Diagnosis: Acute Appendicitis
The diagnosis is acute appendicitis (Answer A). This 10-year-old girl presents with the classic clinical triad: right lower quadrant pain with rebound tenderness, nausea, and vomiting—findings that strongly support appendicitis as the primary diagnosis. 1, 2
Why Appendicitis is the Correct Diagnosis
At 10 years old, this patient is in the peak age range for appendicitis, which most commonly occurs between ages 10-30 years. 1, 3 The clinical presentation is textbook:
- Right lower quadrant pain with rebound tenderness indicates peritoneal irritation, the hallmark of appendicitis when the inflamed appendix contacts the parietal peritoneum. 2, 4
- Nausea and vomiting are common presenting features in pediatric appendicitis. 2, 5
- Physical examination findings of pain and rebound tenderness in the RLQ are among the best clinical signs for ruling in acute appendicitis. 4
The combination of these three features—RLQ pain, nausea/vomiting, and peritoneal signs—makes appendicitis the overwhelmingly most likely diagnosis. 2, 6
Why the Other Options Are Less Likely
Intussusception (Option B)
Intussusception is much more common in younger children, particularly those under 5 years of age, and is rare at 10 years old. 2, 7 The classic presentation differs significantly:
- Intermittent colicky pain (not constant RLQ pain with rebound tenderness) 2, 7
- Bloody stools ("currant jelly" stools) are characteristic 2
- Typically presents with a palpable mass, not focal rebound tenderness 7
Meckel's Diverticulum (Option C)
Meckel's diverticulum typically presents differently:
- Painless rectal bleeding is the most common presentation 5
- When symptomatic, it more commonly causes obstruction or diverticulitis mimicking appendicitis, but this is less common than true appendicitis 5
- The clinical presentation described (RLQ pain with rebound tenderness, nausea, vomiting) is classic for appendicitis, not Meckel's diverticulum 2, 6
Recommended Immediate Next Steps
Obtain ultrasound of the right lower quadrant immediately as the first-line imaging modality due to zero radiation exposure and good diagnostic accuracy in pediatric patients. 1, 7, 3
If ultrasound is equivocal or non-diagnostic and clinical suspicion remains high (as it should in this case), proceed directly to CT abdomen/pelvis with IV contrast or MRI, which provide 90-94% sensitivity and 94-98% specificity for appendicitis. 1, 3
Critical Pitfall to Avoid
Do not delay surgical consultation while waiting for imaging in a patient with this classic presentation. 4 The combination of RLQ pain, rebound tenderness, and vomiting in a 10-year-old warrants immediate surgical evaluation, as prolonged delay increases perforation risk from 17-32%. 4 Clinical examination findings this clear should prompt urgent action even as imaging is being arranged. 1, 2