Is a nonocclusive thrombus in the right common iliac artery extending to the infrarenal inferior vena cava (IVC) anatomically possible?

Anatomical Impossibility of Thrombus Extending from Iliac Artery to Inferior Vena Cava

A thrombus extending from the right common iliac artery to the infrarenal inferior vena cava is anatomically impossible in normal vascular anatomy, as these are separate vessels in different circulatory systems with no direct connection.

Anatomical Explanation

The right common iliac artery and the inferior vena cava belong to completely separate circulatory systems:

• Arterial System: The right common iliac artery is part of the arterial system, carrying oxygenated blood from the heart to the lower extremities.
• Venous System: The infrarenal inferior vena cava (IVC) is part of the venous system, returning deoxygenated blood from the lower body to the heart.

These vessels run in proximity to each other but are anatomically distinct structures with no normal direct communication between them 1.

Possible Explanations for Such a Finding

If such a finding is reported, several possibilities should be considered:

1. Reporting Error: Most likely a documentation or dictation error where "artery" was mistakenly used instead of "vein" 1.

2. Rare Anatomical Variants:

   • Arteriovenous fistula between the iliac artery and IVC (traumatic or congenital) 2
   • Variant of May-Thurner syndrome (though this typically involves compression of the left iliac vein by the right iliac artery, not direct communication) 2

3. Pathological Conditions:

   • Tumor thrombus invading both vessels (rare but reported in advanced malignancies) 3
   • Complex vascular malformation with abnormal connections 4

Diagnostic Considerations

If such a finding is reported, further investigation is warranted:

• Review the imaging: Confirm whether the finding represents a documentation error or true pathology
• Additional cross-sectional imaging: CTA is the preferred method for evaluating vascular anatomy and thrombus characteristics 5
• Consider vascular consultation: For expert interpretation of complex vascular findings

Clinical Implications

Understanding the correct anatomy is crucial because:

• Treatment approaches differ: Arterial thrombi and venous thrombi have different management protocols 1
• Misdiagnosis risks: Incorrect identification of vessel involvement could lead to inappropriate treatment decisions
• Rare conditions require specialized care: True arteriovenous communications require specialized vascular expertise 2

Common Pitfalls to Avoid

• Terminology confusion: Ensure precise anatomical terminology in reporting
• Assuming normal anatomy: Consider rare anatomical variants when findings seem implausible
• Overlooking pathological connections: In cases of trauma or malignancy, abnormal communications between arterial and venous systems can occur

In summary, a thrombus extending from the right common iliac artery to the IVC should prompt careful review of imaging and consideration of either a reporting error or rare pathological condition, as this is not possible in normal vascular anatomy.