A 68-year-old man with a history of abdominal surgery 10 years ago presents to the emergency department with acute onset colicky abdominal pain, abdominal distension, and vomiting. On examination, he has visible peristaltic waves and a palpable abdominal mass. Plain abdominal radiograph shows multiple dilated small bowel loops with air-fluid levels and a transition point in the pelvis. What is the most appropriate next step in management?