Ultrasound is useful for assessment of small intestinal diseases. In Part I (June 2018 blog at blog.oncurapartners.com), we discussed normal appearance of small intestine with tips for taking measurements. In this blog, we are going to a look at a few of the most common findings you may see with diffuse small intestinal disease.
Remember our layers of small intestine:
Most common diffuse small intestinal diseases:
Altered patterns of layering. Thickened muscularis layer is one of the more common changes you will see in association with diffuse small intestinal disease.
In this case, you can see that the muscularis layer is thickened and is as thick as the mucosal layer. This is abnormal and is most commonly seen in cats with inflammatory bowel disease.
This change can also be with intestinal lymphoma. It can be seen in dogs with chronic enteropathies as well but it is less commonly seen in dogs. This change can be seen with increased or normal wall thickness.
Complete loss of layering can be seen with severe inflammatory processes or neoplasia. Loss of layering can also be seen with edema, hemorrhage or other processes that might disrupt layering.
In this case, loss of layering is associated with asymmetric thickening of the wall and findings are consistent with a small bowel mass. This cat has small intestinal lymphoma which is usually a non-obstructing mass.
Changes in echogenicity of the mucosal layer may include mucosal speckling or vertical striations. Mild mucosal speckling can be an incidental finding. Vertical striations may be associated with lymphangiectasia.
The mucosal layer should normally be dark/black. In this case, you can see the vertical striations within the mucosal layer. This dog had protein losing enteropathy/lymphangiectasia.
Corrugated bowel may be seen in associated with enteritis or regional causes of inflammation including peritonitis or pancreatitis.
This corrugated bowel is seen in a patient with acute non-specific enteritis.
These are a few of the more common patterns that you may see with diffuse small intestinal disease.
Remember that ultrasound is not always sensitive to diffuse changes and therefore, normal ultrasonographic appearance does not rule out diffuse small intestinal disease. Always interpret ultrasound findings in conjunction with clinical signs, physical exam findings and laboratory findings. Ultrasound is an important tool in aiding you with diagnosis but histopathology is necessary for definitive diagnosis of small intestinal disease.