Multiple variations of the azygos venous system

In a dissection performed in our department, we observed multiple variation s of the azygos venous system. The hemiazygos vein was absent. The posterio r 8th, 9th, and 10th intercostal veins united and their common trunk crosse d the vertebral column obliquely lying anterior to the aorta and posterior to the esophagus and opening into the azygos vein at the level of T7-T8 ver tebrae. The 7th left posterior intercostal vein also crossed the column ant eriorly and joined the common trunk. The present report identifies the vari able positions and courses of the veins related to the azygos system. It is important to keep in mind that different courses of the azygos system do e xist, so that extra caution is required during surgery of the mediastinum a nd also in appropriately interpreting the radiographs.