Internal hernia after pancreaticoduodenectomy with Roux-en-Y reconstruction

Clinical History

A 58-year-old male patient with acute epigastric pain and vomiting was admitted. The patient underwent a pancreaticoduodenectomy with Roux-en-Y reconstruction due to a pancreatic neuroendocrine tumour two years before. Physical examination showed a tympanic and tender abdomen with no bowel sounds. Blood tests showed elevated amylase, C-reactive protein and liver enzymes.

Imaging Findings

A CT scan was performed which showed intestinal obstruction with retrograde dilatation of small bowel loops of the biliopancreatic limb (Fig. 1) and proximal loops of the efferent limb (Fig. 2). In addition, twisted and dilated mesenteric vessels were also seen (Fig. 3) with a beaked appearance of the superior mesenteric vein (Fig. 4). Some signs of complicated obstruction were also identified, like absence of contrast enhancement of distal bowel (Fig. 5) and ascites. An emergency laparotomy was performed and a transmesenteric hernia was found as a cause of obstruction. The obstruction was successfully reduced with no loss of intestinal viability.

Discussion

Roux-en-Y reconstruction is a procedure that is often performed after a duodenopancreatectomy. It consists of the creation of two limbs: a gastrojejunal anastomosis (Roux limb) and a jejunojejunal anastomosis (biliopancreatic limb). There is an increased risk of small bowel obstruction related to this intervention [1].
The symptoms of small bowel obstruction are nonspecific, including abdominal pain, vomiting and distension. CT is used to determine whether there is obstruction, to look for the cause of the obstruction (postoperative adhesions, malignancy and hernias are the most common aetiologies) and to diagnose possible complications [2].
A small bowel obstruction is seen in CT as dilated bowel loops with collapsed bowel after a transition point. Abdominal adhesions after previous surgeries are the most frequent cause of small bowel obstruction. Most of the times it is an exclusion diagnosis if no abdominal masses or inflammatory signs are seen in the transition point, as adhesions cannot generally be seen in CT scans.
Another important cause in patients who have a Roux-en-Y reconstruction done is a transmesenteric hernia due to defects in the mesentery after the surgery [3]. Lockhart et al established seven signs of internal hernia in CT: swirled appearance of mesenteric fat or vessels, mushroom shape of hernia, tubular distal mesenteric fat surrounded by bowel loops, small-bowel obstruction, clustered loops of small bowel, small bowel other than duodenum posterior to the superior mesenteric artery, and right-sided location of the distal jejunal anastomosis [4]. Dilauro et al added two more signs: “beaking” of the superior mesenteric vein and criss-cross of the mesenteric vessels. The combination of small bowel obstruction and swirled mesentery was the most sensible and the combination of small bowel obstruction and “beaked” superior mesenteric vein was the most specific [5].
It is essential to distinguish between a simple obstruction and a closed-loop obstruction. In a closed loop obstruction there are two points of the obstructed bowel in a single location and it is associated with a higher risk of strangulation ischaemia [2].
Millet et al evaluated the combination of three CT findings (reduced bowel wall enhancement, closed-loop mechanism, diffuse mesenteric haziness) was a good predictor of strangulation [3]. Whenever a complicated obstruction is found in the CT, emergency surgery must be performed in order to avoid intestinal ischaemia [2].

Differential Diagnosis List

Final Diagnosis

Internal hernia after a Roux-en-Y reconstruction.

URL:	https://eurorad.org/case/15660
DOI:	10.1594/EURORAD/CASE.15660
ISSN:	1563-4086