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ICD-10 Coding for Toenail Fungus(B35.1)

Complete ICD-10-CM coding and documentation guide for Toenail Fungus. Includes clinical validation requirements, documentation requirements, and coding pitfalls.

Also known as:

OnychomycosisTinea Unguium

Related ICD-10 Code Ranges

Complete code families applicable to Toenail Fungus

B35-B49Primary Range

Mycoses

This range includes fungal infections, with B35.1 specifically for onychomycosis.

Disorders of skin appendages

Includes codes for nail disorders that may be used as ancillary codes with onychomycosis.

Key Information: ICD-10 code for toenail fungus

Essential facts and insights about Toenail Fungus

The ICD-10 code for toenail fungus is B35.1, used when a fungal infection is confirmed by lab tests.

Primary ICD-10-CM Code for toenail fungus

Tinea unguium
Billable Code

Decision Criteria

clinical Criteria

  • Presence of hyphae on KOH prep

documentation Criteria

  • Documented failure of OTC antifungals

Applicable To

  • Onychomycosis

Excludes

  • Nail dystrophy (L60.3)
  • Yellow nail syndrome (L60.5)

Clinical Validation Requirements

  • Positive KOH test
  • Fungal culture
  • PCR test

Code-Specific Risks

  • Using without lab confirmation can lead to audit issues.

Coding Notes

  • Sequence B35.1 first, followed by complication codes.

Ancillary Codes

Additional codes that should be used in conjunction with the main diagnosis codes when applicable.

Onycholysis

L60.1
Use when nail separation is present.

Pain in toe

M79.67-
Use if pain impacts function.

Differential Codes

Alternative codes to consider when ruling out similar conditions to the primary diagnosis.

Nail dystrophy

L60.3
Use only if non-fungal cause is confirmed.

Yellow nail syndrome

L60.5
Requires exclusion of fungal etiology.

Documentation & Coding Risks

Avoid these common documentation and coding issues when documenting Toenail Fungus to ensure proper reimbursement, maintain compliance, and reduce audit risk. These guidelines are particularly important when using ICD-10 code B35.1.

Impact

Clinical: Inadequate treatment planning., Regulatory: Potential for claim denials., Financial: Loss of reimbursement opportunities.

Mitigation Strategy

Document all symptoms impacting function., Use appropriate ancillary codes.

Impact

Reimbursement: Claims may be denied or audited., Compliance: Non-compliance with coding standards., Data Quality: Inaccurate medical records.

Mitigation Strategy

Ensure lab tests confirm fungal infection before coding.

Impact

Coding B35.1 without lab confirmation can trigger audits.

Mitigation Strategy

Ensure all diagnoses are supported by lab results.

Documentation errors, coding pitfalls, and audit risks are interconnected aspects of medical coding and billing. Addressing all three areas helps ensure accurate coding, optimal reimbursement, and regulatory compliance.

Frequently Asked Questions

Common questions about ICD-10 coding for Toenail Fungus, with expert answers to help guide accurate code selection and documentation.

Documentation Templates for Toenail Fungus

Use these documentation templates to ensure complete and accurate documentation for Toenail Fungus. These templates include all required elements for proper coding and billing.

Podiatry visit for onychomycosis

Specialty: Podiatry

Required Elements

  • History of present illness
  • Physical examination findings
  • Lab test results
  • Treatment plan

Example Documentation

S: 62M reports thickened, yellowed R great toe x8mo. Failed clotrimazole cream. Pain 6/10 with shoes. O: R hallux nail: 4mm thickness, onycholysis >3mm, subungual keratosis. +KOH hyphae. No erythema/purulence. A: 1. Onychomycosis (B35.1) R hallux 2. Onycholysis (L60.1) 3. M79.674 (Pain R toe) P: Oral terbinafine 250mg daily x12w; debridement (11721) performed.

Examples: Poor vs. Good Documentation

Poor Documentation Example
Toenail fungus
Good Documentation Example
Distal subungual onychomycosis confirmed by KOH microscopy (hyphae present), affecting right hallux with 40% nail plate involvement
Explanation
The good example provides specific clinical findings and lab confirmation.

Need help with ICD-10 coding for Toenail Fungus? Ask your questions below.

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