Teaching Case

A 18-year-old female patient presented with abdominal pain since 5 days associated with vomiting. Clinical examination was normal. Screening ultrasonography was done which was normal.

• X-ray abdomen was done which was normal [Fig. 1].

• CT showed protrusion of part of jejunal bowel loop in left para-umbilical region through a defect of size 3 cm with resultant dilatation of proximal jejunum, duodenum and stomach [Fig. 2].

• On post IV contrast venous phase, inferior mesenteric vein was seen anteromedial to the herniated sac [Fig. 3]. Wall of involved bowel loop showed increased enhancement, suggestive of venous congestion [Fig. 4].

Internal hernias are protrusion of the viscera through the defect in peritoneum or mesentery but remaining within the abdominal cavity [1]. Overall incidence of internal hernias is 0.2-0.9%. Paraduodenal hernias, are the most common type of internal hernia. Left sided paraduodenal hernia is more common in which 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. Landzert's fossa is present in approximately 2% of the population [2-4]. It has slight male predominance [4].

Anatomical landmark of hernia sac:

• Cluster of small bowel loops in the left anterior pararenal space behind the inferior mesenteric vein (IMV) and ascending left colic artery.

• Sac-like mass of small-bowel loops interposed between the stomach and pancreatic tail with a mass effect on the stomach posteriorly [2, 5].

Symptoms are often vague and clinical findings of paraduodenal hernias vary, ranging from mild digestive complaints to acute or chronic symptoms of obstruction, sometimes asymptomatic [4, 6].

Diagnosis of asymptomatic paraduodenal hernia has been difficult and many of them can be diagnosed incidentally at laparotomy, autopsy or during radiological investigation for disease [5].

While plain radiograph and ultrasound findings may be inconclusive, enhanced CT can be helpful in establishing a diagnosis of paraduonenal hernia which may show evidence of small-bowel obstruction; clustering of small bowel; stretched, displaced, crowded, and engorged mesenteric vessels and displacement of the main mesenteric trunks to the left with other bowel loops, especially the transverse colon and fourth part of the duodenum [5-7].

Reduction of the hernia sac and closure of the defect or incision of the hernia sac is necessary as paraduodenal hernia has lifetime risk of incarceration, leading to bowel obstruction and strangulations. Based upon the embryologically normal anatomy with restoration of the inferior mesenteric vein to its normal retroperitoneal position, hernia repair should be done which effectively reduces the sac and predisposing arch containing the inferior mesenteric vein, without section of the vein [8]. This can be achieved with ease by laparoscopic method because of its minimal invasiveness and aesthetic advantage [9].

Take home message: Paraduodenal hernias are difficult to diagnose on conventional radiographs and ultrasound. CT is the sole modality for preoperative diagnosis and detection of complications.

Written informed patient consent for publication has been obtained.