Left Lower Abdominal Pain with Nausea in a 9-Year-Old Child
Most Likely Diagnoses
In a 9-year-old with left lower abdominal pain and nausea, you must first rule out appendicitis (even though it typically presents on the right), followed by constipation, mesenteric adenitis, gastroenteritis, and urinary tract infection. 1, 2
Primary Differential Diagnoses to Consider:
Appendicitis with atypical presentation: Children under 10 years present with atypical symptoms more frequently than older children, making clinical diagnosis particularly challenging and leading to higher rates of delayed diagnosis and perforation 2. The appendix can be elongated and project into the left lower quadrant, mimicking left-sided pathology 2.
Constipation: This is a frequent cause of abdominal pain in children that can localize to the lower quadrants and is often accompanied by nausea 2. Ask specifically about stool frequency, consistency, and any straining.
Mesenteric adenitis: Often follows viral illness and can mimic appendicitis with similar pain and nausea 2. Look for recent upper respiratory infection or viral symptoms.
Gastroenteritis: Characterized by diarrhea which may be accompanied by nausea, vomiting, fever, and abdominal pain 3. The pain is typically diffuse but can localize.
Urinary tract infection: Young children may not localize symptoms well, and UTI can present as lower abdominal pain with nausea 2.
Intussusception: Less likely at age 9 but should be considered if there is intermittent colicky pain, vomiting, or bloody stools 2.
Immediate Clinical Assessment
Critical Physical Examination Findings:
Assess for peritoneal signs: Guarding, rebound tenderness, or rigidity suggest surgical abdomen 1, 4.
Evaluate hydration status: The three most useful predictors of 5% or more dehydration are abnormal capillary refill, abnormal skin turgor, and abnormal respiratory pattern 3.
Check vital signs carefully: Tachycardia, tachypnea, fever, or hypotension indicate more serious pathology 4.
Palpate for masses or organomegaly: May indicate abscess, tumor, or other structural abnormality 4.
Examine for abdominal bruising: Could indicate trauma or physical abuse 1.
Diagnostic Algorithm
Step 1: Immediate Laboratory Tests
Urinalysis: Obtain immediately to rule out urinary tract infection or nephrolithiasis 2.
Complete blood count with differential: A WBC <10,000/mm³ dramatically decreases the likelihood of appendicitis (likelihood ratio 0.18-0.22) 2.
C-reactive protein: May help assess severity of inflammation if available 2.
Step 2: Imaging Strategy
Ultrasound is the mandatory first-line imaging study due to zero radiation exposure, wide availability, and ability to identify appendicitis, intussusception, mesenteric adenitis, and other causes 2.
If ultrasound is equivocal or non-diagnostic and clinical suspicion for appendicitis remains high, proceed directly to CT abdomen and pelvis with IV contrast rather than repeating ultrasound 2.
CT offers higher sensitivity (98-100%) and specificity for diagnosing appendicitis and can identify the elongated appendix projecting into the left lower quadrant 2.
Management Based on Findings
If Appendicitis Confirmed:
- Proceed to appendectomy as standard treatment 2.
- For perforated appendicitis with abscess, use percutaneous drainage followed by interval appendectomy with broad-spectrum antibiotics 2.
If Gastroenteritis Diagnosed:
- Oral rehydration therapy is equally efficacious as intravenous rehydration for mild to moderate dehydration 3.
- Ondansetron (oral or IV) may be effective in decreasing vomiting, improving oral hydration success, and preventing need for IV hydration 3.
If Constipation Confirmed:
- Initiate bowel regimen with osmotic laxatives and dietary modifications 2.
If UTI Diagnosed:
- Start appropriate antibiotic therapy based on age and local resistance patterns 2.
Critical Red Flags Requiring Immediate Surgical Consultation
- Fever with inability to pass gas or stool 5
- Severe abdominal tenderness with guarding or rebound 4
- Signs of shock (tachycardia, hypotension, altered mental status) 4
- Bilious vomiting suggesting bowel obstruction 1
- Bloody stools with severe pain 4
- Abdominal distension with absent bowel sounds 1
Common Pitfalls to Avoid
Do not dismiss left-sided pain as "not appendicitis": The appendix can be elongated and project into the left lower quadrant, and children under 10 present atypically more often 2.
Do not rely solely on clinical scoring systems: Clinical scoring systems perform variably and often less well than imaging or a combination of scoring and imaging 1.
Do not skip urinalysis: Young children may not localize UTI symptoms well, and this simple test can prevent unnecessary imaging 2.
Do not assume viral gastroenteritis without considering surgical causes: Approximately 14.8% of children presenting with abdominal pain have clinically significant abdominal pathology requiring intervention 6.