What is the appropriate workup for a 5-year-old patient presenting to the emergency room (ER) with right lower quadrant abdominal pain?

Workup for 5-Year-Old with Right Lower Quadrant Abdominal Pain in the Emergency Department

Begin with abdominal ultrasound as the initial imaging study, combined with complete blood count, urinalysis, and C-reactive protein if available. 1, 2

Initial Clinical Assessment

History and Physical Examination

• Assess for pain migration to the right lower quadrant, which has a likelihood ratio of 4.81 for appendicitis in children with undifferentiated abdominal pain 3
• Evaluate for cough/hop pain or percussion tenderness, which has a likelihood ratio of 7.64 for appendicitis 3
• Check for Rovsing's sign (pain in RLQ when palpating LLQ), which has a likelihood ratio of 3.52 in children suspected of appendicitis 3
• Document fever and rebound tenderness, as these are significantly more common in appendicitis versus other causes of RLQ pain 4

Critical caveat: Children under 5 years present with atypical symptoms more frequently than older children, making diagnosis particularly challenging, and classic symptoms (periumbilical pain migrating to RLQ, anorexia, nausea, vomiting) are less reliable in this age group 1, 2

Laboratory Testing

Obtain the following labs immediately: 1, 2

• Complete blood count (CBC) to assess for leukocytosis
• Urinalysis to rule out urinary tract infection or nephrolithiasis
• C-reactive protein if available to assess severity of inflammation
• Basic metabolic panel to evaluate for electrolyte abnormalities

Important limitation: The absence of fever and normal WBC count are common in early appendicitis and do not rule out the diagnosis, as classic symptoms (fever and leukocytosis) are present in only approximately 50% of patients with appendicitis 1

Imaging Strategy

First-Line Imaging: Ultrasound

Abdominal ultrasound is the initial imaging study of choice for pediatric patients with RLQ pain due to: 1, 2

• Lack of radiation exposure
• Wide availability
• Ability to identify multiple potential causes
• Reasonable sensitivity (76-87%) and specificity (83-89%) for appendicitis 1
• Children typically have less body fat, making visualization easier than in adults 1

Second-Line Imaging: CT with IV Contrast

If ultrasound results are equivocal or inconclusive and clinical suspicion remains high, proceed to CT scan with IV contrast, which offers: 1, 2

• Higher sensitivity (90-94%) for diagnosing appendicitis 1
• Higher specificity (94%) for diagnosing appendicitis 1
• Better evaluation of alternative diagnoses 5

The American College of Radiology recommends CT abdomen and pelvis as an excellent diagnostic modality for evaluation of patients with nonspecific RLQ pain because of its high diagnostic yield for detection of appendicitis and alternative diagnoses 5

Differential Diagnosis Considerations

Primary Concerns in a 5-Year-Old

Appendicitis remains the primary concern despite being less common and more atypical in this age group, as it is the most common surgical emergency causing RLQ pain in children overall 2

Other critical diagnoses to consider: 2, 6

• Intussusception - more common in this age group, typically presenting with intermittent colicky pain, vomiting, and potentially bloody stools
• Mesenteric adenitis - can mimic appendicitis, often following viral illness
• Constipation - frequent cause of abdominal pain in young children that can localize to RLQ
• Urinary tract infection/pyelonephritis - can present with abdominal pain in young children who may not localize symptoms well
• Ovarian torsion - must be considered in any female with RLQ pain
• Ovarian cyst - can cause pain if large or ruptured

Critical Management Pitfalls

Do not discharge based solely on absence of fever and normal WBC, as this would risk missing early appendicitis or other serious pathology 1

Do not rely on clinical examination alone, as clinical determination of appendicitis is notoriously poor in children, with negative appendectomy rates as high as 25% when relying on clinical assessment alone 1, 3

Do not assume clinical decision tools like the Alvarado score are sufficient, as they have not improved diagnostic accuracy sufficiently to rely on clinical examination alone 1

Children under 5 years have a higher rate of perforated appendicitis due to delayed presentation and diagnosis, making timely imaging even more critical 1, 2

Observation Strategy

If imaging is negative and clinical suspicion is low, active observation with repeated physical examinations is safe and effective 4

The combination of imaging with clinical observation provides the highest diagnostic yield while minimizing unnecessary surgery 1