ICD code T86.03 – Bone marrow transplant infection

Key takeaways

T86.03 is the billable ICD-10-CM code for an infection of a bone marrow transplant, valid for FY2027 with no 7th character.

Assign it only when the physician links the infection to the graft, and add a second code that names the infection.

Leave Z94.81 off a T86.03 claim, because the complication code already shows the transplant status.

Stem cells from peripheral blood or cord blood move the complication to T86.5, so confirm the graft source first.

An infection that doesn’t affect the graft gets its own code, with Z94.81 for the transplant status instead of T86.03.

ICD-10 code T86.03 covers infection of a bone marrow transplant

ICD-10 code T86.03 is the billable code for bone marrow transplant infection. Use it when the physician documents an infection that affects the transplanted marrow and states that link. It’s one of five codes under T86.0, Complications of bone marrow transplant.

The code sits in Chapter 19 of ICD-10-CM, in category T86 for complications of transplanted organs and tissue. You can browse its neighbors in our ICD-10-CM codes library. The FY2027 code set from CMS, effective October 1, 2026, keeps T86.03 valid and unchanged.

T86.03 never travels alone. The ICD-10-CM Official Guidelines, Section I.C.19.g.3.a, require two codes for a transplant complication. The first is the T86 code, and the second identifies the complication, which here is the infection itself.

T86.03 is one of five bone marrow transplant codes

Each T86.0 code answers one question about the marrow graft: what went wrong? The table sets the five codes side by side, so you can rule them out quickly.

An infection can sit alongside another complication. If the physician documents both an infection and graft failure, report T86.02 with T86.03 rather than picking one. Documented rejection goes to T86.01.

Two codes catch the leftovers. A note that only says “BMT complication” belongs to T86.00 until a query names the type. A named complication that isn’t rejection, failure or infection goes to T86.09.

Confirm the graft came from marrow, not blood

Before you open T86.0, check where the donor cells came from. ICD-10-CM separates marrow grafts from stem cells collected any other way:

• Marrow harvested from the donor’s bone goes to T86.0-, so an infected graft is T86.03.
• Stem cells collected from peripheral blood go to T86.5, Complications of stem cell transplant.
• Stem cells from umbilical cord blood also go to T86.5.

T86.5 is a single code with no infection subcode. You still add the code that names the infection. Many transplant teams now collect stem cells from blood, so “stem cell transplant” in a note doesn’t prove a marrow code. Query the physician when the source isn’t stated.

T86.03 applies only when the infection affects the graft

A marrow recipient stays immunosuppressed for months, so infections are common after transplant. Most of them don’t make T86.03 the right code. The guidelines assign a transplant complication code only when the complication affects the function of the transplanted organ.

The decision path below runs the three checks in order, from graft source to sequencing.

That puts the decision with the physician. The note has to say the infection involves or affects the graft. Here’s how common documentation maps to codes.

The central line row trips coders most often. T80.211A is the code for a bloodstream infection due to a central venous catheter, and it carries a 7th character. T86.03 has none, so the two codes are easy to tell apart on a claim.

T86.03 needs an infection code beside it

T86.03 says the graft is infected, but not with what. The second code names the organism or the condition. In the FY2027 Tabular List, kidney (T86.13) and liver (T86.43) transplant infections carry a “use additional code” note. T86.03 has no such note, yet the two-code guideline still applies.

Common partner codes after a marrow transplant include:

• B25.0, B25.1, B25.8 or B25.9 for cytomegaloviral pneumonitis, hepatitis, other CMV disease or unspecified CMV disease
• B44.0 for invasive pulmonary aspergillosis
• B37.7 for candidal sepsis, which includes disseminated candidiasis
• B59 for pneumocystosis, including Pneumocystis jirovecii pneumonia
• B34.0 for adenovirus infection, unspecified
• A41.9 for sepsis when no organism is documented

Sequencing follows the reason for the encounter. When the infected graft brings the patient in, T86.03 goes first and the infection code follows. Sepsis changes the order. The transplant guideline points to Section I.C.1.d.4, which puts the systemic infection first when sepsis is present on admission.

Add a code from R65.2- when the physician documents severe sepsis. T86.03 itself is complete at five characters. T86 codes take no 7th character, so T86.03XA isn’t valid and fails front-end claim edits.

Why Z94.81 stays off a T86.03 claim

Z94.81 is bone marrow transplant status. It looks like a natural partner for T86.03, but the classification blocks the pairing in two places:

• Category Z94 carries an Excludes1 note for complications of transplanted organ or tissue.
• Guideline Section I.C.21.c.3 bars a status code when the diagnosis code already includes that information. Its own example is Z94.1 with a T86.2 code.

So Z94.81 belongs on encounters where the transplant is background, not the problem. Use it for an infection that doesn’t affect the graft, or for a visit with no complication. A blood stem cell recipient takes Z94.84 in the same situations.

Long-term drug therapy codes are different, because they add detail the T86 code lacks. Report them when the physician documents the regimen:

• Z79.621 for a calcineurin inhibitor, such as tacrolimus or cyclosporine
• Z79.623 for an mTOR inhibitor, such as sirolimus
• Z79.624 for inhibitors of nucleotide synthesis, such as mycophenolate or azathioprine
• Z79.52 for systemic steroids
• D84.821 when the physician documents immunodeficiency due to drugs

Before you submit: Five checks that support T86.03

Payers and auditors look for a clear chain from the transplant to the infection. Run these five checks against the record before the claim goes out.

• Transplant history: the record states a bone marrow transplant, allogeneic or autologous, with the date where known.
• Graft source: the record says marrow, peripheral blood or cord blood. That choice decides between T86.0- and T86.5.
• Named infection: the physician names the organism or the site, so the partner code can be assigned.
• Link to the graft: the note says the infection affects or involves the transplant.
• Provider documentation: a physician, NP or PA documents the diagnosis. A nursing note or a lab result alone doesn’t carry the code.

A positive CMV PCR, for example, needs the provider’s interpretation in the note before it becomes a diagnosis. When the record is unclear, query during the stay. An addendum written after a denial is much harder to defend on audit.

Inpatient claims need a POA indicator and keep their HCC credit

T86.03 isn’t on the FY2027 POA-exempt list, so inpatient claims need a present-on-admission indicator. Report “Y” when the infection was present at admission and “N” when it developed during the stay. Ask the physician when the timing isn’t clear.

Risk adjustment adds one more reason to code it well. In the CMS 2027 ICD-10 mappings, T86.03 maps to HCC 454 in the V28 model. Z94.81 maps to the same HCC, so leaving it off a T86.03 claim costs no risk score credit.

How a T86.03 claim moves from note to payment

A transplant infection claim passes several checkpoints before it’s paid. Each one can stall it, so it helps to know where they sit.

1. Physician note: the provider names the infection and states its link to the graft.
2. Coding: the coder confirms the graft source, assigns T86.03 and the infection code, and sets the sequence.
3. Inpatient fields: an inpatient claim gets a POA indicator for T86.03 and its partner codes.
4. Front-end edits: the clearinghouse rejects invalid codes such as T86.03XA. Some scrubbers also flag the Excludes1 pair with Z94.81.
5. Payer review: a claim without a documented graft link can come back denied, or with a request for records.
6. Remittance: the payer returns the claim as paid, denied or adjusted, and denials go back to the coder.

A rejection at the front-end edit is the cheapest one to fix. The claim hasn’t reached the payer yet, so a corrected code goes straight back out.

Six mistakes that get T86.03 claims denied

Each of these errors is easy to catch at the coding step, long before a payer sees the claim.

• Wrong organ: an infected kidney transplant is T86.13, not T86.03. Check which organ was transplanted before you code.
• Missing infection code: T86.03 goes out on its own. Add the code that names the organism or condition.
• Status code added: Z94.81 sits beside T86.03 despite the Excludes1 note. Remove it.
• Invalid 7th character: the claim lists T86.03XA. Submit plain T86.03.
• Wrong graft source: a blood stem cell transplant was coded to T86.0-. Use T86.5 where it applies.
• No stated link: any infection in a BMT patient was coded to T86.03. Query the physician about the graft first.

Tracking which of these keeps coming back shows where documentation needs work. A denial management workflow turns those patterns into fixes at the source.

How Pabau keeps T86.03 claims moving after submission

Transplant admissions are costly, so a stalled claim is costly too. The usual problem is visibility. A rejected or unpaid claim sits in a payer portal until someone thinks to check it.

Pabau, the practice management platform we build, handles claim submission and tracking in one place. Its claims management software sends claims electronically through Claim.MD in the US, Healthcode in the UK and Tyro in Australia.

Each submitted claim then carries a status, such as paid, unpaid or reissued. Your billing team sees which T86.03 claims need follow-up, while coders keep ownership of the code choice.

Track every transplant claim after submission

Pabau submits claims through Claim.MD, Healthcode and Tyro, then tracks each one by status. Unpaid transplant claims surface for follow-up instead of going stale.

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Conclusion

T86.03 asks coders two questions before they code. Did the cells come from marrow, and did the infection affect the graft? A yes to both, plus the infection code, makes a claim you can defend.

The trade-off sits with Z94.81. Leaving the status code off can feel like losing detail, but the classification bars it here and the HCC credit stays the same. Put the graft question into your query template, and fewer claims come back.

Book a demo to see how Pabau submits transplant claims and tracks each one until it’s paid.

Continue your research

Need a framework for handling claim denials systematically? Denial codes in medical billing walks through the most common CARC codes and the workflows that resolve them fastest.

Want to understand how clearinghouses handle ICD-10 claims? Medical claims clearinghouse explains how electronic claim scrubbing works and what gets flagged before a claim reaches the payer.

Looking for a structured approach to revenue cycle management? What is revenue cycle management covers the end-to-end billing process from coding through payment posting.

Coding an infected kidney graft instead? T86.13 covers kidney transplant infection, with the same two-code rule and the same status-code bar.

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