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T21.72XA vs T21.72XD

T21.72XA (Corrosion of third degree of abdominal wall, initial encounter) compared with T21.72XD (Corrosion of third degree of abdominal wall, subsequent encounter), from the official CMS tabular data. T21.72XA and T21.72XD code the same injury at a different phase of treatment. MedCoder-derived

Can these codes be reported together?

Review

Encounter relationship

T21.72XA
Initial encounter
Corrosion of third degree of abdominal wall, initial encounter
↔
T21.72XD
Subsequent encounter
Corrosion of third degree of abdominal wall, subsequent encounter

What we found

Same injury, other encounter phase.T21.72XA and T21.72XD code the same injury at a different phase of treatment, set by the 7th character.

The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.

What to review

Use the 7th character that matches the encounter being coded (initial, subsequent or sequela); one encounter takes one of them.

Guide: 7th characters: initial, subsequent, sequelaCheck these on a claim

Why it matters

The 7th character records the phase of care for the encounter being coded, so a single encounter takes one of these characters, not several. Review whether both phases belong on the same episode of care.

Source / rule

ICD-10-CM Official Guidelines, Section I.C.19.a

Side by side

T21.72XACorrosion of third degree of abdominal wall, initial encounterT21.72XDCorrosion of third degree of abdominal wall, subsequent encounter
Billing statusBillableBillable
ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionCorrosion of third degree of abdominal wall, initial encounter is a billable ICD-10-CM diagnosis code (T21.72XA).Corrosion of third degree of abdominal wall, subsequent encounter is a billable ICD-10-CM diagnosis code (T21.72XD).
7th characterThe appropriate 7th character is to be added to each code from category T21The appropriate 7th character is to be added to each code from category T21
Includes
burns and corrosion of hip region
burns and corrosions of first degree [erythema]
burns and corrosions of second degree [blisters][epidermal loss]
burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss]
burns and corrosion of hip region
burns and corrosions of first degree [erythema]
burns and corrosions of second degree [blisters][epidermal loss]
burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss]
Excludes2
burns and corrosion of axilla (T22.- with fifth character 4)
burns and corrosion of scapular region (T22.- with fifth character 6)
burns and corrosion of shoulder (T22.- with fifth character 5)
burns and corrosion of axilla (T22.- with fifth character 4)
burns and corrosion of scapular region (T22.- with fifth character 6)
burns and corrosion of shoulder (T22.- with fifth character 5)
Code first
(T51-T65) to identify chemical and intent
(T51-T65) to identify chemical and intent
Use additional code
external cause code to identify place (Y92)
code from category T31 or T32 to identify extent of body surface involved
external cause code to identify place (Y92)
code from category T31 or T32 to identify extent of body surface involved

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2026). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources