Anat Cell Biol.  2023 Dec;56(4):448-455. 10.5115/acb.23.074.

Variations of azygos vein: a cadaveric study with clinical relevance

• Priya A
• Philip SE
• Jain A
• Sikka A

• KMID: 2548897
• DOI: http://doi.org/10.5115/acb.23.074

Abstract

The azygos vein can be formed as a single root, two roots, and three roots, namely lateral, intermediate and the medial roots respectively. The hemiazygos vein and the accessory hemiazygos vein are the tributaries of azygos vein rather than its left side equivalents. Its variations, especially in young persons without any relevant risk factors, may result in thromboembolic illness. This study aimed to describe the morphological and morphometric variations of azygos system of veins. The present study was conducted on thirty formalin fixed adult human cadavers by dissecting azygos vein from formation to termination and variations were noted. The azygos vein was formed by a single root in 56.7%, by two roots: the lateral root and intermediate root in 36.7% cases and by the lateral root and medial root in 6.6%. The vertebral level of termination of azygos vein was seen at the level of T4 vertebrae in 70% cases, at the level of T3 vertebrae in 20% of cases and at the level of T5 vertebrae in 10% cases. The course of azygos vein was varying in 13.3%. These morphological variations can be useful while performing mediastinal surgery, mediastinoscopy, surgery of the deformations of the vertebral column, neurovascular surgeries of the retroperitoneal organs, disc herniation and fracture of thoracic vertebrae.

Keyword

Azygos vein; Aneurysm; Embryology; Mediastinum

Figure

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  Fig. 1 Schematic representation of normal roots of origin of azygos vein (AV). (A) Origin only by lateral root. (B) Origin by lateral and intermediate root. (C) Origin by lateral and medial root. RBCV, right brachiocephalic vein; LBCV, left brachiocephalic vein; SVC, superior vena cava; AHAV, accessory hemiazygos vein; HAV, hemiazygos vein; LRA, lateral root of AV; RSCV, right sub costal vein; RALV, right ascending lumbar vein; RK, right kidney; IVC, inferior vena cava; LK, left kidney; IRA, intermediate root of AV; MRA, medial root of AV.

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  Fig. 2 Showing both azygos vein (AV) and hemiazygos vein (HV) arising from common medial root (CMR). It also shows AV arising from both lateral root and CMR. (A) Cadaveric image. (B) Schematic representation. LRA, lateral root of AV; RSV, right subcostal vein; RALV, right ascending lumbar vein; IVC, inferior vena cava; RK, right kidney; LK, left kidney.

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  Fig. 3 Showing two longitudinal venous channels on either side of vertebral column. (A) Cadaveric image. (B) Schematic representation. LBV, left brachiocephalic vein; RBV, right brachiocephalic vein; SVC, superior vena cava; RLVC, right longitudinal venous channel; LLVC, left longitudinal venous channel.

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  Fig. 4 Showing two communicating veins (CVs) present between intermediate root of azygos vein (IRA) and intermediate root of hemiazygos vein (IRHV). (A) Cadaveric image. (B) Schematic representation. AV, azygos vein; HV, hemiazygos vein; IVC, inferior vena cava; LRV, left renal vein; RK, right kidney; LK, left kidney.

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  Fig. 5 Showing a communicating vein (CV) present between azygos vein (AV) and intermediate root of azygos vein (IRA). (A) Cadaveric image. (B) Schematic representation. LRA, lateral root of azygos vein; RSV, right subcostal vein; RALV, right ascending lumbar vein; IVC, inferior vena cava.

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  Fig. 6 Showing both azygos vein (AV) and hemiazygos vein (HV) formed from lateral root and common intermediate root (CIR) arising from left renal vein (LRV). (A) Cadaveric image. (B) Schematic representation. LRA, lateral root of azygos vein; LRHV, lateral root of hemiazygos vein; IVC, inferior vena cava; RK, right kidney; LK, left kidney.

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  Fig. 7 Flow diagram of the development of azygos vein.

Reference

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