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Chapter 160 The Spleen and Its Disorders 2319

EXAMINATION OF THE SPLEEN examination. Accessory spleens tend not to be well visualized on
routine ultrasonography. In the hands of a skilled operator, endoscopic
Maneuvers for examination of the spleen involve inspection, percus- ultrasound-guided biopsy permits accurate diagnosis of lesions as
sion, and palpation, but their sensitivity and specificity vary based on small as a centimeter or less, which compares well with results obtained
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patient factors (such as body habitus) and operator skill. The pretest using computed tomography (CT). High-frequency sonography has
probability of splenomegaly, based on associated historical and significantly better resolution and can visualize both nodularity within
clinical data, influences the positive–predictive value of finding the spleen, which occurs in childhood as immunity is acquired, and
splenomegaly on physical examination. If the pretest probability of accessory spleens and splenosis after splenic rupture or trauma.
splenomegaly is less than 10%, then physical examination maneuvers CT imaging has the advantage of showing the anatomy and some
are inadequate for determining the presence or absence of spleno- aspects of splenic function. Contrast material in the gastrointestinal
megaly. For those patients with a greater than 10% pretest probability tract helps delineate splenic tissue when it impinges on this system.
of splenomegaly (for instance, patients with suspected infectious Intravenous contrast material is required to delineate splenic lesions
mononucleosis), the examination begins with inspection and then whose density is the same as normal splenic tissue. Abscesses have a
percussion of Traube’s space—defined by the sixth rib superiorly, the rim of contrast agent enhancement.
anterior axillary line, and the costal margin. For adequate examina- CT can be used to estimate the volume of the spleen. Accessory
tion of the spleen, the patient must be fully supine, relaxed, with arms spleens have the same attenuation as a normal spleen, which is some-
adjacent to the trunk. Dullness to percussion in Traube’s space should what less than that of liver. Accessory spleens are usually located in the
be followed by palpation. Beginning in the right iliac fossa, the gastrosplenic ligament near the hilum. Subcapsular and intrasplenic
examiner’s hand gently advances toward the left upper quadrant. This hematomas and splenic lacerations are clearly seen on CT. Leukemias
minimizes the likelihood that a grossly enlarged spleen will be missed, and many inflammatory diseases produce diffuse splenomegaly, while
and the lower pole and medial border should be easily appreciated. granulomas and infarcted areas eventually calcify. Cysts, abscesses, and
If the spleen cannot be felt with this approach, the left hand of the some malignancies may have a homogeneous pattern on CT scan.
examiner is placed on the left flank, lifting the lower part of the rib Although not replacing other methods of staging, splenic enlargement
cage to displace the spleen medially toward the examiner’s right hand. on CT may direct follow-up studies and indicate prognosis.
The splenic notch should be felt in the inferior medial border. Rotat- In addition to imaging the spleen, CT can be used to direct thera-
ing the patient into the right lateral decubitus position while still peutic interventions. Abscesses, hematomas, and cysts can be drained
recumbent may make it easier to palpate the spleen. The spleen (see box on Management of Splenic Cysts). As long as portal pressures
should move with deep inspiration. The degree of enlargement is are normal and vascular lesions have been adequately excluded, thin-
usually measured in centimeters below the costal margin. Depending needle aspiration under CT guidance is generally a safe intervention.
on the position of the spleen within the abdomen, it may be difficult CT scanning of the abdomen, performed as part of the initial emer-
to appreciate even significant enlargement. Normal splenic size in an gency department evaluation of patients with abdominal trauma,
adult is up to 250 g and up to 13 cm in its long axis. Up to half of may avert hospital admission and prevent exploratory laparotomy. 10
spleens weighing 600–750 g are not palpable. Greater degrees of Magnetic resonance imaging (MRI) is useful for identifying vas-
splenomegaly are easier to appreciate on physical examination. In cular lesions, which would otherwise require angiography, and splenic
terms of sensitivity and specificity, there does not appear to be a infections. It is more difficult to image the contents of the upper
difference between examination in the supine position and examina- abdomen with MRI than with CT because of respiratory motion.
tion in the right lateral decubitus position, although both of these With more rapid imaging technology, MRI has gained considerable
parameters are dependent on the experience of the examiner. utility for imaging infectious and vascular lesions of the spleen.
Up to 15% of normal children and 3% of young adults have Hepatosplenic candidiasis and other infections to which immuno-
palpable spleens without evidence of illness. The spleen involutes with compromized patients are susceptible can be identified noninvasively
age, and a spleen that is palpable in an older person is unlikely to be with modern MRI technology.
a normal variant and more likely to be associated with clinical disease. Through the use of T2* sequences MRI imaging of the spleen
Due to various abnormalities, the spleen may not be located in its allows quantitative measurement of iron burden in organs that
usual anatomic position. It may migrate from its normal abdominal accumulate iron, although the liver and heart are more commonly
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position to the left mid-abdomen or even the left lower quadrant. imaged for this purpose. 11
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While a rare finding, this highlights the need to pay particular atten- Positron emission tomography (PET) scanning using F-2-
tion to the lower abdomen when palpating for the spleen. deoxyglucose is used in the diagnosis, staging, and monitoring of
both non-Hodgkin and Hodgkin lymphoma. It is more sensitive than
IMAGING OF THE SPLEEN

Radionuclide scintigraphy assesses anatomic and functional aspects Management of Splenic Cysts
of the spleen. The most common procedure is a liver-spleen scan in
which technetium-99m ( 99m Tc) sulfur colloid is injected intravenously A 37-year-old woman with no past medical history comes in for evalu-
and taken up by hepatic and splenic macrophages. It is the phagocytic ation of early satiety and left shoulder pain. She reports that she feels
activity of macrophages, rather than the presence of the spleen itself full after only a few bites of any meal and sometimes becomes nause-
or any aspects of lymphoid function, that is assessed. A dynamic ated and vomits. Physical examination is remarkable for an enlarged,
99m Tc scan can also assess the distribution of blood within the portal nontender spleen. Imaging shows a large splenic cyst.
system and suggest the presence of portal hypertension. Infusion of • Many conditions can lead to cyst formation in the spleen
99m Tc-labeled or Indium-111–labeled platelets with scintigraphy to including parasitic infections, trauma, hemangiomas, and
polycystic kidney disease.
determine their relative distribution in the liver and spleen has been • Asymptomatic nonparasitic cysts may be observed with
used with considerable, but not absolute, success to predict the clini- careful attention and plan for intervention should they become
cal efficacy of splenectomy in patients with immune thrombocytope- symptomatic, rupture, or become infected.
nia purpura (ITP). • Symptomatic cysts may require percutaneous drainage with
Ultrasonography readily shows the size, shape, and several aspects radiologic guidance or sometimes surgical procedures including
of splenic anatomy, including the presence of cysts and abscesses. The partial or total splenectomy.
procedure is noninvasive, painless, of low cost, avoids radiation • Parasitic cysts should be treated in consultation with infectious
exposure for patients, and is a good screening study when the spleen disease specialists as the particular parasitic infection, radiologic
appearance, and patient comorbidities will guide choice of
is thought to be enlarged. In 95% of the normal population, the therapies.
long axis of the spleen measures less than 12 cm on ultrasound