I don't have a shunt (I've been compensated and functionally asymptomatic my whole life) but when I was diagnosed with congenital hydro, I immediately got a medic alert bracelet. My doc said that if I ever was unresponsive for reasons not related to hydro, and ER staff saw my hydro, they would probably operate and put in a shunt, which would NOT be the thing to do if I was still compensated.