nervous wreck

My wife had mid-period spotting a couple of weeks ago.  She is 24 years old.  Transvaginal ultrasound shows a complex cyst 3.5x2.9x3.2 cm on left ovary. To my layman eyes seems to be 9-10cm diameter.  Her last pelvic exam 6 months ago showed nothing, but 3 months ago she had very sharp pain in her abdomen that lasted about 10 minutes.  

Now her period is about a week late.  She has always been regular.

I cant find any information about what the chances are that this is something normal.  Can any body help?

nervous wreck...

[cardamom]

Thank you for the response.

I should have made my question clearer.  Are these symptoms consistent with Ovarian cancer?

I have learned that the diameter not the circumference is what is used to characterize cysts.  So, it is much smaller than what I had thought.  I feel much better that it is probably something benign.

Apologies if my question was off-topic.