In a 7‑year‑old child with persistent dysuria and hematuria after completing a course of cephalexin for a presumed urinary tract infection, what is the appropriate next management?

Management of Persistent Hematuria and Dysuria After Completing Cephalexin

Immediate Next Steps

Obtain a urine culture via catheterization or clean-catch specimen before starting any new antibiotics, and perform renal and bladder ultrasound to evaluate for anatomic abnormalities, nephrolithiasis, or structural lesions. 1, 2

The persistence of symptoms after completing a full antibiotic course raises three critical possibilities: treatment failure due to resistant organism, incorrect initial diagnosis (not a UTI), or underlying anatomic abnormality. Each requires different management.

Diagnostic Algorithm

Step 1: Confirm True UTI vs. Alternative Diagnosis

• Obtain urinalysis with microscopy immediately to document pyuria (≥5 WBC/HPF) and hematuria (≥3 RBC/HPF), as dipstick alone has 65-99% specificity and can give false positives from myoglobin or dietary pigments 2
• Send urine culture before any new antibiotics to identify the pathogen and confirm susceptibility to cephalexin; diagnosis requires ≥50,000 CFU/mL of a single uropathogen 1, 3
• Evaluate urine sediment for dysmorphic RBCs and red cell casts, which suggest glomerular disease rather than infection and warrant pediatric nephrology referral 2, 4
• Check spot urine protein-to-creatinine ratio; values >0.5 g/g indicate significant proteinuria and suggest renal parenchymal disease rather than simple UTI 2

Step 2: Imaging to Detect Structural Abnormalities

• Order renal and bladder ultrasound as first-line imaging to detect hydronephrosis, nephrolithiasis, Wilms tumor, bladder lesions, or anatomic anomalies that predispose to recurrent infection 1, 2
• Ultrasound is mandatory for all children with gross hematuria and should be performed with the bladder distended to optimize assessment 1, 4
• Do not order CT as initial imaging for non-traumatic hematuria in children; ultrasound is preferred to minimize radiation exposure 1, 2
• Consider unenhanced CT only if ultrasound is negative but clinical suspicion for nephrolithiasis remains high, as ultrasound detects only 75% of all stones and 38% of ureteral stones 2

Step 3: Rule Out Non-Infectious Causes

• Screen for hypercalciuria using spot urine calcium-to-creatinine ratio, as this is a common cause of persistent hematuria and dysuria in children 2, 4
• Evaluate for dysfunctional voiding and constipation, which are major risk factors for recurrent UTI; ask about infrequent voiding (once or twice daily), urgency, daytime incontinence, and stool patterns 1, 3
• Consider myoglobinuria if there is history of muscle injury, trauma, or intense exercise; check serum creatine kinase 2

Treatment Decision Tree

If Culture Confirms Resistant Organism:

• Switch to an antibiotic based on culture sensitivities; local E. coli resistance patterns show cephalexin susceptibility ranges from 67-85% 5
• Use amoxicillin-clavulanate, cefixime, or trimethoprim-sulfamethoxazole (if local resistance <10%) as alternative first-line agents 1, 3
• Complete a full 7-10 day course for non-febrile UTI or 7-14 days if febrile; courses shorter than 7 days are inferior 1, 3

If Culture Shows Cephalexin-Susceptible Organism:

• Consider treatment failure due to inadequate duration or dosing; cephalexin requires 50-100 mg/kg/day divided into 4 doses for UTI 1
• Evaluate for underlying anatomic abnormality that prevents bacterial clearance despite appropriate antibiotics 1, 3
• Obtain VCUG if ultrasound shows hydronephrosis, scarring, or findings suggesting high-grade VUR, or if this represents a second febrile UTI 1, 3

If Culture is Negative:

• Reassess the diagnosis; persistent hematuria without infection suggests glomerulonephritis, hypercalciuria, nephrolithiasis, or dysfunctional voiding 2, 4
• Refer to pediatric nephrology if dysmorphic RBCs, proteinuria, hypertension, or elevated creatinine are present 2, 3
• Treat constipation aggressively with disimpaction followed by maintenance bowel regimen if dysfunctional voiding is identified 3

Critical Pitfalls to Avoid

• Do not start empiric antibiotics before obtaining urine culture; this is your only opportunity for definitive diagnosis and to guide appropriate therapy 1, 3
• Do not assume orange/bloody urine is benign without microscopic urinalysis; gross hematuria can indicate Wilms tumor, nephrolithiasis, or glomerulonephritis 1, 2
• Do not delay imaging beyond 48 hours if fever persists or symptoms worsen despite appropriate antibiotics; this suggests abscess, obstruction, or resistant organism 1, 3
• Do not use nitrofurantoin for any child with fever or suspected pyelonephritis, as it does not achieve adequate serum/parenchymal concentrations 1, 3
• Do not ignore constipation or dysfunctional voiding, as these are modifiable risk factors that increase recurrence risk independent of anatomic abnormalities 1, 3

Follow-Up Strategy

• Clinical reassessment within 24-48 hours is critical to confirm symptom resolution and ensure the new antibiotic (if changed) is effective 3
• If symptoms persist beyond 48 hours on appropriate therapy, reevaluate for antibiotic resistance, anatomic abnormality, or alternative diagnosis 1, 3
• Instruct parents to seek prompt evaluation (within 48 hours) for any future febrile illness, as recurrent UTI risk is significant after initial infection 1, 3