A previously well 14-month-old boy presents with sudden episodes of severe colicky abdominal pain with knee flexion, inconsolable crying, and pallor alternating with lethargy. He has vomited and passed stool mixed with mucus and blood. On examination, a sausage-shaped palpable mass is felt in the right upper abdomen with an empty right iliac fossa (Dance sign). Ultrasound confirms ileocolic intussusception with target sign on transverse section. Air enema reduction fails, and at laparotomy the surgeon finds the structure marked **A** — the terminal ileum — has telescoped into the caecum and ascending colon. Which of the following best describes the pathophysiological consequence of this telescoping of the structure marked **A**?