The cyst which is seen is most likely a corpus luteal cyst
, which is formed after the rupture of the follicle that is ovulation.
There are certain other signs also on USG to confirm ovulation like irregularity of cyst,free fluid in pelvis, increased blood flow around the cystic area which should also be taken into consideration.
Still in small percentage of cases, the follicle might not rupture and remain as lutenised unruptured follicle.
Hope this is helpful.
Dr. Mrs. Sumeet Baheti