Ultrasound scan is the commonest way of diagnosing ovarian cysts. They are often discovered as an incidental finding during an ultrasound scan performed for another reason.
Functional cysts typically appear as a single uniform sac of fluid. Features that raise suspicion about malignancy are large size, multiple compartments within the cyst rather than a single cavity and solid components. The risk of malignancy for a cyst can be estimated by combining the features of the cyst identified on scan with the woman’s age and the levels of a tumour marker known as CA-125.