🧬 ICD-10 CM I82.461 — Acute Embolism and Thrombosis of Right Calf Muscular Vein
Billable Code Confirmed
ICD-10 CM I82.461 is a fully specified, billable 6-character code: the first three characters (I82) identify the category, the fourth character (.4) specifies deep veins of the lower extremity, the fifth character (6) narrows to the calf muscular vein group, and the sixth character (1) specifies laterality as right. Because laterality, vein group, and acuity are all captured, no further specificity is required.
Non-Billable Parent Codes
I82 (venous embolism and thrombosis, unspecified) — lacks any information on site, laterality, or acuity and cannot be billed. I82.4 (acute embolism and thrombosis of deep veins of lower extremity) — identifies acuity and general region but omits the specific vein and laterality. I82.46 (acute embolism and thrombosis of calf muscular vein) — identifies the specific vein group but omits laterality, so it requires a sixth character before it is billable.
Clinical Context
Selection of I82.461 over its siblings depends on documentation of the specific affected vein (calf muscular — i.e., gastrocnemius or soleal — versus peroneal, tibial, popliteal, or femoral) and the affected side; distal calf-vein DVTs are managed differently than proximal DVTs, since some distal clots are monitored with serial ultrasound rather than immediately anticoagulated.
Code Classification
ICD-10 CM I82.461 is a diagnosis code (ICD-10-CM), not a procedure code, and represents an acute vascular/thrombotic condition rather than a chronic status code.
🔍 Code Description
ICD-10 CM I82.461 describes an acute thrombus with or without embolic potential occurring in the calf muscular veins — the gastrocnemius and/or soleal venous plexuses — of the right lower extremity. These calf muscular veins are considered part of the distal deep venous system, distinguishing this code from acute thrombosis of the more proximal deep veins captured by sibling codes such as I82.411 (femoral vein) or I82.421 (popliteal vein, right). Because the calf muscular veins drain directly into the popliteal system, thrombus in this location carries meaningful risk of proximal extension and, less commonly, pulmonary embolization, which is why acuity and precise vein-level documentation both matter for treatment planning and code selection.
Clinically, calf-vein DVT often presents with unilateral calf swelling, tenderness, warmth, and a positive Homans’ sign, though a substantial proportion of cases are asymptomatic and identified incidentally on duplex ultrasound performed for another indication. Distal (calf-vein) DVTs such as I82.461 are managed somewhat differently than proximal DVTs like I82.401 (unspecified deep vein, right) — many isolated, asymptomatic distal DVTs in low-risk patients are surveilled with serial ultrasound rather than immediately anticoagulated, while symptomatic or extending clots are treated with the same anticoagulation protocols used for proximal disease.
🌳 Code Tree / Hierarchy
I82 Venous embolism and thrombosis, unspecified ❌ Non-billable
│
├── I82.4 Acute embolism and thrombosis of deep veins of lower extremity ❌ Non-billable
│ │
│ ├── I82.41 Acute embolism and thrombosis of femoral vein ❌ Non-billable (category)
│ │ └── I82.411 Acute embolism and thrombosis of right femoral vein ✅ Billable
│ │
│ ├── I82.42 Acute embolism and thrombosis of popliteal vein ❌ Non-billable (category)
│ │ └── I82.421 Acute embolism and thrombosis of right popliteal vein ✅ Billable
│ │
│ ├── I82.46 Acute embolism and thrombosis of calf muscular vein ❌ Non-billable (category)
│ │ │
│ │ ├── I82.461 Acute embolism and thrombosis of right calf muscular vein ◀ THIS CODE ✅ Billable
│ │ ├── I82.462 Acute embolism and thrombosis of left calf muscular vein ✅ Billable
│ │ └── I82.463 Acute embolism and thrombosis of calf muscular vein, bilateral ✅ Billable
│ │
│ └── I82.49 Acute embolism and thrombosis of other specified deep vein of lower extremity ❌ Non-billable (category)
│
└── I82.5 Chronic embolism and thrombosis of deep veins of lower extremity ❌ Non-billableSpecificity Matters for Distal vs. Proximal DVT Management
Payers and clinical protocols increasingly distinguish isolated distal (calf) DVT from proximal DVT because management pathways diverge — selecting I82.46x accurately rather than defaulting to an unspecified I82.40x code helps ensure the record supports the actual treatment approach chosen (surveillance vs. immediate anticoagulation).
Tip
Always confirm from the ultrasound report or op note whether the clot is isolated to the gastrocnemius/soleal veins (I82.46x) versus involving the peroneal (I82.45x), posterior/anterior tibial (I82.43x/I82.44x), or popliteal (I82.42x) veins — these are coded as distinct, non-overlapping vein groups.
✅ Includes
- Acute deep vein thrombosis of the right calf muscular vein, including the gastrocnemius vein.
- Acute deep vein thrombosis of the right soleal vein.
- First-time or newly diagnosed thrombus in this specific vein group and laterality, without reference to prior chronic thrombotic disease.
❌ Excludes
Excludes 1
No Excludes1 note applies directly at the I82.461 code level; the Excludes1 relationship between unspecified-vein codes (I82.401-family) and the region-only codes (I82.4Y1/I82.4Z1) exists solely within the I82.40- unspecified-vein branch and does not extend to I82.46-, since the calf muscular vein is already specifically identified.
Danger
A common Excludes1 error occurs when coders apply the I82.40- “unspecified deep vein” logic to I82.46- documentation, mistakenly believing a more specific proximal/distal region code is needed — once the ultrasound or op note names the calf muscular vein specifically, I82.46- is already maximally specific and no substitution is required.
Excludes 2
I26.99 (or other applicable I26.- code) — Acute pulmonary embolism; because calf-vein DVT can embolize to the lungs, both a lower-extremity DVT code and a pulmonary embolism code may be reported together when both conditions are separately documented and clinically present. I81 — Portal vein thrombosis is anatomically and etiologically distinct and may be coded concurrently if separately documented. K55.0-family — Mesenteric vascular thrombosis is coded separately when present, as it reflects a different venous territory entirely.
📋 Clinical Overview
Distal (Calf) DVT vs. Proximal DVT
Distal calf-vein DVT differs meaningfully from proximal DVT in both natural history and management, which is the key clinical distinction driving code selection between I82.46x and its proximal siblings.
| Feature | I82.461 | Related I82.411 | Related I82.421 |
|---|---|---|---|
| Anatomic location | Calf muscular veins (gastrocnemius/soleal), right side. | Femoral vein, right side — a proximal deep vein. | Popliteal vein, right side — the transition point between distal and proximal systems. |
| Embolic risk | Lower embolic risk than proximal DVT, though extension into the popliteal system raises risk. | Higher inherent embolic/PE risk given proximal location. | Intermediate risk; often used as the threshold for determining “proximal” DVT clinically. |
| Typical management | May be surveilled with serial ultrasound in select low-risk, asymptomatic patients rather than immediately anticoagulated. | Standard full-dose anticoagulation is typically initiated promptly given higher PE risk. | Generally managed as proximal DVT with prompt anticoagulation. |
Important
A CDI query is warranted whenever documentation states only “DVT” or “calf DVT” without specifying laterality or the exact vein (gastrocnemius/soleal vs. peroneal vs. tibial), since this level of specificity changes which sixth-character code applies and affects clinical-pathway alignment in the record.
Manifestations & Symptom Burden
- Unilateral calf swelling and tenderness, often localized to the posterior calf.
- Warmth and erythema over the affected calf.
- Positive Homans’ sign (calf pain on forced dorsiflexion of the foot), though this finding is neither sensitive nor specific.
- Asymptomatic presentation, frequently identified incidentally on ultrasound performed for another indication.
- Low-grade fever in some acute presentations.
Tip
Document whether the DVT is symptomatic or an incidental ultrasound finding, since this distinction often drives the medical-necessity rationale for anticoagulation versus surveillance and should be reflected in the physician’s assessment and plan.
💰 HCC Risk Adjustment
| Model | HCC Category | RAF Weight | Notes |
|---|---|---|---|
| CMS-HCC V28 (PY2026) | N/A — not currently a payment HCC | N/A | Acute, self-limited thrombotic events are not modeled as chronic risk-bearing conditions under V28 — flag to verify against current CMS-HCC V28 model software rather than relying solely on this note. |
ICD-10 CM I82.461 does not independently generate risk-adjustment value under the fully phased-in CMS-HCC V28 model used for Payment Year 2026, since acute embolism/thrombosis codes are not among the 115 current payment HCC categories. If the DVT arises secondary to an HCC-eligible chronic condition — active malignancy, an inherited or acquired hypercoagulable disorder, or another chronic risk-bearing diagnosis — that underlying condition should be identified, documented with MEAT criteria, and coded separately, since it (not I82.461 itself) is what carries RAF value.
🏥 MS-DRG Assignment
| DRG | Title | CC/MCC Tier |
|---|---|---|
| 299 | Peripheral Vascular Disorders | With MCC |
| 300 | Peripheral Vascular Disorders | With CC |
| 301 | Peripheral Vascular Disorders | Without CC/MCC |
When reported as principal diagnosis for an inpatient stay focused on DVT management, I82.461 typically groups to MDC 05 Peripheral Vascular Disorders (DRG 299-301); DRG weight** is driven almost entirely by secondary diagnosis capture (bleeding complications, concurrent pulmonary embolism, renal or hepatic impairment affecting anticoagulant choice) rather than by the DVT code itself, so complete and specific secondary-diagnosis documentation is essential to accurate DRG assignment — flag exact DRG relative weights for direct verification against the current IPPS Final Rule. NCD/LCD note: CMS NCD 190.11 (Home Prothrombin Time/INR Monitoring for Anticoagulation Management) explicitly extends coverage to venous thromboembolism, inclusive of deep vein thrombosis, for patients on chronic oral warfarin therapy, provided the patient has been anticoagulated at least 3 months prior to home device use, has completed an anticoagulation education program, and self-tests no more than once weekly.¹ No dedicated LCD specific to I82.461 or calf-vein DVT diagnosis/treatment itself was identified in the current Medicare Coverage Database search — verify local MAC policy for anticoagulation management and duplex ultrasound frequency limits.²
🔗 Related ICD-10-CM Codes
Same Vein Group — Laterality Variants
- I82.462 — Acute embolism and thrombosis of left calf muscular vein
- I82.463 — Acute embolism and thrombosis of calf muscular vein, bilateral
- I82.469 — Acute embolism and thrombosis of unspecified calf muscular vein
Adjacent Deep Vein Groups, Right Lower Extremity
- I82.411 — Acute embolism and thrombosis of right femoral vein
- I82.421 — Acute embolism and thrombosis of right popliteal vein
- I82.431 — Acute embolism and thrombosis of right anterior tibial vein
- I82.451 — Acute embolism and thrombosis of right peroneal vein
- I82.501 — Chronic embolism and thrombosis of unspecified deep veins of right lower extremity
🛠️ Commonly Associated CPT Codes
- 93971 — Duplex scan of extremity veins, unilateral or limited study; the primary diagnostic study confirming and localizing the calf-vein thrombus.
- 93970 — Duplex scan of extremity veins, complete bilateral study; used when bilateral evaluation is clinically indicated rather than a limited unilateral study.
- 37187 — Percutaneous transluminal mechanical thrombectomy, vein(s), including intraprocedural pharmacological thrombolytic injections; used when catheter-directed mechanical clot removal is performed for extensive or symptomatic thrombus.
- 37212 — Transcatheter therapy, venous infusion for thrombolysis, initial treatment day; used when catheter-directed thrombolytic infusion therapy is initiated.
- 37213 — Transcatheter therapy, venous infusion for thrombolysis, continued treatment on subsequent day; used for ongoing thrombolytic infusion beyond the initial day.
- 36000 — Introduction of needle or intracatheter into a vein; commonly reported when peripheral venous access is separately established for anticoagulant infusion.
🏷️ Modifier Reference
| Modifier | Name | When to Apply |
|---|---|---|
| -RT | Right Side | Apply to any associated procedure code (e.g., 93971) to specify that the right-sided calf vein was the one studied or treated, consistent with I82.461’s laterality. |
| -LT | Left Side | Not applicable to this specific right-sided diagnosis, but relevant if a bilateral duplex study is billed separately for each leg. |
| -59 | Distinct Service | Apply when a separately identifiable duplex ultrasound or procedure is performed on a different, unrelated anatomic site on the same date. |
| -76 | Repeat Procedure, Same Physician | Apply when a repeat duplex ultrasound is performed by the same physician to reassess clot progression or resolution on a later date. |
NCCI Bundling Considerations
Diagnostic duplex ultrasound (93971) is generally not bundled with subsequent therapeutic interventions (e.g., 37212 thrombolysis) performed on the same date when clinical documentation supports both a distinct diagnostic evaluation and a separately identifiable treatment decision; append modifier -59 only when medical necessity and distinct service are clearly documented.
💊 Coding Scenarios and Examples
Example 1
Clinical Scenario:
A 68-year-old male is admitted with right calf swelling and pain of two days’ duration. Duplex ultrasound confirms acute thrombus isolated to the right gastrocnemius vein, with no proximal extension. He is started on therapeutic-dose apixaban and discharged the following day.
| Field | Code | Rationale |
|---|---|---|
| CPT | 93971--RT | Unilateral limited duplex scan of the right lower extremity vein confirming the diagnosis. |
| PDx | I82.461 | Acute embolism and thrombosis of the right calf muscular vein is the confirmed, fully specified principal diagnosis. |
Tip
Sequence I82.461 as principal diagnosis since it is the condition that occasioned the admission; no CC/MCC secondary diagnosis is present in this example, so this case would map toward DRG 301 (without CC/MCC).
Example 2
Clinical Scenario:
A 74-year-old female with active breast cancer undergoing chemotherapy develops right calf pain; duplex confirms right calf muscular vein thrombosis. She is admitted for anticoagulation initiation and monitoring given her active malignancy and bleeding risk profile.
| Field | Code | Rationale |
|---|---|---|
| CPT | 93971--RT | Diagnostic duplex ultrasound confirming the right-sided calf vein thrombus. |
| CPT 2 | 36000 | Peripheral venous access established for anticoagulant administration and monitoring. |
| PDx | I82.461 | Principal diagnosis reflecting the confirmed acute right calf muscular vein thrombosis prompting admission. |
Tip
The active malignancy should be coded as an additional diagnosis if it is being actively managed or monitored during this admission, since it is clinically significant to the anticoagulation strategy chosen even though the DVT code itself carries no HCC weight.
Example 3
Clinical Scenario:
A 55-year-old male returns three days after initial diagnosis of right calf muscular vein DVT for a follow-up duplex ultrasound, performed by the same physician, to confirm clot stability prior to continuing outpatient anticoagulation.
| Field | Code | Rationale |
|---|---|---|
| CPT | 93971--RT--76 | Modifier -76 identifies this as a repeat duplex study by the same physician performed to reassess the previously diagnosed thrombus. |
| PDx | I82.461 | The condition being monitored remains the acute right calf muscular vein thrombosis. |
Tip
If the repeat ultrasound demonstrates full resolution, subsequent encounters should transition to an appropriate history-of-DVT or resolved-condition code rather than continuing to report the acute I82.461 code indefinitely.
⚠️ Coding Pitfalls and Tips
- Pitfall 1: Defaulting to an unspecified deep vein code such as I82.401 when the ultrasound report clearly documents the calf muscular vein specifically; Tips: Always read the full imaging report rather than the referring diagnosis alone, since the specific vein name determines the correct fifth-character category.
- Pitfall 2: Omitting laterality and defaulting to the unspecified sixth character I82.469 when the chart clearly documents “right” or “left”; Tips: Query the provider if laterality is ambiguous rather than defaulting to unspecified, since laterality specificity is required for full code accuracy.
- Pitfall 3: Failing to also code a concurrent pulmonary embolism when one is separately documented, since I82.461 alone does not capture embolic sequelae; Tips: Review the full assessment and imaging for any mention of PE and code I26.99 or the applicable I26 code in addition when present.
- Pitfall 4: Assuming I82.461 carries HCC risk-adjustment value under CMS-HCC V28, leading to missed opportunities to instead capture the true HCC-relevant underlying condition (e.g., active cancer); Tips: Review the chart for an HCC-eligible etiology and code it separately with full MEAT documentation.
- Pitfall 5: Applying the I82.40- Excludes1 note (referencing I82.4Y-/I82.4Z-) to I82.46- documentation and second-guessing an already-specific vein-level code; Tips: Recognize that Excludes1 logic for unspecified-vein codes does not apply once a named vein group like the calf muscular vein is documented.
- Pitfall 6: Reporting a chronic DVT code (e.g., I82.501) for a patient with a newly diagnosed, acute finding, or vice versa continuing to use I82.461 after the clot has organized into a chronic/resolved state; Tips: Confirm acuity language in the provider’s documentation at each encounter, since acute and chronic embolism/thrombosis codes are mutually exclusive in ICD-10-CM.
📚 Sources
1. Centers for Medicare & Medicaid Services. *National Coverage Determination (NCD) 190.11: Home Prothrombin Time/International Normalized Ratio (PT/INR) Monitoring for Anticoagulation Management.* CMS Pub. 100-03; 2026. https://www.cms.gov/medicare-coverage-database/details/ncd-details.aspx?ncdid=269 2. Centers for Medicare & Medicaid Services. *Medicare Coverage Database (MCD) — NCD/LCD Search.* CMS.gov; 2026. https://www.cms.gov/medicare-coverage-database 3. Centers for Medicare and Medicaid Services and the National Center for Health Statistics. *ICD-10-CM 2026, Code I82.461.* NCHS; 2026. https://www.icd10data.com/ICD10CM/Codes/I00-I99/I80-I89/I82-/I82.461 4. AAPC. *ICD-10-CM I82.4 — Excludes1/Excludes2 Notes.* Codify by AAPC; 2026. https://www.aapc.com/codes/icd-10-codes/I82.4 5. HCC Buddy. *CMS-HCC V28 Guide 2026: 115 HCCs, Weights.* 2026. https://hccbuddy.com/hcc-v28Sources listed above correspond to superscript citations throughout this note. Verify all Medicare payment figures against your current CMS PFS Lookup tool and applicable MAC LCD prior to claim submission. Please use the latest AAPC/AHIMA Coding Books to verify each code within this note.