I74.3

Embolism and thrombosis of arteries of lower extremities

Embolism and thrombosis of arteries of lower extremities (I74.3) refers to the acute obstruction of blood flow to the legs caused by a blood clot or foreign body. This condition is a primary cause of Acute Limb Ischemia (ALI), a vascular surgical emergency. An embolism occurs when a clot (thrombus) originates in a distant site—most commonly the heart—and migrates through the arterial tree until it becomes lodged in a smaller vessel in the leg (such as the femoral, popliteal, or tibial arteries). Thrombosis involves the local formation of a clot, typically at a site of pre-existing atherosclerotic plaque or within an arterial aneurysm. Rapid diagnosis is critical, as prolonged ischemia can lead to irreversible muscle necrosis, nerve damage, compartment syndrome, and eventually limb loss. Clinical management typically involves urgent anticoagulation and surgical or endovascular revascularization, such as embolectomy, catheter-directed thrombolysis, or arterial bypass.

Clinical Symptoms

  • Sudden and severe pain in the affected lower extremity
  • Pallor or cadaveric blanching of the limb
  • Pulselessness in the pedal or popliteal arteries
  • Paresthesia or numbness in the foot or toes
  • Paralysis or significant motor weakness of the limb
  • Poikilothermia (the affected limb feels cold to the touch)
  • Mottling or cyanosis of the skin
  • Delayed capillary refill time
  • Muscle tenderness or rigidity in the calf

Common Causes

  • Atrial fibrillation (leading to cardioembolism)
  • Recent myocardial infarction with mural thrombus formation
  • Valvular heart disease or prosthetic heart valves
  • Advanced peripheral artery disease (PAD) with atherosclerotic plaque rupture
  • Popliteal artery aneurysm with distal embolization
  • Hypercoagulable states (e.g., Factor V Leiden, malignancy, or antiphospholipid syndrome)
  • Paradoxical embolism via a patent foramen ovale (PFO)
  • Arterial trauma or iatrogenic injury during vascular procedures
  • Stent or graft failure in a previously treated artery

Documentation & Coding Tips

Distinguish between Embolism and Thrombosis

Example: Patient with acute onset of right cold leg and absent pulses. Clinical presentation is highly suggestive of an acute embolism originating from the heart given known history of persistent atrial fibrillation. The occlusion is localized to the right common femoral artery. Assessment: Acute embolism of right common femoral artery. Plan: Immediate heparinization and vascular surgery consultation for embolectomy.

Billing Focus: Document the specific pathological mechanism as embolism rather than a generic thrombosis when a proximal source is suspected to ensure clinical accuracy and specificity for I74.3.

Specify the Laterality and Precise Arterial Site

Example: Physical exam reveals a cool left lower extremity with cyanosis of the toes and no palpable popliteal or pedal pulses. Ultrasound confirms acute thrombosis of the left popliteal artery. Right extremity pulses remain 2+ and normal. Diagnosis: Acute thrombosis of left popliteal artery. This is a new acute event in the setting of known hypercoagulability.

Billing Focus: Laterality is essential for modern ICD-10-CM standards; although I74.3 is the overarching category, documentation must specify left, right, or bilateral status in the narrative to support the code choice.

Document Associated Ischemia Severity Using Rutherford Criteria

Example: Patient presents with Category IIb acute limb ischemia of the right leg due to suspected arterial embolism. Findings include rest pain, mild motor deficit, and loss of sensory function in the foot. No audible arterial signals via Doppler. Diagnosis: Acute arterial embolism of right lower extremity with Rutherford IIb limb threat.

Billing Focus: Detailed descriptions of sensory or motor loss provide clinical evidence for the necessity of emergency surgical interventions or inpatient admission.

Identify the Underlying Etiology and Comorbidities

Example: The patient's acute thrombosis of the right tibial artery is likely a complication of their existing Stage 4 Chronic Kidney Disease and associated hypercalcemia-induced vascular calcification. Current status: Acute arterial thrombosis of right lower extremity, stable on IV anticoagulation.

Billing Focus: Linking the acute event to underlying conditions such as CKD or Diabetes helps justify the medical necessity of complex multi-specialty care.

Clarify Acute vs Chronic Status

Example: Patient has a long history of claudication (I70.211) but now presents with a sudden, significant worsening of symptoms (rest pain and pallor) over the last 6 hours, consistent with acute thrombosis on a background of chronic atherosclerosis. Diagnosis: Acute arterial thrombosis of the right lower extremity.

Billing Focus: It is critical to document the acute nature of the event to distinguish it from chronic peripheral artery disease (I70.x codes) which have different reimbursement structures.

Relevant CPT Codes

Related Diagnoses

Hierarchy