What is the correct ICD-10 code for a 17-year-old female patient with a complicated urinary tract infection (UTI), bilateral pelvocaliectasia, and ascites?

ICD-10 Coding for Complicated UTI with Bilateral Pelvocaliectasis and Ascites

For this 17-year-old female with complicated UTI, bilateral pelvocaliectasis, and ascites, use N39.0 (urinary tract infection, site not specified) as the primary diagnosis code, with N13.6 (pyonephrosis) if there is evidence of infected hydronephrosis, Q62.2 (congenital megaureter) or N13.39 (other hydronephrosis) for the bilateral pelvocaliectasis depending on etiology, and R18.8 (other ascites) as additional diagnosis codes.

Primary Diagnosis: Complicated UTI

The presence of bilateral pelvocaliectasis classifies this as a complicated UTI because anatomical abnormalities of the urinary tract are a defining feature of complicated infections 1. The European Association of Urology guidelines explicitly state that any urological abnormality makes a UTI complicated and requires different management than uncomplicated UTI 1, 2.

Appropriate UTI Codes:

• N39.0 - Urinary tract infection, site not specified (most commonly used for complicated UTI when specific site unclear) 1
• N10 - Acute pyelonephritis (if upper tract involvement confirmed with fever, flank pain, or imaging evidence) 1
• N30.00 - Acute cystitis without hematuria (if lower tract only)
• N30.01 - Acute cystitis with hematuria (if hematuria present) 3

Secondary Diagnosis: Bilateral Pelvocaliectasis

Pelvocaliectasis represents dilation of the renal pelvis and calyces, which was identified as an abnormal ultrasonographic finding in pediatric UTI studies with prevalence of 3.9-4.2% 1. This anatomical abnormality requires specific coding:

Appropriate Codes for Pelvocaliectasis:

• N13.39 - Other hydronephrosis (for acquired bilateral pelvocaliectasis)
• Q62.2 - Congenital megaureter (if congenital etiology suspected)
• N13.6 - Pyonephrosis (if infected obstructed system present) 2

The bilateral nature should be documented in clinical notes, though ICD-10 does not always have specific bilateral modifiers for these codes 4.

Tertiary Diagnosis: Ascites

Ascites in a 17-year-old with UTI is unusual and warrants investigation for underlying liver disease, peritoneal infection, or uroperitoneum from bladder/renal perforation 2.

Appropriate Ascites Code:

• R18.8 - Other ascites (general code for ascites of unspecified etiology) 5
• K70.31 - Alcoholic cirrhosis with ascites (only if cirrhosis documented)
• R18.0 - Malignant ascites (only if malignancy documented)

Critical consideration: In the context of complicated UTI with bilateral obstruction, infected obstructed systems are prone to perforation, potentially causing uroperitoneum 2. If imaging suggests urinary leak into peritoneum, consider adding N99.89 (other postprocedural complications of genitourinary system) or trauma codes if applicable.

Coding Sequence Priority

List codes in order of clinical significance and treatment focus:

1. Primary: N39.0 or N10 (the complicated UTI requiring immediate antimicrobial therapy) 1
2. Secondary: N13.39 or N13.6 (the anatomical complication requiring potential urological intervention) 2
3. Tertiary: R18.8 (the ascites requiring investigation and management) 5

Common Coding Pitfalls to Avoid

• Do not use uncomplicated UTI codes (like simple cystitis codes without modifiers) when anatomical abnormalities are present, as this misrepresents disease severity and may affect reimbursement 1, 6
• Verify bilateral documentation in clinical notes even if ICD-10 code doesn't specify laterality 4
• Do not code asymptomatic bacteriuria (R82.71) if patient has symptomatic UTI 1
• Ensure urine culture was obtained before coding complicated UTI, as this is mandatory for diagnosis 1, 3
• Double-check code accuracy early in documentation, as ICD-10's complexity increases error risk 4