Name Of Medical Condition ........

[Gizmonster]

Does anyone know the name of the medical condition where the person only has a torso - they appear to have been cut in half just below their waist ??
I've tried googling, but it keeps bringing up all kinds of irrelevant stuff :(

[yogasun]

Caudal regression?

[rockyracoon]

I can only find limbless. You might find it in this glossary though

http://www.limbless-association.org/information/amputee-information/glossary/

[Gizmonster]

Sacral agenesis was the term I was trying to remember, but yogasun's answer lead me to it.
From what I can make out, sacral agenesis and caudal regression are the same thing (a.k.a. hypoplasia of the sacrum).
Cheers peeps :)