ICD-10 Codes for Urinary Tract Infection (UTI)

N39.0 is the everyday UTI code — but it's rarely complete on its own. ICD-10 wants the infecting organism coded alongside it, switches to a different chapter entirely in pregnancy, and prefers a site-specific code whenever the documentation supports one.

The everyday code — and why it's usually not enough

N39.0 (urinary tract infection, site not specified) is the right code when the infection's site isn't documented. But ICD-10 carries an instructional note under N39.0 to use an additional code to identify the infectious agent — so when the organism is known (say from a urine culture), you also code it.

CodeDescription
N39.0Urinary tract infection, site not specified
B96.20Unspecified Escherichia coli [E. coli] as the cause of diseases classified elsewhere

E. coli causes most UTIs, so B96.20 is the organism code you'll pair most often. When a culture identifies a different organism, code that one instead.

Code the site when it's documented

If the record localizes the infection — bladder, kidney, urethra — use the site-specific code rather than the unspecified N39.0.

CodeDescription
N30.00Acute cystitis without hematuria
N30.01Acute cystitis with hematuria
N10Acute pyelonephritis
N34.1Nonspecific urethritis
N34.2Other urethritis

These site codes generally carry a similar “use additional code for the infectious agent” instruction. Search the lookup tool for related codes.

Two contexts that change the code entirely

UTI in pregnancy is not N39.0. A urinary tract infection during pregnancy is coded from O23.- (infections of the genitourinary tract in pregnancy), chosen by trimester — for example O23.40 (unspecified trimester). Chapter 15 (pregnancy) codes take sequencing priority; using N39.0 here is a frequent error.

Catheter-associated UTI

For a catheter-associated UTI (CAUTI), sequence T83.511A first (infection and inflammatory reaction due to an indwelling urethral catheter, initial encounter), then add the UTI and organism codes. The “use additional code to identify infection” note under T83.51- makes the device-complication code the first-listed code, with the UTI code (N39.0 or site-specific) additional — not the other way around.

Common UTI coding mistakes

  • Reporting N39.0 alone when the organism is known. ICD-10's “use additional code” note expects the infectious agent (for example B96.20 for E. coli) whenever a culture identifies it.
  • Using N39.0 in pregnancy. A UTI in a pregnant patient is coded from O23.- by trimester, not N39.0.
  • Defaulting to N39.0 when the site is documented. Cystitis (N30.-), acute pyelonephritis (N10), and urethritis (N34.-) are more specific and should be used when documented.
  • Missing the catheter cause. A CAUTI is led by the T83.511A device-infection code (sequenced first), with the UTI and organism codes added.

A worked example

Scenario. A pregnant patient in the second trimester with dysuria; urine culture grows E. coli.
CodesO23.42B96.20

Because the patient is pregnant, the UTI is coded from the pregnancy chapter — O23.42 (UTI in pregnancy, second trimester) — not N39.0. Then add B96.20 for the E. coli identified on culture, per the “use additional code for the infectious agent” instruction.

Recurrent UTI, urosepsis, and asymptomatic bacteriuria

Three adjacent situations trip people up. Recurrent UTI has no special code — each episode is still N39.0 (plus the organism); recurrence lives in the documentation, not a distinct code. “Urosepsis” is not codeable — ICD-10 has no urosepsis code, so when sepsis arises from a UTI you code the sepsis (for example A41.9) first and the UTI as an additional code. And asymptomatic bacteriuria is not a UTI at all: with a positive culture but no symptoms, the code is R82.71 (bacteriuria), not N39.0.

What the note needs to document

  • The site of infection (bladder, kidney, urethra) when known
  • The infectious organism (from culture) for the additional B95–B97 code
  • Whether the patient is pregnant (and the trimester), which moves the code to O23.-
  • Any indwelling catheter as the source (T83.511-)

Frequently asked questions

The general code is N39.0 (urinary tract infection, site not specified). Because ICD-10 carries a “use additional code” note under N39.0, also code the infectious organism when it's known — most commonly B96.20 for E. coli.

Yes, when it's documented. N39.0 and the site-specific UTI codes carry an instruction to use an additional code (from B95–B97) to identify the infectious agent. If a urine culture identifies the organism, code it alongside the UTI.

Not with N39.0. A urinary tract infection during pregnancy is coded from O23.- (infections of the genitourinary tract in pregnancy), selected by trimester — for example O23.40 for an unspecified trimester. Pregnancy-chapter codes take sequencing priority.

Code T83.511A (infection and inflammatory reaction due to an indwelling urethral catheter, initial encounter), and also assign the UTI code and the organism code. The catheter code identifies the device-related source.

Whenever the documentation localizes the infection: acute cystitis is N30.-, acute pyelonephritis is N10, and urethritis is N34.-. N39.0 (site not specified) is for when the site isn't documented.

Code descriptions are from the CMS FY2026 ICD-10-CM release (public domain); coding conventions reference the ICD-10-CM Official Guidelines for Coding and Reporting. Educational reference only, provided as-is with no guarantee of accuracy or outcome — not a substitute for professional coding judgment. Always verify a code's active status for the date of service.
Last reviewed: June 19, 2026