What is the diagnosis and treatment for a 13-year-old male student with bilateral flank pain, vomiting, decreased urine output, frequency, urgency, and reddish discoloration of urine, who has been experiencing these symptoms for 4 days and has a history of completed vaccinations?

Diagnosis and Management of Bilateral Flank Pain with Hematuria in a 13-Year-Old Male

This 13-year-old male most likely has bilateral urolithiasis (kidney stones) causing obstructive uropathy, and requires immediate ultrasound imaging followed by urinalysis, urine culture, and basic metabolic panel to assess for complications including acute kidney injury and infection. 1

Immediate Diagnostic Workup

First-Line Imaging

• Ultrasound is the strongly recommended initial imaging modality for children with suspected urolithiasis 1
• US has 45% sensitivity for ureteral stones and 88% specificity for renal stones, but is radiation-free and readily available 1
• If US is non-diagnostic or cannot provide required information, proceed to low-dose non-contrast CT as second-line imaging 1
• The bilateral nature of symptoms raises concern for bilateral obstruction, which can cause acute renal failure as seen in pediatric case reports 2

Essential Laboratory Tests

• Obtain urinalysis with dipstick for leukocyte esterase, nitrite, and microscopic examination for RBCs and WBCs immediately 3, 4
• Urine culture is mandatory before any intervention to rule out infection 1, 5
• Complete blood count with differential to assess for leukocytosis indicating infection 4
• Basic metabolic panel including creatinine, electrolytes (sodium, potassium), ionized calcium, and uric acid 1
• C-reactive protein (CRP) to assess inflammatory response 1

Critical Clinical Considerations

Rule Out Infection First

• The combination of bilateral flank pain, vomiting, decreased urine output, and hematuria requires immediate assessment for pyelonephritis or pyonephrosis 3, 4
• Fever, if present, strongly suggests upper urinary tract infection (pyelonephritis) rather than simple cystitis 3, 4
• However, absence of fever does not exclude pyelonephritis—50-64% of children with febrile UTI have acute pyelonephritis even with subtle clinical signs 6
• Neonates and young children can have concomitant bacteremia in 4-36% of UTI cases, though this patient's age (13 years) places him at lower risk 6

Assess for Acute Obstruction

• Decreased urine output (oliguria) with bilateral flank pain suggests bilateral obstruction, which is a urologic emergency 2
• Bilateral UPJ (ureteropelvic junction) stone impaction can cause acute renal failure, as documented in a 10-month-old with creatinine elevation to 4.5 mg/dl 2
• If imaging confirms bilateral obstruction with hydronephrosis, immediate urologic consultation for decompression (pigtail catheter placement or percutaneous nephrostomy) is required 2

Stone Characteristics and Metabolic Evaluation

• Stone size and location determine management: stones <5mm have high spontaneous passage rates, while stones >10mm typically require intervention 1, 7
• All first-time stone formers should have stone analysis performed 1
• For children presenting with stones, consider genetic testing and metabolic evaluation, particularly if bilateral disease is present 1
• Quantitative urinary amino acid analysis should be obtained to screen for cystinuria, especially given the young age and bilateral presentation 2

Treatment Algorithm

Conservative Management (if no infection or severe obstruction)

• Pain control with NSAIDs as first-line therapy 7
• Medical expulsive therapy with an alpha-blocker for stones 5-10mm 7
• Aggressive hydration to promote stone passage 7
• Follow-up imaging within 14 days to monitor stone position and assess for hydronephrosis 7

Indications for Immediate Intervention

• Urinary tract infection with obstruction (requires urgent decompression before definitive stone treatment) 5, 7
• Bilateral obstruction causing acute kidney injury 2
• Persistent fever despite 72 hours of appropriate antibiotics 4
• Stones >10mm (low spontaneous passage rate) 1, 7
• Intractable pain or vomiting 7

Antibiotic Therapy (if infection confirmed)

• If pyuria is present with positive culture, initiate culture-specific antibiotics 4, 5
• For outpatient management of uncomplicated pyelonephritis: ciprofloxacin 500-750mg twice daily for 7 days or levofloxacin 750mg once daily for 5 days 4
• For hospitalized patients or those with suspected urosepsis: IV ceftriaxone 1-2g once daily, cefotaxime 2g three times daily, or cefepime 1-2g twice daily 4
• Fluoroquinolones show excellent results in preventing post-operative infections after stone removal procedures 5

Special Considerations for This Age Group

Metabolic Stone Disease Screening

• Children aged ≤25 years with stones should be considered for genetic testing, especially with bilateral disease 1
• Cystinuria is a critical diagnosis to exclude given the bilateral presentation and young age—it can cause recurrent stones, UTIs, and progressive renal dysfunction 2
• All patients with kidney stones should be screened for recurrence risk with medical history, basic laboratory evaluation, and imaging 7

Long-Term Complications

• 15% of children develop renal scarring after their first UTI episode 6
• Risk of recurrent UTI ranges from 14-23% depending on presence of vesicoureteral reflux 6
• Renal abscesses, though uncommon, can occur—most pediatric renal abscesses ≤3cm resolve with IV antibiotics alone, but larger lesions require percutaneous drainage 8

Common Pitfalls to Avoid

• Do not rely solely on urine cloudiness, odor, or color change to diagnose UTI—these can occur with asymptomatic bacteriuria 3
• Do not delay imaging if bilateral obstruction is suspected—acute renal failure can develop rapidly 2
• Do not assume absence of fever excludes serious infection—children can have pyelonephritis without fever 6
• Do not obtain VCUG acutely—this should be deferred until after acute infection resolves, if indicated at all 8
• Do not discharge without ensuring adequate pain control and clear follow-up plan with repeat imaging 7