ICD-10 Coding for Urinary Tract Infections
The appropriate ICD-10 code for a urinary tract infection depends on the specific anatomical location and clinical characteristics of the infection, requiring differentiation between cystitis (lower tract), pyelonephritis (upper tract), and whether the infection is complicated or uncomplicated.
Primary Code Selection Algorithm
For Lower Urinary Tract Infections (Cystitis)
- N30.00: Acute cystitis without hematuria (most common uncomplicated UTI code)
- N30.01: Acute cystitis with hematuria
- N30.90: Cystitis, unspecified without hematuria
- N30.91: Cystitis, unspecified with hematuria
Cystitis is defined as infection limited to the bladder, typically presenting with frequency, urgency, and dysuria without systemic symptoms 1.
For Upper Urinary Tract Infections (Pyelonephritis)
- N10: Acute pyelonephritis (acute tubulo-interstitial nephritis)
- N11.0: Nonobstructive chronic pyelonephritis
- N11.9: Chronic tubulo-interstitial nephritis, unspecified
Pyelonephritis involves kidney infection and typically presents with systemic symptoms including high fever, malaise, vomiting, abdominal or flank pain, and tenderness 1.
For Unspecified Location
- N39.0: Urinary tract infection, site not specified (use only when documentation is insufficient to determine anatomical location)
Clinical Differentiation for Accurate Coding
Key Clinical Features to Document
Lower tract (cystitis) indicators 1:
- Localized urinary symptoms only (dysuria, frequency, urgency)
- Absence of fever or minimal low-grade fever
- No flank pain or tenderness
- No systemic symptoms
Upper tract (pyelonephritis) indicators 1:
- High fever (typically >38.5°C)
- Flank pain or costovertebral angle tenderness
- Systemic symptoms (malaise, nausea, vomiting)
- May have concurrent lower tract symptoms
Special Populations Requiring Additional Codes
Pregnancy-Related UTI
- O23.4: Unspecified infection of urinary tract in pregnancy
- Use additional code from N30-N39 to identify specific infection type
- Pregnant women require urine culture confirmation with ≥10⁵ CFU/mL 2
Complicated UTI Characteristics
When any of the following are present, document as complicated and consider additional codes 3, 4:
- Structural abnormalities (cystocele, diverticula, obstruction)
- Indwelling catheter or foreign body
- Diabetes mellitus (E08-E13)
- Immunosuppression (D84.-)
- Male gender (all UTIs in males are considered complicated)
- Recurrent infection (≥3 episodes in 12 months)
- Treatment failure or rapid recurrence within 2 weeks
Pediatric UTI Considerations
- Use same N30-N39 codes as adults
- Document whether febrile or afebrile
- 50-64% of febrile UTIs in children represent acute pyelonephritis even without classic symptoms 1
Common Coding Pitfalls to Avoid
Do not use N39.0 (unspecified site) when 1:
- Clinical documentation clearly indicates cystitis symptoms only → use N30.00/N30.01
- Patient has fever with flank pain → use N10 for acute pyelonephritis
- Documentation states "bladder infection" → use N30.00 for acute cystitis
Do not confuse asymptomatic bacteriuria with UTI 5:
- Asymptomatic bacteriuria should not be coded as UTI in most populations
- Exception: pregnancy requires treatment and coding as O23.4 2
Document hematuria status 1:
- Presence or absence of blood in urine changes the fifth digit
- Gross hematuria after infection resolution may indicate complicated UTI requiring additional evaluation 3, 4
Laboratory Confirmation Standards
Diagnostic thresholds for coding 1, 5:
- Catheterized specimen: ≥5 × 10⁴ CFU/mL
- Voided specimen: ≥10⁵ CFU/mL
- Symptomatic women: even 10² CFU/mL may reflect true infection
- Pyuria alone without bacteriuria does not confirm UTI, particularly in elderly 5