ICD code T45.626S – Underdosing of hemostatic drugs, sequela

Key takeaways

T45.626S is a billable ICD-10-CM code for sequela of hemostatic drug underdosing, valid for FY 2025 reporting.

List the sequela condition code first, with T45.626S sequenced after it and never as the primary diagnosis.

Seventh character S applies only after the acute underdosing episode is fully resolved, distinguishing it from A (initial) and D (subsequent) encounters.

Claims management software like Pabau flags sequencing errors before submission, which cuts T45.626S denials at the clearinghouse.

ICD-10 code T45.626S: Quick-reference overview

ICD-10 code T45.626S is the billable code for a sequela of hemostatic drug underdosing. It covers the residual condition left after a patient took less of a clotting drug than prescribed and the acute episode resolved.

The code sits in the T45.6 block, which covers drugs affecting fibrinolysis. That block belongs to Chapter 19 of the ICD-10-CM tabular list (S00-T88), for injury, poisoning and certain other consequences of external causes. The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS) maintain ICD-10-CM jointly.

What “underdosing of hemostatic drugs” means in ICD-10-CM

The ICD-10-CM Official Guidelines for Coding and Reporting (Section I.C.19) define underdosing. It occurs when a patient takes less of a medication than the prescriber or manufacturer directed. It is coded separately from an adverse effect or a poisoning, and each of the three follows its own billing rules.

Hemostatic drugs are agents that promote clotting or reduce bleeding. The T45.6 category captures drugs primarily affecting fibrinolysis and coagulation. Common agents coded under this block include tranexamic acid and aminocaproic acid (Amicar). Say a patient consistently takes less than the prescribed dose of one of these agents. If they later present with a sequela condition after the acute underdosing episode has resolved, T45.626S applies.

T45.626S stays the same whatever the reason for underdosing, but the medical record still needs that reason. Noncompliance, cost barriers, a prescriber change or a deliberate dose reduction all belong in the note, because they support the code assignment.

What seventh character S (sequela) means

Seventh character S indicates a sequela. The ICD-10-CM Official Guidelines define a sequela as the late effect of an injury or condition once its acute phase has ended. On this code, the sequela is the residual condition left behind after the underdosing episode. Use S only after the acute encounter for underdosing is closed.

Three seventh characters apply to T45.626: A for initial encounter, D for subsequent encounter, and S for sequela. Confusing them is one of the most common coding errors on this parent code. The AAPC’s ICD-10-CM code reference consistently flags seventh-character misuse as a top denial driver for T-code claims.

T45.626A vs T45.626D vs T45.626S: Choosing the right seventh character

The seventh character tracks the phase of care for the underdosing episode, whatever the patient’s overall visit count. A patient seen twice during an active episode gets A on the first visit and D on the second. S applies only once the acute issue has resolved and a residual condition persists.

A practical test: Ask whether the acute underdosing episode is still being actively treated. If yes, use A or D. If the episode is closed and what remains is a late-effect condition, S applies.

• T45.626A: First encounter with an active hemostatic underdosing episode. Documentation must confirm the patient is being seen for the first time for this specific episode.
• T45.626D: Return visit during the same active underdosing episode. The problem is ongoing; healing or resolution has not occurred.
• T45.626S: The underdosing episode is resolved. A sequela condition (such as coagulopathy or hematoma formation) persists and is the reason for the current encounter. The sequela code is listed first on the claim.

Underdosing vs adverse effect vs poisoning in ICD-10-CM

All three classifications share the T45.62 hemostatic drug subcategory, but each has its own codes, coding rules and documentation. Misclassifying an adverse effect as underdosing, or the reverse, is a compliance risk.

The ICD-10-CM Official Guidelines (Section I.C.19) are explicit: Underdosing requires evidence the patient took less than prescribed. An adverse effect requires confirmation that the drug was correctly administered. Coders who conflate these categories create compliance exposure that can trigger payer audits.

The diagram below runs both decisions in order: The dose question comes first, then the phase of care.

Additional codes to report with T45.626S

ICD-10-CM sequela coding convention requires the code for the sequela condition to be listed before T45.626S on the claim. On its own, T45.626S explains why the sequela developed, but it doesn’t describe what’s being treated at this encounter. The claim needs both codes.

Common sequela conditions reported ahead of T45.626S include coagulopathy, persistent hematoma, abnormal bleeding episodes and complications of altered coagulation. Look up the right residual condition code in the ICD-10-CM tabular list before submission to avoid incomplete-claim denials. Also confirm the patient’s insurance eligibility is current, since some payers restrict coverage when T45.626S is the only diagnosis code.

• Sequela condition code: Always listed first (e.g. D68.9 for coagulopathy, unspecified).
• T45.626S: Listed second, as the cause of the sequela.
• Underdosing reason code (if applicable): Some payers and AHA Coding Clinic guidance recommend coding the reason for underdosing when the note documents it. For noncompliance, use a billable child code such as Z91.190 (financial hardship) or Z91.198 (other reason).
• No POA indicator required for outpatient claims. Inpatient facilities must assign a present-on-admission indicator per their facility policy.

A superbill that captures all active diagnoses in the correct sequence prevents incomplete-code denials on T45.626S claims.

Documentation requirements for T45.626S

Payers and auditors look for five documented elements before they accept T45.626S. A claim missing any one of them is exposed to denial.

On sequela T-codes, medical billing compliance depends on a provider note that states the underdosing outright. “Patient appears to have taken less medication” doesn’t meet that standard. “Patient reports taking half the prescribed dose of tranexamic acid for three weeks due to cost” does.

• Explicit provider statement of underdosing: The provider must document that underdosing occurred, not leave it to the coder to infer from other details.
• Drug name identified: The specific hemostatic agent that was underdosed (e.g. aminocaproic acid, tranexamic acid) must appear in the record.
• Reason for underdosing documented: The visit note should give one reason, such as noncompliance, cost, a prescriber change or the patient’s own decision. Some payers and AHA Coding Clinic guidance treat the reason as evidence for underdosing over adverse effect.
• Acute episode resolved: A provider statement or clinical note must confirm the underdosing episode has ended and the current presentation is a residual condition. Seventh character S applies only then.
• Sequela condition identified: The medical record must describe the residual condition being treated at this encounter.

Checking the record against this list before submission is what makes each T45.626S claim a clean claim. It also cuts the time coders spend working denials after the fact.

Common claim denials for T45.626S and how to avoid them

Most T45.626S denials fall into a small number of identifiable patterns. Knowing them lets billing teams build checks before submission instead of working appeals afterward.

The table below lists the five that come up on this code. When one does reach the payer, the reference on medical billing denial codes explains the reason code that comes back.

T45.626S in the context of the T45 code block

Seeing where T45.626S sits in the T45 hierarchy makes it easier to spot when a neighboring code applies instead. T45 covers poisoning, adverse effects, and underdosing of primarily systemic agents. The CDC/NCHS ICD-10-CM web tool provides a navigable tabular view of the full T45 hierarchy.

After submission, electronic remittance advice (ERA) returns denial reason codes faster than a paper explanation of benefits (EOB). On T45.626S, that means a sequencing or seventh-character error can be corrected and resubmitted sooner.

How Pabau’s claims management software prevents T45.626S denials

Without a check before submission, a T45.626S error usually surfaces as a denial. A coder then reworks the claim by hand and waits on the resubmission.

Practice management software like Pabau moves that check ahead of submission. Its claims software for practices reviews diagnosis sequencing and seventh-character accuracy, so a missing sequela condition code gets flagged before the claim goes out.

Practices that route claims through Pabau’s Claim.MD clearinghouse integration get a second layer of checks. The integration validates ICD-10-CM codes against CMS code sets and flags incorrect encounter characters. Fewer T45.626S claims come back for manual rework, and your billing team spends less time on appeals.

Reduce coding errors before claims leave your practice

Pabau’s claims management software checks diagnosis code sequencing and seventh-character accuracy before submission. T45.626S errors get caught before the claim reaches the payer.

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Conclusion

T45.626S rarely gets denied because of the code itself. Denials come from the claim around it: The order of the codes, the seventh character and the wording of the provider note.

So put the check where the error starts. Before a T45.626S claim leaves the practice, confirm the residual condition code comes first and the note says the episode has resolved. A provider query costs minutes, while a denied sequela claim costs a resubmission and a delayed payment.

Book a demo to see how Pabau checks diagnosis sequencing before your T45.626S claims reach a payer.

Continue your research

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Looking for a clearinghouse that validates ICD-10-CM codes in real time? Medical claims clearinghouse guide explains how clearinghouse validation works and what to look for in a US clearinghouse partner.

Want to understand how remittance data helps track denial patterns? Electronic remittance advice explained covers how ERA data surfaces CARC denial codes and accelerates posting.

Listing diagnoses in the right order on every encounter? What is a superbill? explains what goes on a superbill and how it feeds the claim.

Worried about audit exposure on T-code claims? Medical billing compliance: The laws and violations walks through the rules and includes a downloadable checklist.

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