What is ICD-10 code T86.00?

T86.00 is the ICD-10-CM diagnosis code for Unspecified complication of bone marrow transplant. A complication following a bone marrow transplant that is not further specified, such as graft-versus-host disease or other transplant-related problems. T86.00 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. T86.00 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. T86.00 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. T86.00 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does T86.00 map to under V28?

T86.00 maps to CMS-HCC V28 HCC 454 (Stem Cell, Including Bone Marrow, Transplant Status/Complications). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM T86.00: Unspecified complication

T86.00 maps to CMS-HCC V28 454. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupT86.00

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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)

T86.00

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

Unspecified complication of bone marrow transplant

A complication following a bone marrow transplant that is not further specified, such as graft-versus-host disease or other transplant-related problems.

Buddy Insight

This indicates a complication following bone marrow transplant that requires ongoing monitoring and treatment, reflecting the complex immunosuppressed state and high risk for serious adverse events.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 454

Stem Cell, Including Bone Mar...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 251

HHS-HCC 251 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 186

Major Organ Transplant or Rep...

Code-level coefficient reference

RXHCC

Mapped

HCC 395

Stem Cell, Including Bone Mar...

Code-level coefficient reference

Code Book Path

Official

T86Complications of transplanted organs and tissue T86.0Complications of bone marrow transplant T86.00Unspecified complication of bone marrow transplant

Inclusion Terms

Official

No inclusion terms are included in this display for T86.00. Check the code and parent instructions in the Code Book.

Excludes 2

Official

birth trauma (P10-P15)Inherited from S00-T88, T80-T88
obstetric trauma (O70-O71)Inherited from S00-T88, T80-T88
any encounters with medical care for postprocedural conditions in which no complications are present, such as:Inherited from S00-T88, T80-T88
artificial opening status (Z93.-)Inherited from S00-T88, T80-T88
closure of external stoma (Z43.-)Inherited from S00-T88, T80-T88
fitting and adjustment of external prosthetic device (Z44.-)Inherited from S00-T88, T80-T88
burns and corrosions from local applications and irradiation (T20-T32)Inherited from S00-T88, T80-T88
complications of surgical procedures during pregnancy, childbirth and the puerperium (O00-O9A)Inherited from S00-T88, T80-T88
mechanical complication of respirator [ventilator] (J95.850)Inherited from S00-T88, T80-T88
poisoning and toxic effects of drugs and chemicals (T36-T65 with fifth or sixth character 1-4 or 6)Inherited from S00-T88, T80-T88
postprocedural fever (R50.82)Inherited from S00-T88, T80-T88
specified complications classified elsewhere, such as:Inherited from S00-T88, T80-T88
cerebrospinal fluid leak from spinal puncture (G97.0)Inherited from S00-T88, T80-T88
colostomy malfunction (K94.0-)Inherited from S00-T88, T80-T88
disorders of fluid and electrolyte imbalance (E86-E87)Inherited from S00-T88, T80-T88
functional disturbances following cardiac surgery (I97.0-I97.1)Inherited from S00-T88, T80-T88
intraoperative and postprocedural complications of specified body systems (D78.-, E36.-, E89.-, G97.3-, G97.4, H59.3-, H59.-, H95.2-, H95.3, I97.4-, I97.5, J95.6-, J95.7, K91.6-, L76.-, M96.-, N99.-)Inherited from S00-T88, T80-T88
ostomy complications (J95.0-, K94.-, N99.5-)Inherited from S00-T88, T80-T88
postgastric surgery syndromes (K91.1)Inherited from S00-T88, T80-T88
postlaminectomy syndrome NEC (M96.1)Inherited from S00-T88, T80-T88
postmastectomy lymphedema syndrome (I97.2)Inherited from S00-T88, T80-T88
postsurgical blind-loop syndrome (K91.2)Inherited from S00-T88, T80-T88
ventilator associated pneumonia (J95.851)Inherited from S00-T88, T80-T88

Related Codes

Official

T86.01Bone marrow transplant rejection T86.02Bone marrow transplant failure T86.03Bone marrow transplant infection T86.09Other complications of bone marrow transplant

Includes

Official

No Includes notes are included in this display for T86.00. Check the code and parent instructions in the Code Book.

Excludes 1

Official

No Excludes 1 notes are included in this display for T86.00. Check the code and parent instructions in the Code Book.

Code First

Official

No Code First sequencing instructions are included in this display for T86.00. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify any retained foreign body, if applicable (Z18.-)Inherited from S00-T88, T80-T88, T86
code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)Inherited from S00-T88, T80-T88, T86
code(s) to identify the specified condition resulting from the complicationInherited from S00-T88, T80-T88, T86
code to identify devices involved and details of circumstances (Y62-Y82)Inherited from S00-T88, T80-T88, T86
code to identify other transplant complications, such as:Inherited from S00-T88, T80-T88, T86
graft-versus-host disease (D89.81-)Inherited from S00-T88, T80-T88, T86
malignancy associated with organ transplant (C80.2)Inherited from S00-T88, T80-T88, T86
post-transplant lymphoproliferative disorders (PTLD) (D47.Z1)Inherited from S00-T88, T80-T88, T86

Code Also

Official

No Code Also instructions are included in this display for T86.00. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

History of bone marrow or stem cell transplant

Type of complication (if known)

Date of original transplant procedure

Current symptoms or manifestations

MEAT Support

HCC Buddy guidance

History of bone marrow or stem cell transplant

Type of complication (if known)

Date of original transplant procedure

Current symptoms or manifestations

Audit Caution

HCC Buddy guidance

Using status codes when complications are present

Failing to code specific complication types when documented

Missing additional codes for specific manifestations

Confusing with other organ transplant complications

Common Mistakes

HCC Buddy guidance

T86.01 — Specific bone marrow transplant rejection

T86.02 — Specific bone marrow transplant failure

T86.03 — Specific bone marrow transplant infection

Z94.81 — Bone marrow transplant status without complication

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 T86.00 an HCC code?

Yes. T86.00 (Unspecified complication of bone marrow transplant) maps to HCC 454, Stem Cell, Including Bone Marrow, Transplant Status/Complications under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.068. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: T86.00 is billable and maps to V28 HCC 454, Stem Cell, Including Bone Marrow, Transplant Status/Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: T86.00
Description: Unspecified complication of bone marrow transplant
HCC (V28): HCC 454 — Stem Cell, Including Bone Marrow, Transplant Status/Complications
RAF reference coefficient: 1.068
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 454, Stem Cell, Including Bone Marrow, Transplant Status/Complications

1.068

ESRDHCC 186, Major Organ Transplant or Replacement Status

Not separately weighted

RxHCCHCC 395, Stem Cell, Including Bone Marrow, Transplant Status/Complications

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work T86.00 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for T86.00

For T86.00, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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What This Code Means

T86.00 is the ICD-10-CM diagnosis code for unspecified complication of bone marrow transplant. A complication following a bone marrow transplant that is not further specified, such as graft-versus-host disease or other transplant-related problems. T86.00 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, T86.00 maps to Stem Cell, Including Bone Marrow, Transplant Status/Complications (HCC 454) with a source-labeled community, non-dual, aged reference coefficient of 1.068. No V24 mapping is shown for T86.00; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Use this code only when the specific type of complication is not documented; attempt to obtain more specific documentation. For T86.00, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for T86.00 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when the specific type of complication is not documented; attempt to obtain more specific documentation
•Requires a seventh character to indicate the episode of care (A, D, or S)

Clinical Significance

This indicates a complication following bone marrow transplant that requires ongoing monitoring and treatment, reflecting the complex immunosuppressed state and high risk for serious adverse events. These patients require specialized hematologic care and frequent monitoring for graft-versus-host disease, infection, and other transplant-related complications.