Paraduodenal hernias, although uncommon, have classically been the most common type of internal hernia. However, the incidence of postoperative internal hernias has been increasing recently. The two most common types, the left and right paraduodenal hernia involve small bowel herniating through a congenital opening in the mesenteries. These internal hernias may result in closed-loop bowel obstruction.
The patient typically presents with symptoms of small bowel obstruction: abdominal pain, nausea, vomiting.
Left paraduodenal hernia
- the more common of the two paraduodenal hernias (75%)
- small bowel herniates through the fossa of Landzert, a congenital failure of fusion of the descending colon mesentery to the peritoneum in the left upper quadrant
Right paraduodenal hernia
- the less common of the two paraduodenal hernias (25%)
- small bowel herniates through the fossa of Waldeyer, a congenital failure of fusion of the ascending colon mesentery to the peritoneum in the right lower quadrant
- associated with small bowel malrotation
These hernias usually appear as a sac-like cluster of small bowel loops in an atypical presentation. A closed-loop obstruction may occur within these loops due to the hernia.
However, it is not unusual for small bowel loops to cluster in an atypical position in normal patients. Thin patients may be especially challenging since it may be difficult to follow the course of the collapsed loops of small bowel.
Because of this, vascular landmarks around a potential internal hernia "sac" are critical for making a confident diagnosis.
- left paraduodenal hernia
- cluster of small bowel loops in the left anterior pararenal space
- the cluster of small bowel loops is behind the inferior mesenteric vein (IMV) and behind the ascending left colic artery
- right paraduodenal hernia