A client returns to the postoperative unit after a gastroduodenostomy (Billroth I) for treatment of a perforated ulcer. The healthcare provider's prescriptions include morphine with a patient-controlled analgesia (PCA), nasogastric tube (NGT) to low intermittent nasogastric suction, and IV fluids and antibiotics. The client complains of increasing abdominal pain 12 hours after returning to the surgical unit. The nurse determines the client has no bowel sounds, and 200 ml of bright red nasogastric drainage is in the suction canister in the past hour. What is the priority action the nurse should implement?