Avaliação semiológica e diagnóstico em pequenos animais - Aula 16 a 16.1

Summary

This lesson focuses on the semiological evaluation and diagnostic process in small animals, particularly examining lymph nodes. It covers their anatomical features, role in the immune system, and the importance of ultrasonography in diagnosing conditions related to these nodes. The script explores various lymph node types, their locations, and the associated diagnostic tools, including transducers and ultrasonographic features. Key points include assessing the size, shape, and texture of lymph nodes to detect potential abnormalities, with emphasis on identifying possible malignancies and utilizing additional diagnostic tests for accurate interpretation.

Takeaways

• 😀 The lesson focuses on semiological evaluation and diagnosis in small animals, with a particular emphasis on lymph node assessment.
• 😀 Lymph nodes are crucial components of the immune system, responsible for filtering lymph and defending against foreign agents, such as bacteria and viruses.
• 😀 Ultrasonography is an important diagnostic tool for assessing lymph node size, structure, and any pathological changes.
• 😀 Lymph nodes can be categorized based on their location and the organs they drain, including gastric, pancreatic, hepatic, and splenic nodes.
• 😀 Each lymph node has a connective tissue capsule that appears as hyperechoic (bright) on ultrasound, which helps in identifying them.
• 😀 Lymph nodes may have varied shapes depending on their location, ranging from fusiform to oval, with regular borders.
• 😀 The central area of lymph nodes can show hyperechoic areas due to dense tissue, and may also contain blood and lymphatic vessels.
• 😀 In small animals, different types of transducers (high-frequency) are used to assess superficial or deep lymph nodes depending on their location.
• 😀 Lymph node enlargement or structural changes can indicate inflammation or malignancy, with careful analysis required to determine the severity.
• 😀 The ratio of lymph node size in longitudinal and transverse axes should generally be less than 0.7 cm to avoid suggesting malignancy; larger values could raise suspicion.
• 😀 Additional diagnostic tests, beyond ultrasonography, are required for a comprehensive evaluation, especially in the case of potential malignancy.

Q & A

What is the primary function of lymph nodes in the body?

Lymph nodes are part of the immune system, and their primary function is to filter lymph, removing harmful microorganisms such as bacteria and viruses, and aiding in immune responses, including the production of antibodies.

Why is ultrasound used to assess lymph nodes?

Ultrasound is used to evaluate lymph nodes as it allows for a non-invasive, real-time imaging technique that can help detect changes in lymph node size, structure, and density, which could indicate potential pathology such as inflammation or malignancy.

What does the capsule around a lymph node appear as on ultrasound?

On ultrasound, the capsule of a lymph node appears as a hyper-echoic halo, which is a bright ring surrounding the node. This capsule is made of connective tissue and is an important feature for identification.

What are some of the specific types of lymph nodes in the body?

Lymph nodes are named based on the organs they drain. For example, gastric lymph nodes drain the stomach, pancreatic lymph nodes drain the pancreas and duodenum, splenic lymph nodes drain the spleen, and mesenteric lymph nodes drain the intestines.

What is the importance of selecting the appropriate ultrasound transducer for imaging lymph nodes?

The choice of ultrasound transducer is crucial because different lymph nodes are located at varying depths in the body. A high-frequency transducer is typically used for superficial nodes in small animals, while other transducers may be needed for deeper nodes.

How do lymph nodes appear on ultrasound in terms of echogenicity?

Lymph nodes typically appear iso-echoic or slightly hypo-echoic compared to the surrounding adipose tissue. The texture is fine, and the borders of the lymph node should be smooth and well-defined.

What does the central area of a lymph node contain, and how is this relevant on ultrasound?

The central area of a lymph node contains blood vessels and lymphatic vessels. On ultrasound, this area may appear more hyperechoic due to the denser tissue in the center, and larger vessels may become more visible with increased inflammation or pathology.

What are the implications of an enlarged lymph node based on ultrasound measurements?

Enlarged lymph nodes can indicate inflammation, infection, or malignancy. If the size ratio (measured in transverse and longitudinal axes) exceeds 0.7 cm, this may suggest a pathological condition, with a ratio above 0.5 cm potentially indicating malignancy.

What are the different types of lymph nodes in the abdominal region, and what do they drain?

In the abdominal region, there are several types of lymph nodes including renal lymph nodes (drain the kidneys), iliac lymph nodes (drain the lower abdomen), sacral lymph nodes (drain the pelvic area), and others associated with the spleen, liver, pancreas, and gastrointestinal system.

What factors should be considered when evaluating lymph nodes in clinical practice?

When evaluating lymph nodes, clinicians should assess several factors including size, shape, echogenicity, border smoothness, and texture. Additionally, the ratio of transverse to longitudinal size should be considered, and other diagnostic tests may be required to confirm findings.