2027 ICD-10-CM Diagnosis Code Z77.31Contact with and (suspected) exposure to Gulf War theater

ICD-10-CM Codes›Z00–Z99›Z77-Z99›suspected

ICD-10-CM Z77.31
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z77.31 is a billable ICD-10-CM diagnosis code for contact with and (suspected) exposure to Gulf War theater. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified status.

Code Identity

ICD-10-CM Code
Z77.31
Billable Status
Yes — Valid for Submission
Code Describes
Contact with and (suspected) exposure to Gulf War theater
Short Description
Contact with and (suspected) exposure to Gulf War theater
Same as the full description in the CMS dataset.
Parent Code
Z77.3
Contact with and (suspected) exposure to war theater

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ77-Z99Persons with potential health hazards related to family and personal history and certain conditions influencing health status
CategorysuspectedOther contact with and exposures hazardous to health (Z77)
This CodeZ77.31Contact with and (suspected) exposure to Gulf War theater

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z77.31.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z77.31 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99).

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z77.31: its own notes plus those printed at Z77, block Z77-Z99, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Z77 Other contact with and (suspected) exposures hazardous to health applies to 31 codes
  • contact with and (suspected) exposures to potential hazards to health

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Contact with and (suspected) exposure to Persian Gulf War theater

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Z77 Other contact with and (suspected) exposures hazardous to health applies to 31 codes
  • contact with and (suspected) exposure to communicable diseases (Z20.-)
  • exposure to (parental) (environmental) tobacco smoke in the perinatal period (P96.81)
  • newborn affected by noxious substances transmitted via placenta or breast milk (P04.-)
  • occupational exposure to risk factors (Z57.-)
  • retained foreign body (Z18.-)
  • retained foreign body fully removed (Z87.821)
  • toxic effects of substances chiefly nonmedicinal as to source (T51-T65)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Block Z77-Z99 Persons with potential health hazards related to family and personal history and certain conditions influencing health status applies to 567 codes
  • any follow-up examination (Z08-Z09)

Notes

General instructions on how these codes are used.

From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z77.31, its category, or a range that includes it.

Excludes1 3

These codes carry an Excludes1 note naming Z77.31: they are not reported together with it, unless the two conditions are unrelated.

  • Block T51-T65 Toxic effects of substances chiefly nonmedicinal as to source
    contact with and (suspected) exposure to toxic substances (Z77.-) names Z77.-, which includes this code
  • Z03 Encounter for medical observation for suspected diseases and conditions ruled out
    contact with and (suspected) exposures hazardous to health (Z77.-) names Z77.-, which includes this code
  • Z13.88 Encounter for screening for disorder due to exposure to contaminants
    those exposed to contaminants without suspected disorders (Z57.-, Z77.-) names Z77.-, which includes this code

Excludes2 2

These codes carry an Excludes2 note naming Z77.31: its condition is not part of those codes, and both may be reported when the patient has both.

  • P04 Newborn affected by noxious substances transmitted via placenta or breast milk
    newborn in contact with and (suspected) exposures hazardous to health not transmitted via placenta or breast milk (Z77.-) names Z77.-, which includes this code
  • Z91 Personal risk factors, not elsewhere classified
    contact with and (suspected) exposures hazardous to health (Z77.-) names Z77.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC025
Other specified status
Default principal diagnosis: inpatient No · outpatient Yes

Patient EducationClinical

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Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement Z77.31 replaces the following previously assigned code(s):

  • Z77.3 - Contact with and (suspected) exposure to war theater
FY 2026AddedAdded to the ICD-10-CM code setEffective October 1, 2025.
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z77.31Overview

What is the ICD-10 code for contact with and (suspected) exposure to Gulf War theater?

The ICD-10-CM code for contact with and (suspected) exposure to Gulf War theater is Z77.31 (sometimes written as Z7731). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Z77.31 (Contact with and (suspected) exposure to war theater) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report contact with and (suspected) exposure to Gulf War theater on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z77.31 group to?

On inpatient claims, contact with and (suspected) exposure to Gulf War theater maps to MS-DRG 951 (other Factors Influencing Health Status), which carries a relative weight of 0.5574. Higher weights mean higher Medicare reimbursement.

Can Z77.31 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because contact with and (suspected) exposure to Gulf War theater describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z77.31 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for contact with and (suspected) exposure to Gulf War theater on inpatient claims. The code appears in the Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99) range of the CMS exempt list.