I82.402

Acute embolism and thrombosis of unspecified deep veins of left lower extremity

Acute embolism and thrombosis of unspecified deep veins of the left lower extremity, commonly referred to as acute Deep Vein Thrombosis (DVT), is a critical cardiovascular condition involving the formation of a blood clot (thrombus) within the deep venous system of the left leg. Unlike superficial venous thrombosis, deep vein thrombosis poses a significant risk of fragmenting and traveling to the lungs, resulting in a potentially fatal pulmonary embolism (PE). The term 'acute' indicates the recent onset of the clot (typically within the last 14 days), during which the thrombus is loosely attached to the vessel wall and highly friable. The 'unspecified' designation is used when the specific deep vein (such as the femoral, popliteal, or tibial vein) is not explicitly named in the clinical documentation, though the laterality is confirmed as the left side. Pathophysiology generally follows Virchow's Triad: venous stasis, endothelial injury, and hypercoagulability. Clinical management typically requires immediate anticoagulation therapy to prevent clot propagation and embolization.

Clinical Symptoms

Unilateral swelling of the left lower extremity (edema)
Deep, aching pain in the left calf or thigh
Tenderness along the course of the deep venous system
Increased warmth of the affected left limb compared to the right
Erythema or bluish-purple skin discoloration (cyanosis)
Distention of superficial collateral veins
Pain upon dorsiflexion of the foot (Homan's sign, though non-specific)
Pitting edema restricted to the left leg
Phlegmasia cerulea dolens (severe cases with massive swelling and cyanosis)

Common Causes

Recent major surgery, particularly orthopedic procedures of the hip or knee
Prolonged immobilization or bed rest (e.g., hospitalization, long-haul travel)
Active malignancy or recent chemotherapy
Inherited thrombophilias (e.g., Factor V Leiden mutation, Protein C or S deficiency)
Acquired hypercoagulable states (e.g., Antiphospholipid syndrome, pregnancy, postpartum period)
Use of estrogen-containing oral contraceptives or hormone replacement therapy
Mechanical trauma or vessel wall injury to the left lower extremity
Advanced age and obesity (Body Mass Index > 30)
Previous history of venous thromboembolism (VTE)
Chronic inflammatory conditions or autoimmune diseases

Documentation & Coding Tips

Distinguish between unspecified deep veins and specific deep veins like the femoral or popliteal to avoid unspecified codes when imaging results are available.

Example: Patient with acute left calf swelling and tenderness. Venous duplex ultrasound reveals an acute occlusive thrombus in a deep vein of the left lower extremity. No specific vein was identified in the radiology report beyond the deep venous system. Patient has no prior history of DVT. Initiated Eliquis 10mg BID for 7 days then 5mg BID for 3 months. Acute deep vein thrombosis of left leg is the primary diagnosis.

Billing Focus: Laterality (left) and acuity (acute) must be documented to support I82.402. Site specificity is the primary driver for this code block.

Document the clinical evidence of acuity, such as sudden onset of symptoms or recent diagnostic confirmation, to differentiate from chronic conditions.

Example: Follow-up for acute DVT of the left lower leg. Patient presented 3 days ago with sudden onset left-sided edema. Ultrasound confirms acute clot. Patient is currently on therapeutic Lovenox bridging to Warfarin. No signs of pulmonary embolism. History of morbid obesity (BMI 42) and recent pelvic surgery (6 weeks ago) are noted as contributing risk factors.

Billing Focus: Clinical indicators of acuity support the first-listed diagnosis. Ensure the presence of symptoms is linked to the thrombus location.

Always specify the laterality in every note to justify the fourth or fifth character in the ICD-10-CM code.

Example: Left lower extremity deep vein thrombosis, acute, confirmed by ultrasound in the emergency department. No involvement of the right lower extremity. Patient complaining of heavy ache in the left leg only. Calf circumference measures 3cm larger on the left compared to the right.

Billing Focus: Left-sided laterality is required for I82.402. Unspecified laterality (I82.409) is frequently rejected by payers when a side is known.

Link the thrombosis to any underlying causes or provoking factors such as trauma, surgery, or malignancy when known.

Example: Acute deep vein thrombosis of the left lower extremity in a patient with active metastatic lung cancer. The thrombus is acute and located in the deep venous system. No evidence of superficial thrombophlebitis. Patient is high risk for recurrence due to underlying malignancy.

Billing Focus: Coding for both the DVT (I82.402) and the provoking condition (e.g., C34.90) provides a more complete picture of patient complexity.

Document the presence or absence of pulmonary embolism (PE) to ensure proper secondary coding and risk assessment.

Example: Patient diagnosed with acute DVT of unspecified deep veins of the left lower extremity. CTA chest was negative for pulmonary embolism. Patient is stable for outpatient management with Xarelto. No respiratory distress or tachycardia noted.

Billing Focus: If PE is present, I26.99 would be coded as well, which often takes precedence in billing hierarchy.

Relevant CPT Codes

99213 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a low level of medical decision making and 20-29 minutes of total time spent on the date of the encounter.
Used for routine follow-up of a stable DVT patient to monitor anticoagulation and symptom resolution.
99214 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a moderate level of medical decision making and 30-39 minutes of total time spent on the date of the encounter.
Applicable when the patient has multiple comorbidities or is experiencing complications that increase the complexity of the DVT management.
99215 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a high level of medical decision making and 40-54 minutes of total time spent on the date of the encounter.
Required for patients with acute DVT presenting with life-threatening complications or requiring highly complex care coordination.
99203 - Office or other outpatient visit for the evaluation and management of a new patient, which requires a low level of medical decision making and 30-44 minutes of total time spent on the date of the encounter.
Initial evaluation of a new patient referred for a simple, provoked DVT.
99204 - Office or other outpatient visit for the evaluation and management of a new patient, which requires a moderate level of medical decision making and 45-59 minutes of total time spent on the date of the encounter.
Initial consultation for a new patient with acute DVT, requiring extensive review of history and imaging.
93970 - Duplex scan of extremity veins including responses to compression and other maneuvers; complete bilateral study
Diagnostic tool used to confirm the presence and location of the thrombus in both legs for comparison.
93971 - Duplex scan of extremity veins including responses to compression and other maneuvers; unilateral or limited study
Focused scan used to confirm DVT when symptoms are clearly localized to the left leg.
37211 - Transcatheter therapy, arterial or venous infusion for thrombolysis; initial day
Procedure used for extensive or limb-threatening DVT to dissolve the clot.
37191 - Insertion of intravascular vena cava filter, endovascular approach
Performed when anticoagulation is contraindicated or has failed in a patient with acute DVT.
93799 - Unlisted cardiovascular service or procedure
May be used for novel DVT treatments or monitoring not covered by specific codes.