I74.5

Embolism and thrombosis of iliac artery

Embolism and thrombosis of the iliac artery involves the sudden or progressive occlusion of the common, internal, or external iliac arteries by a blood clot. An embolism typically originates from a distant source, most frequently the heart (cardioembolism), while thrombosis is the localized formation of a clot, often at the site of pre-existing atherosclerotic plaque. Occlusion of these major vessels severely compromises blood flow to the pelvic organs and lower extremities. Acute iliac occlusion is a surgical emergency that can lead to acute limb-threatening ischemia (ALTI), potentially resulting in limb loss or systemic metabolic crisis if not treated promptly through embolectomy, thrombolysis, or bypass surgery. Chronic occlusion may manifest as Leriche syndrome if the bifurcation is involved, characterized by the triad of claudication, absent femoral pulses, and erectile dysfunction.

Clinical Symptoms

Sudden, severe pain in the hip, buttock, or lower extremity
Pallor or mottled appearance of the leg skin
Pulselessness in the femoral and distal lower extremity sites
Paresthesia or numbness in the affected limb
Paralysis or decreased motor function of the foot/leg
Poikilothermia (coldness of the limb relative to the torso)
Intermittent claudication specifically in the buttocks and thighs
Erectile dysfunction (in males with internal iliac involvement)
Muscle tenderness or rigidity in the leg
Cyanosis of the toes (blue toe syndrome)

Common Causes

Atrial fibrillation (most common source of arterial emboli)
Atherosclerosis obliterans (underlying plaque providing a substrate for thrombosis)
Mural thrombus following myocardial infarction
Prosthetic heart valves
Iliac artery aneurysm with mural thrombus
Hypercoagulable states (e.g., Factor V Leiden, malignancy)
Vascular trauma or iatrogenic injury during catheterization
Infective endocarditis with vegetative emboli
Aortic dissection extending into the iliac vessels
Tobacco use and chronic hypertension (risk factors for plaque rupture)

Documentation & Coding Tips

Distinguish between embolism and thrombosis when possible to improve clinical specificity and pathophysiological clarity.

Example: Patient with history of paroxysmal atrial fibrillation presents with sudden onset of cold, pulseless right lower extremity. CTA reveals an acute embolism of the right common iliac artery. No chronic atherosclerotic changes noted. This acute event is classified under I74.5 with risk adjustment highlighting the high severity of acute limb ischemia without gangrene.

Billing Focus: Identify laterality as right or left and specify the pathological mechanism as embolic versus thrombotic.

Always document the presence or absence of gangrene and the specific location of the occlusion.

Example: Evaluation of the left external iliac artery shows subacute thrombosis. Foot is cool but viable with no evidence of gangrene or tissue loss. Documenting the specific iliac segment and the absence of gangrene supports I74.5 and ensures accurate HCC 108 mapping for vascular disease without life-threatening complications.

Billing Focus: Specification of the iliac artery segment and laterality.

Link the embolism or thrombosis to an underlying condition such as Atrial Fibrillation or Peripheral Artery Disease.

Example: Chronic thrombosis of the right internal iliac artery in a patient with Stage 3 Chronic Kidney Disease and severe peripheral artery disease. The thrombosis is documented as secondary to chronic hypercoagulability and stasis. Documentation clearly links the vascular event to the systemic risk factors.

Billing Focus: Causal relationship between the thrombus and comorbidities like AFib or PAD.

Specify the acuity of the event as acute, subacute, or chronic.

Example: Acute on chronic thrombosis of the left common iliac artery. The patient has known iliac stenosis and now presents with worsening claudication and a new occlusive thrombus visualized on duplex ultrasound. The documentation captures the acute exacerbation of a chronic condition.

Billing Focus: Episode of care details and temporal progression of the vascular occlusion.

Document the precise anatomical branch of the iliac artery affected.

Example: Thrombosis identified in the right internal iliac artery. Patient presents with pelvic pain and buttock claudication. Distinguishing internal versus external iliac involvement is critical for surgical planning and ICD-10-CM specificity within the I74 series.

Billing Focus: Anatomic specificity beyond the general iliac artery descriptor.

Relevant CPT Codes

34201 - Embolectomy or thrombectomy, with or without catheter; aortoiliac artery, by leg incision
Direct surgical intervention for acute iliac embolism or thrombosis.
37221 - Revascularization, endovascular, open or percutaneous, iliac artery, unilateral; with transluminal stent placement(s), includes angioplasty within the same vessel, when performed
Common treatment for thrombotic iliac occlusions caused by underlying atherosclerosis.
75710 - Angiography, extremity, unilateral, radiological supervision and interpretation
The gold standard for diagnosing the exact location and extent of iliac artery thrombosis.
99214 - Office or other outpatient visit for the evaluation and management of an established patient, moderate level of medical decision making, 30-39 minutes
Appropriate for managing complex vascular patients with multiple comorbidities requiring moderate MDM and 30-39 minutes of time.
99213 - Office or other outpatient visit for the evaluation and management of an established patient, low level of medical decision making, 20-29 minutes
Used for routine check-ups where the condition is stable, requiring Low MDM and 20-29 minutes of encounter time.
93922 - Noninvasive physiologic studies of upper or lower extremity arteries, single level, bilateral
Initial screening tool to detect hemodynamically significant iliac artery obstruction.
37184 - Primary percutaneous transluminal mechanical thrombectomy, arterial, including intraprocedural pharmacological thrombolytic injection and fluoroscopic guidance
Used for acute iliac thrombosis to rapidly remove the clot burden.
37223 - Revascularization, endovascular, open or percutaneous, iliac artery, each additional vessel
Necessary when thrombosis extends through multiple segments of the iliac system.
99204 - Office or other outpatient visit for the evaluation and management of a new patient, moderate level of medical decision making, 45-59 minutes
Standard for a new patient workup involving moderate complexity and 45-59 minutes of time.
99205 - Office or other outpatient visit for the evaluation and management of a new patient, high level of medical decision making, 60-74 minutes
Required for highly complex new cases with significant morbidity risk, involving High MDM and 60-74 minutes.