A 52-year-old previously healthy male patient sought for medical assistance due to a colicky abdominal pain which had begun about 18 hours before and had since worsened. He had not passed stool or flatus for more than 24 hours. On physical examination, he presented with diffuse abdominal distension and tenderness. He also presented with a tympanic percussion note in the left lumbar and hypochondriac regions. His pain seemed more intense in the lower abdomen. An anteroposterior abdominal radiography was carried out with the patient lying in a supine position.

Picture 1: Anteroposterior abdominal radiograph

Question:
Based on the clinical history and image provided herein, the most likely diagnosis is: