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B35.1
ICD-10-CM
Onychomycosis of Toenails

Find information on onychomycosis of toenails, including clinical documentation, ICD-10 codes (B35.1), medical coding, and healthcare guidance. Learn about diagnosis, treatment, and best practices for documenting toenail fungus in medical records. This resource provides essential information for healthcare professionals on managing and coding onychomycosis. Explore details on fungal nail infections, distal subungual onychomycosis, and proximal subungual onychomycosis for accurate diagnosis and treatment.

Also known as

Toenail Fungus
Tinea Unguium

Diagnosis Snapshot

Key Facts
  • Definition : Fungal infection of the toenails.
  • Clinical Signs : Thickened, discolored, brittle nails, separation from nail bed.
  • Common Settings : Communal showers, locker rooms, nail salons, sweaty footwear.

Related ICD-10 Code Ranges

Complete code families applicable to AAPC B35.1 Coding
B35.1

Onychomycosis

Fungal infection of the nail.

B35.0

Tinea unguium

Onychomycosis specifically caused by dermatophytes.

L00-L99

Diseases of the skin and subcutaneous tissue

Encompasses various skin and nail conditions, including infections.

Code-Specific Guidance

Decision Tree for

Follow this step-by-step guide to choose the correct ICD-10 code.

Is the onychomycosis confirmed by a physician?

Code Comparison

Related Codes Comparison

When to use each related code

Description
Toenail fungal infection
Nail psoriasis
Toenail trauma

Documentation Best Practices

Documentation Checklist
  • Onychomycosis toenail diagnosis ICD-10 code
  • Document affected toenail(s) (e.g., hallux, lesser digits)
  • Clinical findings: discoloration, thickening, debris
  • KOH prep or fungal culture results
  • Differential diagnoses considered and ruled out

Coding and Audit Risks

Common Risks
  • Unspecified Laterality

    Coding onychomycosis without specifying affected toenail(s) (right, left, bilateral) leads to inaccurate data and potential claim rejections. Use B35.1 with laterality codes.

  • Missing Causative Agent

    Failing to document the causative organism (dermatophyte, yeast, nondermatophyte mold) when known impacts treatment and statistical reporting. Add appropriate ICD-10-CM code.

  • Confusing with Ingrown Nail

    Misdiagnosing ingrown toenail (L60.0) as onychomycosis (B35.1) results in incorrect treatment and coding errors. Careful clinical documentation is crucial.

Mitigation Tips

Best Practices
  • Confirm diagnosis via KOH prep or culture for accurate ICD-10 coding (B35.1)
  • Document location, severity, and duration for proper CDI and E/M coding
  • Consider risk factors like diabetes, immunosuppression for HCC coding compliance
  • Document treatment plan, patient education on hygiene for improved outcomes tracking
  • Rule out differential diagnoses like psoriasis, trauma with clear clinical documentation

Clinical Decision Support

Checklist
  • Confirm toenail thickening, discoloration, debris
  • KOH prep or fungal culture positive
  • Exclude other nail dystrophies psoriasis lichen planus
  • Document clinical findings ICD-10 B35.1 SNOMED CT 70892009
  • Review risk factors diabetes peripheral vascular disease

Reimbursement and Quality Metrics

Impact Summary
  • Onychomycosis toenail billing codes: ICD-10 B35.1, CPT 11750, 11765 impact reimbursement.
  • Accurate coding, diagnosis, procedure documentation maximizes onychomycosis treatment payments.
  • Hospital quality reporting: onychomycosis treatment outcomes, patient satisfaction affect reimbursement.
  • Onychomycosis: coding compliance prevents denials, audits, improves hospital revenue integrity.

Streamline Your Medical Coding

Let S10.AI help you select the most accurate ICD-10 codes. Our AI-powered assistant ensures compliance and reduces coding errors.

Quick Tips

Practical Coding Tips
  • Code B35.1 for onychomycosis
  • Specify laterality: left, right, both
  • Document causative agent if known
  • Consider KOH test confirmation
  • Rule out other nail conditions

Documentation Templates

Patient presents with symptoms consistent with onychomycosis, also known as toenail fungus.  Clinical findings include thickened, discolored (yellow, brown, or white), brittle, and possibly crumbling toenails. The patient reports [Insert patient's subjective complaints, e.g., nail thickening, discoloration, pain, foul odor, difficulty trimming nails].  Affected toenails are [Specify location, e.g., great toe, lesser toes, unilateral, bilateral].  The patient denies any recent trauma to the affected area.  Differential diagnoses considered include psoriasis, lichen planus, and traumatic nail dystrophy.  Based on clinical presentation, a diagnosis of distal subungual onychomycosis is made.  Treatment options discussed include topical antifungal medications such as ciclopirox nail lacquer or efinaconazole solution, oral antifungal medications such as terbinafine or itraconazole, and laser therapy.  Risks and benefits of each treatment option were explained.  Patient elected to begin treatment with [Specify chosen treatment].  Patient education provided regarding proper nail hygiene, including keeping nails trimmed short, dry, and clean.  Follow-up appointment scheduled in [Duration] to monitor treatment response and assess for any adverse effects.  ICD-10 code B35.1 is assigned for onychomycosis.  CPT codes for potential procedures, such as nail debridement (11720, 11721), were reviewed and will be applied if performed during subsequent visits.  Patient understands the diagnosis, treatment plan, and importance of adherence.