A 35-year-old man is seen in consultation in the emergency department (ED) after several unsuccessful attempts by the ED physician to extract a foreign body in the rectum. The patient is hemodynamically stable but very uncomfortable with severe lower abdominal cramping. Abdominal and pelvic radiography demonstrates a 7-cm cylindrical foreign body above the sacral promontory, without evidence of free intra-abdominal air. What is the best next step in management?