damage to
the lower urinary tract or postoperative bladder bleeding is a possibility, the bladder must be adequately
drained and not become overdistended. Cystoscopy
may be helpful for determining the cause of blockage
and evacuation of clots when bladder drainage fails
because of obstruction, kinking, knotting, or displacement of the catheter. However, severe hematuria may
obscure the cystoscopic view and necessitate high-flow
irrigation, which carries a risk of bladder rupture [77].
Transvaginal sonography is an effective and safe tool in
the treatment of acute urinary retention due to intravesical blood clots [78]. It can help in identifying and
localizing the clots without causing further instrumental injury to the bladder wall, and it can also aid in
estimating the irrigating volume infused in order to
prevent bladder overdistension. Intravesical suction
and irrigation to remove the clots may then be performed more efficiently [78].

Future Investigations
The levator ani muscle is believed to play an important
role in supporting pelvic organs and maintaining normal
pelvic floor function. Magnetic resonance imaging (MRI),
which gives high-resolution images of muscular tissues,
has been widely used for morphologic investigation of
the pelvic floor. MRI findings in subjects with pelvic

organ prolapse and urinary incontinence include focal
changes in muscle width, configuration and signal inten-

132

sity of the levator ani muscles, loss of connection with
the urethra, and an increase in urogenital hiatus size,
straining levator plate angle, and levator hiatus height
[79]. However, not all women with pelvic floor prolapse have abnormal morphologic features [80]. There
is considerable variation in the size and configuration
of the pelvic floor structures in nulliparous asymptomatic women [81]. Therefore, it has been suggested
that abnormal anatomic findings on MRI be regarded as pathogenic only if corresponding symptoms
are present [81]. It would require a study with a large
sample size and strict inclusion criteria to precisely
define the functional implications of specific MRI
findings. However, MRI is currently not suitable for a
large-scale survey because of its sophistication and
expense. On the other hand, ultrasonography is suitable
for a large-scale survey owing to its popularity and
availability [9,18,52]. Furthermore, three-dimensional
ultrasound allows volume calculation and scans pelvic
organs in axial, transverse, and coronal planes simultaneously. It is quite possible that ultrasound may replace
MRI in evaluating the morphology and function of the
levator ani muscle in the near future.
The function of the levator ani muscle has been
assessed indirectly by the displacement of intrapelvic
structures (e.g. bladder neck or bladder base) on its
contraction by perineal ultrasound [82]. The bladder
and urethra move upwards and ventrally during pelvic
floor contractions. Correlations between the shift in the

bladder neck and palpation/perineometry are good
[82]. Ultrasonography can provide visual biofeedback
in pelvic floor re-education [83]. However, the assessment of levator ani function is still regarded as inherently problematic in ultrasonography. Further studies
will be needed to verify the reproducibility and validity of
ultrasound in investigating the levator ani muscle.

Conclusions
A comprehensive evaluation of the female lower urinary
tract is based on clinical history, physical examination,
urodynamics, and imaging studies. Ultrasound is a
valuable alternative to radiography and allows functional–morphologic documentation. With increasing
knowledge of its application in the female lower urinary
tract, more diagnostic and surgical procedures may
be performed in a less invasive way with the aid of
ultrasound. For female LUTS, it is convenient and helpful to perform transvaginal and introital sonography
at the same time using an endovaginal probe, because
LUTS may be secondary to gynecologic or non-gynecologic conditions.

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Ultrasonography in Female Lower Urinary Tract Symptoms

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