What is the recommended approach for assessing and managing acute appendicitis in pediatric patients?

Pediatric Assessment for Acute Appendicitis

Risk Stratification Using Clinical Scores

Do not diagnose appendicitis based on clinical scores alone—use them to stratify risk and determine who needs imaging. 1, 2

• Use the Pediatric Appendicitis Score (PAS) or AIR score to categorize children into low, intermediate, or high-risk groups, as these tools help identify which patients can safely avoid imaging versus those requiring diagnostic workup 1, 2

• The AIR score outperforms both Alvarado and PAS in discriminating appendicitis in children, particularly because it incorporates CRP values and allows for different severity levels of clinical findings 1

• Low-risk patients (PAS <3 or low AIR score) can be safely observed without imaging, as clinical scores are sufficiently sensitive to exclude appendicitis 1, 2

• Intermediate-risk patients require imaging—this is where clinical scores provide the most value by identifying who needs further diagnostic workup 1

• High-risk patients may proceed directly to surgical consultation, though imaging is still recommended to confirm diagnosis and assess for complications 1, 2

Laboratory Testing

Routinely obtain white blood cell count with differential (including absolute neutrophil count) and C-reactive protein in all children with suspected appendicitis. 1, 2

• CRP ≥10 mg/L and leukocytosis ≥16,000/mL are strong predictive factors for appendicitis in pediatric patients, particularly in children under 6 years old 1

• Combine biomarker results with clinical scores to predict inflammation severity and guide imaging decisions—this combination significantly improves diagnostic accuracy over either approach alone 1

• Normal laboratory values do not exclude appendicitis—appendicitis can occur with normal WBC and CRP, particularly in early presentations 3

• Consider adding procalcitonin if available, as it has greater diagnostic value for identifying complicated appendicitis (sensitivity 0.89, specificity 0.90) though it performs poorly for diagnosing uncomplicated disease 1

Imaging Algorithm

Start with ultrasound as the first-line imaging study in all children due to lack of radiation exposure and excellent accuracy when results are definitive. 1, 2

• Ultrasound using graded compression technique should be performed in all potential appendix locations, with sensitivity of 88-97% and specificity of 87-100% when the study is diagnostic 1

• If ultrasound is definitively positive or negative, no further imaging is needed—sensitivity approaches 99% with excellent specificity in these cases 2

• If ultrasound is equivocal or non-diagnostic and clinical suspicion persists, proceed directly to MRI or CT—do not repeat ultrasound, as this delays diagnosis without improving accuracy 1, 2

• MRI is preferred over CT to avoid radiation exposure in children, though CT has slightly higher sensitivity (94%) and specificity (95%) 1

• CT remains appropriate when MRI is unavailable or when there is suspicion for complications such as bowel obstruction 1

Special Population Considerations

Maintain an extremely high index of suspicion in preschool children (under 5 years), as they frequently present with atypical symptoms and have higher perforation rates. 1

• Children under 5 years are more likely to have lower PAS and Alvarado scores than school-aged children despite having appendicitis, making clinical diagnosis particularly unreliable in this age group 1

• Delayed presentation is common in young children, contributing to perforation rates as high as 85% when all three risk factors (symptoms >1 day, fever >38°C, WBC >13,000/mm³) are present 1

• All adolescent female patients should undergo diagnostic imaging regardless of clinical score to exclude gynecologic pathology—PAS ≥8 shows 89% specificity in this population 1, 2

Post-Imaging Management

For positive imaging, initiate broad-spectrum antibiotics promptly and obtain immediate surgical consultation. 2

• For negative imaging with persistent clinical suspicion, admit for hospital observation to evaluate symptom evolution over time rather than discharging home 2

• In complicated cases with abscess formation, consider percutaneous drainage followed by interval appendectomy rather than immediate surgery 1

Critical Pitfalls to Avoid

• Never rely on clinical scores alone to confirm or exclude appendicitis in children—they must be combined with laboratory testing and imaging in intermediate-risk patients 1, 2

• Do not repeat ultrasound if the first study is equivocal—this wastes time without improving diagnostic accuracy; proceed directly to MRI or CT 2

• Do not rule out appendicitis based solely on normal laboratory values—up to 8.4% of children with appendicitis have normal inflammatory markers 3

• Recognize that fever and vomiting together have high negative predictive value (0.97) but poor positive predictive value (0.27), so their absence is more useful than their presence 4

• Be aware that boys have 3-fold higher risk of appendicitis than girls (15% vs 5% in children presenting with acute abdominal pain) 4