Endo?

Rachel
Hello :)
A little about me: I'm almost 20 and have been on Sprintec birth control for 4 years. I initially went on BC for extremely painful cramps (I would be on the bathroom floor clutching my stomach and basically pass out from pain) but it then came in handy when I became sexually active. 
Sooooo I went to my first visit with my OB becuase I have pretty painful cramps, lower back pains, severe fatigue, among a few other things. She said that it could be endo or unexplained causes but the only want to find out if I have endo or not would be to have surgery.. Is that true? I thought I read that an ultrasound could diagnosis a woman?