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T33.529A ICD-10-CM Code: Superficial frostbite of unspecified hand, initial encounter

Compare with another codeCheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
1 inclusion term · 2 Excludes2

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Excludes2Not included here; may be reported together
  • superficial frostbite of fingers (T33.53-)
  • hypothermia and other effects of reduced temperature (T68, T69.-)
IncludesWhat this code covers
  • frostbite with partial thickness skin loss

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 922 — OTHER INJURY, POISONING AND TOXIC EFFECT DIAGNOSES WITH MCC (MDC 21)
  • MS-DRG 923 — OTHER INJURY, POISONING AND TOXIC EFFECT DIAGNOSES WITHOUT MCC (MDC 21)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T33.529A in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on T33.529A itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • frostbite with partial thickness skin loss

Source: inherited from T33

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

7th Character Guide

"The appropriate 7th character is to be added to each code from category T33"

  • A — initial encounter (this page’s code)
  • D — subsequent encounter
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

T33.529A, T33.529D, T33.529S

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for T33.529A

MedCoder structured workflow — derived from this code’s own official record

Before you code T33.529A

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, T33.529A may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewT33.521A, T33.522A

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. This page’s code carries “A”. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  3. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: unspecified). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

    ReviewT33.521A · right, T33.522A · left

    Guide: Laterality coding →

  4. Confirm the injury type, the anatomical site at the most specific level documented, laterality where the family codes it, and the encounter for the 7th character. Each injury is coded separately unless the classification provides a combination code, and a superficial injury is not coded when a more severe injury of the same site is documented. Injury chapter guidelines (Guidelines I.C.19.b, I.C.19.b.1).

    Guide: 7th characters: initial, subsequent, sequela →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — T33.529A is appropriate when the documentation goes no further.

    ReviewT33.521A, T33.522A

  2. Is the side documented?
    Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
    No → Use the unspecified-side code only when the record states no side; a query is the alternative.

    ReviewT33.521A · right, T33.522A · left

  3. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider T33.529A. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Anatomical site
At the most specific level the record states; a site the classification separates cannot be assumed from a procedure or a measurement.
Laterality
Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
External cause, place and activity
For the external cause codes reported with the injury or poisoning, where documented (Guidelines I.C.20.a).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes2 — not part of T33.529A(2 notes)

    Coding workflow: The conditions named in this note are not included in T33.529A. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareT33.53, T68, T69

    See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewT33.521A, T33.522A

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Documentation: The record documents the condition on one side only.

Coding question: Which code in this family applies?

Path: Select the sibling code for the documented side.

Reason: Laterality is assigned from the documented side; the unspecified-side code is for records that state no side (Guidelines I.B.13).

ReviewT33.521A · right, T33.522A · left

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse T33.529A with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of T33.529A — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • T33.521A— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented right side moves the case to T33.521A.

    Full comparison: T33.529A vs T33.521A →

  • T33.522A— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented left side moves the case to T33.522A.

    Full comparison: T33.529A vs T33.522A →

  • T33.529D— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a subsequent encounter moves the case to T33.529D.

    Full comparison: T33.529A vs T33.529D →

  • T33.529S— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a sequela moves the case to T33.529S.

    Full comparison: T33.529A vs T33.529S →

  • T33.53— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of superficial frostbite of fingers adds T33.53; it is not part of this code and both may be reported when both are documented.

    Full comparison: T33.529A vs T33.53 →

  • T68— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of hypothermia and other effects of reduced temperature adds T68; it is not part of this code and both may be reported when both are documented.

    Full comparison: T33.529A vs T68 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Superficial frostbite of unspecified hand, initial encounter is a billable ICD-10-CM diagnosis code (T33.529A).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name T33.529A or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: T07 — Unspecified multiple injuries (via T33.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 113 Excludes2 notes across 2 chapters: I73 — Other peripheral vascular diseases (via T33.-), S00 — Superficial injury of head (via T33.-), S00-S09 — Injuries to the head (S00-S09) (via T33.-), S01 — Open wound of head (via T33.-), S02 — Fracture of skull and facial bones (via T33.-), S03 — Dislocation and sprain of joints and ligaments of head (via T33.-), S04 — Injury of cranial nerve (via T33.-), S05 — Injury of eye and orbit (via T33.-), S06 — Intracranial injury (via T33.-), S07 — Crushing injury of head (via T33.-), S08 — Avulsion and traumatic amputation of part of head (via T33.-), S09 — Other and unspecified injuries of head (via T33.-), S10 — Superficial injury of neck (via T33.-), S10-S19 — Injuries to the neck (S10-S19) (via T33.-), S11 — Open wound of neck (via T33.-), S12 — Fracture of cervical vertebra and other parts of neck (via T33.-), S13 — Dislocation and sprain of joints and ligaments at neck level (via T33.-), S14 — Injury of nerves and spinal cord at neck level (via T33.-), S15 — Injury of blood vessels at neck level (via T33.-), S16 — Injury of muscle, fascia and tendon at neck level (via T33.-), +93 more.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 44 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 922 (MDC 21), DRG 923 (MDC 21).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INJ021 — Effect of other external causes, initial encounter (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

T33.2XXA — Superficial frostbite of thorax, initial encounter, T33.3XXA — Superficial frostbite of abdominal wall, lower back and pelvis, initial encounter, T33.40XA — Superficial frostbite of unspecified arm, initial encounter, T33.41XA — Superficial frostbite of right arm, initial encounter, T33.42XA — Superficial frostbite of left arm, initial encounter, T33.511A — Superficial frostbite of right wrist, initial encounter, T33.512A — Superficial frostbite of left wrist, initial encounter, T33.519A — Superficial frostbite of unspecified wrist, initial encounter, T33.521A — Superficial frostbite of right hand, initial encounter, T33.522A — Superficial frostbite of left hand, initial encounter, T33.531A — Superficial frostbite of right finger(s), initial encounter, T33.532A — Superficial frostbite of left finger(s), initial encounter, T33.539A — Superficial frostbite of unspecified finger(s), initial encounter, T33.60XA — Superficial frostbite of unspecified hip and thigh, initial encounter, T33.61XA — Superficial frostbite of right hip and thigh, initial encounter, T33.62XA — Superficial frostbite of left hip and thigh, initial encounter, T33.70XA — Superficial frostbite of unspecified knee and lower leg, initial encounter, T33.71XA — Superficial frostbite of right knee and lower leg, initial encounter, T33.72XA — Superficial frostbite of left knee and lower leg, initial encounter, T33.90XA — Superficial frostbite of unspecified sites, initial encounter, +23 more

Same condition, opposite side

Same category and title, differing only in which side of the body is affected.

T33.521A — Superficial frostbite of right hand, initial encounter (right)Compare T33.529A vs T33.521A →, T33.522A — Superficial frostbite of left hand, initial encounter (left)Compare T33.529A vs T33.522A →

Same injury, other encounter phase

Same injury, coded at a different phase of treatment via the 7th character.

T33.529D — Superficial frostbite of unspecified hand, subsequent encounterCompare T33.529A vs T33.529D →, T33.529S — Superficial frostbite of unspecified hand, sequelaCompare T33.529A vs T33.529S →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Effect of other external causes, initial encounter).

T33.2XXA — Superficial frostbite of thorax, initial encounter, T33.3XXA — Superficial frostbite of abdominal wall, lower back and pelvis, initial encounter, T33.40XA — Superficial frostbite of unspecified arm, initial encounter, T33.41XA — Superficial frostbite of right arm, initial encounter, T33.42XA — Superficial frostbite of left arm, initial encounter, T33.511A — Superficial frostbite of right wrist, initial encounter, T33.512A — Superficial frostbite of left wrist, initial encounter, T33.519A — Superficial frostbite of unspecified wrist, initial encounter, T33.521A — Superficial frostbite of right hand, initial encounter, T33.522A — Superficial frostbite of left hand, initial encounter, T33.531A — Superficial frostbite of right finger(s), initial encounter, T33.532A — Superficial frostbite of left finger(s), initial encounter, T33.539A — Superficial frostbite of unspecified finger(s), initial encounter, T33.60XA — Superficial frostbite of unspecified hip and thigh, initial encounter, T33.61XA — Superficial frostbite of right hip and thigh, initial encounter, T33.62XA — Superficial frostbite of left hip and thigh, initial encounter, T33.70XA — Superficial frostbite of unspecified knee and lower leg, initial encounter, T33.71XA — Superficial frostbite of right knee and lower leg, initial encounter, T33.72XA — Superficial frostbite of left knee and lower leg, initial encounter, T33.811A — Superficial frostbite of right ankle, initial encounter, +149 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Frostbite”; these codes share that main term but sit in a different category of the Tabular List.

T34.01 — Frostbite with tissue necrosis of ear (ear, with tissue necrosis), T34.02 — Frostbite with tissue necrosis of nose (nose, with tissue necrosis), T34.09 — Frostbite with tissue necrosis of other part of head (head, with tissue necrosis), T34.1 — Frostbite with tissue necrosis of neck (neck, with tissue necrosis), T34.2 — Frostbite with tissue necrosis of thorax (thorax, with tissue necrosis), T34.3 — Frostbite with tissue necrosis of abdominal wall, lower back and pelvis (pelvis, with tissue necrosis), T34.4 — Frostbite with tissue necrosis of arm (arm, with tissue necrosis), T34.51 — Frostbite with tissue necrosis of wrist (wrist, with tissue necrosis), T34.52 — Frostbite with tissue necrosis of hand (hand, with tissue necrosis), T34.53 — Frostbite with tissue necrosis of finger(s) (finger, with tissue necrosis), T34.6 — Frostbite with tissue necrosis of hip and thigh (hip, with tissue necrosis), T34.7 — Frostbite with tissue necrosis of knee and lower leg (knee, with tissue necrosis), T34.81 — Frostbite with tissue necrosis of ankle (ankle, with tissue necrosis), T34.82 — Frostbite with tissue necrosis of foot (foot, with tissue necrosis), T34.83 — Frostbite with tissue necrosis of toe(s) (toes, with tissue necrosis), T34.90 — Frostbite with tissue necrosis of unspecified sites (with, tissue necrosis), T34.99 — Frostbite with tissue necrosis of other sites (leg, with tissue necrosis)

Contextual Map

Every relationship of T33.529A in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run T33.529A with these 9 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes (113)

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 21 — Injuries, Poisonings and Toxic Effects of Drugs[MDC crossing]: “Injuries, Poisonings and Toxic Effects of Drugs — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 32,063 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Does T33.529A require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T33.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "T33.529A — Superficial frostbite of unspecified hand, initial encounter." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/t33.529a-superficial-frostbite-of-unspecified-hand-initial-encounter

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Superficial frostbite of unspecified hand, initial encounter

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T33.529A in its code family, with their registry titles.

View all codes in the T33 family