Morphological, morphometric and histological evaluation of the iliolumbar veins in a South African population: implications for spinal surgery.

Objective: The iliolumbar veins (ILVs) and their high frequency of variations are crucial to lumbosacral spine surgical interventions. Related damage during surgery may result in significant hemorrhage. Variations of ILVs are population specific but such reports are limited in the South African population. The current study examined the anatomy and variations and the tissue composition of the ILVs in South African cadavers of European descent. Methods: Following the ethical waiver: W-CBP-210401-01, Eighty-nine adult cadavers were dissected for ILVs. The variations, morphometrics, and topography of ILVs were studied. Nineteen (ten proximal, nine distal) ILVs were processed for Hematoxylin and Eosin, Masson's trichrome and Verhoeff's histological stains to determine the tissue composition. Results: ILVs were identified in 100% of cases. 45% of ILVs anastomose with each other bilaterally. Right sided ILVs terminated into posterior surfaces of the iliac vessels (p=.001), while left sided terminated into lateral surfaces (p=.001). 61% of the cadavers exhibited classification type 1 of ILVs pattern. 42% of ILVs were at S1 vertebral level with 31% lying between L4 and L5 spinal nerve roots. Left side PILVs had higher elastic fiber composition (p=.030). ILVs elastic to collagen fiber area ratio was 1:9. Conclusion: ILV variations described in this study present new additional patterns, like bilateral anastomosis and laterality of the terminal drainage and ILV lying between L4 and L5 spinal nerve roots. ILVs have more collagen fibers than elastic fibers, predisposing them to avulsion during surgical retraction. Identification of all ILVs is important to minimize inadvertent hemorrhage and injury to adjacent structures. [ABSTRACT FROM AUTHOR]