2027 ICD-10-CM Diagnosis Code Z86.51Personal history of combat and operational stress reaction

ICD-10-CM Codes›Z00–Z99›Z77-Z99›Z86

ICD-10-CM Z86.51
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z86.51 is a billable ICD-10-CM diagnosis code for personal history of combat and operational stress reaction. 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 restricted by the Medicare Code Editor to adult patients (age 15 through 124), not accepted as a principal diagnosis, and exempt from POA reporting. Coders also document this condition as history of combat and operational stress reaction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Personal history of other disease.

Code Identity

ICD-10-CM Code
Z86.51
Billable Status
Yes — Valid for Submission
Code Describes
Personal history of combat and operational stress reaction
Short Description
Personal history of combat and operational stress reaction
Same as the full description in the CMS dataset.
Parent Code
Z86.5
Personal history of mental and behavioral disorders

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
CategoryZ86Personal history of certain other diseases
This CodeZ86.51Personal history of combat and operational stress reaction

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z86.51.

Adult diagnoses
The Medicare Code Editor detects inconsistencies in adult cases by checking a patient's age and any diagnosis on the patient's record. The adult code edits apply to patients age range is 15–124 years inclusive (e.g., senile delirium, mature cataract).
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

Z86.51 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).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • History of combat and operational stress reaction

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z86.51: its own notes plus those printed at Z86, block Z77-Z99, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Code First

The underlying condition named in the note is sequenced before this code.

From Z86 Personal history of certain other diseases applies to 40 codes
  • any follow-up examination after treatment (Z09)

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 Z86.51, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and Z86.51 is one of the codes named.

  • Z09 Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm
    code to identify any applicable history of disease code (Z86.-, Z87.-) names Z86.-, 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 FAC030
Personal history of other disease
Default principal diagnosis: inpatient No · outpatient Yes

Patient EducationClinical

Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a mental health disorder that some people develop after they experience or see a traumatic event. The traumatic event may be life-threatening, such as combat, a natural disaster, a car accident, or sexual assault. But sometimes the event is not necessarily a dangerous one.

The full article covers:

  • What is post-traumatic stress disorder (PTSD)?
  • What causes post-traumatic stress disorder (PTSD)?
  • Who is more likely to develop post-traumatic stress disorder (PTSD)?
  • What are the symptoms of post-traumatic stress disorder (PTSD)?
  • How is post-traumatic stress disorder (PTSD) diagnosed?
  • What are the treatments for post-traumatic stress disorder (PTSD)?
  • Can post-traumatic stress disorder (PTSD) be prevented?

Read the full article at MedlinePlus

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

Convert Z86.51 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V11.4 Hx combat/stress reactn
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z86.51Overview

What is the ICD-10 code for personal history of combat and operational stress reaction?

The ICD-10-CM code for personal history of combat and operational stress reaction is Z86.51 (sometimes written as Z8651). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Z86.51 (Personal history of mental and behavioral disorders) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report personal history of combat and operational stress reaction on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z86.51 group to?

On inpatient claims, personal history of combat and operational stress reaction 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 Z86.51 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because personal history of combat and operational stress reaction describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Who can Z86.51 be reported for?

The Medicare Code Editor checks personal history of combat and operational stress reaction against patient demographics: this code is intended for adult patients (age 15 through 124). Claims outside these limits are flagged as inconsistent.