R31.21 - Asymptomatic Microscopic Hematuria

Short Description

R31.21: Use for microscopic hematuria (blood in urine detected only by laboratory testing, not visible to naked eye) when the patient has NO urinary symptoms - this is the code for incidental microscopic hematuria found on routine screening, wellness exams, pre-operative testing, or other asymptomatic presentations. The patient does NOT have dysuria, frequency, urgency, pain, or other urinary complaints.

Full Description & Clinical Context

R31.21 - Asymptomatic microscopic hematuria describes blood in the urine that is NOT visible to the naked eye, is detected by urinalysis (dipstick or microscopic examination), AND occurs in a patient who has NO urinary symptoms whatsoever.

Key Clinical Features:

Microscopic hematuria - RBCs detected on urinalysis but urine appears normal/clear to the eye
ASYMPTOMATIC - patient has NO urinary symptoms (no dysuria, frequency, urgency, pain, etc.)
Incidental finding - often discovered on routine physical, wellness exam, pre-op clearance, or insurance screening
Requires evaluation - American Urological Association guidelines recommend workup even when asymptomatic
Common causes: Benign (exercise, menstruation), stones, tumors, glomerular disease, benign prostatic hyperplasia

Distinction from other hematuria codes:

NOT visible (would be R31.0 - gross hematuria)
NOT symptomatic (would be R31.29 - other microscopic hematuria)
NOT benign essential (would be R31.1 - benign essential microscopic hematuria)
This is specifically for ASYMPTOMATIC microscopic hematuria

Clinical significance:

Asymptomatic microscopic hematuria requires investigation per AUA guidelines
Even without symptoms, can indicate serious underlying pathology
Conservative workup approach compared to symptomatic hematuria
Important to rule out malignancy, especially in patients >35 years with risk factors

Code Details

Code set: ICD-10-CM
Full code: R31.21
Title: Asymptomatic microscopic hematuria
Code type: Billable/specific diagnosis code
Clinical category: Hematuria (symptom code)
Parent code: R31.2 (Other microscopic hematuria)
Created: R31.2 was expanded to R31.21 and R31.29 to distinguish asymptomatic from symptomatic/other types

Coding notes from R31:

Excludes 1:
- Hematuria included with underlying conditions, such as:
  - Acute cystitis with hematuria → N30.01
  - Recurrent and persistent hematuria in glomerular diseases → N02.-

R31 Family - Complete Hematuria Code Set

The Complete Hematuria Hierarchy

Code	Description	Type	When Used	Clinical Scenario
R31.0	Gross hematuria	Visible	Blood visible to naked eye (red/pink/tea-colored urine)	Patient sees blood in urine
R31.1	Benign essential microscopic hematuria	Microscopic	Frequent, heavy microscopic hematuria; benign, no serious cause	Chronic benign microhematuria[web:196]
R31.2	Other microscopic hematuria	Microscopic	Parent code (use R31.21 or R31.29 instead)	DO NOT USE - use child codes
R31.21	Asymptomatic microscopic hematuria	Microscopic	Microscopic hematuria WITHOUT symptoms; incidental finding	NO symptoms, routine UA[web:212][web:214][web:196] ← YOU ARE HERE
R31.29	Other microscopic hematuria	Microscopic	Microscopic hematuria WITH symptoms OR not fitting R31.21/R31.1	HAS symptoms OR not classified[web:211][web:212]
R31.9	Hematuria, unspecified	Unspecified	Hematuria type not specified (avoid when possible)	Hematuria NOS

Coding Principle:

R31.0 = VISIBLE blood (gross hematuria)
R31.1 = Benign essential microscopic (chronic, benign)
R31.21 = ASYMPTOMATIC microscopic hematuria ← YOU ARE HERE
R31.29 = SYMPTOMATIC microscopic hematuria (or other type)
R31.9 = Unspecified (avoid when type is known)

CRITICAL: R31.21 vs R31.29 (The Symptom Question)

Decision Tree: Which Microscopic Hematuria Code?

This is THE most important distinction for microscopic hematuria coding:

Use R31.21 (Asymptomatic) when:

Microscopic hematuria detected on UA
Patient has NO urinary symptoms whatsoever
Found incidentally (routine physical, pre-op screening, wellness exam, insurance exam)
No dysuria, frequency, urgency, pain, or other urinary complaints
“Asymptomatic microscopic hematuria” explicitly documented
Patient completely unaware of any urinary problem

Example for R31.21:

“Annual physical exam. Patient denies any urinary symptoms. UA shows 5-10 RBC/hpf on routine screening. Urine appears clear. Diagnosis: Asymptomatic microscopic hematuria. Plan: Refer to urology for evaluation.”

Use R31.29 (Other) when:

Microscopic hematuria detected on UA
Patient HAS urinary symptoms (dysuria, frequency, urgency, pain, etc.)
OR: Microscopic hematuria is symptomatic or requires investigation beyond routine
OR: Does not fit criteria for R31.21 (asymptomatic) or R31.1 (benign essential)

Example for R31.29:

“Patient presents with dysuria and suprapubic discomfort. UA shows 10-20 RBC/hpf. Diagnosis: UTI with microscopic hematuria. Plan: Antibiotics.”

Why R31.21 Exists (Important History)

American Urological Association requested this code split:

In the early 2010s, the AUA petitioned to split R31.2 (Other microscopic hematuria) into two distinct codes:

R31.21 - Asymptomatic microscopic hematuria
R31.29 - Other microscopic hematuria

Rationale:

Clinical pathways differ based on symptom presence
Asymptomatic hematuria follows AUA consensus guidelines for conservative evaluation
Symptomatic hematuria requires more aggressive workup
Proper code selection helps:
- Guide appropriate clinical management
- Track outcomes
- Support research
- Justify medical necessity for procedures

AUA Guidelines for Asymptomatic Microscopic Hematuria:

Defined as ≥3 RBCs per high-power field on properly collected urinalysis
Risk stratification based on age, smoking history, occupational exposures
Workup may include cystoscopy, upper tract imaging, nephrology referral
Lower threshold for invasive testing compared to symptomatic cases in some scenarios

When to Use R31.21

Use R31.21 ONLY when ALL are true:

Microscopic hematuria confirmed:
- Positive dipstick for blood (heme-positive)
- Elevated RBCs on microscopic exam (typically ≥3 RBC/hpf)
- Urine NOT visibly discolored (not gross hematuria)
Patient is COMPLETELY ASYMPTOMATIC:
- NO dysuria (no pain with urination)
- NO frequency (not urinating more often than normal)
- NO urgency (no sudden strong urge to void)
- NO suprapubic pain or discomfort
- NO flank pain
- NO visible blood in urine
- NO urinary retention
- NO other urinary complaints whatsoever
Incidental finding:
- Found on routine screening (annual physical, wellness exam)
- Pre-operative testing
- Insurance physical
- Employment physical
- NOT because patient complained of urinary symptoms
NOT excluded by underlying diagnosis:
- If acute cystitis WITH hematuria documented → use N30.01, not R31.21
- If glomerular disease documented → use N02.-, not R31.21
Documentation explicitly states “asymptomatic”:
- Provider notes patient has no symptoms
- OR: Chart clearly indicates incidental finding

Typical scenarios for R31.21:

“Annual physical. No urinary complaints. UA shows 5 RBC/hpf. Asymptomatic microscopic hematuria.”
“Pre-op clearance. Patient asymptomatic. Routine UA positive for microscopic hematuria.”
“Wellness exam. No symptoms. Incidental finding of microscopic hematuria on screening UA.”
“Insurance physical. Patient denies any symptoms. UA shows trace blood, 3-5 RBC/hpf. Asymptomatic microhematuria.”

When NOT to Use R31.21

Do NOT use R31.21 when:

Scenario	Use Instead	Why
Patient HAS ANY urinary symptoms	R31.29	Not asymptomatic; symptomatic = R31.29
Blood is VISIBLE to naked eye	R31.0	That’s gross hematuria, not microscopic
Benign essential microscopic hematuria	R31.1	Specific benign essential type
Acute cystitis WITH hematuria documented	N30.01	Hematuria already included in code
Glomerular disease with hematuria	N02.-	Hematuria included in glomerular codes
Chronic cystitis with hematuria	N30.21	Hematuria included in code
Hematuria type not documented	R31.9	Unspecified (but try to avoid)
Patient has dysuria, pain, frequency, etc.	R31.29	Has symptoms = not asymptomatic

Documentation Requirements for R31.21

MINIMUM documentation needed to assign R31.21:

✅ MUST include:

Microscopic hematuria confirmed:
- “Microscopic hematuria,” “RBCs in urine,” “blood on urinalysis”
- Dipstick positive for blood OR RBCs elevated on microscopy
- Urine NOT visibly discolored
Explicitly documented as ASYMPTOMATIC:
- “Asymptomatic microscopic hematuria” OR
- “Patient denies urinary symptoms” OR
- “No dysuria, frequency, urgency” OR
- “Incidental finding on routine screening”
Context showing incidental discovery:
- “Annual physical exam”
- “Pre-operative clearance”
- “Routine screening”
- “Wellness visit”
No urinary symptoms documented:
- Chart should NOT mention dysuria, frequency, urgency, pain, etc.
- If ANY urinary symptom present → use R31.29 instead

❌ CANNOT use if:

Any urinary symptoms mentioned (use R31.29)
Blood is visible (use R31.0)
Hematuria inherent in underlying diagnosis code

✅ SHOULD document (best practice):[web:212]

Urinalysis results (RBC count, dipstick heme result)
Risk factors (age >35, smoking history, occupational exposures)
Prior episodes of hematuria
Medications (anticoagulation, aspirin)
Comorbidities
Plan for workup (cystoscopy, imaging, nephrology referral)

Clinical Significance & AUA Guidelines

Why R31.21 matters clinically:

Even though asymptomatic, microscopic hematuria can indicate:

Bladder cancer - especially in patients >35 with risk factors
Kidney cancer - renal cell carcinoma
Urothelial carcinoma - upper tract
Kidney stones - asymptomatic nephrolithiasis
Glomerular disease - IgA nephropathy, thin basement membrane disease
benign prostatic hyperplasia (BPH) - in older males

AUA Consensus Guidelines (summarized):

Definition: ≥3 RBCs/hpf on properly collected urinalysis without obvious benign cause
Risk stratification:
- Low risk: Age <35, no risk factors, isolated finding
- Intermediate risk: Age 35-60, some risk factors
- High risk: Age >60, smoking history, occupational exposures, gross hematuria history
Recommended workup:
- Cystoscopy (for most patients over age 35)
- Upper tract imaging (CT urography or MRI urography preferred)
- Nephrology referral if glomerular disease suspected
Follow-up: Annual urinalysis for 2 years if initial workup negative

Coding impact:

Accurate R31.21 coding supports medical necessity for these evaluations
Distinguishing R31.21 from R31.29 helps track clinical pathways
Important for outcomes research

HCC Information

R31.21 does NOT map to a CMS-HCC - symptom codes generally do not have HCC impact
No direct HCC weight or RAF score impact
HCC mapping typically comes from underlying condition (malignancy, kidney disease, etc.), not from R31.21 itself

Use R31.21 primarily for:

Medical necessity for workup (cystoscopy, imaging, labs)
Accurate symptom documentation
Supporting complexity of evaluation
Tracking asymptomatic hematuria for outcomes research

RVU / wRVU Information

ICD-10-CM codes (including R31.21) do NOT carry RVUs or wRVUs
RVUs apply to CPT/HCPCS procedure codes only
R31.21 supports medical necessity for:
- Cystoscopy (52000)
- Advanced imaging (CT urogram, renal ultrasound)
- Laboratory testing (UA, cytology)
- Nephrology or urology consultation

Typical E/M levels with R31.21:

Often moderate complexity due to need for workup planning
Justifies referral to urology or nephrology
May support preventive medicine codes when found on wellness exam

Common CPT Procedure Pairings with R31.21

Laboratory:

81001 - Urinalysis, automated with microscopy
81002/81003 - Urinalysis without microscopy
81015 - Urinalysis; microscopic only
88112 - Cytopathology, urine (voided/catheterized)
87086/87088 - Urine culture (if concurrent UTI suspected)

Imaging:

76770 - Ultrasound, retroperitoneal (kidneys), complete
74178 - CT abdomen and pelvis with contrast (CT urogram protocol)
74181/74182/74183 - MRI abdomen with/without contrast (MR urography)

Endoscopy (urology):

52000 - Cystourethroscopy (diagnostic) - most common procedure for asymptomatic microhematuria workup
52204 - Cystourethroscopy with biopsy (if lesion found)
52214- Cystourethroscopy with fulguration

E/M Services:

99202-99205 - Office visit, new patient (initial evaluation)
99211-99215 - Office visit, established patient (follow-up)
99381-99397 - Preventive medicine services (when found on wellness exam)
99242-99245 - Office consultation (if referred to urology/nephrology)

Common Associated ICD-10-CM Codes

Frequently coded WITH R31.21 when underlying cause found:

Neoplasms (if malignancy discovered):

C64.9 - Malignant neoplasm of kidney, unspecified
C67.9 - Malignant neoplasm of bladder, unspecified
D41.4 - Neoplasm of uncertain behavior of bladder
D30.0 - Benign neoplasm of kidney

Stones (if nephrolithiasis found):

N20.0 - Calculus of kidney
N20.1 - Calculus of ureter
N20.9 - Urinary calculus, unspecified

Prostatic disease (males):

N40.0/N40.1 - Benign prostatic hyperplasia (with/without LUTS)
N42.1 - Congestion and hemorrhage of prostate

Glomerular disease (if nephrology diagnosis):

N02.9 - Recurrent and persistent hematuria, unspecified
N05.9 - Unspecified nephritic syndrome

Other urinary conditions:

N28.0 - Ischemia and infarction of kidney
N28.81 - Hypertrophy of kidney
N39.0 - Urinary tract infection, site not specified

Clinical Examples: When to Use R31.21

✅ Example 1 - Annual Physical, Incidental Finding

SCENARIO: 
45-year-old male for annual physical exam.
Patient reports feeling well, no complaints.
Review of systems negative for urinary symptoms.

Provider: "Any issues with urination?"
Patient: "No, everything is normal."

UA Results (routine screening):
- Color: Yellow, clear (NO visible blood)
- RBC: 5-10/hpf (ELEVATED)
- WBC: 0-2/hpf (normal)
- Bacteria: None
- Blood: 1+ positive (on dipstick)

Assessment: Asymptomatic microscopic hematuria found on routine screening
Plan: Refer to urology for cystoscopy and imaging per AUA guidelines

CODE: R31.21 (Asymptomatic microscopic hematuria)
├─ Microscopic hematuria confirmed (RBC elevated, but urine clear)
├─ Patient is COMPLETELY ASYMPTOMATIC (no urinary complaints)
├─ Incidental finding on routine physical exam
├─ Documentation clearly states "asymptomatic"
└─ R31.21 is CORRECT

✅ Example 2 - Pre-Operative Clearance

SCENARIO:
60-year-old female scheduled for elective knee replacement surgery.
Pre-operative clearance exam and labs ordered.
Patient denies any urinary symptoms.

UA Results (pre-op screening):
- RBC: 3-5/hpf (elevated)
- Urine clear, no visible blood
- Patient asymptomatic

Assessment: Asymptomatic microscopic hematuria on pre-op screening
Plan: Surgery to proceed; refer to urology post-operatively for hematuria workup

CODE: R31.21
├─ Found incidentally on pre-op testing
├─ Patient asymptomatic (no urinary symptoms)
├─ Microscopic only (not visible)
└─ R31.21 appropriate

✅ Example 3 - Insurance Physical

SCENARIO:
35-year-old male for insurance life insurance physical.
No medical complaints, feels healthy.
Denies all urinary symptoms.

UA Results (insurance requirement):
- RBC: 8-12/hpf
- No visible blood
- Otherwise normal UA

Assessment: Asymptomatic microscopic hematuria, incidental
Plan: Patient advised to follow up with PCP for urology referral

CODE: R31.21
├─ Insurance screening (incidental finding)
├─ Completely asymptomatic
├─ Microscopic only
└─ R31.21 correct

❌ Example 4 - WRONG: Patient HAS Symptoms

SCENARIO:
40-year-old female reports increased urinary frequency x 1 week.
Also notes urgency and mild suprapubic discomfort.
UA ordered.

UA Results:
- RBC: 10-15/hpf (elevated)
- WBC: 5-10/hpf
- Urine appears clear (microscopic hematuria)

Assessment: UTI with microscopic hematuria

WRONG CODE: R31.21 (this is for ASYMPTOMATIC)
CORRECT CODE: R31.29 (other microscopic hematuria)

WHY:
├─ Patient HAS symptoms (frequency, urgency, suprapubic discomfort)
├─ R31.21 is ONLY for asymptomatic patients
├─ Any urinary symptoms = NOT asymptomatic
├─ R31.29 is for symptomatic microscopic hematuria
└─ Could also use N30.01 if acute cystitis diagnosed

KEY POINT: Even ONE urinary symptom = NOT R31.21

❌ Example 5 - WRONG: Visible Blood

SCENARIO:
Patient for wellness exam.
Reports no urinary symptoms but mentions urine "looks a little pink sometimes."
UA ordered.

UA Results:
- Urine appears pink-tinged
- RBC: Too numerous to count
- Blood: 4+ positive

Assessment: Gross hematuria

WRONG CODE: R31.21 (this is for MICROSCOPIC only)
CORRECT CODE: R31.0 (gross hematuria)

WHY:
├─ Blood is VISIBLE (patient saw it; urine appears pink)
├─ "Microscopic" means NOT visible to naked eye
├─ Even though patient didn't complain of symptoms, visible blood = gross
├─ R31.0 (gross hematuria) is correct
└─ R31.21 is ONLY for microscopic (invisible) hematuria

❌ Example 6 - WRONG: “Probably Asymptomatic” But Not Documented

SCENARIO:
Patient for follow-up visit for diabetes.
UA done as routine diabetes monitoring.
Provider doesn't specifically ask about urinary symptoms.
UA shows RBC 5-10/hpf.

Documentation: "UA shows microscopic hematuria. Will monitor."
NO documentation about whether patient is symptomatic or asymptomatic.

SHOULD CODE: R31.9 (Hematuria, unspecified) OR query provider
SHOULD NOT CODE: R31.21 without documentation of "asymptomatic"

WHY:
├─ Documentation does NOT explicitly state "asymptomatic"
├─ Cannot assume asymptomatic without documentation
├─ R31.21 requires documentation of "no symptoms" or "asymptomatic"
└─ Best practice: Query provider to clarify if patient is asymptomatic

CORRECTED: After query, if provider documents "patient denies 
urinary symptoms," THEN code R31.21

Common Documentation Errors to AVOID

❌ Error 1: Assuming Asymptomatic Without Documentation

WRONG: Coding R31.21 without documentation of "asymptomatic"
├─ Cannot infer "asymptomatic" just because symptoms not mentioned
├─ Must have explicit documentation: "asymptomatic," "denies symptoms," etc.
└─ CORRECT: Query provider if symptom status unclear

✅ CORRECT: Wait for documentation stating "asymptomatic" or "denies urinary symptoms"

❌ Error 2: Using R31.21 When Patient Has ANY Symptoms

WRONG: Coding R31.21 when patient has even mild symptoms
├─ R31.21 means NO symptoms whatsoever
├─ Even ONE urinary symptom = use R31.29 instead
└─ CORRECT: Any symptom = R31.29, not R31.21

✅ CORRECT:
- Zero symptoms → R31.21
- Any symptoms (even mild) → R31.29

❌ Error 3: Not Distinguishing Microscopic from Gross

WRONG: Using R31.21 when blood is visible
├─ "Microscopic" means NOT visible to naked eye
├─ If patient saw blood or urine appears discolored = gross
└─ CORRECT: Visible = R31.0, invisible = R31.21

✅ CORRECT:
- Urine clear, RBCs on lab only → R31.21 (if asymptomatic)
- Urine red/pink/visible blood → R31.0 (gross)

❌ Error 4: Using R31.21 When Hematuria Included in Diagnosis

WRONG: N30.01 (Acute cystitis with hematuria) + R31.21
├─ Hematuria already captured in N30.01
├─ Excludes1 note prohibits coding both
└─ CORRECT: Code N30.01 only (hematuria included)

✅ CORRECT: Check if hematuria already in diagnosis code
- N30.01 = includes hematuria → don't add R31.21
- N02.- = includes hematuria → don't add R31.21

❌ Error 5: Using Parent Code R31.2 Instead of Child Code

WRONG: Coding R31.2 (parent code)
├─ R31.2 is NOT billable in current ICD-10
├─ Must use R31.21 or R31.29
└─ CORRECT: Choose specific child code

✅ CORRECT:
- R31.2 = parent code (do NOT use)
- R31.21 = asymptomatic (USE when appropriate)
- R31.29 = other/symptomatic (USE when appropriate)

Compliance Checklist

Before coding R31.21, verify:

Quick Reference Card

ICD-10-CM R31.21 - Asymptomatic Microscopic Hematuria
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
USE WHEN:
• Microscopic hematuria (detected by lab, NOT visible)
• Patient has NO urinary symptoms (completely asymptomatic)
• Incidental finding (routine physical, pre-op, wellness exam)
• Urine appears clear/normal (not red/pink)
• RBCs elevated on UA microscopy or positive dipstick
• Documentation states "asymptomatic" or "denies symptoms"
 
DON'T USE WHEN:
• Patient HAS ANY urinary symptoms → use R31.29
• Blood is VISIBLE to naked eye → use R31.0 (gross)
• Benign essential microscopic hematuria → use R31.1
• Acute cystitis with hematuria → use N30.01 (includes hematuria)
• Glomerular disease with hematuria → use N02.- (includes hematuria)
• Symptom status not documented → query or use R31.9
 
KEY DISTINCTION:
• R31.21 = Asymptomatic (NO symptoms) ← YOU ARE HERE
• R31.29 = Other/Symptomatic (HAS symptoms)
 
CRITICAL RULE:
• Even ONE urinary symptom = NOT asymptomatic = NOT R31.21
• Must be COMPLETELY asymptomatic to use R31.21
 
CREATED BY AUA REQUEST:
• Split from R31.2 to guide clinical pathways
• Asymptomatic = conservative workup approach
• Follows AUA consensus guidelines for evaluation
 
NOT HCC:
• No direct HCC mapping
• Supports medical necessity for cystoscopy, imaging
 
BOTTOM LINE:
R31.21 = microscopic hematuria with ZERO symptoms,
found incidentally. Any symptoms = use R31.29 instead.
Documentation must explicitly state "asymptomatic."

Last Updated: February 9, 2026
For coding reference only - always verify against the current ICD-10-CM, official guidelines, payer policies, and facility rules.
Key concept: R31.21 is specifically for ASYMPTOMATIC microscopic hematuria; requires explicit documentation of no symptoms. Even one urinary symptom excludes R31.21 and requires R31.29 instead.
Created when R31.2 was expanded per American Urological Association request to distinguish asymptomatic from symptomatic microscopic hematuria for clinical pathway guidance.
Follows AUA consensus guidelines: asymptomatic microscopic hematuria defined as ≥3 RBCs/hpf without obvious benign cause, requiring cystoscopy and upper tract imaging in most patients >35 years.

Explorer

R31.21