Alphabetic Index FY2027

T79.4XXA

Traumatic shock, initial encounter

FY2027Chapter 19: Injury, poisoning and certain other consequences of external causes/T79 Certain early complications of trauma

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - OtherHospital MCC · if discharged alive

T79.4XXA (also written T794XXA) is a billable ICD-10-CM diagnosis code for traumatic shock, initial encounter. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 54 codes in category T79 (Certain early complications of trauma, not elsewhere classified). The Alphabetic Index lists it under 14 entries. Its 7th character, A, means initial encounter. Its coding notes include a Use additional code instruction, 13 Excludes1 entries and 6 Excludes2 entries.

7th character

Category T79 requires a 7th character. T79.4 has only 4 characters, so a placeholder X fills the empty positions.

Assembled code T79.4XXA Open code

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.

Guidelines I.C.19.aInjuries: application of 7th charactersRead the official text

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (1 note)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • code to identify any retained foreign body, if applicable (Z18.-)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from T79.4 Traumatic shock
  • anaphylactic shock due to adverse food reaction (T78.0-)
  • anaphylactic shock due to correct medicinal substance properly administered (T88.6)
  • anaphylactic shock due to serum (T80.5-)
  • anaphylactic shock NOS (T78.2)
  • electric shock (T75.4)
  • nontraumatic shock NEC (R57.-)
  • obstetric shock (O75.1)
  • postprocedural shock (T81.1-)
  • septic shock (R65.21)
  • shock complicating abortion or ectopic or molar pregnancy (O00-O07, O08.3)
  • shock due to anesthesia (T88.2)
  • shock due to lightning (T75.01)
  • shock NOS (R57.9)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from T79 Certain early complications of trauma, not elsewhere classified
  • acute respiratory distress syndrome (J80)
  • complications occurring during or following medical procedures (T80-T88)
  • complications of surgical and medical care NEC (T80-T88)
  • newborn respiratory distress syndrome (P22.0)
Also from chapter/block level (2 notes)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • birth trauma (P10-P15)
  • obstetric trauma (O70-O71)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Other clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Hospital MCC · alive discharges only

Counts as an MCC only if the patient is discharged alive. Otherwise it is a non-CC. Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 64 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C (Part 2)

Inclusion terms

Conditions classified to this code.

Inherited from T79.4 Traumatic shock
  • Shock (immediate) (delayed) following injury

Notes

Also from chapter/block level (2 notes)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

Alphabetic Index terms

Terms the official Alphabetic Index lists for T79.4. This code adds the 7th character. 14 entries

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