A 62-year-old man from rural India presents with acute onset abdominal distension, colicky pain, and vomiting for 18 hours. On examination, he is dehydrated with visible peristaltic waves. Plain abdominal radiograph shows multiple dilated small bowel loops with air-fluid levels and a transition zone in the distal ileum. No free air is visible. Vital signs are stable. What is the most appropriate next step in management?