The nurse is caring for a client recovering from gastrojejun…

The nurse is caring for a client recovering from gastrojejunostomy (Billroth II) surgery 36 hours ago. The client has 200 ml of bright red fluid in the nasogastric tube.  The client has no bowel sounds and is complaining of increasing abdominal pain. Vital signs include temperature 98°F; heart rate 116; respirations 28; blood pressure 100/69. Which action by the nurse is the highest priority?