A 55-year-old woman undergoes elective cholecystectomy. On postoperative day 6 she has mild abdominal discomfo and bloating. She has received antibiotics, morphine for pain and metoclopramide for nausea. She has not passed flatus or stools since the surgery. On auscultation bowel sounds are hypoactive. The doctor on duty orders an abdominal x-ray for the same. What is the most possible cause for her symptoms?