I feel like I should add this for the next poor soul looking for answers about an absent inferior vena cava considering the rarity of the condition. We feel much better. My sister met with a VS that has had 3 previous cases of this and also consulted via phone with an additional specialist. They agree that he will be on blood thinners for 6 months then moved to one aspirin daily. This is protocol for a situation such as his. They believe trauma, due to some work he was doing that this is what triggered the 2 clots. He has no swelling in his stomach or his legs. They do not believe this is something he will grapple with and they assured us that though it is rare, there is consensus that this is less rare than what is known as people live with it their entire lives without incident. Providing the fetus survives, the body heals itself by making collateral veins that do the work albeit, less efficiently. My nephew has no other congenital abnormalities which is helpful in this situation and they believe he will go on to live a normal life. If someone happens on this as I did because you are scouring the internet for information while waiting for that coveted appointment with the specialist... FULL STOP. We are not doctors and we cannot easily discern what we are reading. The information is frightening and worst case scenario. In most cases, it will be OK. Blessings

My son was just diagnosed earlier this month after bilateral DVT Nov 2023. We were transported from northern suburbs to Lurie Children’s in Chicago. They told us they don’t see this bc it is that rare. We are following up with Luries but they gave us a name of a Dr at Northwestern in Chicago who has treated this quite a bit and has reconstructed IVC several times. You don’t want to do that unless you have to.