Internal Hernias: Key Considerations in Imaging

The most common presentation of internal herniation is acute small bowel obstructions
The orifice that the small bowel herniates through is usually a pre-existing anatomic structure.
Pathologic defects of the mesentery and visceral peritoneum, such as from congenital maldevelopment of the mesenteries, and surgery also create potential internal herniation orifices.
CT is the gold standard imaging for evaluation of suspected internal hernias and subsequent bowel obstruction.
CT findings of internal hernias include evidence of small bowel obstruction (SBO); the most common manifestation of internal hernias is strangulating SBO, which occurs after closed-loop obstruction.
The following factors may be helpful in preoperative diagnosis of internal hernias with CT:

knowledge of the normal anatomy of the peritoneal cavity and the characteristic anatomic location of each type of internal hernia


observation of a saclike mass or cluster of dilated small bowel loops at an abnormal anatomic location in the presence of SBO


observation of an engorged, stretched, and displaced mesenteric vascular pedicle and of converging vessels at the hernial