Left Upper Quadrant Pain



Left Upper Quadrant Pain


Sheryl E. Goss



Objectives



• List the basic anatomy and physiology of the spleen.


• Describe the sonographic appearance of a normal spleen.


• List the congenital variants of the spleen that may occur, and describe the associated sonographic appearances.


• List the causes of splenomegaly.


• Describe the most common benign splenic neoplasms.


• Identify the sonographic findings associated with blunt trauma to the spleen.


• Define the most common malignant splenic neoplasms.


• Differentiate between the sonographic appearances of benign and malignant neoplasms.


• List the causes of splenic infarct.


• Identify Doppler findings associated with specific splenic anomalies.



Clinical Scenario


An African American infant was recently hospitalized for hemolytic disease and right hemiparesis secondary to cerebral infarctions, ischemia, and clinical enlargement of the liver and spleen. Computed tomography (CT) scan of the abdomen performed 3 days before the sonogram revealed significant hepatosplenomegaly with heterogeneity of the spleen (Fig. 8-1, A). The sonogram demonstrates hypoechogenicity of the posterolateral aspect of the spleen compared with the anteromedial aspect (Fig. 8-1, B). Color Doppler shows flow in the anteromedial tissue and absence of flow in the posterolateral aspect (Fig. 8-1, C; see Color Plate 8). What is the most likely diagnosis?


image
FIGURE 8-1 (A), CT image demonstrates hepatosplenomegaly with irregularity of the spleen. Heterogeneity of spleen (B) and absence of color flow in the regions of hypoechogenicity (C).


Sonography of the spleen is not commonly requested as a focused examination, but rather the spleen is visualized with abdominal sonography, or a splenic sonogram is ordered as a follow-up from other imaging modalities, such as CT or magnetic resonance imaging (MRI). The advantages of sonography include cost-effectiveness, safety because of nonionizing imaging, and portability. The spleen is less often a site for primary disease. Pathologic processes such as portal hypertension, hematologic disorders, and infectious disorders are more commonly encountered. This chapter explores a variety of variants and congenital anomalies, neoplasms, and diseases that may affect the spleen, in conjunction with the clinical significance and sonographic findings.



Anatomy and Physiology


The spleen, an intraperitoneal organ, is located in the left upper quadrant (LUQ), with fixation to the greater curvature of the stomach by the gastrosplenic ligament and fixation inferiorly to the left kidney by the splenorenal ligament. Additional ligaments include the phrenicosplenic, providing support from the diaphragm, and splenocolic, providing support from the colic flexure. The shape of the spleen is often described as being convex on its smooth outer surface with close proximity to the diaphragm and pleural cavity. The medial surface is concave, containing the splenic hilum where the splenic artery, vein, and lymphatic vessels enter and exit.


The splenic artery, a branch of the celiac trunk, gives rise to the superior and inferior terminal branches on entering the hilum. Each of these vessels divides further into four to six segmental arteries. The intrasplenic arterial supply is unique in that the branch arteries do not anastomose or communicate with each other, and there is an increased risk for infarction because collateral flow does not occur. The central arterioles, small branches from the segmental arteries, provide blood to the white pulp, terminating in small sinuses. From these sinuses, blood is picked up by the pulp veins and ultimately flows into the portal venous system through the splenic vein. Splenic circulation along with the lymphatics aids the spleen in its physiologic functions.


Physiology of the spleen is complex because the spleen has multiple functions. It is the largest organ of the reticuloendothelial system. The spleen is responsible for filtering aged or damaged blood cells and assists in the body’s immune response to blood-borne pathogens. Although the spleen is not vital for life, it provides several key functions, including phagocytosis, antibody production, production of lymph cells, and a reservoir for erythrocytes and plasma cells. The composition of white and red pulp directs splenic function. The white pulp is responsible for immunity through production of antibodies, lymphocytes, and plasma cells. The red pulp comprises the reticuloendothelial tissue, which is responsible for phagocytosis, filtration of aged blood cells, and removal of misshapen or abnormal cells (referred to as culling and pitting).




Variants and Congenital Anomalies


Accessory Spleen


Accessory spleen, or splenunculus, is the most common congenital anomaly affecting the spleen, occurring in approximately 10% of the population.2 This variant is most commonly singular and located in the splenic hilum, although it may be located elsewhere in the abdomen, with a small percentage being multiple (spleniculi). The presence of an accessory spleen is usually insignificant, but accessory spleens may rarely undergo torsion or infarction; affected patients present with acute LUQ pain. Clinical symptoms should also be considered in differentiating between probable accessory spleens, neoplasms, and lymphadenopathy, which may have a similar sonographic appearance.



Sonographic Findings


Accessory spleens are usually round and have an echogenicity and homogeneity equal to the normal spleen (Fig. 8-3). Demonstration of the vascular connection from the accessory spleen to the normal spleen assists in confirmation of the diagnosis.


image
FIGURE 8-3 Accessory spleen is identified in the region of splenic hilum.


Ectopic Spleen


Ectopic spleen, a rare entity, may also be referred to as splenia ectopia or wandering spleen. The term “wandering spleen” describes an anomaly in which the spleen migrates from its normal position because of congenital or acquired laxity of the suspensory ligaments. Because of the mobility of the wandering spleen, it may also undergo torsion, resulting in acute abdominal pain and infarction.




Asplenia and Polysplenia


Asplenia and polysplenia are rare congenital anomalies most often associated with visceral heterotaxy, situs ambiguus complexes, or cardiopulmonary abnormalities. Asplenia is the absence of splenic tissue and a bilateral right-sidedness morphology of the heart and lungs. Other anomalies include a reversed aorta and inferior vena cava position or abdominal structures oriented in the midline, such as horseshoe kidney.


Polysplenia is characterized by the development of multiple small splenic nodules. Polysplenia is often associated with a left-sided dominance of lung and cardiac morphology and anomalous development of abdominal structures.




Splenomegaly


Splenomegaly, or enlargement of the spleen, is one of the most common anomalies of the spleen encountered by sonographers. Numerous causes of splenomegaly exist; congestive etiologies associated with portal hypertension are the most common (Fig. 8-5, A and B). Other causes include infection, hematologic disorders, immunologic disorders, trauma, neoplasia, vascular anomalies, and storage diseases. In addition to clinical symptoms associated with the underlying disease, patients with splenomegaly may have LUQ pain.


image
FIGURE 8-5 Longitudinal (A) and transverse (B) images show enlargement of the spleen with hilar vessel dilation associated with portal hypertension. (C), Extended field-of-view technique demonstrates enlarged spleen extending beyond the lower pole of the kidney. (A and B, Courtesy GE Medical Systems.)


Sonographic Findings


A diagnosis of splenomegaly (Fig. 8-5, C) may be made when the length of the spleen is greater than 12 cm.1 A subjective diagnosis of splenomegaly may also be made when the inferior tip of the spleen covers or extends beyond the inferior pole of the left kidney.




Cysts


With the detection of a cyst in the LUQ, sonographic examination can be useful in identifying the origin of the cyst—arising in the spleen or arising from adjacent organs such as the adrenal gland, gastrointestinal tract, or a pancreatic pseudocyst extending into the spleen (see Chapter 4). Laboratory tests and patient history may also aid in the differentiation of cyst origin. Cysts arising in the spleen may be classified as primary or true cysts, when they have an epithelial or endothelial lining, or secondary (pseudocysts), resulting from trauma, infection, or degeneration. Cysts in the spleen are uncommon and are usually benign. Splenic cysts may be identified on sonograms in asymptomatic patients as an incidental finding, although patients may have symptoms related to the cyst size or origin and may have LUQ pain.



Sonographic Findings


Sonographically, a cyst should appear as a well-defined, round or ovoid, thin-walled, anechoic lesion that shows acoustic enhancement (Fig. 8-6, A). Cysts associated with infection or trauma may show calcification of the cyst wall (Fig. 8-6, B). Cysts may also show fluid-debris levels from purulent material or hemorrhage. Splenic cysts are rare; in the absence of the classic sonographic features of a cyst, additional imaging or clinical follow-up is indicated to exclude neoplasm.


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FIGURE 8-6 (A), Coronal scan of spleen shows a 1.5-cm diameter cyst. (B), Calcified splenic cyst.

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Aug 27, 2016 | Posted by in ULTRASONOGRAPHY | Comments Off on Left Upper Quadrant Pain

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