Hello Lmc162 and thanks for posting us a question,

Any sort of test can pick up something unexpected that isn't associated with whatever problem is under investigation. I assume the ultrasound has shown something that falls under the umbrella of gynaecology so a speciaist from this field of medicine would need to be involved to decide if anything needs to be done.

I expect there could be a number of explanations, for example iIt could be something like a complex ovarian cyst or thickening of the womb lining, but this is only guesswork and I am not sure if speculation helps much. I can appreciatte that not knowing is unsettling, but for now I think all you can do is hold your nerve and wait it out to see what they have to say. There are lots of gynaecological conditions, so if you are, try not to think only in terms of cancer. 

Best wishes, 

Julia