ICD code I82.409 – Acute DVT of unspecified deep veins and leg

Key takeaways

I82.409 is the billable ICD-10-CM code for an acute DVT of the leg when the record names neither the vein nor the side.

A documented femoral vein DVT is coded to I82.411, I82.412, I82.413 or I82.419, never to I82.409.

Laterality may come from another clinician’s note, such as the duplex report, so an unspecified side should be rare.

Chronic DVT needs the word chronic in the provider’s documentation and moves the code to I82.50- or a vein-specific I82.5- code.

Pabau’s claims tools help practices code DVT encounters to the documented vein and side before the claim leaves.

ICD-10 Code I82.409: What it covers and when to use it

ICD-10 Code I82.409 is the billable code for acute embolism and thrombosis of unspecified deep veins of unspecified lower extremity. The CDC ICD-10-CM tabular list places it under DVT of the leg when the record names neither the vein nor the side.

The code carries two separate “unspecified” elements. The first is the vein, because no deep vein such as the femoral or popliteal is named. The second is laterality, because the record does not say right, left or bilateral.

I82.409 sits in subcategory I82.40, where the tabular list places “Deep vein thrombosis NOS” and “DVT NOS.” Once the documentation adds detail, the code moves:

• Side documented, vein not named: I82.401 (right), I82.402 (left) or I82.403 (bilateral).
• Femoral vein named: I82.411 (right), I82.412 (left), I82.413 (bilateral) or I82.419 (side unspecified).
• Another deep vein named: iliac (I82.42-), popliteal (I82.43-), tibial (I82.44-), peroneal (I82.45-), calf muscular (I82.46-) or other specified (I82.49-).
• Only the region named: thigh or upper leg goes to I82.4Y-, and calf or lower leg goes to I82.4Z-.
• DVT documented as chronic: the I82.5- subcategories, starting with I82.509 for the unspecified vein and leg.

Code details at a glance

The table below summarizes the administrative attributes of ICD-10 Code I82.409 as listed in the official ICD-10-CM tabular list from the CDC/NCHS ICD-10-CM web tool.

Inclusions, exclusions and instructional notes

The notes that govern I82.409 sit at three levels: subcategory I82.40, category I82 and the neighboring phlebitis category I80.

What I82.409 includes: An acute DVT of the leg documented without a named vein and without a side. “DVT NOS” and “deep vein thrombosis NOS” index here when the provider adds no detail.

What I82.409 does not include: A named deep vein always takes its own subcategory. The superficial femoral vein is anatomically a deep vein despite its name, and the Alphabetic Index sends femoral vein thrombosis to I82.41-. A documented superficial femoral vein DVT is therefore coded to I82.411, I82.412, I82.413 or I82.419.

Thrombosis of the superficial veins of the leg is a different condition, coded to I82.81-. The tabular notes that matter at each level are:

• Excludes1 at I82.40: unspecified deep veins of the proximal leg (I82.4Y-) and of the distal leg (I82.4Z-). If the record says thigh or calf, I82.409 is the wrong code.
• Code first at I82: venous embolism and thrombosis complicating abortion, ectopic or molar pregnancy (O00-O07, O08.7), or pregnancy, childbirth and the puerperium (O22.-, O87.-).
• Excludes2 at I82: venous thrombosis of cerebral, coronary, intracranial, intraspinal, mesenteric, portal and pulmonary vessels. An Excludes2 condition may be reported alongside I82.409 when both are present, which is why a coexisting pulmonary embolism (I26.-) is coded separately.
• Excludes1 at I80: the phlebitis category excludes venous embolism and thrombosis of the lower extremities (I82.4-, I82.5-, I82.81-). A documented leg DVT is coded to I82, not to a deep-vessel phlebitis code from I80.2-.

Budd-Chiari syndrome (I82.0) is a sibling code in the same category for hepatic vein thrombosis, not an exclusion note. It has no bearing on how a leg DVT is coded.

Anticoagulant status: The tabular “use additional code” note for Z79.01 (long-term current use of anticoagulants) sits at I82.5, the chronic subcategory, not at I82.4. For an acute DVT, Z79.01 follows the general Z79 guideline instead.

That guideline assigns a Z79 code for continuous long-term or prophylactic drug therapy. It excludes medication given for a brief period to treat an acute illness. The provider’s documented anticoagulation plan decides whether Z79.01 belongs on the claim. When the practice injects the anticoagulant itself, the drug bills on its own line, such as J1652 for fondaparinux.

I82.409 vs adjacent codes: Choosing the vein and the side

Two decisions drive code selection in subcategory I82.4: which vein is involved and which side. Section I.B.13 of the ICD-10-CM Official Guidelines for Coding and Reporting says codes for an unspecified side “should rarely be used.”

Laterality is one of the few elements a coder may take from a clinician other than the treating provider. When the physician note says only “DVT” but the duplex report says “left,” the guidelines allow I82.402.

The vein works differently. The diagnosis itself must come from the patient’s provider. A duplex report naming the femoral vein does not move the code to I82.41- on its own. Query the provider to confirm the site, and query again when two documents disagree on the side.

The grid below maps each combination of documented vein, leg region and side to its I82.4- code.

Acute vs chronic DVT: Coding the correct acuity

ICD-10 Code I82.409 is always acute. The chronic counterpart for the unspecified vein and leg is I82.509, chronic embolism and thrombosis of unspecified deep veins of unspecified lower extremity.

Because the index defaults an unqualified DVT to the acute subcategory, coders do not need a query to reach I82.409. A query is warranted when the record mixes signals, such as “known DVT” alongside a new duplex finding.

Coding DVT with pulmonary embolism

Category I82 carries an Excludes2 note for pulmonary embolism, so I26.- and I82.409 may appear on the same claim. Sequencing follows the UHDDS principal diagnosis definition: the condition established after study to be chiefly responsible for the admission. When anticoagulation can’t be used, an acute DVT diagnosis often supports filter placement under CPT 37191.

• PE is the reason for admission: Sequence the appropriate I26.- code as principal. I82.409 becomes a secondary diagnosis.
• DVT found during the PE workup: PE remains principal, and I82.409 is coded as an additional diagnosis.
• DVT is the admitting diagnosis and PE is found later: Apply the UHDDS definition to the circumstances of admission. Query the physician if the record does not settle it.
• Both documented and treated: Report both codes. The PE code depends on whether acute cor pulmonale is documented, such as I26.99 without it or I26.09 with it.

Sequencing errors between PE and DVT codes change the DRG, so they draw payer review.

Documentation requirements to support I82.409

The provider’s note must state a confirmed DVT, not a “rule out” or “suspected” diagnosis. In the outpatient setting, an unconfirmed DVT is coded to its signs and symptoms instead. Sound medical billing compliance starts with capturing these elements at the point of care:

• Provider diagnosis: A confirmed acute DVT of the leg, documented by the treating provider.
• Imaging confirmation: A duplex ultrasound report confirming the thrombus. CPT 93970 covers a complete bilateral study, and CPT 93971 a unilateral or limited one.
• Vein and side: The named vein from the provider and the side from any clinician’s note. When neither can be determined, a brief statement of that supports I82.409.
• Acuity: Whether the DVT is acute or chronic, documented by the provider.
• Anticoagulation plan: The drug and the intended duration, which decides whether Z79.01 applies.

Most I82.409 claims can carry a more specific code once the duplex report is read alongside the note. Submitting clean claims for DVT encounters depends on settling the vein and side before the claim is built.

Payer requirements and prior authorization

Medicare and commercial payer requirements for ICD-10 Code I82.409 vary by setting and by the services rendered. Tracking them is part of revenue cycle management for vascular, cardiology and hospitalist practices.

Payers increasingly read the attached imaging report. A claim for a named-vein, named-side DVT that carries I82.409 invites a specificity edit.

Common claim denial reasons for I82.409

I82.409 claims deny for a predictable set of reasons. Knowing them in advance is the most efficient denial management approach for billing teams. Five common triggers and their fixes:

• Unspecified code when the record is specific: The imaging report names the left femoral vein, but the claim carries I82.409. Fix: confirm the vein with the provider, recode to I82.412, and resubmit.
• Missing imaging report: A duplex ultrasound (93970/93971) billed with I82.409 is denied for medical necessity. Fix: attach the radiology report or send it as claim documentation.
• Acute/chronic mismatch: I82.409 is billed when the note describes a long-standing DVT documented as chronic. Fix: recode to I82.509 or the vein-specific I82.5- code.
• Rule-out diagnosis coded as confirmed: I82.409 is billed for an outpatient scan that ruled out DVT. Fix: code the documented signs or symptoms instead. See denial codes in medical billing for the CARC codes that accompany diagnosis denials.
• PE/DVT sequencing error: I82.409 is sequenced as principal when PE drove the admission. Fix: apply the UHDDS definition and resubmit with the corrected principal diagnosis.

ICD-9-CM crosswalk for I82.409

The General Equivalence Mappings (GEMs) map I82.409 to ICD-9-CM 453.40. That code is acute venous embolism and thrombosis of unspecified deep vessels of lower extremity. The 2018 GEMs files flag the match as approximate, and the backward map returns 453.40 to I82.409.

ICD-9-CM had no laterality, so the right, left and bilateral codes all collapse to the same ICD-9 code. Understanding medical billing fundamentals across code generations still matters for audits, legacy conversion and retrospective data work.

GEMs were last updated for FY2018 and are not a substitute for the codes themselves. Use them for legacy data conversion or retrospective audits, never for claim submission.

Related ICD-10 codes to report alongside I82.409

The codes below are often reported on the same claim as I82.409. Verify current-year validity for each with the AAPC Codify ICD-10-CM lookup.

How Pabau keeps DVT claims coded to the documented vein and side

Most I82.409 denials start with a claim built from the visit note alone, while the duplex report sits in another system. The coder never sees the side or the vein, so the least specific code goes out.

Pabau, the practice management and billing platform we build, keeps the note, the imaging report and the claim on one patient record. Its claims management software captures ICD-10 codes at the point of care, so the coder can check the documented vein and side before submission.

US claims go out electronically through Claim.MD, with eligibility checks before the visit. Electronic remittances return the denial reason codes, so a specificity denial can be corrected and resubmitted quickly.

Code DVT claims to the documented vein

Pabau keeps the visit note, imaging report and claim on one record, then submits US claims through Claim.MD. Coders can match the code to the documented vein and side before the claim leaves.

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Conclusion

I82.409 is a fallback code, and the guidelines treat it that way. Use it only when neither the vein nor the side can be found anywhere in the record and the provider cannot clarify.

Read the duplex report before you settle on it. The side can be taken from that report directly, and the vein usually needs one short provider query. That small step moves most DVT claims to I82.40-, I82.41- or another vein-specific code that payers accept on the first pass.

Book a demo to see how Pabau keeps the note, imaging and claim together, so DVT claims match the documented vein and side.

Continue your research

Need to track denial patterns across DVT claims? Denial management in healthcare covers the frameworks practices use to monitor, categorize, and resolve recurring claim rejections.

Want to understand how claims flow from submission to payment? Medical claims clearinghouse explains the clearinghouse role in validating and transmitting ICD-10-coded claims to payers.

Looking for the 837P EDI format for professional claims? 837 file guide walks through the transaction set structure used to transmit DVT and VTE claims electronically.

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