This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
[{'content': 'Petersen hernia is \nSelect and explain. \nA. Internal hernia behind roux en Y limb, B. Internal hernia transverse mesocolon, C. Cervical hernia, D. Hernia epiploic foramen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Peterson Hernia Petersen hernias are internal hernias which occur in the potential space posterior to a gastrojejunostomy. This hernia is caused by the herniation of intestinal loops through the defect between the small bowel limbs, the transverse mesocolon and the retroperitoneum, after any type of gastrojejunostomy. The laparoscopic approach facilitates the occurrence of this type of hernia, due to the lack of post-operative adhesions which prevent bowel motility and hence, herniation. These hernias occur in patients with a Roux-en-Y gastric bypass Clinical presentation usually presents with diffuse abdominal pain (could be caused by bowel obstruction with spontaneous reduction) may present as intestinal obstruction late postoperative obstruction may be due to adhesions, fibrotic stenosis, intussusception or more often, internal hernias Ref: internet sources', 'role': 'assistant'}]