Proposal for classification of the circumaortic renal collar's morphology

Area of Science:

• Vascular Anatomy
• Radiology
• Surgical Anatomy

Background:

• The circumaortic renal collar is a rare anatomical variation of the left renal vein.
• Variations in renal venous anatomy can have significant clinical implications, particularly in abdominal surgery.

Purpose of the Study:

• To propose a classification system for the different forms of the circumaortic renal collar.
• To enhance the understanding of this vascular anomaly for improved surgical planning and patient safety.

Main Methods:

• Analysis of CT angiography scans from 319 patients.
• Literature review to support the proposed classification.
• Categorization of observed circumaortic renal collar variations.

Main Results:

• The circumaortic renal collar was identified in 2.5% (8 out of 319) of patients.
• A three-type classification (Type I, II, III) was proposed based on the configuration of the left renal vein and its relationship to the aorta.
• Type I: Single left renal vein with preaortic and retroaortic branches.
• Type II: Separate preaortic and retroaortic left renal veins.
• Type III: Anastomoses or multiple veins without anastomoses.

Conclusions:

• The proposed classification provides a framework for understanding circumaortic renal collar morphology.
• Recognition of this anomaly is vital for preventing intraoperative hemorrhage during procedures like abdominal aortic aneurysm repair and renal transplantation.
• Accurate preoperative identification of the retroaortic component is critical for surgical success.