Acute Pancreatitis — Sentinel Loop Sign

A 45-year-old man with a 10-year history of alcohol use disorder presents to the emergency department with acute onset epigastric pain radiating to the back, associated with vomiting. On examination, he is febrile and tachycardic. A supine abdominal radiograph is obtained as part of the initial imaging workup. The structure marked **A** in the diagram shows a focal, gas-filled dilated loop of small bowel in the left upper quadrant adjacent to the pancreas. Which of the following best describes the pathophysiological mechanism underlying this radiological finding?