Tuesday, 23 June 2015

xrayoftheweek 25: why is this woman in pain?

This is a coronal CT reconstruction in someone who attends the emergency department with a short history of severe abdominal pain. On examination, they have diffuse tenderness across the mid and lower abdomen. From these images, can you:

  1. work out what type of surgery they have had in the past?
  2. what is the current problem?

You can scroll through these images on my Radiopaedia upload of this case.

The previous surgery is a Roux-en-Y gastric bypass, in this case, for management of obesity. This is indicated by division of the stomach, a gastro-jejunostomy, and a further anastomosis between small bowel loops which is a jejunojejunostomy.
Schematic diagram of Roux-en-Y gastric bypass. Taken from my BJR publication: Imaging in bariatric surgery: service set-up, post-operative anatomy and complications (http://www.birpublications.org/doi/abs/10.1259/bjr/18405029)

One of the concerns in someone presenting with acute abdominal pain after this surgery is an internal hernia. This used to be seen more commonly than now, due to an iatrogenic defect in the transverse mesocolon where the small bowel was brought up to anastomose onto the stomach. However, the procedure has changed and is now done with an "antecolic" approach meaning that the transverse mesocolon is not breached. However, other small mesenteric defects may still be created - leading to herniation of small bowel loops behind the gastrojejunostomy. This is know as a Petersen's hernia.

This is a case of an internal mesenteric hernia but not a Petersen's type. There is abnormal clustering of small bowel loops in the lower abdomen, with pinching of the mesenteric vessels and mild fat stranding around the involved loops. Some enhance poorly, raising the possibility of ischaemia. This is in keeping with a mesenteric hernia, which may have been iatrogenic but this is difficult to surmise purely from the images. These are most commonly seen at the site of the jejunojejunostomy. At surgery, a hernia sac was identified and the small bowel loops, whilst being ischaemic were not necrotic and no resection was necessary.

Learning points: 
  • contrast enhanced CT is the test of choice in someone presenting with abdominal pain following Roux-en-Y gastric bypass surgery.
  • keep a high index of suspicion for internal hernia formation

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