o_1977r8vv9vk1ts2ms0kd8pksa.pdf

572 I. Zalud
Fig. 39.4. Corpus luteum vascularization detected by color
Doppler sonography. Such small randomly dispersed vessels
are difficult to study without color as a guide
mature follicle that has completed development. Increased
vascularity on the innermost rim of the follicle
may represent the dilatation of new vessels that
have developed between the relatively vascular theca
cell layer and the normally hypoxic granulose cell
layer of the follicle. It is hoped that information on
ovarian perfusion may be used both to predict ovulation
and to investigate ovulatory dysfunction.
Color flow is more easily obtainable from ovarian
tissue in the luteal phase. The qualitative postovulatory
changes in intraovarian blood flow are characterized
by increased turbulent flow accompanying morphological
changes in the intraovarian vascular network and
appearance of numerous arteriovenous shunts during
the luteal phase (Fig. 39.4). In summary, changes in
the intraovarian blood flow occur before ovulation, implying
a complexity of these changes that may involve
both angiogenesis and hormonal factors, while postovulatory
vascular accommodation is potentially important
in the luteal phase. Using transvaginal color Doppler,
corpus luteum blood flow, characterized by low
impedance and high flow requirements, can easily be
detected in normal early pregnancy, ectopic pregnancy,
and nonpregnant women.
Benign Uterine Pathology
Transabdominal ultrasonography permits gross visualization
of the uterine corpus through the distended
urinary bladder. Estimates of size in terms of the
sagittal, anteroposterior, and transverse diameters are
easily obtained. In the clinical setting of an enlarged
uterus (e.g., leiomyomata uteri) transabdominal scanning
may be helpful.
Transvaginal scanning permits close examination of
a structure of interest within the corpus or cervix of the
normal or slightly enlarged uterus. Proximity and higher-frequency
probes provide improved imaging and infrastructural
detail not possible with the transabdominal
approach. With the advent of color Doppler analysis,
additional physiologic/functional and pathologic
states may be identifiable. The blood supply to the
uterus, the uterine arteries, are direct branches of the
hypogastric artery and have a typically high-resistance/low-diastolic-flow
velocity waveform. Pulsedwave
Doppler analysis of the uterine artery has been
described previously. Color Doppler analysis allows
identification of the small vessels within the myometrium
(e.g., arcuate arteries and their branches). Again,
the age of the patient, phase of the menstrual cycle,
pregnancy state, and pathologic conditions influence
the type of velocity waveform obtained.
Fibroids/Leiomyomas
Leiomyomas are benign tumors of the uterine myometrium.
They are derived from the mitotic division
of a smooth muscle cell within the uterine wall.
Among a screened population of women over 40
years of age, 25%±30% exhibit findings of intramural
leiomyomas. They are often incidental findings, as
they may occur in a uterus of overall normal size.
Utilizing two-dimensional transvaginal scanning in
the sagittal and transverse planes, leiomyomas can be
described as intramural, submucous, subserosal, fundal,
cervical, or intracavitary; anterior or posterior;
lateral left or right. A variety of sonographic images
are seen in leiomyomas. The internal echogenicity depends
on the amount of smooth muscle and fibrous
tissue, degeneration, and vascularity. Leiomyomas can
undergo cystic degeneration (echo-lucent) or, conversely,
calcific degeneration (echogenic) with shadowing,
as well as the spectrum in between.
The addition of color Doppler analysis facilitates
determination of the predominance of myometrial
vessels feeding a leiomyoma and the type of flow present.
The Zagrebgroup studied uterine flow and
myometrial vessel flows in women with fibroids [4].
Diastolic flow is present in the myometrial vessels
and is usually increased relative to that seen in the
uterine arteries. Uterine artery flow velocity in the
normal uterus has a mean RI of 0.84. In women with
leiomyomas a slight decrease in the mean RI to 0.74
was observed. The mean RI of myometrial blood flow
in these patients was 0.54.
In the clinical setting localization and flow determinations
of leiomyomas may be helpful. Such information
might influence one's surgical approach. In
addition, the utility and effectiveness of new treatment
modalities may become subjects of color Doppler
analysis.
Investigations on the use of gonadotropin-releasing
hormone (GnRH) analogs for treatment of leiomyoma