Читать книгу Point-of-Care Ultrasound Techniques for the Small Animal Practitioner - Группа авторов - Страница 299

It is important for the nonradiologist veterinarian to respect the limitations of the POCUS spleen examination because of the sonographic variability of many diffuse and nodular conditions. Fortunately, the spleen is amenable to minimally invasive cytological evaluation by percutaneous needle biopsy or aspirates when sonographic abnormalities are identified.

Although hemorrhage is an uncommon complication of percutaneous fine needle biopsy, the AFAST format with fluid scoring system (see Chapters 6 and 7) is an excellent tool for postsampling monitoring (four hours post procedure and as needed thereafter), and is more sensitive than traditional means such as packed cell volume (hematocrit) for occult hemorrhage. Finally, a splenectomy with appropriate culture and histopathological testing may be required for definitive diagnosis and treatment plan, and the spleen may be surgically removed with little long‐term consequence in both dogs and cats. Global FAST is an especially helpful approach to rapidly survey for pleural and pericardial effusion, and cardiac and pulmonary abnormalities, and is used as a screening test to rapidly discriminate between localized and disseminated disease, comorbidities, and complications (see Chapters XX and XX).

 Evaluation of splenomegaly is a subjective assessment in dogs unless splenic enlargement is severe.

 Splenomegaly in cats is almost always due to pathology and warrants additional evaluation.

 Nodular and mass lesions within the splenic parenchyma are common and usually easy to identify. It is not possible to distinguish benign and malignant processes without cytology or histopathology.

 Splenic hematoma and hemangiosarcoma cannot be differentiated on the basis of ultrasound alone, and may be concurrent. However, use of the Global FAST approach is helpful to rapidly screen for localized versus disseminated disease.

 If the origin of an abdominal mass is difficult to determine, move the patient from dorsal to lateral recumbency. By doing so, the liver and spleen will often separate from one another, helping to better determine the origin of the mass.

 Needle visualization by ultrasound facilitates fine needle percutaneous biopsy of the spleen. Nonspecific cytology results with fine needle biopsy do not rule out the possibility of a malignant lesion, and further diagnostics are required. However, the use of the Global FAST approach is helpful to rapidly screen for localized versus disseminated disease.

 Mild diffuse changes in echogenicity are subjective and can be challenging for the novice sonographer.

 Remember the mnemonic “SLiCK” regarding the echogenicity between the spleen (S), liver (Li), and cortex of the kidney (CK). The echogenicity of the spleen is greater (brighter) than the liver, which is slightly greater (brighter) or isoechoic (same as) than the cortex of the kidney. For the feline, hepatic echogenicity is often compared to the adjacent falciform fat and the feline liver should be isoechoic to slightly hypoechoic to the falciform fat.

 Several benign processes cause mild to moderate diffuse changes in echogenicity including extramedullary hematopoiesis, passive congestion, and antigenic stimulation.

 Diffuse changes associated with lymphosarcoma or other myeloproliferative disorders can be variable in appearance and occasionally can be associated with a normal or unremarkable splenic appearance.

 Fine needle percutaneous biopsies are indicated in cases of moderate to severe splenomegaly or in animals with diffuse changes in echogenicity.