Diagnostic ultrasound ( PDFDrive )

158 PART II Abdominal and Pelvic Sonography
S
FIG. 5.29 Gaucher Disease. Enlarged spleen containing a 2-cm
heterogeneous nodule. (Courtesy of M. Maas, MD, Amsterdam.)
Splenic Trauma
he spleen is the most frequently injured visceral organ in patients
with blunt abdominal trauma. he spectrum of splenic injuries
ranges from contusion to a completely shattered spleen. he
severity of the splenic injury can be scored using the American
Association for the Surgery of Trauma Organ Injury Scoring
Scale. 77 Treatment options depend on hemodynamic and clinical
criteria and include conservative management with or without
embolization and surgery. 4
Ultrasound can be very helpful and highly accurate in the
diagnosis of splenic injury. However, CT has proved particularly
useful in this area because the severity of splenic injury is better
assessed and other abdominal injuries can be identiied in one
examination. 78 In addition, traumatic splenic vascular injuries
(e.g., active bleeding, pseudoaneurysms, arteriovenous istulas)
are diicult to detect with ultrasound. 79 However, splenic injury
is not always clinically apparent and spontaneous splenic rupture
or pathologic splenic rupture can occur ater negligible trauma
or insigniicant events such as coughing. 26 his is typically seen
in patients with a pathologically enlarged spleen caused by the
altered consistency and splenic extension below the rib cage.
Advantages of ultrasound are that it is fast, portable, and
easily integrated into the resuscitation of patients with trauma
without delaying therapeutic measures. 80 In addition, if the patient
is hemodynamically unstable, obtaining a CT scan may not be
feasible. 81 herefore ultrasound examinations performed in the
emergency department ater blunt abdominal trauma should
not only focus on free intraabdominal luid but also evaluate
the solid organs. Further, now that nonsurgical management is
preferred, ultrasound is helpful for numerous follow-up examinations.
CEUS may also be used to increase the sensitivity of
ultrasound for parenchymal injury. 82
When the spleen is involved in blunt abdominal trauma, two
outcomes are possible. If the capsule remains intact, the result
may be an intraparenchymal or subcapsular hematoma (Fig.
5.30). If the capsule ruptures, a focal or free intraperitoneal
hematoma may result. With capsular rupture, it might be possible
to demonstrate luid surrounding the spleen in the LUQ. Although
blood oten spreads within the peritoneal cavity and can be found
in the pelvis or in the Morison pouch, on some occasions it
becomes walled of in the LUQ (Fig. 5.31).
It is important to consider the timing of the sonographic
examination relative to the trauma. Immediately ater the
traumatic incident, the hematoma is liquid and can easily be
diferentiated from splenic parenchyma. Ater the blood clots,
and for the subsequent 24 to 48 hours, the echogenicity of the
perisplenic hematoma may closely resemble the echogenicity of
normal splenic parenchyma and may mimic splenomegaly.
Subsequently, the blood re-liqueies and the diagnosis becomes
easy again. In splenic injuries, there are oten focal areas of
inhomogeneity within the spleen, but these can be subtle (Fig.
5.32).
here is no clear consensus as to whether imaging follow-up is
clinically useful. 83 If follow-up is performed, the clinician may see
the subcapsular hematoma diferentiated from the pericapsular,
organized hematoma by the capsule itself (see Fig. 5.30B). he
splenic capsule is very thin and frequently not visualized separately
from adjacent luid. In these cases the shape of the luid collection
can provide an important clue to the location of the hematoma.
If the collection is crescentic and conforms to the contour of the
spleen, the hematoma is likely subcapsular. Irregularly shaped
collections are seen more with perisplenic hematomas.
Perisplenic luid may persist for weeks or even months ater
splenic injury. Although there may actually be a condition of
delayed rupture of the spleen, it is possible that all ruptures of
the spleen occurred at the time of injury and were walled of
initially. 84 Delayed rupture may be only the extension of blood
into the peritoneal cavity ater liquefaction of a perisplenic
hematoma.
Aside from splenic capsule rupture, there may be internal
damage to the spleen with an intact splenic capsule. his can
result in intraparenchymal or subcapsular hematoma of the spleen,
which initially appears only as an inhomogeneous area in the
otherwise uniform splenic parenchyma. Subsequently, the
hematoma may resolve, and repeat scans may show cystic change
at the site of the original injury.
Sonographically, a perisplenic hematoma can closely mimic
a perisplenic abscess. A hematoma can also become infected
and transform into a let subphrenic abscess. 44 If the distinction
cannot be made clinically, ine-needle aspiration can diferentiate
between a hematoma and an abscess.
CONGENITAL ANOMALIES
Accessory spleens, also known as splenunculi, are common
normal variants found in up to 30% of autopsies. hey are typically
located near the splenic hilum and have similar echogenicity as
the normal spleen. Splenunculi may be confused with enlarged
lymph nodes around the spleen or with masses in the tail of the
pancreas. When the spleen enlarges, the accessory spleens may
also enlarge. Ectopic accessory spleens described in various
locations, including the pancreas and scrotum, are typically
confused with abnormal masses or, in rare cases, can undergo
torsion and cause acute abdominal pain. 85,86 he vast majority