Diagnostic ultrasound ( PDFDrive )

506 PART II Abdominal and Pelvic Sonography
M
A
B
M
C
FIG. 14.3 Optimization of Technique. Stage 3 Papillary Serous Adenocarcinoma of
the Ovary. (A) Suprapubic sagittal image of the right adnexa using a 5.2-MHz curvilinear
transducer, taken at the initial survey, shows ascites and a solid, lobulated, hypoechoic
mass (M). The ield of view includes the full depth of the peritoneal cavity. (B) Transabdominal
sagittal image of the left lank using a higher frequency, 7.4-MHz, curvilinear transducer
shows ascites and hypoechoic seeding on the serosal surface of the descending colon
(arrows). A low gain setting is used to optimize visualization of the seeding, seen as a thin,
continuous line on the serosal surface of the gut, which contains shadowing air. (C) Transverse
TVS of the right adnexa using an 8.4-MHz probe shows the right adnexal mass (M) and
particulate ascites. A high gain setting is used to better characterize the particulate ascites.
he ield of view (FOV) is set to include the full depth of the
peritoneal cavity, but no more; this adds perspective to the image.
he focal zone is continually adjusted to evaluate in detail diferent
depths within the FOV. he power and gain settings are also
adjusted using a high gain setting to characterize free luid as
anechoic or particulate and a low gain setting to visualize
hypoechoic nodules or masses optimally. Once the initial survey
is complete, higher-frequency transducers are used to more
carefully evaluate and characterize abnormalities in the near
ield (Fig. 14.3B).
When scanning transabdominally, graded compression is used
to displace bowel gas. Determination of the site of origin of a
peritoneal process may be aided by several techniques. Palpation
of an abnormal mass, either with the transducer or with the free
hand, will determine both the compliance and the mobility of
a mass. Masses arising from the parietal peritoneum are oten
ixed, whereas masses arising from the visceral peritoneum may
be mobile. his distinction may also be demonstrated by changing
the patient’s position or with changes in respiration. For example,
in the right upper quadrant, a lesion in the near ield is likely
to be located on the parietal peritoneum if the liver moves
independent of it with respiration.
A transvaginal sonography (TVS) examination is critical
for all female patients at risk for or with suspected peritoneal
disease (Fig. 14.3C). he pelvic pouch of Douglas is a common
site of involvement, particularly in carcinomatosis and acute
conditions. his technique allows exquisite assessment of both
the parietal and the visceral pelvic peritoneum. 10,11 In addition
to assessing the uterus and ovaries, the probe should be directed
to the pouch of Douglas, by elevating the examining hand (Fig.
14.4), and to both pelvic side-walls. A dynamic assessment is
oten helpful to help establish the origin of a nodule or mass
(Videos 14.2 and 14.3). he TVS may also facilitate improved
visualization of pelvic bowel loops and the urinary bladder.
Ultrasound is an accurate, fast, and eicient means of guiding
interventions involving the peritoneum and peritoneal cavity
and is frequently the modality of choice to guide diagnostic and
therapeutic paracentesis and biopsy of peritoneal masses. 12
ASCITES
One of the earliest uses of sonography in the abdomen and pelvis
involved the detection of ascites. 13 Normally, 50 to 75 mL of free
luid is present in the peritoneal cavity, acting as a lubricant.
Ascites occurs with excess accumulation of peritoneal luid.
Ascites can be classiied as transudate or exudate depending
on the protein content. In North America, cirrhosis, peritoneal
carcinomatosis, congestive heart failure, and tuberculosis account