2026 ICD-10-CM Diagnosis Code T86.91Unspecified transplanted organ and tissue rejection

ICD-10-CM Codes›S00–T88›T80-T88›T86

ICD-10-CM T86.91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T86.91 is a billable ICD-10-CM diagnosis code for unspecified transplanted organ and tissue rejection. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 919 through 921. Coders also document this condition as acute cellular graft rejection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication of transplanted organs or tissue, initial encounter.

Code Identity

ICD-10-CM Code
T86.91
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified transplanted organ and tissue rejection
Short Description
Unspecified transplanted organ and tissue rejection
Same as the full description in the CMS dataset.
Parent Code
T86.9
Complication of unspecified transplanted organ and tissue

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT80-T88Complications of surgical and medical care, not elsewhere classified
CategoryT86Complications of transplanted organs and tissue
This CodeT86.91Unspecified transplanted organ and tissue rejection

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute cellular graft rejection
  • Chronic active graft rejection
  • Chronic graft rejection
  • Chronic inactive graft rejection
  • Graft reaction AND/OR rejection
  • Graft rejection
  • Hyperacute graft rejection
  • Mild cellular graft rejection
  • Moderate cellular graft rejection
  • Transplanted organ rejection

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Complications of transplanted organs and tissue (T86). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Complication(s) (from) (of)
      • transplant
        • rejection
    • Disorder(of)
      • tubulo-interstitial (in)
        • transplant rejection
    • Pyelonephritis
      • in (due to)
        • transplant rejection
    • Rejection
      • transplant
    • Rejection
      • transplant
        • organ (immune or nonimmune cause)

Clinical ClassificationClinical

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

CCSR INJ036
Complication of transplanted organs or tissue, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Graft Rejection

    an immune response with both cellular and humoral components, directed against an allogeneic transplant, whose tissue antigens are not compatible with those of the recipient.

  • Graft Rejection

    rejection of transplanted tissue secondary to an immune response from the recipient.

  • Hyperacute Allograft Rejection

    an immediate rejection of transplanted tissue caused by the presence of preformed antibodies to donor human leukocyte antigens.

  • Regimen Used to Treat or Prevent Graft Rejection

    any regimen that can be used to treat or prevent graft rejection.

Patient EducationClinical

Organ Transplantation

You may need an organ transplant if one of your organs has failed. This can happen because of illness or injury. When you have an organ transplant, doctors remove an organ from another person and place it in your body. The organ may come from a living donor or a donor who has died.

Read the full article at MedlinePlus

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

Convert T86.91 to ICD-9-CMHistory

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

ICD-9-CM
996.80 Comp organ transplnt NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T86.91Overview

Is T86.91 (Complication of unspecified transplanted organ and tissue) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified transplanted organ and tissue rejection on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does T86.91 group to?

When unspecified transplanted organ and tissue rejection is the principal diagnosis on an inpatient stay, it groups to MS-DRG 919, 920, 921, with relative weights from 0.6884 to 1.8308 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of T86.91?

Under the General Equivalence Mappings, unspecified transplanted organ and tissue rejection converts to ICD-9-CM 996.80 (comp organ transplnt NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.