Drs. Feigin, Rosenblatt,
and
Papanicolaou
are in the Department of Radiology at The New York Hospital-
Cornell Medical Center, New York, NY and
Dr. Kutcher
is with the Department of Radiology at White Plains Medical
Center, White Plains, NY.
A search for anatomic disorders of the uterus, fallopian tubes,
and ovaries is often indicated in infertile women. Traditional
diagnostic methods have included hysterosalpingography (HSG),
hysteroscopy, abdominal and endovaginal sonography, and magnetic
resonance imaging (MRI). In general, HSG and hysteroscopy are used
for evaluation of the endometrial cavity and fallopian tubes, while
sonography has been widely used for evaluation of the myometrium
and ovaries. The introduction of sonohysterography (SHG) over the
last several years has contributed significantly to the evaluation
of all components of the female genital tract.
Each of the traditional imaging techniques of the female genital
tract has distinct advantages and disadvantages. HSG is a
relatively noninvasive and widely used procedure, however, it
involves the use of ionizing radiation to the pelvic organs,
requires the use of iodinated contrast material, and is relatively
costly. In HSG, proper technique is crucial; inadequate uterine
distension may result in poor visualization and excessive
instillation of contrast may obscure uterine pathology. In
addition, evaluation for intramural and extrauterine pathology is
limited to those cases in which the uterine cavity is distorted.
Hysteroscopy is generally considered the gold standard of
endometrial evaluation. It is more invasive than the other
techniques, however, requiring the risks of anesthesia and costs of
an operating room. Sonography is able to demonstrate myometrial and
adnexal pathology, but its ability to evaluate the endometrial
cavity is limited. MRI can render detailed images of the uterus and
is accurate in the diagnosis of congenital uterine anomalies
1-3
and uterine pathology,
4
however its widespread use has been restricted by lack of expertise
in pelvic MR imaging and by the fact that its advantages are not
well known to referring clinicians and third-party payers.
5,6
Sonohysterography (SHG), also commonly known as saline contrast
hysterosonography, hysterosalpingosonography, or
endohysterosonography, is transvaginal ultrasonography (TVUS) of
the uterus enhanced by instillation of sterile saline (or another
contrast medium such as galactose, dextran, glycine, lactated
Ringer's solution, or water) into the uterine cavity. The saline
distends the uterine cavity and acts as a contrast medium, thereby
improving visualization of the endometrium. Thus, SHG combines the
advantages of sonography with improved endometrial evaluation.
Common indications for SHG include abnormal or postmenopausal
uterine bleeding;
7-15
the presence of uterine abnormalities such as polyps, fibroids, or
adhesions;
8,9
and the assessment
of tamoxifen-related endometrial changes.
16
This article will discuss ano-ther common and important role of
SHG, the evaluation of female infertility.
The technique of SHG was first described by Richman et al
17
in 1984, who used it with transabdominal sonography to determine
tubal patency. In the infertile patient, SHG is usually performed
within the first 10 days of the menstrual cycle to minimize the
possibility of disrupting an early intrauterine pregnancy and to
utilize the backdrop of a peri-
ovulatory endometrium, against which many pathologic conditions are
best demonstrated.
Generally, a baseline TVUS examination with a 5 or 7.5 MHz probe
is performed first to demonstrate the thickness of the endometrium
and myometrium and to evaluate the ovaries. The transvaginal probe
is then removed and a sterile speculum is inserted. The cervix is
cleansed with an antiseptic solution and a hysterosalpingography or
insemination catheter, pediatric feeding tube, or Foley catheter,
prefilled with saline to exclude air, is introduced into the
uterine cavity. Some operators prefer the use of a cervical
tenaculum to provide tension while inserting the catheter. The
speculum is then removed and the transvaginal probe, covered with a
condom and sterile gel, is inserted into the posterior vaginal
fornix. Sterile saline is then injected into the catheter under
continuous sonographic visualization until resistance is
encountered or until the entire uterine cavity is observed clearly.
The uterus is surveyed from cornu to cornu in a long axis
projection. Then the transducer is rotated 90
o
into a coronal plane and the uterus is surveyed from the fundus to
the endocervical canal. In the normal uterus, the endometrium
appears symmetric, surrounding the anechoic contrast-distended
endometrial cavity (figures 1 and 2).
18-24
The entire procedure takes approximately 15 minutes
14,21,23,24
and is generally well tolerated. The use of prophylactic
antibiotics is generally not necessary,
18-21
and most hystero-sonographers see no need for analgesics or
anesthesia, other than non-steroidal anti-inflammatory medications
as needed.
18,19,22
Structural abnormalities within the uterine cavity, such as
leiomyomata or polyps, uterine adhesions, and Muellerian
abnormalities, are believed to play a role in obstetric
complications, such as primary infertility, implantation failure,
premature delivery, and malpresentation.
25-28
SHG has been shown to be useful in the detection of all of these
anatomic disorders.
Congenital disorders
Muellerian duct abnormalities (MDA) result from total or partial
failure of fusion of the paired Muellerian ducts from which the
uterus and fallopian tubes develop. Most of these congenital
disorders are believed to be asymptomatic:
29
however, congenital uterine malformations have been associated with
primary infertility, spontaneous abortion, preterm labor and
increased perinatal mortality, fetal growth retardation, and
malpresentation. Obstetric prognosis varies with different types of
malformations, with septate and bicornuate uteri carrying the
highest rate of pregnancy loss.
15,30
Arcuate uteri are considered normal variants and are not associated
with infertility or obstetric difficulties.
31
The rare uterus didelphys represents a complete lack of fusion of
the Muellerian ducts resulting in two completely separate uterine
cavities and two cervices. The unicornuate uterus is also uncommon
and results from the development of only one Muellerian duct.
Vaginal atresia is usually associated with an abnormal or absent
uterus.
The treatment of MDA is dependent on the type of abnormality,
with septate and bicornuate uteri usually considered surgically
amenable. Until recently, both septate and bicornuate uteri were
repaired by means of transabdominal surgery. However, outpatient
hysteroscopic metroplasty is now the treatment of choice for the
septate uterus, making the preoperative distinction critical.
Traditionally, hysterosalpingography and/or TVUS have been used
to diagnose congenital uterine anomalies, relying largely on the
relatively indirect measure of the angle of divergence of the
uterine cavities to distinguish septate from bicornuate uteri.
Sonohysterography has the distinct advantage over both HSG and TVUS
of being able to visualize both the uterine cavity and myometrium
in the nonpregnant woman. In addition, septal height and thickness
may be determined directly by SHG.
20,32
Early studies reported that TVUS is sensitive for detecting MDA,
but its ability to distinguish between different types of anomalies
is limited.
33-35
Salle et al
32
studied 14 patients with infertility problems and an abnormal
uterus, based on the results of HSG or TVUS. These investigators
concluded that SHG was preferable to TVUS and HSG in evaluation of
septate uteri, as it allowed clear visualization as well as
measurement of the height and maximal thickness of the septum. SHG
detected all 14 septate uteri, while TVUS and HSG each detected 8
of 14, the other 6 were ascribed to bicornuate abnormalities with
each technique. Following surgical resection of the septa,
confirmation of successful repair was more accurate by SHG than by
hysteroscopy, as hysteroscopy could mistake the natural spur of the
uterine fundus as a remainder of a septum.
32
Similarly, in a large study of 264 patients with septate uteri,
Kupesic and Kurjak
36
demonstrated superior sensitivity and specificity of SHG to TVUS in
making the appropriate diagnosis.
Recent reports demonstrate that MRI is accurate in the diagnosis
of MDA
1-3
and is indicated when conventional imaging techniques are
nondiagnostic or when additional information is needed for
appropriate patient management.
5
Leiomyomata
Leiomyomata are the most common neoplasms of the uterus. They
consist of smooth muscle and varying amounts of fibrous tissue.
They may be submucosal, intramural, or subserosal in location. The
myomata that generally interfere with fertility are submucosal, as
these may distort the endometrial cavity, interfere with proper
nutrition and function of the endometrium, and/or block the
cervical os or fallopian tubes. Additionally, large or numerous
submucosal or intramural myomata may be associated with spontaneous
abortion and preterm labor. Hysteroscopic myomectomy has become the
treatment of choice for preserving fertility, and this procedure
requires precise knowledge of the number, location, and size of
submucosal myomas.
Typically, leiomyomata are diagnosed by HSG and TVUS, with
hysteroscopy being the gold standard for submucosal tumors. Unless
calcified, leiomyomata are detected during HSG only to the extent
that they may enlarge and distort the cavity of the uterus.
Submucosal myomata produce filling defects within the uterine
cavity, which must be distinguished from air bubbles, polyps,
prominent folds, and blood clots. It is important to evaluate early
HSG images for filling defects, as many lesions can be obscured by
large amounts of contrast in the uterine cavity. On sonography, the
fibroid uterus usually appears large and lobulated, with myomata
generally appearing isoechoic or hypoechoic (figure 3). MRI has
also been shown to be highly sensitive in detecting uterine myomata
and is considered superior to sonography in
differentiating fibroids from adenomyosis.
5
This may have significant therapeutic implications, because
symptomatic adenomyosis often requires hysterectomy for relief of
symptoms.
Many studies have demonstrated comparable or superior
sensitivity of SHG to HSG, TVUS, and hysteroscopy in detecting
myomata.
14,20,22-24,37-39
Hoezinger
37
compared SHG to HSG in vitro. He found SHG superior to HSG in
determining the presence, number, and location of myomata. One
limitation of SHG was its inability to detect very small myomata,
secondary to the limited resolution of the technique. Also,
acoustic shadowing behind larger myomata may obscure smaller
myomata within the shadow. Lindheim and Sauer
23
studied 50 patients undergoing ovum donation and compared HSG to
SHG, confirming pathology with hysteroscopy. SHG resulted in one
false positive in which an intramural myoma was misinterpreted as
having a significant submucosal component. Lindheim suggests that
false positive results of SHG could be minimized by performing
studies during the follicular phase 1 to 2 days upon completion of
a spontaneous or progestin-induced withdrawal bleed. In this phase
of the menstrual cycle, the endometrium is thin, which reduces the
likelihood of over-
reading pathology. In another study, SHG was found to be superior
to TVUS in localizing the myomata and superior to hysteroscopy in
estimating their sizes and degree of submucosal and intramyometrial
extension.
24
Polyps
Endometrial polyps consist of endometrial tissue attached to the
mucosa by a stalk. They generally appear as filling defects on HSG
without enlarging or deforming the uterine cavity, in contrast to
larger submucosal myomata. Polyps are seen on SHG as pedunculated,
hyperechoic soft-tissue masses projecting into the endometrial
cavity and surrounded by anechoic injected fluid, with the point of
attachment and thickness of the stalk clearly demonstrated (figure
4). They are usually asymptomatic, however, they have been
associated with vaginal bleeding and infertility. Polyps are
treated by hysteroscopic excision followed by curettage.
As with myomata, the sensitivity of SHG in the detection of
polyps is remarkably good. Syrop and Sahakian
13
studied 14 patients with polyps seen on SHG. All of these were
confirmed histologically. Parsons and Lense
14
report that during TVUS, small polyps may blend smoothly into
secretory or atrophic endometrium, producing only an asymmetric
thickening in contour and large polyps may not be distinguished
from normal secretory endometrium. Using SHG, they found that 16
polyps were easily delineated, appearing as smooth-margined,
echogenic masses with relatively homogeneous echotexture. These
polyps were all verified at surgery. Lindheim's series
23
revealed excellent sensitivity of SHG (100%) compared to HSG (80%)
in detecting 10 pathologically proven polyps. Other investigators
have supported these findings as well.
22,38
Uterine adhesions
Intrauterine adhesions, or synechiae, usually result from
vigorous therapeutic curettage of the uterine cavity. The denuded
endometrium heals by forming fibrous bands that may adhere to one
another (Asherman's syndrome). Adhesions may cause primary
infertility, recurrent abortion, or premature labor. They are
usually treated by hysteroscopic-guided lysis. On HSG, points of
adherence form angular or linear filling defects around which
contrast flows. On SHG, adhesions appear as thick bridging bands or
thin membranes of echogenic tissue that may distort the uterine
cavity (figure 5).
Most studies comparing various imaging methods include only a
very small number of patients with adhesions.
14,23,38,39
Regardless, there appears to be a trend suggesting that SHG is a
reliable method for diagnosing clinically significant adhesions.
Parsons and Lense
14
diagnosed four patients with adhesions on SHG and confirmed all
four by hysteroscopy. Ayida's series
38
had two patients with adhesions on hysteroscopy, one of whom was
diagnosed by SHG, while none were detected using TVUS alone. In the
case in which the adhesions were missed by SHG, they were deemed
clinically insignificant. Similarly, Fleischer et al
39
found that SHG missed three cases in which there were minimal
(<2 mm) adhesions.
Tubal pathology
Fallopian tube pathology is the cause of infertility in up to
40% of women.
40
Infection, endometriosis, and pelvic surgery are the leading causes
of tubal scarring.
41
Evaluation of tubal patency is usually undertaken by HSG or
laparoscopic chromopertubation. With SHG, if increased fluid is
noted in the cul-de-sac at the end of the procedure, tubal patency,
at least unilaterally, can be inferred. By this criterion, Richman
et al,
17
using transabdominal sonohysterography, dem-onstrated bilateral
tubal occlusion with a sensitivity of 100% (9 of 9) and tubal
patency with a reported specificity of 96% (24 of 25).
While others report similar success with indirect measures of
tubal patency,
21,39
most investigators agree that SHG is not as effective as HSG for
defining tubal anatomic structure in detail. Diechert et al
42
required that flow into the tubal isthmus or ampulla be
demonstrated directly in their study for the tubes to qualify as
patent. As expected, many tubes could not be adequately visualized
to apply this criterion. Bonilla-Musoles et al
43
also used direct tubal visualization as their criterion for
diagnosing tubal patency with SHG. They found that in only 18 of 37
patients with laparoscopically--or HSG--proven tubal patency, could
SHG demonstrate the tubal lumens. Color Doppler, pulsed wave
Doppler, and various contrast agents are
currently under investigation for improving visualization of
fallopian tubes with SHG.
21,40,42,44,45
Theoretical risks of SHG are infection and perforation,
10
although no cases of perforation have been reported. Most
investigators similarly report no infection and no significant
pain; however, mild cramping and vaginal spotting are not uncommon.
18-20,22
Potential contraindications of the procedure have been described.
Cervical stenosis may prevent introduction of the endocervical
catheter. Cervical dilatation may occasionally be helpful in such
cases. A patulous cervix may lead to transcervical fluid leakage,
but this does not severely limit the study, as more fluid may be
instilled or a catheter balloon inflated to tamponade the cervical
canal.
Conclusion
SHG enhances transvaginal ultrasound examination of the uterine
cavity and is a valuable adjunct to HSG in the radiologic
evaluation of female infertility. SHG is performed easily and
rapidly at relatively low cost, and is virtually devoid of
complications. Its use in selected infertile patients obviates the
need for more invasive diagnostic procedures, such as
hysteroscopy.
Currently, the integration of MRI in the work-up of female
infertility and its complementary role to HSG, TVUS, and SHG are
being investigated. It is likely that the use of MRI will continue
to expand as healthcare providers realize its potential
benefits.
AR
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