Introduction
The most common reason for obstruction of the small bowel in adults is adhesion bands, malignancy, and hernias. Congenital hernias are most prevalent in infants and early childhood but infrequently seen in adults.
What Is an Internal Hernia?
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Internal hernias, characterized as viscus protrusion through a normal or abnormal orifice within the peritoneal cavity, is a rare clinical condition that accounts for only up to 5.8 percent of small bowel obstructions, with an overall prevalence of 0.5 to 0.9 percent.
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Internal hernias are frequently misdiagnosed before emergency laparotomy because their symptoms can range from mild abdominal pain to sudden onset of intestinal obstruction. Moreover, it can cause gangrene, possibly requiring bowel resection of various extents, contributing to a significant mortality rate.
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The majority of internal hernias constitute small bowel loops and are caused by either acquired or congenital defects in the attachment of distinct peritoneal folds, with 53 percent paraduodenal and 13 percent pericecal, 8 percent of hernias through the foramen of Winslow, 2 percent transmesenteric and 1 percent transomental hernias being among the most frequent.
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These are the most uncommon internal hernias, but they're also congenital in a small percentage of pediatric cases; they are almost always iatrogenic. Most transomental hernias are caused by previous abdominal surgery, most commonly Roux-en-Y gastric bypass.
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Moreover, even in patients with no prior surgical history, senile omentum atrophy may result in this unusual type of internal hernia.
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Internal hernias are frequently misdiagnosed prior to emergency laparotomy because their symptoms can range from mild abdominal pain to sudden onset intestinal obstruction. Moreover, it can cause gangrene, requiring bowel resection of various extents, resulting in high mortality.
What Is a Transomental Hernia?
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Transomental hernias through omentum are uncommon, contributing to only about 4 percent of all internal hernias. Transomental hernias are most commonly seen in patients above the age of fifty.
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Acquired transomental hernias are common in conditions such as iatrogenic and arise from surgical interventions, trauma, or peritoneal inflammation.
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Congenital abnormalities cause transomental hernias in children in the greater omentum or the gastrocolic ligament. It occurs most commonly in males than females, with a ratio of 2:1. The severity of the disease in children is determined by the size of the orifice and the length of the herniated small bowel loops.
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However, in adults, transomental herniation of small bowel loops is more frequently iatrogenic, most generally caused by Roux-en-Y anastomosis during gastric bypass surgery.
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Adult transomental hernias can occur as a result of either blunt trauma of the abdominal cavity or inflammation of the peritoneal cavity. In addition, transomental hernias can occur due to senile atrophy of the greater omentum in patients with no history of surgery, trauma, or inflammation. This is termed a spontaneous transomental hernia.
What Is the Classification of Transomental Hernias?
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Yamaguchi classified transomental hernias into three types:
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Type A (peritoneal cavity greater omentum peritoneal cavity).
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Type B (peritoneal cavity omental bursa peritoneal cavity).
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Type C (peritoneal cavity omental bursa peritoneal cavity).
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Type A is slightly more common than type C and is more prevalent in elderly patients.
What Are the Clinical Manifestations of Transomental Hernia?
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Clinical manifestations are nonspecific and resemble acute obstructive syndrome symptoms such as nausea, vomiting, pain in the abdomen, dilated abdomen, and constipation.
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Patients with transomental hernias present with strangulation of the small bowel more commonly than patients with other internal hernias. A gangrenous bowel is evident at the exploratory laparotomy in most cases.
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As a result, transomental hernias have a 30 percent postoperative mortality rate, making prompt diagnosis and treatment crucial.
What Is the Diagnosis of Transomental Hernia?
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Transomental hernias can be difficult to detect. When necrosis of the intestine occurs, pre-operative diagnosis is problematic, resulting in delayed surgical management. This is especially true for transomental hernias, where very narrow defects typically cause a lack of hernial sac.
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In the clinical situation of small bowel obstruction, the diagnosis of an internal hernia is frequently based on findings of computed tomography (CT), which are rarely specific.
What Are the Computed Tomography (CT) Findings of Transomental Hernia?
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CT scans of the abdomen aid in the diagnosis of transomental hernias. Abdominal CT scans may show dilation of the small bowel loops with a ‘beak sign,’ which is a triangular arrangement of the transition zone between proximal dilated bowels and herniated bowel segments or between dilated, herniated bowel segments and distal, collapsed bowel segments.
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CT may also show a swirling pattern of mesenteric vessels, distended mesenteric vessels with a significant impact on the adjacent organs, and bowel wall thickening.
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Furthermore, a transomental hernia should be assumed if the dilatable small bowel loops are localized in the lesser sac (that is surrounded to the right by the gallbladder and liver, to the left by the stomach, and posteriorly by the pancreas) and the neck of the hernia opening is viewed as mesenteric vessels traveling through the omental defect, with abdominal CT scans confirming no evidence of loops traveling through the foramen of Winslow between the inferior vena cava and the portal triad confirmed. In most cases, however, a definitive diagnosis is made intraoperatively.
What Is the Treatment of Transomental Hernias?
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The surgical treatment is the excision of the herniated intestinal segments. If the herniated viscera has necrosis, perforation, or irreversible ischemia, resection of the bowel is required. The omentum defect must be repaired.
Conclusion
Internal hernias should be suspected in all cases presenting with small bowel obstruction, and typical radiological signs can help guide the diagnosis. Even without risk factors such as prior abdominal surgery, trauma, or peritoneal inflammation, the possibility of bowel obstruction due to an internal hernia, particularly a transomental hernia, should be considered.
