Simple(benign) ovarian cyst
are harmless and usually resolve on their own with subsequent cycles.
The possibility can be many like follicular cyst
, dermoid cyst
, serous or mucinous cyst
of ovary. ALL these are best diagnosed after their removal following tissue diagnosis.
In your case the cyst is around 5cm so there can be lesser chances of resolving.
If you are more than 40years , having irregular bleeding or post menopausal then you need to take any cyst seriously. The most important thing is to rule out cancer. This can be done by a tissue report which is obtained only after surgery.
But if you are less than 40 years , you can take a course of antibiotic for a week. If it is infectious, it might resolve. You can repeat your ultrasound
after 3 months to check if the cyst is not increasing.
If it persists or increases, then surgical removal is required.