- Clinical science
An internal hernia is the protrusion of visceral contents through a congenital or acquired defect in the peritoneum or mesentery within the abdominal cavity. Internal hernias have an incidence of < 1% and are significantly less common than external hernias. Patients with a history of Roux-en-Y gastric bypass or liver transplant are especially at risk of internal hernia formation. Small bowel loops are the most common content of an internal hernia. For this reason, the typical clinical presentation is that of a mechanical small bowel obstruction (i.e., colicky abdominal pain, vomiting, constipation, abdominal distention). Contrast-enhanced CT scan is the imaging modality of choice in most cases, but surgical intervention is often required for definitive diagnosis and treatment. Incarceration or strangulation of internal hernias carries a high mortality rate; rapid diagnosis and surgical repair is therefore imperative.
- Internal hernias have an overall incidence of < 1%.
Epidemiological data refers to the US, unless otherwise specified.
- Features of intermittent or acute :
- Evidence of bowel incarceration with subsequent strangulation :
- Abdominal x-ray: nonspecific signs of (e.g., distended loops of bowel, absent air in distal colon, air fluid levels proximal to obstruction)
- CT scan (best initial and gold standard imaging modality)
- Laparoscopy or laparotomy (confirmatory and therapeutic)
The diagnosis of an internal hernia is confirmed by laparoscopy in the majority of cases.
- Conservative management
- Surgery: either open or laparoscopic
If an internal hernia leads to incarceration, the mortality rate is ∼ 80%!