Ultrasound for Vets, by Dr.Kishor Mahind---Spleen

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The Spleen:

The spleen is variable in position and may be difficult to find in the normal animal, especially in cats. The animal should be placed in right lateral recumbency. The head of the spleen can usually be found next to the stomach by placing the transducer parallel to the last rib on the left, several inches from the midline. Once the head is found, the rest of the spleen can be followed obliquely across the ventral abdomen or running down the left flank.

Normal appearance: The spleen is more densely textured than the liver and so generally appears more echogenic. The outline of the spleen should be smooth and well defined. The head of the spleen is in a fixed position but the tail is relatively mobile and its exact location reflects those of the surrounding organs. In many cases, the caudal portions of the liver lobes can be imaged in the same slice as the spleen. However, the stomach is located between these 2 organs and if it is distended then it may displace the spleen caudally therefore increasing the distance between them. The splenic artery supplies the spleen, which can be difficult to identify on ultrasound without the aid of Doppler. It is drained by the splenic veins and unlike the liver where the veins can be seen throughout the parenchyma, splenic veins are only visible in the perihilar region. They are broad vessels, which can be followed, as they leave the spleen.

Spleen Spleen

Liver and Spleen

Abnormal findings: Focal abnormalities within the parenchyma may be hypoechoic or, more commonly, of mixed echogenicity. They often protrude from the surface of the spleen, and may be highlighted by the presence of free abdominal fluid. Such masses are usually neoplasms or hematomas. A diffuse decrease in echogenicity has been described in association with splenic torsion. Study has revealed ultrasound to be most accurate single diagnostic tool for detecting splenic hemangiosarcoma and resulting hepatic metastasis. The vagueness of the clinical signs, the inability to palpate all splenic masses, the concurrent peritoneal effusion comprising radiographic interpretation and the lack of specific lab tests made these procedures less reliable than USG

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