Ultrasound offers a non-invasive means of “seeing” inside the body.

The ultrasound may be used to “guide” the doctor to a specific area for biopsy or aspirate of an organ or tissue. A biopsy obtains a core of tissue, whereas an aspirate collects a group of cell from the tissue.

The advantage of ultrasound guided biopsy and aspirates are that they are “non-invasive”. In other words, a body wall incision is not needed.

Why Ultrasound?

• Ultrasound offers a non-invasive means of “seeing” inside the body. By using ultra-high frequency sound waves instead of radiation, the ultrasound computer generates a picture of the various organs in the abdomen and chest. Ultrasound cannot be used to assess bones or air filled structures (lungs, trachea) because of the inability of ultra-high frequency sound waves to penetrate bone or be transmitted through air. Since ultrasound waves cannot travel through the air, your pet will need to have hair removed (clipped) in the area to be examined before the ultrasound study. Hair traps air and will interfere with the quality of the ultrasound study.
• Ultrasound studies allow your doctor to see changes occurring within the organs in the body. Regular radiographs (x-rays) allow determination of the sizes and shapes of structures within the body, but they do not allow for visualization inside of these structures. Ultrasound affords the clinician the ability to see inside the organs of the body.
• Changes seen within an organ are not necessarily consistent with only one disease; many diseases cause similar changes within an organ or tissue. However, ultrasound will often assist the clinician in narrowing the list of possible diseases affecting the patient. Ultrasound is also valuable in detecting the presence of cancer.
• Because of the limits of resolution afforded by ultrasound or from interference by gas within organs or overlying bone structures, a normal ultrasound study does not necessarily discount the presence of disease or cancer.
  

Ultrasound Guided Tissue Biopsies and Aspirates

• The ultrasound may be used to “guide” the doctor to a specific area for biopsy or aspirate of an organ or tissue. A biopsy obtains a core of tissue (see biopsy needle above right and needle seen on the ultrasound below right), whereas an aspirate collects a group of cell from the tissue. The major risk associated with an ultrasound guided biopsy or aspirate is bleeding from the biopsy or aspirate site. Some diseases can affect the body’s ability to form a blood clot. Testing for this ability may be required before the biopsy or aspirate is done in order to ensure that your pet can properly form a clot and to minimize the chance of potentially fatal bleeding. In some situations, bleeding will still occur, and if severe, may require a blood transfusion.
• There are certain conditions that make it difficult or impossible to perform an ultrasound guided biopsy or aspirate. These include delayed clotting ability, fluid within the abdomen or chest cavity, or the organ being too small or too far away from the body wall to reach. If there is fluid in the abdomen (ascites) or chest, the ultrasound needle cannot adequately penetrate the organ or tissue (similar to bobbing for apples). If the organ is too small, the biopsy needle may go through other organs before reaching it, endangering the pet and decreasing the quality of the biopsy. Because the size of the biopsy obtained with an ultrasound guided needle is smaller than that obtained via surgery or laparoscopy, a disease that is localized may not be found, or if more than one condition is occurring the biopsy may not be big enough to allow the pathologist to evaluate all the changes occurring.
• The advantage of ultrasound guided biopsy and aspirates are that they are “non-invasive”. In other words, a body wall incision is not needed. Recuperation consists of restricted activity for the first 24 hours. An aspirate can usually be done without using anesthesia in a cooperative animal; a biopsy requires anesthesia and intravenous fluids. Anesthetic recovery is typically 3-4 hours, if severe bleeding occurs recovery could be longer.