don-don, hi, when he began school ,changing for pe etc ,he was very embarassed and self conscious about it , because it did look very different it would poke out and be visible though his t-shirt, so it was only done really for cosmetic reasons and his self esteem .
It was 1 hour surgery at the hosptial under a general ,and he has a tiny 'smile' scar under his button now and it no longer sqeeks . He felt loads better after and even would go swimming with his friends so he got his self esteem back it was well worth the worry of the op itself.
Your the first person I've met who child has an umbilical hernia also so I'm guessing they're not that common .I wish you and your LO all the best xx