A 62-year-old man with a history of two previous laparotomies for peptic ulcer disease presents with acute onset colicky abdominal pain, abdominal distension, and vomiting. Examination reveals a distended abdomen with visible peristaltic waves and high-pitched bowel sounds. Plain abdominal X-ray shows dilated small bowel loops with air-fluid levels and a transition zone. What is the most appropriate next step in management?