Tony Mathew

A 75-year-old male with 4 days of abdominal distention, constipation, and decreased PO intake due to nausea. He reports that his symptoms are worse after eating or drinking and that he is able to pass gas but has not had a bowel movement in the past 4 days.  On initial presentation to the ED, he appears anicteric while his abdomen is soft, non-tender, but massively distended asymmetrically with no bowel sounds heard on auscultation. What is the most likely diagnosis?