I82.431

🩸 ICD-10-CM I82.431 — Acute Embolism and Thrombosis of Right Popliteal Vein

Billable Code Confirmed

ICD-10-CM I82.431 is a valid, billable 7-character ICD-10-CM diagnosis code for FY2026. Characters 1-3 (I82) identify the category as other venous embolism and thrombosis; character 4 (.4) specifies acute embolism and thrombosis of deep veins of the lower extremity; character 5 (3) identifies the popliteal vein as the specific vessel; character 6 (1) designates the right side. All 7 characters are required — no additional extension characters are needed.

Non-Billable Parent Codes — Never Submit These

• ❌ I82 — 3-character category header — does not specify vein type, acuity, or laterality
• ❌ I82.4 — 5-character subcategory — does not specify vessel or laterality
• ❌ I82.43 — 6-character subcategory — does not specify right vs. left vs. bilateral

Always submit I82.431 (all 7 characters) when acute embolism or thrombosis of the right popliteal vein is documented.

Clinical Context: Acute vs. Chronic — Acuity Must Drive Code Selection

ICD-10-CM I82.431 is assigned only when the thrombosis is documented as acute — meaning new-onset or of recent origin, typically presenting with pain, swelling, warmth, and erythema in the posterior knee/calf region with confirmed imaging findings. When the same vessel has a chronic thrombosis (organized thrombus, post-thrombotic changes, longstanding DVT), assign I82.531 instead. When documentation does not specify acute vs. chronic, ICD-10-CM coding guidelines default to the acute code — but a CDI query is appropriate when clinical context suggests chronicity (e.g., no acute symptoms, incidental imaging finding, long-standing symptoms).

Code Classification

ICD-10-CM Diagnosis Code — This is a venous thromboembolic disease diagnosis code under ICD-10-CM Chapter 9. wRVU, assistant-at-surgery payable, and global period fields are not applicable to diagnosis codes. For associated procedural coding, refer to the CPT Procedural Crosswalk section (vascular imaging and interventional codes) and the ICD-10-PCS Crosswalk section (inpatient thrombectomy and thrombolysis coding).

---

🔍 Code Description

ICD-10-CM I82.431 classifies acute embolism and thrombosis of the right popliteal vein — the formation of a thrombus (blood clot) within the popliteal vein located behind the right knee, at the juncture of the superficial femoral vein proximally and the anterior/posterior tibial veins distally. The code encompasses both thrombosis (in situ clot formation) and embolism (clot that has partially migrated from a distal source) involving this specific venous segment.

The popliteal vein is a proximal deep vein of the lower extremity — its involvement places this DVT in the proximal DVT risk category, which carries substantially higher risk of pulmonary embolism propagation than distal (calf) vein thrombosis. Virchow’s triad (venous stasis, endothelial injury, and hypercoagulability) drives clot formation, and clinical risk factors include prolonged immobility, recent surgery (particularly orthopedic — hip and knee arthroplasty), malignancy, inherited thrombophilia (D68.51, D68.52), antiphospholipid syndrome, hormone therapy, and prior VTE history. Propagation proximal into the femoral or iliac vein — or embolization to the pulmonary vasculature — represents the primary life-threatening complication.

---

🌳 Code Tree / Hierarchy

I82   Other venous embolism and thrombosis ❌ Non-billable
│
├── I82.0   Budd-Chiari syndrome ✅ Billable
├── I82.1   Thrombophlebitis migrans ✅ Billable
├── I82.2   Embolism and thrombosis of vena cava and other thoracic veins ❌ Non-billable
│
├── I82.4   Acute embolism and thrombosis of deep veins of lower extremity ❌ Non-billable
│   │
│   ├── I82.40  Acute embolism/thrombosis, unspecified deep veins of lower extremity ❌ Non-billable
│   │   ├── I82.401  Acute embolism and thrombosis, unspecified deep veins, right lower extremity ✅ Billable
│   │   ├── I82.402  Acute embolism and thrombosis, unspecified deep veins, left lower extremity ✅ Billable
│   │   ├── I82.403  Acute embolism and thrombosis, unspecified deep veins, bilateral ✅ Billable
│   │   └── I82.409  Acute embolism and thrombosis, unspecified deep veins, unspecified ✅ Billable
│   │
│   ├── I82.41  Acute embolism and thrombosis of femoral vein ❌ Non-billable
│   │   ├── I82.411  Acute embolism and thrombosis of right femoral vein ✅ Billable
│   │   ├── I82.412  Acute embolism and thrombosis of left femoral vein ✅ Billable
│   │   ├── I82.413  Acute embolism and thrombosis of femoral vein, bilateral ✅ Billable
│   │   └── I82.419  Acute embolism and thrombosis of unspecified femoral vein ✅ Billable
│   │
│   ├── I82.42  Acute embolism and thrombosis of iliac vein ❌ Non-billable
│   │
│   ├── I82.43  Acute embolism and thrombosis of popliteal vein ❌ Non-billable
│   │   ├── ▶▶ I82.431 ◀◀  Acute embolism and thrombosis of right popliteal vein ← YOU ARE HERE ✅ Billable
│   │   ├── I82.432  Acute embolism and thrombosis of left popliteal vein ✅ Billable
│   │   ├── I82.433  Acute embolism and thrombosis of popliteal vein, bilateral ✅ Billable
│   │   └── I82.439  Acute embolism and thrombosis of unspecified popliteal vein ✅ Billable
│   │
│   ├── I82.44  Acute embolism and thrombosis of tibial vein ❌ Non-billable
│   │   ├── I82.441  Acute embolism and thrombosis of right tibial vein ✅ Billable
│   │   ├── I82.442  Acute embolism and thrombosis of left tibial vein ✅ Billable
│   │   ├── I82.443  Acute embolism and thrombosis of tibial vein, bilateral ✅ Billable
│   │   └── I82.449  Acute embolism and thrombosis of unspecified tibial vein ✅ Billable
│   │
│   └── I82.45  Acute embolism and thrombosis of peroneal vein ❌ Non-billable
│       ├── I82.451  Acute embolism and thrombosis of right peroneal vein ✅ Billable
│       ├── I82.452  Acute embolism and thrombosis of left peroneal vein ✅ Billable
│       ├── I82.453  Acute embolism and thrombosis of peroneal vein, bilateral ✅ Billable
│       └── I82.459  Acute embolism and thrombosis of unspecified peroneal vein ✅ Billable
│
├── I82.5   Chronic embolism and thrombosis of deep veins of lower extremity ❌ Non-billable
│   └── I82.531  Chronic embolism and thrombosis of right popliteal vein ✅ Billable
│
└── I82.9   Embolism and thrombosis of unspecified vein ❌ Non-billable

Popliteal = Proximal DVT — Clinical and DRG Impact

The popliteal vein is classified as a proximal deep vein — placing I82.431 in the same clinical risk tier as femoral and iliac DVT. Proximal DVT carries a significantly higher PE risk (~50% untreated propagation rate) than distal (tibial/peroneal) DVT and typically mandates anticoagulation therapy rather than watchful waiting. From a DRG perspective, when I82.431 is the principal diagnosis, it directly groups to DRG 294/295 (Deep Vein Thrombophlebitis, MDC 05) — but if a concurrent PE is also documented and coded (I26.09, I26.99), the PE code will drive a higher-weighted DRG grouping under the Pulmonary Embolism family (DRG 175/176/177).

---

✅ Includes

The following clinical terms and scenarios map to I82.431 when documented:

• Acute DVT of the right popliteal vein
• Acute deep venous thrombosis behind the right knee (popliteal region)
• Acute venous thromboembolism of the right popliteal vein
• Right popliteal vein thrombosis, new-onset or recent-onset
• Acute thrombophlebitis of the right popliteal vein (embolic/thrombotic etiology)

---

❌ Excludes

Excludes 1 — Cannot Be Coded Simultaneously with I82.431

Code	Description	Note
O22.-	Venous embolism and thrombosis complicating pregnancy	When DVT occurs during pregnancy, obstetric complication codes in Chapter 15 take precedence — code first the O22.- code; I82.431 is not separately assigned
O87.-	Venous embolism and thrombosis in the puerperium	Same principle — puerperium DVT codes under Chapter 15; I82.431 is not used concurrently

Excludes 1 Violation Risk

The most common Excludes 1 error is assigning I82.431 alongside an obstetric encounter code (O22.-, O87.-) for a pregnant or postpartum patient with right popliteal DVT. In these cases, O22.3x (deep phlebothrombosis in pregnancy) or O87.1 (deep phlebothrombosis in the puerperium) must be coded first, and I82.431 is excluded. Always verify the patient’s pregnancy status before assigning I82.x DVT codes.

Excludes 2 — May Be Coded in Addition if Separately Present

Code	Description	Note
I26.09	Other pulmonary embolism without acute cor pulmonale	When PE is concurrently documented alongside the DVT, code both I82.431 AND the appropriate I26.x code — PE is a distinct, separately reportable complication of DVT and must not be omitted
I26.99	Other pulmonary embolism with acute cor pulmonale	Same principle — code both when documented; PE as MCC significantly elevates DRG grouping
I80.221	Phlebitis and thrombophlebitis of right popliteal vein	Inflammatory phlebitis may co-exist; separately reportable when documented as a distinct process from the embolic/thrombotic DVT

---

📋 Clinical Overview

Acute vs. Chronic — Acuity Documentation Drives Code Family

Correct assignment of I82.431 (acute) vs. I82.531 (chronic) hinges entirely on provider documentation of acuity — ICD-10-CM does not define time thresholds for “acute” vs. “chronic” DVT, so clinical context and explicit provider language govern code selection.

Feature	I82.431 — Acute	I82.531 — Chronic	I82.439 — Unspecified
Acuity Status	New-onset / recent thrombosis	Longstanding / organized thrombus	Acuity not documented
Typical Presentation	Pain, swelling, warmth, erythema, tenderness posterior knee	May be asymptomatic; post-thrombotic syndrome features	Variable
Imaging Characteristics	Non-compressible vein, echogenic fresh thrombus, absent Doppler flow	Partially recanalized vein, hyperechoic organized thrombus, collateral flow	N/A
Treatment Implication	Urgent anticoagulation initiation (LMWH, DOAC, UFH bridge)	Ongoing anticoagulation vs. observation; compression; evaluate for PTS	Treat as acute pending clarification
Code Default (no acuity)	Per ICD-10-CM guidelines, default to acute	N/A	Use I82.439 only when laterality is also unspecified

CDI Query Trigger — Acuity Not Specified

When imaging reports describe findings consistent with DVT but the ordering provider’s note does not specify “acute” vs. “chronic” — or when there is a discrepancy between the imaging report (e.g., “chronic-appearing thrombus with recanalization”) and the provider’s note (“DVT”) — a CDI query is appropriate. Ask the provider to clarify whether the DVT is acute, chronic, or acute-on-chronic. Acute-on-chronic DVT is coded to the acute code (I82.431) per ICD-10-CM convention.

Manifestations & Symptom Burden

Document all complications and underlying risk factors as secondary diagnoses to support clinical complexity, medical necessity, and DRG tier:

• Pulmonary embolism — I26.09 or I26.99: most serious complication; always query for PE when respiratory symptoms accompany DVT; code separately when documented — PE is the MCC that drives DRG 294
• Post-thrombotic syndrome (PTS) — I87.011 / I87.012: chronic venous insufficiency with pain, edema, skin changes as sequela of prior DVT; not assigned at the acute DVT encounter but important for follow-up care coding
• Underlying hypercoagulable state — D68.51 (Activated protein C resistance / Factor V Leiden), D68.52 (Prothrombin gene mutation), D68.59 (Other thrombophilia): code as secondary diagnosis when documented; these are CC-level codes that elevate DRG grouping
• Malignancy as underlying cause — active cancer (C-code) is a known VTE risk factor and CC/MCC; code separately and sequence appropriately per ICD-10-CM Neoplasm guidelines
• Immobility/prolonged bedrest — Z74.01: when documented as a contributing factor, supports medical necessity narrative

Coding Manifestations

Always code all documented concurrent conditions to fully capture clinical complexity. Critical secondary codes to review:

• I26.09 — Other pulmonary embolism without acute cor pulmonale (MCC — drives DRG 294)
• D68.51 — Activated protein C resistance / Factor V Leiden thrombophilia (CC)
• I87.011 — Postthrombotic syndrome with ulcer of right lower extremity (chronic sequela — not acute encounter)
• Z86.718 — Personal history of other venous thrombosis and embolism (prior VTE history)

---

💰 HCC Risk Adjustment (CMS-HCC v28)

Field	Detail
CMS-HCC Model Version	v28 (Fully operative — Payment Year 2026)
HCC Assignment	❌ Not HCC-Mapped
HCC Category	N/A
RAF Coefficient	N/A

I82.431 does not map to an HCC category under CMS-HCC v28. Acute DVT is not modeled as a chronic condition for risk adjustment purposes.

HCC Opportunity — Code the Underlying Cause

While I82.431 itself carries no HCC weight, the underlying conditions that precipitate DVT often do. Active malignancy (HCC 10-23 depending on type), congestive heart failure (HCC 85), and CKD (HCC 329) are all HCC-mapped conditions that may coexist with DVT as contributing risk factors. Ensure all documented comorbidities driving the hypercoagulable state are captured and coded at every qualifying encounter to support accurate RAF scoring for Medicare Advantage patients.

---

🏥 MS-DRG Assignment

MDC 05 — Diseases and Disorders of the Circulatory System

DRG	Title	Est. Relative Weight*
DRG 294	Deep Vein Thrombophlebitis with CC/MCC	~0.9-1.1
DRG 295	Deep Vein Thrombophlebitis without CC/MCC	~0.6-0.8

Approximate. Verify against IPPS FY2026 Final Rule tables (CMS v43 MS-DRG Definitions Manual).

Sequencing, PE, and DRG Override

When I82.431 is the principal diagnosis, it groups to DRG 294 (with CC/MCC) or DRG 295 (without CC/MCC). Critical override scenario: If pulmonary embolism (I26.x) is also documented, the PE code should be evaluated for sequencing as the principal diagnosis — PE is typically the condition that necessitated admission and carries higher DRG weight (DRG 175/176/177, Pulmonary Embolism family). Never bury a documented PE as a secondary code when it was the reason for admission — this is an inpatient sequencing error with significant compliance and DRG weight implications. Additionally, concurrent documentation of a hypercoagulable disorder (D68.51, D68.52) will function as a CC and elevate the case to DRG 294, substantially increasing reimbursement over DRG 295.

---

🔗 Related ICD-10-CM Codes

Laterality and Acuity Variants — Popliteal Vein (I82.43x / I82.53x)

Code	Description
I82.431	Acute embolism and thrombosis of right popliteal vein ← This Code
I82.432	Acute embolism and thrombosis of left popliteal vein
I82.433	Acute embolism and thrombosis of popliteal vein, bilateral
I82.439	Acute embolism and thrombosis of unspecified popliteal vein
I82.531	Chronic embolism and thrombosis of right popliteal vein
I82.532	Chronic embolism and thrombosis of left popliteal vein

Adjacent Deep Vein Segments — Right Lower Extremity (Acute)

Code	Description
I82.411	Acute embolism and thrombosis of right femoral vein (proximal — higher risk)
I82.441	Acute embolism and thrombosis of right tibial vein (distal)
I82.451	Acute embolism and thrombosis of right peroneal vein (distal)
I82.401	Acute embolism and thrombosis, unspecified deep veins of right lower extremity (use only when specific vein not identified)

Thromboembolism Complications and Related Conditions

Code	Description
I26.09	Other pulmonary embolism without acute cor pulmonale
I26.99	Other pulmonary embolism with acute cor pulmonale
I87.011	Postthrombotic syndrome with ulcer of right lower extremity
I87.311	Chronic venous hypertension with ulcer of right lower extremity
Z86.718	Personal history of other venous thrombosis and embolism

---

🛠️ Commonly Associated CPT Codes (Vascular / Interventional / IM)

Outpatient and Inpatient Setting Context

ICD-10-CM I82.431 is the primary diagnosis supporting diagnostic imaging (venous duplex ultrasound), anticoagulation initiation E/M visits, and — in more severe or refractory cases — interventional procedures (catheter-directed thrombolysis, mechanical thrombectomy). In the outpatient/profee setting, CPT 93971 is the most commonly paired code for initial diagnostic confirmation.

CPT Code	Description	Profee Coding Notes
93971	Duplex scan of extremity veins, unilateral or limited	Primary diagnostic imaging code for DVT evaluation; unilateral right lower extremity venous duplex; Modifier -26 for professional component in hospital outpatient setting
93970	Duplex scan of extremity veins, bilateral	Use when both lower extremities are imaged in the same session; do not bill 93971 x2 for bilateral — use 93970
37212	Thrombolytic therapy, percutaneous, arterial or venous, initial treatment day	Catheter-directed thrombolysis for extensive or iliofemoral-extending DVT; requires concurrent vascular access and imaging codes per NCCI — verify edit pairs
37187	Percutaneous transluminal mechanical thrombectomy, vein	Mechanical thrombectomy of popliteal or femoral vein thrombus; verify NCCI bundling with 37212 when CDT performed same session
37191	Insertion of intraluminal vena cava filter, endovascular approach	IVC filter placement when anticoagulation is contraindicated; separately reportable; document clinical indication explicitly
99285 / 99291	Emergency department E/M Level 5 / Critical care	ED evaluation for acute DVT/PE presentation; supports I82.431 as primary diagnosis for ED encounter

NCCI Bundling Considerations

• 93971 billed same day as an E/M (e.g., 99213, 99214): Modifier -25 must be appended to the E/M code — not 93971 — when the provider performs a distinct evaluation and decision-making service beyond ordering and interpreting the scan. Documentation must support a separately identifiable service.
• 37212 (CDT) billed same session as 37187 (mechanical thrombectomy): These may be bundled depending on NCCI edit status — verify current edits; Modifier -59 or -XS may be required if separate vascular territories are treated.

---

🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)

When I82.431 is an inpatient diagnosis, these PCS codes are relevant for associated inpatient procedures.

PCS Section	Body System	Root Operation	Clinical Application
0 (Medical and Surgical)	6 (Lower Veins)	C (Extirpation)	Surgical thrombectomy — removal of thrombus from right popliteal vein: 06CQ3ZZ (Percutaneous approach) or 06CQ0ZZ (Open approach)
3 (Administration)	E (Physiological Systems and Anatomical Regions)	0 (Introduction)	Catheter-directed thrombolysis — introduction of thrombolytic agent (tPA) into peripheral vein: 3E034GC (Percutaneous, other therapeutic substance)
0 (Medical and Surgical)	6 (Lower Veins)	H (Insertion)	Central venous catheter or infusion catheter placement into popliteal or adjacent vein for CDT delivery: 06HQ33Z
5 (Imaging)	B (Lower Veins)	3 (Ultrasonography)	Inpatient bedside venous duplex for DVT confirmation: B543ZZZ — Ultrasonography of Right Lower Extremity Veins

PCS Character Analysis — 06CQ3ZZ

Position	Character	Value	Definition
1	Section	0	Medical and Surgical
2	Body System	6	Lower Veins
3	Root Operation	C	Extirpation (taking or cutting out solid matter from a body part — the solid matter may be an abnormal byproduct of a biological function, such as a thrombus)
4	Body Part	Q	Right Popliteal Vein
5	Approach	3	Percutaneous
6	Device	Z	No Device
7	Qualifier	Z	No Qualifier

PCS Root Operation: Extirpation (C) vs. Fragmentation (F) vs. Introduction (Administration)

• Use Extirpation (C) when thrombus is physically removed via surgical or percutaneous thrombectomy — the solid matter (clot) is extracted from the vein
• Use Fragmentation (F) when thrombus is broken up in place (e.g., mechanical fragmentation without extraction) — body part remains; fragments remain in situ
• Use Introduction (Section 3 — Administration) for catheter-directed thrombolysis — the root operation captures drug introduction, not the mechanical removal; the thrombus is dissolved by a substance introduced into the vessel
• When both CDT and mechanical thrombectomy are performed in the same session, assign separate PCS codes for each distinct root operation

---

💊 Coding Scenarios and Examples

---

Scenario 1 — Emergency Department: New-Onset Right Leg DVT, Anticoagulation Initiated

Clinical Vignette: A 58-year-old male presents to the ED with 3-day history of right posterior knee and calf pain, swelling, and warmth following a 6-hour flight. Venous duplex ultrasound right lower extremity confirms non-compressible right popliteal vein with absent Doppler flow consistent with acute DVT. No chest pain or dyspnea; no evidence of PE on clinical evaluation. Attending documents: “Acute DVT, right popliteal vein — initiating rivaroxaban per ACCP guidelines. No PE symptoms.” Patient is discharged home with anticoagulation plan and vascular surgery follow-up.

CPT / HCPCS (Profee):

• 93971-26 — Duplex scan of extremity veins, unilateral; modifier -26 professional component for radiologist/vascular interpretation
• 99285-25 — Emergency department E/M, high complexity; modifier -25 documents separately identifiable evaluation beyond the imaging order

Primary Diagnosis:

• I82.431 — Acute embolism and thrombosis of right popliteal vein (confirmed by duplex; reason for ED visit)

Secondary Diagnoses:

• Z86.718 — Personal history of other venous thrombosis and embolism (if prior VTE documented)

---

Scenario 2 — Inpatient: Acute DVT with Concurrent Pulmonary Embolism and Thrombophilia

Clinical Vignette: A 44-year-old female is admitted through the ED with acute right lower extremity swelling and new onset dyspnea and pleuritic chest pain. CT pulmonary angiography confirms bilateral pulmonary emboli. Right lower extremity venous duplex confirms acute right popliteal and femoral DVT. Labs return positive for Factor V Leiden mutation (heterozygous). Attending documents: “Acute bilateral pulmonary embolism and acute DVT right popliteal and femoral veins. Known Factor V Leiden thrombophilia. Initiating IV heparin bridge — transitioning to long-term anticoagulation.”

Principal Diagnosis:

• I26.09 — Other pulmonary embolism without acute cor pulmonale (PE is the reason for admission — sequences as principal; higher DRG weight than DVT alone)

Secondary Diagnoses:

• I82.431 — Acute embolism and thrombosis of right popliteal vein (concurrent DVT — CC)
• I82.411 — Acute embolism and thrombosis of right femoral vein (additional DVT segment — CC)
• D68.51 — Activated protein C resistance / Factor V Leiden (underlying thrombophilia — CC; must be documented by provider, not assumed from lab results alone)

MS-DRG Assignment: I26.09 as principal diagnosis with D68.51 and DVT codes as CCs groups to the Pulmonary Embolism DRG family (DRG 175/176/177, MDC 05) — substantially higher weight than the DVT-only DRG 294/295 grouping.

---

Scenario 3 — CDI Query: Acuity Not Documented

Clinical Vignette: A 67-year-old female is admitted from her orthopedic surgeon’s office 3 weeks post right total knee arthroplasty. The surgeon’s admitting note states: “DVT right popliteal vein on duplex — admit for anticoagulation.” The imaging report reads: “Echogenic, partially organized thrombus in right popliteal vein with partial compressibility and some collateral flow — findings may represent subacute to chronic DVT.” No explicit acuity designation appears in the admitting note.

Action / Outcome: Documentation conflict exists — the imaging suggests subacute/chronic DVT but the admitting note does not specify acuity. Per ICD-10-CM guidelines, when acuity is not specified, the acute code is the default — however, the imaging description may indicate this is a post-surgical thrombus of intermediate age, not truly new-onset. A CDI query is appropriate before finalizing code assignment, as acute vs. chronic coding affects DRG grouping, treatment documentation, and long-term anticoagulation planning coding.

Query Response: Provider updates documentation to confirm: “Acute DVT right popliteal vein — 3-week-old post-operative thrombus, consistent with acute perioperative DVT. Initiating therapeutic anticoagulation.”

Corrected ICD-10-CM Coding:

• I82.431 — Acute embolism and thrombosis of right popliteal vein (provider confirmed acute; post-TKA DVT is correctly classified as acute)
• Z96.651 — Presence of right artificial knee joint (post-TKA status — supports clinical context and medical necessity)
• Z79.01 — Long-term (current) use of anticoagulants (when anticoagulation is initiated; assign at encounters where anticoagulant use is documented)

---

⚠️ Coding Pitfalls and Tips

	Pitfall or Tip
❌	Assigning I82.431 when PE is the reason for admission. When both DVT and PE are documented at the same inpatient encounter, the sequencing of principal diagnosis determines the DRG family. If the PE drove the admission decision, I26.x (PE code) should sequence as principal, with I82.431 as a secondary diagnosis. Incorrect sequencing of DVT as principal when PE is the admission diagnosis results in significant DRG weight loss and is a common inpatient coding audit finding.
❌	Using I82.431 during a pregnancy or puerperium encounter. When the patient is pregnant or postpartum, DVT must be coded under Chapter 15 obstetric codes (O22.-, O87.-) — not I82.431. Assigning I82.431 alongside an obstetric principal diagnosis violates the Excludes 1 instruction and can generate claim edits. Always check the patient’s obstetric status before assigning I82.x.
❌	Defaulting to I82.401 (unspecified deep veins) when imaging identifies the specific vessel. If the duplex ultrasound report and/or the provider note specifies the right popliteal vein, assign I82.431 — not the unspecified code. Unspecified codes (I82.401, I82.409) should be reserved for cases where the specific vein is genuinely not identified in the documentation. Using unspecified codes when specific documentation is available is a coding accuracy failure.
✅	Always query for concurrent PE when DVT is confirmed. A documented DVT — especially proximal (popliteal, femoral, iliac) — warrants review of the clinical notes for any mention of dyspnea, chest pain, hypoxia, or CT angiography results. A missed or unbundled PE code is both a clinical documentation gap and a significant DRG weight opportunity. When clinical findings suggest PE but imaging is not yet reported, query the provider before finalizing the principal diagnosis.
✅	Code the underlying hypercoagulable condition as a CC. Factor V Leiden (D68.51), prothrombin gene mutation (D68.52), and other thrombophilias (D68.59) are CC-level secondary diagnoses that elevate the DVT encounter to DRG 294. These conditions must be explicitly documented by the treating provider — lab results alone are not sufficient for code assignment. A query is appropriate when a coagulation workup is performed but the provider has not documented the clinical diagnosis.
✅	Assign Z79.01 (long-term anticoagulant use) at all applicable encounters. When the patient is discharged on therapeutic anticoagulation (DOAC, warfarin, LMWH) for DVT treatment, Z79.01 should be assigned as a secondary code at the initiating encounter and at all subsequent encounters where anticoagulation use is documented. This supports medication reconciliation, drug interaction screening flags, and risk documentation in the outpatient follow-up record.

---

📚 Sources

¹ CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. Section I.C.9 (Diseases of the Circulatory System), Section I.B.7 (Laterality), Section II (Principal Diagnosis Selection).

² CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual v43. MDC 05 Deep Vein Thrombophlebitis DRG 294/295 logic tables. https://www.cms.gov/icd10m/FY2026-fr-v43-fullcode-cms/fullcode_cms/

³ CMS. ICD-10-CM/PCS MS-DRG v42.1 Definitions Manual. MDC 05, DVT Grouping tables. https://www.cms.gov/icd10m/fy2025-version42.1-fullcode-cms/fullcode_cms/P0147.html

⁴ CMS. 2025-2026 Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings. DVT codes confirmed non-HCC-mapped under v28.

⁵ AMA. CPT Professional Edition 2026. Vascular Surgery and Interventional Radiology subsections — 93970, 93971, 37187, 37212, 37191.

⁶ CMS. Medicare Coverage Database — Billing and Coding: Non-Invasive Peripheral Venous Studies (A57594). I82.431 listed as a covered diagnosis for 93971. https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=57594

⁷ Pinson & Tang. “MCC-CC Listings for MS-DRGs FY2026.” (2025). D68.51, D68.52 confirmed as CC-level codes under FY2026 grouper. https://www.pinsonandtang.com/resources/mcc-cc-listings-for-ms-drgs-fy2026/

⁸ icdlist.com. “ICD-10-CM Diagnosis Code I82.431 — Acute embolism and thrombosis of right popliteal vein.” (2025). https://icdlist.com/icd-10/I82.431

⁹ AAPC. “ICD-10 Code I82.431 for Acute embolism and thrombosis of right popliteal vein.” https://www.aapc.com/codes/icd-10-codes/I82.431

¹⁰ CarePatron. “DVT ICD-10-CM Codes.” (2025). I82.431 confirmed in deep vein DVT code family reference. https://www.carepatron.com/icd/dvt/

¹¹ Optum. DRG Expert — Volume I and Volume II, DRG 2026. Popliteal vein acute DVT codes confirmed in DRG 294/295 grouper logic.