Specializing in one area like OB?

I was just wondering if it was a possibility to specialize in one area of your choice as an CRNA. I realize it will highly depend on the position choosen. What I am asking, I guess, is it unheard of to specialize in say OB and do only epi's, sections, etc.?

Just wondering if all CRNA's just work an array of cases daily depending on the position/hospital or if some do veer off and do more of one type of case as their daily position?

Thanks in advance!