Multiple variations of the azygos venous system.

In a dissection performed in our department, we observed multiple variations of the azygos venous system. The hemiazygos vein was absent. The posterior 8th, 9th, and 10th intercostal veins united and their common trunk crossed 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 vertebrae. The 7th left posterior intercostal vein also crossed the column anteriorly and joined the common trunk. The present report identifies the variable 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 exist, so that extra caution is required during surgery of the mediastinum and also in appropriately interpreting the radiographs.