Diagnostic ultrasound ( PDFDrive )

570 PART II Abdominal and Pelvic Sonography
FIG. 16.6 Postmenopausal Large Ovarian Cyst. TVS image of a
7-cm ovarian cyst that contains no internal echoes or septations and
had not changed in size over 4 years.
and greater than 1 cm in diameter be followed by serial yearly
sonographic examinations without surgical intervention unless
there is an increase in size or change in the characteristics of
the lesion. Cysts measuring less than 1 cm are felt to be almost
certainly benign and follow-up is not necessary. Surgery is usually
recommended for postmenopausal simple cysts greater than 7 cm
and for those containing multiple internal septations or one or
more solid nodules. However, magnetic resonance imaging (MRI)
is better able to characterize these larger cysts in which small
mural nodules can be missed by ultrasound and thus may be a
reasonable alternative to surgery. 28
NONNEOPLASTIC LESIONS
Functional Cysts
Functional cysts are physiologic and not neoplastic lesions of
the ovary whose appearance and disappearance is hormonally
driven. hese cysts may be simple or hemorrhagic and are commonly
divided into three categories: follicular, corpus luteum,
and theca lutein cysts. Acute abdominal pain caused by internal
hemorrhage, rupture, or leakage is the most common symptom,
but pelvic discomfort may simply be the result of the large size,
greater than 2.5 to 3.0 cm.
A follicular cyst develops when a mature follicle fails to ovulate
or to involute. Because normal follicles can vary from a few
millimeters up to 2.5 cm, a follicular cyst cannot be diagnosed
with certainty until it is larger than 2.5 cm. herefore a simple
cyst less than 2.5 cm in a premenopausal woman should be
referred to as a follicle and considered to be normal. Follicles
and follicular cysts are usually unilateral, asymptomatic, and
frequently detected incidentally on sonographic examination.
Follicular cysts usually regress spontaneously.
Ater ovulation, the corpus luteum develops and may be
identiied sonographically as a small, hypoechoic or isoechoic
structure within the ovary. he corpus luteum usually contains
low-level internal echoes, frequently with a thicker wall than a
follicle and a crenulated appearance. It typically has a peripheral
rim of color around the wall on color Doppler ultrasound (ring
of ire; see Fig. 16.3C). he corpus luteum usually involutes before
menstruation but may persist because of failure of absorption
or internal bleeding. Timor-Tritsch and Goldstein 35 recommend
using the term corpus luteum rather than corpus lutein cyst unless
it is greater than 4 cm. Corpus lutein cysts are less common than
follicular cysts but tend to be larger and more symptomatic. Pain
is the major symptom. hese cysts are usually unilateral and are
prone to hemorrhage and, less commonly, rupture. If the ovum
is fertilized, the corpus luteum continues as the corpus luteum
of pregnancy, which may become enlarged with a simpler cystic
appearance than the original corpus luteum. Maximum size is
reached at 8 to 10 weeks of gestation, and by 16 weeks the cyst
has usually resolved. 36
heca lutein cysts are associated with high beta–human
chorionic gonadotropin (B-hCG) levels and are the largest of
the functional ovarian cysts, increasing the risk of ovarian torsion.
hese cysts typically occur in patients with gestational trophoblastic
disease but can also be seen as a complication of drug
therapy for infertility causing ovarian hyperstimulation syndrome.
Sonographically, theca lutein cysts are usually bilateral, multilocular,
and very large. Similar to other functional cysts, they
may undergo hemorrhage or rupture.
Although hemorrhage may occur in all types of functional
cysts, it is most frequently seen in corpus luteal cysts. Women
with hemorrhagic cysts frequently present with acute onset of
pelvic pain. Hemorrhagic cysts show a spectrum of indings
because of the variable sonographic appearance of blood (Fig.
16.7, Video 16.2). he appearance depends on the amount of
hemorrhage and the time of the hemorrhage relative to the time
of the sonographic examination. 37-39 he internal architecture is
much better appreciated on TVS when compared to TAS because
of its superior resolution. An acute hemorrhagic cyst is usually
hyperechoic and may mimic a solid mass. However, it usually
has a smooth posterior wall and shows posterior acoustic enhancement,
indicating the cystic nature of the lesion. Difuse low-level
internal echoes may be appreciated, although this appearance
is more frequently seen in endometriomas. As the clot hemolyzes,
a reticular-type pattern is demonstrated internally containing
intertwining linear internal echoes representing ibrin strands. 40
hese should not be confused with septations, which are thicker.
As the clot retracts, it will have a concave outer margin with
angularity compared with a solid mural nodule, which will have
a convex outer margin. Color Doppler ultrasound will show no
low within the clot but will demonstrate peripheral vascularity
within the cyst wall. Care should be taken when assessing for
low in hemorrhagic cysts, because a clot can move and show
color without true vascularity. Spectral Doppler can be helpful
in these cases. Patel et al. 40 found that a speciic diagnosis could
be made in approximately 90% of hemorrhagic cysts by demonstrating
the presence of a reticular pattern or a retractile clot.
he presence of echogenic, free intraperitoneal luid in the