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

It has been suggested that the information obtained during ultrasonographic evaluation of the female lower urinary tract should include the patient’s position, blad-der volume, liquid us

A PPLICATIONS OF U LTRASONOGRAPHY IN F EMALE L OWER

Wen-Chen Huang, Jenn-Ming Yang1,2*, Shwu-Huey Yang2

Department of Obstetrics and Gynecology, Cathay General Hospital, 1 Division of Urogynecology, Department of

Obstetrics and Gynecology, Mackay Memorial Hospital, and 2 Taipei Medical University, Taipei, Taiwan.

*Correspondence to: Dr Jenn-Ming Yang, Division of

Urogyne-cology, Department of Obstetrics and GyneUrogyne-cology, Mackay

Memorial Hospital, 92 Chung-Shan North Road, Section 2,

Taipei 104, Taiwan.

E-mail: yangjm0211@hotmail.com

Received: March 4, 2004

Revised: March 23, 2004

Accepted: March 23, 2004

Introduction

Lower urinary tract symptoms (LUTS) are a common

health problem causing considerable inconvenience for

many women LUTS consists of irritative and

obstruc-tive 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

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-invasive-ness, 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 Dop-pler ultrasound analyzes the frequency shift of flow velocity information, while power Doppler technology uses the amplitude component of received signals to

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 non-gynecologic 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

■ REVIEW ARTICLE ■

quantify the number of moving particles.

Basic Procedure

Many approaches have been proposed for the

ultra-sound evaluation of the lower urinary tract These

in-clude transabdominal [1], transvaginal [6],

transrec-tal [7], perineal (or translabial) [8], and introitransrec-tal

ap-proaches [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

fre-quency between 3.5 and 5 MHz [13], while introital

ultrasound uses a sector endovaginal probe with

fre-quency 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,

blad-der volume, liquid used for bladblad-der filling, method of

bladder filling (spontaneous or retrograde filling),

simultaneous pressure measurement (cystometry,

urethral pressure profile, or voiding study), size of

ultra-sound transducer, ultraultra-sound machine (type and

manufacturer), ultrasound frequency, picture

orienta-tion, and approach (introital, perineal, vaginal, rectal,

or abdominal) [10,15] There is disagreement

regard-ing 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

struc-tures on the left [10]

The examination can be performed in a dorsal

li-thotomy, semireclining, or standing position [16,17]

There are no significant differences in the dynamic

as-sessment of the bladder neck between the semireclining

and standing positions [17] The ultrasonographic

evalu-ation of the lower urinary tract begins with the midsag-ittal plane This results in an image including the sym-physis pubis, urethra, bladder neck, vagina, cervix, rectum, and anal canal (Figure 1) By moving the trans-ducer to the left or to the right, additional areas of periurethral structures can be assessed [17] The pres-sure 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, necessi-tates 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 trans-vaginal approach, although the accuracy is not reliable for bladder volumes less than 50 mL In the transab-dominal approach, three parameters, including height (H), depth (D), and width (W), are obtained from two perpendicular planes (sagittal and transverse) In sagit-tal scanning, height and depth correspond to the great-est superior–inferior measurement and the greatgreat-est 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 for-mula 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.

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

hy-perechogenic 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

blad-der mucosa varies with the degree of bladblad-der 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

struc-ture 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

hyper-mobility and no bladder neck funneling are noted in

normal continent women compared with those with

stress urinary incontinence (SUI) and pelvic organ

pro-lapse [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,

occa-sionally with some free-floating particles on

ultrasono-graphy With infection, the echogenicity of the urine

in-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 demon-strated in some rare conditions, such as surgical dam-age 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, medica-tion, chemical toxins, or pelvic irradiation [25] A thick-ened and hypervascular bladder wall with either active bleeding from the bladder wall or formation of intra-vesical 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, ex-cretory urography is still helpful because not all uro-lithiasis can be detected by ultrasonography The sonographic characteristics of a distal ureteral calculus include unilateral dilatation of the ureter, which is invi-sible in normal conditions [30], and the existence of a hyperechogenic stone within the ureter accompanied

by a strong acoustic shadow and surrounding edema-tous tissue [31] Bladder calculi account for 5% of uro-lithiasis and usually occur as a result of foreign objects, obstruction, or infection [32] In the situation of blad-der calculi secondary to a suture from a bladblad-der 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 neo-plasm 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 in-tegrity 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

by cervical cancer [35].

Ultrasonography is also a useful diagnostic

modal-ity for screening and detecting bladder tumors [36] On

ultrasonography, bladder tumors can be polypoid,

ses-sile, or plaque-like, with a regular or irregular surface

and with or without calcified foci [36] Color and power

Doppler ultrasonography may demonstrate

neovas-cularization 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

visu-alization 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

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 ob-struction 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 ab-dominal pressure on a full bladder, permitting pseudo-antegrade filling of the proximal urethra [42] A hyper-echoic structure around the urethral mucosa on ultra-sonography indicates a fibrotic and nondistensible ure-thral 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] Ure-thral diverticulum is an uncommon cause of female LUTS The reported incidence of female urethral di-verticulum is 1% to 6% [45] Transvaginal ultrasound

is effective in the evaluation of suspected urethral di-verticulum [45], which is demonstrated as single or multiple cystic lesions with hypo- or mixed

echogenici-ty 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, allow-ing 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] En-teroceles 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

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

three-dimensional sonographic examination revealing a polypoid

mass protruding from the bladder wall.

A

B

Ultrasonography in Female Lower Urinary Tract Symptoms

[47,48] With a cutoff value of 5 mm, bladder wall

thick-ness together with symptoms of overactive bladder

have sensitivity of 84% and specificity of 89% for

detect-ing detrusor overactivity [47,48] These authors

speculat-ed that the increasspeculat-ed bladder wall thickness in this

disor-der 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

detru-sor 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]

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 post-operative 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 hori-zontal line drawn at the lower border of the symphysis pubis (Figure 4C) The first two methods use the sym-physis 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 be-cause 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 de-scent 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 blad-der through the urethra on real-time scanning This can

be confirmed by color or power Doppler ultrasono-graphy 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 down-ward along the urethral axis (sliding descent) [2,9] Although the exact pathophysiology of SUI is unknown, the great majority of women with primary

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.

A

B

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.

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

blad-der neck position, smaller bladblad-der neck angle at rest and

during straining, and less rotational angle can be

ob-served after both open and laparoscopic Burch

colpo-suspension [58–61] Other reported ultrasonographic

findings after open colposuspension include decreased

posterior urethrovesical angle, ventrocranial

displace-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

elevat-ed, 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 sus-pension defect, cystocele and enterocele may be de-tected 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-A

B

C

Bladder

SP Dy

`

Dx

Urethra

Bladder

Urethra

SP

` H

Horizontal line Lower border of SP SP

Bladder cx

R

A

a

`

_

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

com-plaints, 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,

blad-der neck mobility remains unchanged after TVT

Ure-thral 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

dy-namic kinking of the urethra during straining or

com-pression 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

in-creased postoperatively [69] Profound angulation of

the midurethra at rest suggests over-lift of the

ure-thra by the tape [63,70], while acute narrowing of

the central echolucent area of the urethra at rest

im-plies voiding dysfunction postoperatively [71]

Voiding dysfunction

The cause of voiding dysfunction may relate to the

bladder or urethra, or both Bladder factors include

de-trusor underactivity or areflexia; urethral causes

con-sist of functional or mechanical obstruction, which can

further be categorized as compressive or constrictive

On sonography, the urethra is shown as a tubular

struc-ture 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

im-pacted 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

urethral orifice [74,75] The urethra itself is not com-pressed or distorted

Interventional Application

Minimally invasive methods are the current trend in health care Transvaginal ultrasound provides high-resolution 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, percutan-eous suprapubic cystostomy may be performed via a stab technique with minimal risk to the surrounding pelvic organs [76] In the procedure of urethral dilation

.

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).

A

B

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

treat-ment of a vesicovaginal fistula includes bladder

drain-age 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-inva-sive 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

bleed-ing 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

displace-ment 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

intra-vesical blood clots [78] It can help in identifying and

localizing the clots without causing further

instrumen-tal 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

per-formed 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-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 pro-lapse have abnormal morphologic features [80] There

is considerable variation in the size and configuration

of the pelvic floor structures in nulliparous asympto-matic women [81] Therefore, it has been suggested that abnormal anatomic findings on MRI be

regard-ed 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 simultane-ously 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 assess-ment of levator ani function is still regarded as inher-ently 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 func-tional–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 help-ful to perform transvaginal and introital sonography

at the same time using an endovaginal probe, because LUTS may be secondary to gynecologic or non-gyneco-logic conditions

Ultrasonography in Female Lower Urinary Tract Symptoms

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