When having a transvaginal ultrasound, you can see things closer, and more clearly. An ovarian cyst that is non-cancerous, will typically look black, or hollow in the middle, that is fluid. A cyst that could possibly be cancerous, will look like a white mass. While it is not guaranteed that if the cysts look this way, it is cancer, transvaginal ultrasounds can tell a lot. Speak with a doctor if you are concerned.