a hat! The one "remedy" for a shunt replacement!
I also have somewhat of a "lump" in my abdomen where my shunt is, though it is soft and easily compressed. I personally think I have fluid collected in my abdomen, although this has never really been investigated. Unless Jayden is in pain, I would say it is nothing to worry about.
Just to reassure you - no one will notice any scars on Jayden's head once his head has grown. In fact, he will probably have
more hair over the scar

!
Nat.