What could cause left costovertebral angle (LCVA) tenderness, left lower quadrant (LLQ) pain, and left upper quadrant (LUQ) pain in a 12-year-old patient with no apparent distress?

Differential Diagnosis for LCVA Tenderness with LLQ and LUQ Pain in a 12-Year-Old

In a 12-year-old with left costovertebral angle tenderness combined with left lower and upper quadrant pain but no distress, the most likely diagnoses are renal pathology (pyelonephritis, nephrolithiasis), constipation with fecal loading, or early inflammatory bowel disease, and ultrasound should be the immediate first imaging study.

Primary Diagnostic Considerations

Renal and Urologic Causes

• Pyelonephritis or urinary tract infection is a leading consideration given the LCVA tenderness, which indicates kidney involvement, and can present with referred pain to both LLQ and LUQ without severe distress in children 1, 2.
• Nephrolithiasis should be considered as children can present with atypical pain patterns and may not appear severely distressed despite significant pathology 3, 2.
• The combination of flank tenderness (LCVA) with lower quadrant pain is more consistent with urologic pathology than gastrointestinal causes in this age group 1, 2.

Gastrointestinal Causes

• Constipation with fecal impaction is extremely common in 12-year-olds and can cause diffuse left-sided abdominal pain including both LLQ and LUQ, though LCVA tenderness would be atypical 4, 2.
• Gastroenteritis remains the most common medical cause of abdominal pain in children but typically presents with diarrhea and vomiting, and would not explain LCVA tenderness 4, 2.
• Early inflammatory bowel disease (Crohn's disease or ulcerative colitis) can present with left-sided abdominal pain in adolescents, though LCVA tenderness would be unusual 3, 2.

Musculoskeletal Considerations

• Musculoskeletal strain or costochondritis affecting the lower ribs could theoretically cause both LCVA tenderness and referred abdominal pain, particularly if the child is athletic 3.
• However, true intra-abdominal pathology must be excluded first before attributing symptoms to musculoskeletal causes 3, 2.

Immediate Diagnostic Approach

Initial Laboratory Testing

• Obtain urinalysis immediately to assess for pyuria, hematuria, nitrites, and leukocyte esterase, which would indicate urinary tract infection or nephrolithiasis 1, 2.
• Complete blood count should be obtained to evaluate for leukocytosis suggesting infection or inflammation 1, 2.
• C-reactive protein can help assess severity of inflammation if present 1, 2.
• Basic metabolic panel to evaluate renal function and electrolyte abnormalities 1.

Imaging Strategy

• Abdominal ultrasound is the mandatory first imaging study due to zero radiation exposure, excellent visualization in children with less body fat, and ability to evaluate kidneys, ureters, and intra-abdominal structures with 76-87% sensitivity for most pediatric abdominal pathology 1, 5.
• Ultrasound can identify hydronephrosis, renal stones, pyelonephritis, appendicitis (if appendix extends into LLQ), ovarian pathology in females, and bowel abnormalities 1, 5.
• If ultrasound is equivocal or non-diagnostic and clinical suspicion remains high, proceed to CT abdomen/pelvis with IV contrast, which provides 90-94% sensitivity and specificity for serious pathology 1, 6.

Critical Red Flags to Assess

Signs Requiring Urgent Intervention

• Fever, rigidity, guarding, or peritoneal signs would mandate immediate surgical consultation even in the absence of apparent distress, as children can appear deceptively well with serious pathology 1, 2.
• Inability to pass gas or stool, bilious vomiting, or hematochezia are surgical red flags requiring urgent evaluation 2.
• Testicular pain in males could indicate testicular torsion with referred abdominal pain 2.

Important Clinical Pitfalls

• Never rely on the absence of distress to rule out serious pathology in a 12-year-old, as children often minimize symptoms and can appear well even with significant disease like early appendicitis or pyelonephritis 1, 6.
• LCVA tenderness is not a typical finding for common benign causes of pediatric abdominal pain and should prompt thorough investigation for renal pathology 2.
• The combination of multiple quadrant involvement (LUQ and LLQ) with flank tenderness creates an atypical pattern that requires imaging rather than clinical observation alone 1, 5.

Age-Specific Considerations

• At 12 years old, this patient is in early adolescence where appendicitis, inflammatory bowel disease, and renal pathology become more common than in younger children 1, 2.
• Gynecologic causes (ovarian torsion, cyst) must be considered in post-menarchal females presenting with left-sided pain 1, 2.
• Clinical examination alone has notoriously poor diagnostic accuracy in children, with negative appendectomy rates as high as 25% when imaging is not utilized 1, 6.