Image of the Month—Diagnosis

Figure 1. A plain abdominal radiograph shows a distribution of gas throughout the colon.

Figure 2. A single-contrast barium enema x-ray film shows a loop of transverse colon herniating through a defect in the falciform ligament, with dilation of the proximal colon.

An internal hernia is defined as a protrusion of abdominal viscera through a normal or abnormal aperture within the confines of the peritoneal cavity. These hernias may be either congenital or acquired and account for less than 10% of all cases of intestinal obstruction. Internal hernias may involve defects in the mesentery of the small or large intestine, the mesoappendix, the broad ligament, the lesser omentum, and the foramen of Winslow. Alternatively, they may occur in one of the multiple fossae and recesses among the peritoneal folds, such as paraduodenal, paracecal, supravesical, retrovesical, retrorectal, or the foramen of Winslow.

The paraduodenal hernia is the most common type of internal hernia, accounting for more than 50% of cases.¹ It is most commonly left-sided, and the sac usually contains the inferior mesenteric artery, the inferior mesenteric vein, and the left colic artery. The anterior wall of the sac constitutes the descending mesocolon.

Paracecal hernias arise when a loop of terminal ileum enters one of the peritoneal recesses in the ileocecal region, ie, the superior or inferior ileocecal recesses, the retrocecal recess, or the paracolic sulci.

Transmesenteric hernias occur most commonly after abdominal surgery in which a bowel anastomosis has been performed. They may also occur in patients with congenital mesenteric defects.² These intraperitoneal hernias most commonly involve a defect of the transverse mesocolon and do not have a sac. Other defects that have been reported include those in the ileocolic region, sigmoid mesocolon, mesentery of the Meckel diverticulum, and the mesoappendix. In a series of 14 patients with transmesenteric hernias, 8 patients underwent orthotopic liver transplantation with Roux-en-Y biliary-enteric reconstruction, and 5 others had surgery with small or large intestinal resection.³

Chilaiditi syndrome has been described as an interposition of the colon between the diaphragm and the liver, ie, the transverse colon protrudes into the right anterior subphrenic space along the anterior of the liver.⁴ Herniation of the large intestine through a defect in the diaphragm can occur following severe blunt or penetrating abdominal trauma to the left-upper quadrant.⁵

The patient's clinical presentation may include signs and symptoms of acute or chronic abdominal pain. In the latter, patients have a long history of intermittent abdominal pain without any definitive diagnosis until they develop complications, such as strangulation or acute obstruction.

A computed tomographic scan of the abdomen and contrast studies of the small or large bowel are the cornerstones of diagnosis in this condition. The computed tomographic scan shows a clustering of dilated small or large bowel. Radiographic findings consistent with a paraduodenal hernia include a saclike mass with encapsulation at or above the ligament of Treitz with a mass effect on the posterior stomach wall or engorgement and crowding of the mesenteric vessels. An internal hernia should be considered in patients who present with acute or subacute intestinal obstruction without any previous abdominal surgery or obvious external hernia on physical examination.

Corresponding author and reprints: Adrian A. Indar, FRCS, Section of Surgery, Queens Medical Centre, Nottingham NG7 2UH, England (e-mail: adrian.indar@nottingham.ac.uk).

Accepted for publication October 5, 2002.