Causes of Right Lower Quadrant Abdominal Pain in a Four-Year-Old Girl
In a four-year-old girl with right lower quadrant pain, appendicitis remains the primary concern despite being less common and more atypical in this age group, but you must also consider gastroenteritis, mesenteric adenitis, constipation, intussusception, urinary tract infection, and ovarian pathology. 1
Age-Specific Considerations Critical for This Patient
Children under 5 years present with atypical symptoms more frequently than older children, making diagnosis particularly challenging. 1 This age group has a higher rate of perforated appendicitis due to delayed presentation and diagnosis. 1 Classic symptoms such as periumbilical pain migrating to the right lower quadrant, anorexia, nausea, and vomiting are less reliable in children under 5 years. 1
Primary Differential Diagnoses
Surgical Causes
Appendicitis: Although uncommon in preschool children under 5 years, it remains the most common surgical emergency causing RLQ pain in children overall. 1 Fever is the single most useful sign associated with appendicitis (likelihood ratio 3.4), and its absence decreases the chance of appendicitis (likelihood ratio 0.32). 2 Rebound tenderness triples the odds of appendicitis when present. 2
Intussusception: More common in this age group (typically 6 months to 3 years, but can occur at 4 years), presenting with intermittent colicky pain, vomiting, and potentially bloody stools. 1
Medical Causes
Gastroenteritis: The most common medical cause of acute abdominal pain in children. 3 In medical conditions, vomiting generally precedes pain, whereas in surgical conditions pain precedes vomiting. 3 Diarrhea is often associated with gastroenteritis. 3
Mesenteric adenitis: Inflammation of mesenteric lymph nodes, often following viral illness, can mimic appendicitis. 1
Constipation: A frequent cause of abdominal pain in young children that can localize to the RLQ. 1
Urinary tract infection/pyelonephritis: Can present with abdominal pain in young children who may not localize symptoms well. 1
Gynecologic Causes (Important in Female Patients)
Ovarian torsion: Though less common at age 4, it must be considered in any female with RLQ pain. 4
Ovarian cyst: Can cause pain if large or ruptured. 4
Diagnostic Approach Algorithm
Initial Laboratory Testing
Complete blood count (CBC): White blood cell count less than 10,000/μL decreases the likelihood of appendicitis (likelihood ratio 0.22), and absolute neutrophil count of 6,750/μL or lower further reduces likelihood (likelihood ratio 0.06). 2
Urinalysis: Essential to rule out urinary tract infection or nephrolithiasis. 1
C-reactive protein: May help assess severity of inflammation if available. 1
Initial Imaging Strategy
Abdominal ultrasound is the initial imaging study of choice for pediatric patients with abdominal pain due to lack of radiation exposure, wide availability, and ability to identify multiple potential causes. 1 Ultrasound is particularly valuable in children as they typically have less body fat, making visualization of abdominal structures easier than in adults, with reasonable sensitivity (76-87%) and specificity (83-89%) for identifying appendicitis, intussusception, and other causes. 1 Sonography is the primary modality for evaluating children with acute right lower quadrant pain. 5
If Ultrasound is Equivocal
If ultrasound results are equivocal or inconclusive and clinical suspicion remains high for a serious condition, CT scan with IV contrast should be considered, offering higher sensitivity (90-94%) and specificity (94%) for diagnosing appendicitis and other causes. 1 However, radiation exposure must be weighed against diagnostic benefit in this young patient.
Clinical Pitfalls to Avoid
Do not rely on absence of classic symptoms to exclude appendicitis in this age group. The absence of RLQ tenderness makes appendicitis less likely but does not exclude it, as atypical presentations occur frequently in children under 5. 1
Repeated physical examination by the same physician is often useful when the diagnosis is not clear after initial evaluation. 3
Signs suggesting acute surgical abdomen include involuntary guarding or rigidity, marked abdominal distention, marked abdominal tenderness, and rebound tenderness—any of these warrant immediate surgical consultation. 3
Do not allow imaging findings to supersede clinical judgment in patients believed to be at high clinical risk of appendicitis based on clinical signs and symptoms. 5