Morphological Variation in Azygos Vein

Introduction: The variant azygos venous system might be confused with thoracic aorta aneurysms, lymphadenopathy and tumours of posterior mediastinum. The anatomical knowledge of the variability of the azygos venous system is important for the surgical interventions of the posterior mediastinum and also during radiological investigations/diagnosis especially CT and MRI. Methods: The present study was undertaken on 22 embalmed adult human cadavers irrespective of age, sex used for undergraduate dissection from the Department of Anatomy, Osmania Medical College over a period of 2 years. In this present study, azygos system of veins was observed in 22 dissected human cadavers. Out of which 6 cadavers showed the variation. Results: In the present study, a total of normal azygos venous system was found in 16 specimens accounting for 73 %. Variations were found in 6 specimens (27 %) ; all specimens presented with shifting of azygos vein towards left of vertebral column with presence of normal positioning of accessory hemiazygos vein and hemiazygos vein, 2 transverse channels across vertebral column. Conclusion: Accurate knowledge about this kind of variation is very important to identify, especially in the computed tomography and magnetic resonance imaging of mediastinum. The abnormal azygos venous system may easily be confused with aneurysm, lymphadenopathy and other abnormalities like tumour. It is important to keep these kinds of variations in mind while performing the mediastinal operations or surgery of large vessels.