A 76-year-old man with a history of hemicolectomy 3 years ago presents to his GP with worsening colicky abdominal pain associated with vomiting, and abdominal distension. Basic observations on arrival are: pulse 98/min, BP 165/75mmHg, temperature 37.8°C. On abdominal examination there is a distended abdomen with no tenderness, rebound or guarding. Bowel sounds are tinkling. What is the most likely cause for the clinical findings?