What is the recommended approach for diagnosing and managing appendicitis in children?

Diagnosis of Appendicitis in Children

Start with ultrasound as the first-line imaging modality in all children with suspected appendicitis, followed by MRI or CT if ultrasound is equivocal and clinical suspicion persists. 1, 2, 3

Initial Clinical Assessment

Begin with risk stratification using validated clinical scoring systems before proceeding to imaging:

• Use the Pediatric Appendicitis Score (PAS) or AIR score to identify low-risk children who may not need imaging and intermediate-risk children who require diagnostic imaging 1
• The Alvarado score and PAS are useful for excluding appendicitis but should not be used alone to confirm the diagnosis 1
• Clinical scores alone are insufficient for diagnosis in pediatric patients, particularly in preschool-aged children who often present with atypical features 1, 4, 5

Key clinical pitfall: Children under 3 years are especially challenging to diagnose due to difficulty obtaining reliable history and physical examination, leading to higher perforation rates (17-57%) 1, 4

Laboratory Testing

• Routinely obtain white blood cell count with differential and C-reactive protein (CRP) in all children with suspected appendicitis 1
• CRP ≥10 mg/L and leukocytosis ≥16,000/mL are strong predictive factors for appendicitis in pediatric patients 1
• Combine biomarker results with clinical scores to predict inflammation severity and guide imaging decisions 1

Imaging Algorithm

First-Line Imaging: Ultrasound

Ultrasound should be the initial imaging study in all children due to lack of radiation exposure, wide availability, and excellent accuracy when results are definitive 1, 2, 3

• When ultrasound is definitively positive or negative, sensitivity approaches 99% with excellent specificity 3
• Ultrasound can confirm appendicitis but cannot definitively exclude it 1
• The operator-dependent nature of ultrasound means equivocal results are common 1

Second-Line Imaging: MRI or CT

If ultrasound is equivocal or non-diagnostic and clinical suspicion persists, proceed to MRI or CT rather than repeating ultrasound 1, 3

• MRI is preferred over CT as the second-line modality to avoid radiation exposure, though it may require sedation in young children and is not always readily available 1, 6, 3
• CT with IV contrast is usually appropriate when performed after equivocal ultrasound, with sensitivity 88-97% and specificity 87-100% depending on contrast protocol 1, 3
• CT without IV contrast may be appropriate in select cases but has lower sensitivity (66-97%) and produces inconclusive results in 20-25% of cases 1

Critical consideration: CT exposes children to ionizing radiation, which is a significant concern in the pediatric population 1, 2

Post-Imaging Management

Positive Imaging

• Initiate antimicrobial therapy promptly and proceed with surgical consultation 2
• Appendectomy remains the standard treatment, with laparoscopic approach preferred when feasible 5

Negative Imaging with Persistent Clinical Suspicion

• Hospital observation is necessary to evaluate symptom evolution over time 2
• Consider observation and supportive care with or without antibiotics 1
• If strong clinical suspicion persists after equivocal imaging, exploratory laparoscopy or laparotomy may be considered if subsequent imaging would delay appropriate management 1, 3

Negative Imaging with Resolved Suspicion

• Discharge with alternative diagnosis and arrange 24-hour follow-up 6

Special Populations

Preschool children (under 3 years):

• Maintain extremely high index of suspicion as atypical presentations are the norm 1, 4, 5
• Lower PAS and Alvarado scores are common in this age group despite true appendicitis 1
• Perforation rates are significantly higher due to diagnostic delays 1, 4

Female adolescents:

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

Key Pitfalls to Avoid

• Never rely on clinical scores alone to make the diagnosis in children 1
• Do not repeat ultrasound if the first study is equivocal—proceed directly to MRI or CT 1, 3
• Avoid delaying imaging in young children due to radiation concerns, as this increases perforation risk 4
• Do not dismiss appendicitis in children with normal or mildly elevated inflammatory markers, especially in early presentation 1
• Recognize that noncontrast CT produces inconclusive results in 20-25% of cases, requiring repeat imaging with contrast 1