Review Question - QID 103467

A 7-month-old boy is brought to the ED by his mother because of abdominal pain. Two weeks ago, she noticed he had a fever and looser stools, but both resolved after a few days. One week ago, he began to experience periodic episodes during which he would curl up into a ball, scream, and cry. The episodes lasted a few minutes, and were occasionally followed by vomiting. Between events, he was completely normal. She says the episodes have become more frequent over time, and this morning, she noticed blood in his diaper. In the ED, his vitals show a temperature of 36.8°C (98.2°F), blood pressure 92/60 mmHg, pulse 100/min, respirations 20/min, oxygen saturation of 100% on room air. His abdomen is soft, not distended, and mildly tender in the right lower quadrant where there is a small palpable mass. After confirming the diagnosis with an abdominal ultrasound, what is the most appropriate next step in management?