Is the doctor right? Is the surgery necessary?

After having abdominal pain for several months that is gradually getting worse I went to see the doctor. The first thing she did was an ultrasound which came back normal. Then yesterday I went back to see her and she asked a few questions told me she was going to do another ultrasound to look for kidney stones, and then proceeded to examine me. She got done left the room and came back and gave me some paperwork then told me her nurse will call me monday to schedule my laparoscopy to verify her thoughts of endometrosis and I basically had a week to decide if I wanted to get a hysterectomy during the surgery. How did she go from ultrasound to all this so fast and is she right?