He/She Issue

[Satin Kiss]

I prefer to just move to plural:
"Before doctors perform a surgery..."
as someone before has said.

In a book, the person kept switching: "When your child needs that, he will do this to show it. It's important to nurture your child during her younger years..." I thought it was an interesting take. For every paragraph, the author would change the gender.  

[Mystiquamorphus]

I would go with the last one because it flows the best. Stopping to say "he or she" every time you are referring to someone distracts the reader.