Radiology Case
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Radiographic findings: There
is decreased definition and lateral deviation of the abdominal wall in
the right inguinal region which contains small intestinal loops.Radiographic
impression:
The findings are consistent with a right-sided inguinal hernia.
Comments: Abdominal wall hernias are uncommon sequelae to trauma. Common locations for abdominal hernias are the inguinal, prepubic, and paracostal regions. Less commonly muscular dorsolateral hernias may occur. These hernias are commonly due to avulsions or tears in muscular attachments near the bone.
A BRIEF review of the regional anatomy is helpful in understanding these hernias. The prepubic tendon is present as a shallow "v" shape that extends from the attachment of the pectineus (ileopectineal eminence), attaches on mid-line at the symphysis (pubic tubercle), and continues laterally to the opposite origin of the pectineus. It is composed of fibers from the rectus abdominus. The external abdominal oblique aponeurosis is also closely associated. The inguinal ligament arises from the ileum (tuber coxae) and blends with the prepubic tendon. It serves as the caudal border of the internal inguinal ring. The external abdominal oblique and the transversus abominus muscles have costal attachments. 1,2
Trauma can cause avulsion of the prepubic tendon and/or damage to the inguinal ring leading to hernias in these regions. An avulsion of the prepubic tendon can be appreciated radiographically (not in this case) as a small bone fragment cranial and ventral to the pubis (most easily seen on the lateral view). Damage to the muscular attachments of the external abdominal oblique muscle, the transversus abdominus, and internal abdominal oblique can lead to paracostal hernias. Damage to muscular attachments to the transverse processes of the vertebrae can lead to dorsolateral hernias. 1
Hernias are detected radiographically by a deviation or abnormal contour
to the abdominal wall. Abdominal viscera may or may not be present within
the hernia. When gas filled bowel is present, as in this case, the diagnosis
is apparent. If the bowel is fluid filled, or if there is decreased abdominal
contrast (lack of fat, fluid) the diagnosis of herniated viscera can be
more challenging. Inspection for displacement of abdominal organs can
aid in the diagnosis and if a herniated intestinal loop is suspected,
a positive contrast upper GI series can be performed. 3 There are very
little intestines in the mid-abdomen of this patient.
References
- Smeak D. Abdominal Hernias In: Slatter D, ed. Textbook of Small Animal Surgery. 2nd ed. Philadelphia: W.B. Saunders, 1993;433-454.
- Farrow CS, Green R, Shively MJ. The Abdomen In: Shively MJ, ed. Radiology of the Cat. St. Louis: Mosby, 1994;142-144.
- O'Brien T. Small Intestine In: O'Brien T, ed. Radiographic Diagnosis of Abdominal Disorders in the Dog and Cat : Radiographic Interpretation, Clinical Signs, Pathophysiology. Philadelphia: Saunders, 1978;343-349.
Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR