What is the most appropriate test to confirm the diagnosis in a boy with peri-umbilical (around the belly button) pain that has shifted to the right iliac fossa (RIF), accompanied by vomiting and tenderness, and who has leucocytosis (elevated white blood cell count)?

Diagnostic Confirmation for Suspected Acute Appendicitis

Order abdominal ultrasound or CT scan immediately to confirm the diagnosis of acute appendicitis (Option A). This boy presents with the classic textbook presentation of appendicitis—periumbilical pain migrating to the right iliac fossa (RIF), vomiting, tenderness on examination, and leukocytosis—and requires imaging confirmation before surgical intervention 1, 2.

Why Imaging is Essential

The clinical presentation strongly suggests appendicitis, but imaging is critical to:

• Confirm the diagnosis before proceeding to surgery, as preoperative imaging reduces the negative appendectomy rate from 16.7% (clinical evaluation alone) to 8.7% with CT 3
• Exclude alternative diagnoses that can mimic appendicitis clinically 4
• Identify complications such as perforation or abscess formation that would alter surgical planning 4
• Reduce long-term morbidity associated with negative laparotomy 4

Recommended Imaging Approach for Pediatric Patients

First-Line: Ultrasound

• Start with abdominal ultrasound as the initial imaging modality in pediatric patients to avoid radiation exposure while maintaining diagnostic accuracy 4, 2
• Ultrasound achieves 93% accuracy with 86% sensitivity and 97% specificity in intermediate-risk pediatric patients 4
• The graded compression technique should be used to optimize visualization 4, 3

Second-Line: CT or MRI if Ultrasound is Inconclusive

• If ultrasound is non-diagnostic or inconclusive, proceed to MRI without contrast as the next step to avoid radiation in children 2
• CT abdomen and pelvis with IV contrast should be reserved for cases where ultrasound and MRI are unavailable or inconclusive, achieving sensitivities of 85.7-100% and specificities of 94.8-100% 1, 3
• MRI has comparable accuracy to CT (sensitivity 96.5%, specificity 96.1%) without radiation exposure 4

Why Other Options Are Inappropriate

Option B (IV fluids and observation) is WRONG:

• While this patient needs IV hydration for vomiting, observation alone without imaging confirmation delays definitive diagnosis and treatment 1
• The classic presentation with leukocytosis indicates high probability of appendicitis requiring surgical intervention 4
• Increased duration of pre-hospital symptoms is associated with perforation risk; further delay is harmful 5

Option C (Discharge and reassess in 48 hours) is DANGEROUS:

• Discharging a patient with suspected appendicitis risks perforation, which occurs with longer symptom duration (median 50 hours for perforated vs 17 hours for simple appendicitis) 5
• This presentation has approximately 50% probability of appendicitis based on classic symptoms 4
• Missing the diagnosis leads to increased morbidity and mortality 1

Option D (High fiber diet and laxatives) is COMPLETELY INAPPROPRIATE:

• This suggests treating constipation, which is not the diagnosis in a patient with acute RIF pain, vomiting, tenderness, and leukocytosis 1, 2
• Administering laxatives to a patient with possible appendicitis could theoretically worsen inflammation or precipitate perforation

Critical Clinical Pearls

• The "classic" presentation (periumbilical pain migrating to RLQ, vomiting, fever, leukocytosis) is present in only approximately 50% of appendicitis cases, making imaging essential even with typical symptoms 4
• Leukocytosis supports but does not confirm the diagnosis; normal inflammatory markers do not exclude appendicitis in pediatric patients 2
• Ultrasound first, then CT/MRI is the evidence-based pathway that balances diagnostic accuracy with radiation safety in children 4, 2
• Once appendicitis is confirmed by imaging, proceed directly to appendectomy as standard treatment with broad-spectrum antibiotics 1, 2