Absence of the Azygos Vein
Congenital absence of the azygos vein is rare, with only two cases reported in the radiologic literature (9, 10). CT may demonstrate absence of the azygos vein, with consequent enlargement of the hemiazygos, accessory hemiazygos, and left superior intercostal veins.
An occlusion is not a congenital absence, but these might be the veins that could serve as collaterals for an occluded azygous.
Dr. Sclafani asks about symptoms, and I think there must've been some reason to get that venogram this week, and I wonder if anything was found that was treatable or if it was just the occluded azygous that was found?
A lot of IRs don't investigate the renal vein, and that also comes to mind, because if the renal vein happened to be blocked it would be diverting a lot of flow into a system already overtaxed by the loss of the azygous.
Interestingly enough the surgeon said to me that if I was anyone else he would say don't worry about it there's plenty of other veins for the blood to find its way through but considering I have MS he didn't know if this same theory applies..
That's somewhat reassuring and somewhat not!