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T86.850 ICD-10-CM Code: Intestine transplant rejection

T86.850 maps to CMS-HCC V28 77 (RAF 1.172). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

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FY 2026 Apr update / Injury, poisoning and certain other consequences of external causes (S00-T88) / Complications of surgical and medical care, not elsewhere classified (T80-T88)

T86.850

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Intestine transplant rejection

The recipient's immune system attacks and rejects a transplanted intestine, causing it to fail.

Buddy the Bee presenting code insight

Buddy Insight

Intestinal transplant rejection represents an immunologic attack on the transplanted bowel, potentially leading to graft loss and life-threatening complications.

CMS-HCC V28

HCC 77

RAF 1.172

CMS-HCC V24

HCC 186

RAF 0.832

ACA/HHS

HCC 41

Varies by metal level

ESRD/PACE

HCC 186

RAF 0.138

RXHCC

HCC 396

Not separately weighted

Code Book Path

Official
T86.8Complications of other transplanted organs and tissues
T86.85Complication of intestine transplant
T86.850Intestine transplant rejection

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for T86.850 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for T86.850 in this effective period.

Related Child Codes

Official
T86.851Intestine transplant failure
T86.852Intestine transplant infection
T86.858Other complications of intestine transplant
T86.859Unspecified complication of intestine transplant

Includes

Official

ICD-10-CM does not list Includes notes for T86.850 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for T86.850 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for T86.850 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for T86.850 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for T86.850 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of intestinal transplant procedure with date
Histologic evidence of rejection from biopsy
Clinical symptoms of rejection (diarrhea, abdominal pain, fever)
Laboratory evidence supporting rejection (inflammatory markers, absorption studies)

MEAT Support

HCC Buddy guidance
Documentation of intestinal transplant procedure with date
Histologic evidence of rejection from biopsy
Clinical symptoms of rejection (diarrhea, abdominal pain, fever)
Laboratory evidence supporting rejection (inflammatory markers, absorption studies)

Audit Caution

HCC Buddy guidance
Not distinguishing rejection from infection or other complications
Using status codes when active rejection is present
Missing biopsy confirmation of rejection when available
Not establishing clear causal relationship to transplant

Common Mistakes

HCC Buddy guidance
T86.851 — intestine transplant failure (rejection vs functional failure)
T86.852 — intestine transplant infection (immunologic vs infectious complication)
K59.1 — diarrhea (transplant rejection vs other causes)
Z94.82 — intestine transplant status (rejection vs stable status)

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is T86.850 an HCC code?

Yes. T86.850 (Intestine transplant rejection) maps to Intestine Transplant Status/Complications under the CMS-HCC V28 risk adjustment model (and Major Organ Transplant or Replacement Status under V24), with a community non-dual aged RAF of 1.172. It is billable for payment year 2026.

Coder answer: T86.850 is billable and maps to V28 HCC 77, Intestine Transplant Status/Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
T86.850
Description
Intestine transplant rejection
HCC (V28)
HCC 77 — Intestine Transplant Status/Complications
RAF
1.172
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 77, Intestine Transplant Status/Complications
1.172
V24HCC 186, Major Organ Transplant or Replacement Status
0.832
ESRDHCC 186, Major Organ Transplant or Replacement Status
0.138
RxHCCHCC 396, Allograft Complications
Not separately weighted

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work T86.850 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for T86.850

For T86.850 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed T86.850 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

T86.850 is the ICD-10-CM diagnosis code for intestine transplant rejection. The recipient's immune system attacks and rejects a transplanted intestine, causing it to fail. T86.850 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering complications of surgical and medical care, not elsewhere classified (t80-t88).

Under the CMS-HCC V28 risk adjustment model, T86.850 maps to Intestine Transplant Status/Complications (HCC 77) with a community, non-dual, aged base RAF weight of 1.172. Under the older CMS-HCC V24 model, T86.850 maps to Major Organ Transplant or Replacement Status (HCC 186) with a community, non-dual, aged base RAF weight of 0.832. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

This code specifically indicates rejection of an intestinal transplant, which is an immune-mediated response. Because T86.850 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for T86.850 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This code specifically indicates rejection of an intestinal transplant, which is an immune-mediated response
  • •Document the timeframe of rejection (acute vs. chronic) if available, as this may affect clinical management

Clinical Significance

Intestinal transplant rejection represents an immunologic attack on the transplanted bowel, potentially leading to graft loss and life-threatening complications. This diagnosis requires immediate immunosuppressive therapy adjustment and intensive monitoring.

Documentation Requirements

  • ✓Documentation of intestinal transplant procedure with date
  • ✓Histologic evidence of rejection from biopsy
  • ✓Clinical symptoms of rejection (diarrhea, abdominal pain, fever)
  • ✓Laboratory evidence supporting rejection (inflammatory markers, absorption studies)
  • ✓Immunosuppressive medication history and levels
  • ✓Endoscopic findings if applicable
  • ✓Provider assessment confirming rejection diagnosis
  • ✓Treatment plan for rejection management

Commonly Confused Codes

  • •T86.851: intestine transplant failure (rejection vs functional failure)
  • •T86.852: intestine transplant infection (immunologic vs infectious complication)
  • •K59.1: diarrhea (transplant rejection vs other causes)
  • •Z94.82: intestine transplant status (rejection vs stable status)
  • •T86.858: other intestine transplant complications (rejection vs other complications)

Child Codes

T86.850Intestine transplant rejection
HCC 77
T86.851Intestine transplant failure
HCC 77
T86.852Intestine transplant infection
HCC 77
T86.858Other complications of intestine transplant
HCC 77
T86.859Unspecified complication of intestine transplant
HCC 77

Code Hierarchy

└T86Complications of transplanted organs and tissue└T86.8Complications of other transplanted organs and tissues└T86.85Complication of intestine transplant└T86.850Intestine transplant rejection
└T86.850Intestine transplant rejection

Because T86.850 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

T86.850 maps to CMS-HCC V28 category 77, Intestine Transplant Status/Complications. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. Because T86.850 carries a payment HCC, you can see what it adds to a RAF score and check the documentation the chart needs before it is submitted.

More on T86.850

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