What are the differential diagnoses for dysuria in an 8‑year‑old girl?

Differential Diagnosis for Burning with Urination in an Eight-Year-Old Female

Urinary tract infection (UTI) is the most common serious cause of dysuria in an 8-year-old girl and must be ruled out first with proper urine culture before considering other diagnoses. 1

Primary Differential: Urinary Tract Infection

• Obtain a midstream clean-catch urine specimen immediately for both urinalysis and culture before starting any antibiotics, as this is the only opportunity for definitive diagnosis. 1, 2
• Diagnosis requires BOTH pyuria (≥5 WBC/HPF or positive leukocyte esterase) AND ≥50,000 CFU/mL of a single uropathogen on culture—urinalysis alone is insufficient. 1
• A combined negative dipstick for leukocyte esterase and nitrite plus negative microscopy has a 95–98% negative predictive value for UTI, effectively ruling it out. 2, 3
• If fever is present (febrile UTI/pyelonephritis), start oral antibiotics immediately (amoxicillin-clavulanate 40–45 mg/kg/day divided BID, cefixime 8 mg/kg once daily, or cephalexin 50–100 mg/kg/day divided QID) for 7–14 days total. 1
• Early treatment within 48 hours of fever onset reduces renal scarring risk by >50%. 1

Secondary Differential: Dysfunctional Voiding/Bladder-Bowel Dysfunction

If urine culture is negative or symptoms persist despite appropriate UTI treatment, evaluate for dysfunctional voiding, which is the second most common cause of dysuria in this age group. 1

Key Clinical Features to Assess:

• Constipation history: ≤2 bowel movements per week is a major modifiable risk factor for both UTI recurrence and voiding dysfunction. 1
• Voiding patterns: Reduced voiding frequency (≤2 voids per day), urgency, daytime wetting, holding maneuvers (squatting, crossing legs). 4, 1
• Incomplete bladder emptying: Check post-void residual if available; large residuals suggest detrusor underactivity. 4

Management Algorithm for Dysfunctional Voiding:

• Treat constipation aggressively first: Initial disimpaction followed by maintenance bowel regimen (polyethylene glycol, increased fiber, adequate hydration). 1
• Implement timed voiding schedule: Every 2–3 hours during the day, with attention to good voiding posture (feet flat on floor, knees apart). 4, 1
• Behavioral interventions: Double voiding (void twice in succession), adequate hydration, avoidance of bladder irritants. 4
• Success rates with this escalating approach reach 90–100%. 4

Tertiary Differential: Chemical/Irritant Vulvovaginitis

• Examine external genitalia for irritation, erythema, or poor hygiene that could cause dysuria without true UTI. 1
• Common irritants include bubble baths, soaps, tight clothing, or inadequate perineal hygiene after toileting. 5
• This diagnosis is made clinically when urine culture is negative and external irritation is visible.

Less Common but Important Differentials

Hypercalciuria

• Screen with spot urine calcium-to-creatinine ratio only if symptoms persist despite negative cultures or if there is isolated frequency without clear infectious etiology. 2
• Hypercalciuria can cause sterile dysuria and frequency in children.

Pinworm Infection (Enterobius vermicularis)

• Consider if nocturnal perineal itching accompanies dysuria, especially with visible perianal excoriation.
• Diagnosed by tape test in the morning before bathing.

Sexual Abuse (Mandatory Consideration)

• Any unexplained genital symptoms in a prepubertal child require consideration of abuse, though most cases have other explanations.
• Look for behavioral changes, genital trauma, or sexually transmitted infections (extremely rare in this age without abuse).

Critical Diagnostic Pitfalls to Avoid

• Do not delay obtaining urine culture before starting antibiotics—this is the only chance for definitive diagnosis. 1
• Do not use bag-collected urine for culture (false-positive rate 12–83%); only use for screening urinalysis. 1, 6
• Do not assume all dysuria is UTI—10–50% of culture-proven UTIs have false-negative urinalysis, but negative culture definitively rules out infection. 2
• Do not overlook constipation—it is present in the majority of children with recurrent UTI and voiding dysfunction. 1
• Do not treat asymptomatic bacteriuria if discovered incidentally; it requires no antibiotics and treatment causes harm. 1

Imaging Recommendations (If UTI Confirmed)

• For an 8-year-old with first non-febrile UTI, NO imaging is required. 1
• Renal and bladder ultrasound is recommended ONLY for febrile UTI in children <2 years. 1
• VCUG is NOT indicated after first UTI but should be performed after a second febrile UTI. 1

When to Refer

• Recurrent febrile UTIs (≥2 episodes). 1
• Abnormal renal ultrasound showing hydronephrosis, scarring, or structural abnormalities. 1
• Poor response to appropriate antibiotics within 48 hours. 1
• Refractory dysfunctional voiding despite behavioral interventions and treatment of constipation. 4