<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 12-year-old boy is brought in by his mother to the emergency department. He has had abdominal pain, fever, nausea, vomiting, and loss of appetite since yesterday. At first, the mother believed it was just a stomach flu, but she is growing concerned about his progressive decline. Vitals include: T 102.3 F, HR 110 bpm, BP 12089 mmHg, RR 16, O2 Sat 100. Abdominal exam is notable for pain over the right lower quadrant. What is the next best step in management in addition to IV hydration and analgesia?? A: Abdominal CT scan with IV and PO contrast, B: Abdominal CT scan with IV contrast, C: Upright and supine abdominal radiographs, D: Right lower quadrant ultrasound, E: Abdominal MRI with gadolinium contrast,  <response>: This is a clinical vignette describing a 12-year-old boy with symptoms and exam findings concerning for appendicitis. The key findings are right lower quadrant abdominal pain, fever, nausea, vomiting, and anorexia. Vital signs show fever, tachycardia, and mild hypertension. The abdominal exam reveals right lower quadrant tenderness. The question asks for the next best diagnostic test to order in addition to IV fluids and analgesia. Options include various imaging modalities - CT scan with IV contrast, CT with IV and PO contrast, abdominal X-ray, ultrasound, and MRI. The best initial imaging test for suspected appendicitis in a pediatric patient is an ultrasound of the right lower quadrant. This avoids unnecessary radiation exposure from CT scans or X-rays. MRI provides excellent visualization but is more time-consuming and expensive. D: Right lower quadrant ultrasound 