Review Question - QID 109265

A 22-month-old girl presents to the emergency department with her parents for intermittent abdominal pain that began yesterday. The abdominal pain seems to last 10-15 minutes at a time and causes the patient to curl up in pain. Between the episodes, the patient seems well and returns to playing normally. She has also had 4 episodes of non-bilious vomiting over the course of the day. Her last bowel movement was 2 days ago and was normal in appearance. There is no visible blood in her diapers, but she had several episodes of diarrhea about 1 week ago. Her medical history is otherwise unremarkable. Her temperature is 99.2°F (37.3°C), blood pressure is 62/41 mmHg, pulse is 122/min, and respirations are 20/min. On physical exam, the patient is in no acute distress. Her abdomen is soft and non-distended with moderate tenderness to palpation in the right upper quadrant. An abdominal ultrasound is performed and demonstrates the finding seen in Figure A. Which of the following is the most appropriate next step in management?