Radiology Case
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Radiographic findings: There
is a moderate amount of pleural effusion within the right hemi-thorax.
The cardiac silhouette is shifted to the left. . The right middle and
caudal lung lobes are partially collapsed. The ventral margin of the right
diaphragmatic border is not well defined. On the lateral projection there
is cranial deviation of the gastric axis. Granular material in the stomach
can be seen superimposed over the caudal aspect of the thorax.
Radiographic impression: Diaphragmatic hernia involving the stomach and most likely the liver.
Comments: The displacement of the ingesta filled stomach into the thorax, best seen on the lateral view (arrows), is a clear indicator that a diaphragmatic hernia is present in this case; however, the diagnosis of a diaphragmatic hernia can present a diagnostic challenge if abdominal viscera can not be clearly identified within the thorax. Other radiographic findings that suggest diaphragmatic hernia are cranial displacement of abdominal viscera (liver, stomach, spleen, small intestine), displacement of the cardiac silhouette and mediastinum by a soft tissue opacity, and loss of visualization of the thoracic border of the diaphragm. Pleural and abdominal effusion may be variably present.
The diaphragm is seen normally radiographically as a convex soft tissue opacity protruding cranially into the thorax. The thoracic border is normally seen due to the air/soft tissue interface. The abdominal surface can be seen if there is enough fat in the falciform ligament. Any soft tissue opacity adjacent to the diaphragm in the thorax will obliterate the air/soft tissue interface and prevent visualization of the diaphragmatic border.1
If a diaphragmatic hernia involving the GI tract is suspected, but can
not be confirmed on plain thoracic radiographs, a positive contrast gastrogram/upper
GI series performed following oral administration of barium (6ml/kg 30%w/v)
will usually confirm the diagnosis. Positive contrast peritoneography
is useful to diagnose diaphragmatic hernias where the gastrointestinal
tract is not herniated. This can be performed by injecting 1 ml/kg of
an iodinated ionic or non-ionic contrast medium intraperitoneally and
positioning the animal so the contrast will coat the diaphragm then repeating
radiographs of the thorax and cranial abdomen. Severe pleural effusion
or abdominal effusion will dilute the contrast material and are contraindications
to the procedure. Warming the contrast may reduce the pain of injecting
the fluid cold and will decrease the viscosity so it will inject more
easily. Identifying a loss in the abdominal surface of the diaphragm is
suggestive of a diaphragmatic hernia. Contrast material may not pass through
the diaphragm into the pleural cavity. This technique is effective in
small patients; however in large patients dilution of the contrast makes
interpretation difficult. Sonographic evaluation of the abdomen and thorax
may be helpful in diagnosing a diaphragmatic hernia.1,2
References
- Park RD. The Diaphragm In: Thrall DE, ed. Textbook of Veterinary Diagnostic Radiology. 3rd ed. Philadelphia: W.B. Saunders, 1998;294-308.
- Rendano VT. Positive contrast peritoneography: An aid in the radiographic diagnosis of diaphragmatic hernia. Journal of the American Veterinary Radiology Society 1979;XX:67-72.
Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR