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Internal hernia

Dr Ian Bickle and Radswiki et al.

Internal hernias are protrusions of the viscera through the peritoneum or mesentery but remaining within the abdominal cavity.

Types of internal hernias include

Clinical presentation

The most common presentation is an acute obstruction of small bowel loops that develops through normal or abnormal apertures. Internal hernias have a low incidence of less than 1% and represent a relatively small amount of presentations, of just under 6%.1

Internal hernias not infrequently self-resolve, making imaging at the time of symptomatology vital.


The orifice that the small bowel herniates through is usually a pre-existing anatomic structures, such as foramina, recesses, and fossae (e.g. fossa of Landzert).

Pathologic defects of the mesentery and visceral peritoneum, such as from congenital maldevelopment of the mesenteries, and surgery also create potential internal herniation orifices.

Radiographic features

In contemporary practice virtually all patient's undergo CT, which is the gold standard imaging modality.   Traditionally barium studies were performed and may still on occasion in niche circumstances.


The appearance depends on the particular internal hernia.

Common features include

  • encapsulation of distended bowel loops with an abnormal location
  • arrangement or crowding of small-bowel loops within a hernial sac;
  • evidence of obstruction with segmental dilatation and stasis.
  • mesenteric vessel abnormalities
    • engorgement, crowding, twisting, stretching of mesenteric vessels

The appearances vary depending on the type and site of the internal hernia.

  • Clustering of small bowel loops
  • Distended bowel proximal to the site of obstruction
  • Abnormal site or displacement of normal parts of the GI tract


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