Diagnostic ultrasound ( PDFDrive )

538 PART II Abdominal and Pelvic Sonography
across the superior aspect of the endometrial edge in the two
cornual regions). 68
In general, if there is an indentation of greater than 1 cm
in the fundal myometrium, one then needs to distinguish
between a bicornuate uterus and uterus didelphys. In bicornuate
uterus, the two endometrial cavities join at some point,
usually just above the cervix. here can be either one cervix
(bicornis unicollis) or two cervices (bicornis bicollis). In
uterus didelphys, there are two separate uterine horns and two
cervices. However, the distinction between a bicornuate uterus
with two cervices versus uterus didelphys may be diicult, and
perhaps not clinically relevant. In a newer classiication system
the overlap between septate and bicornuate uterus is better
described 53 ; however, septate uterus is probably overdiagnosed by
these deinitions. 69
Arrested development of one müllerian duct results in variable
forms of a unicornuate uterus. In general, unicornuate uterus
is easily recognized on 3-D ultrasound because the single horn
coniguration, sometimes referred to as “banana-shaped,” is usually
obvious on the reconstructed coronal plane. he single horn
coniguration of the endometrium, with absence of one cornual
region, is easy to overlook on 2-D ultrasound unless one pays
close attention. A unicornuate uterus may be deviated to one
side of the pelvis, but this uterine deviation can be overlooked
on 2-D ultrasound. When a unicornuate uterus is seen, it is
important to determine if there is a rudimentary horn and if
that rudimentary horn contains endometrium, as such determination
will typically afect management of the patient. 54,70 About
a third of patients with unicornuate uterus will not have a
rudimentary horn. For the approximate two-thirds of patients
with a unicornuate uterus who have a rudimentary horn, about
half will have endometrium in the rudimentary horn. 54,70 In most
patients with a rudimentary horn that has endometrium, the
rudimentary horn does not communicate with the other horn.
hese latter patients are at increased risk for endometriosis and
rudimentary horn pregnancy, which has a high likelihood of
rupture. Hydrometra in the rudimentary horn may be mistaken
for a uterine or adnexal mass. Surgical resection of a rudimentary
horn that contains endometrium, especially if noncommunicating,
is oten recommended. 54 It is not clear how reliably ultrasound,
whether 2-D or 3-D, can exclude the presence of a rudimentary
horn because they are sometimes small and may be obscured
by bowel gas. If a rudimentary horn is not seen on ultrasound,
one should consider MRI to be more conident there is truly no
rudimentary horn.
here are variable and oten complex forms of uterine
hypoplasia or agenesis. One may not be able to perform TVS
in such patients, and MRI may be needed to fully deine the
anatomy as small uterine remnants may be present and diicult
to identify sonographically. he most common form is Mayer-
Rokitansy-Kuster-Hauser syndrome, with most patients having
uterine and vaginal agenesis. 56
Vaginal septa may be transverse or longitudinal in orientation
and are most commonly seen with uterus didelphys, although
they can occur with other MDAs. A transverse septum may
cause obstruction and result in hematocolpos or hematometrocolpos.
A duplicated cervix is a component of uterus didelphys
but can occur with other anomalies. Other than clearly separated
cervices, it can be diicult to distinguish true cervical duplication
from a cervix divided by a septum. With this in mind, in women
with a double cervix it is important to evaluate the full uterine
anatomy because a complete septate uterus is at least as common
as uterus didelphys. 71
he kidneys should be evaluated in patients with MDAs
because renal anomalies occur with increased frequency in
such patients compared with the general population. 54 he
most common renal anomalies are absent or ectopic kidney.
he most common types of MDAs to have associated renal
anomalies are uterus didelphys (oten with renal agenesis
ipsilateral to an obstructed horn) and unicornuate uterus
(usually renal agenesis ipsilateral to the side of the absent or
rudimentary horn).
ABNORMALITIES OF THE
MYOMETRIUM
Leiomyoma
Uterine leiomyomas, commonly referred to as ibroids, are
common benign neoplasms of the uterus. hey are composed
of varying amounts of smooth muscle and ibrous tissue. he
lifetime prevalence of uterine leiomyomas is greater than 80%
among black women and approaches 70% in white women. 72
Some women with leiomyomas are asymptomatic but leiomyomas
can cause abnormal vaginal bleeding, pain, or “bulk” symptoms
such as bowel or bladder dysfunction. 72
Causes of Uterine Enlargement
Normal variant
Fibroids
Adenomyosis
Obstructed uterus
Malignancy
Endometrial cancer
Uterine sarcoma
Cervical cancer
Leiomyomas can be classiied by location: submucosal (abutting
the endometrium), intramural (within the myometrium) and
subserosal (involving the serosal surface of the uterus). Some
subserosal leiomyomas are pedunculated, with a common deinition
having the center of the leiomyoma outside the uterus and
attached to the uterus by a stalk narrower than 50% of the diameter
of the leiomyoma. 73 Pedunculated subserosal leiomyomas may
be diicult to distinguish from a solid ovarian neoplasm if the
ipsilateral ovary is not identiied. In such cases, it is oten helpful
to use color or power Doppler imaging to search for vessels
connecting the leiomyoma to the uterus (Fig. 15.11). Leiomyomas
occasionally occur in the cervix. Submucosal leiomyomas, many
of which can be treated hysteroscopically, are oten subclassiied
into type 0 (completely within the endometrial cavity), type I
(more than 50% in the endometrial cavity), and type II (less than
50% in the endometrial cavity). 74 his distinction is important