Our case shows internal herniation as a complication of the laparoscopic Roux-en-Y gastric bypass. In this surgical procedure, 2 possible internal hernia sites arise: (1) the opening in the mesentery of the jejunojejunostomy and (2) the opening between the mesentery of the alimentary loop and the mesocolon of the colon transversum. The latter is called Petersen's space ()
. In our case, a large part of the small intestine herniated through Petersen's space. This had resulted in an intermitted partial bowel obstruction without a complete obstruction. The probability of developing a Petersen's hernia is correlated with the surgical technique used in the laparoscopic gastric bypass. In patients with a Roux-en-Y gastric bypass with an antecolic alimentary loop as in our case is associated with a lower incidence compared to a retrocolic alimentary loop, 0.4% versus 4.5%, respectively.5
Possible herniation sites after antecolic Roux-and-Y gastric bypass.
Recently, a study reported that closing all potential hernia sites is associated with a considerable decrease in the incidence of internal herniation.6
Closure of the potential hernia sites during the LRYGB does not prevent internal herniation in all patients, as suggested in our case. Due to the reduction of intraabdominal fat after the bariatric procedure, potential hernia sites can re-open.6–8
This case demonstrates 2 diagnostic challenges in patients suffering from an internal hernia. The first challenge is the clinical presentation, which is often with mild and aspecific abdominal complaints. Even the ileus was intermittent, hampering the correct diagnosis.
The second challenge is the interpretation of a radiological investigation. On the first CT, abdominal signs of internal herniation were not identified. Retrospectively, a “swirl sign” was also present on the first CT scan. The “swirl sign” also called “whirlpool sign” is a specific indicator of the presence of an internal herniation through Petersen's space. This radiological finding is caused by a rotation of the complete mesentery, which can by recognized by following the routes of the mesenteric vein and the mesenteric artery.
shows a swirl sign in our patient.9
The swirl sign can be demonstrated by scrolling through our CT scan online. The sensitivity of the swirl sign is 74% and the specificity is 83%.10
Due to the herniation, dilated small intestinal loops will be found along the abdominal wall, and the transverse colon is moved to the center of the abdomen.
Transverse section CT of the abdomen. The red mark shows the superior mesenteric artery, and the blue mark shows the superior mesenteric vein.
We initially missed the proper diagnosis, causing considerable diagnostic delay. In patients with abdominal complaints and a swirl sign on CT after a (laparoscopic) Roux-en-Y gastric bypass, we recommend an immediate laparoscopy. The threshold in performing a laparoscopy should be very low in these patients, because the CT will not show abnormalities in 26% of the patients with an internal herniation.4