Does an ultrasound clearly differentiate between ovarian cyst and ovarian cancer. does ovary/period pain after eating sound like large cyst. ?

Ultrasound: An ultrasound may show whether the ovary is fluid filled or solid, or simple or complex. Ovarian cancer is usually complex and solid, but not always. A repeat ultrasound is often recommended. A CA 125 blood test may help differentiate the two... Refer to: http://www.mayoclinic.org/diseases-conditions/ovarian-cancer/expert-answers/ca-125/faq-20058528

Not always. : A cyst can have a very benign appearance or a very malignant appearance. US findings combined with clinical scenario can help determine if a mass can be watched or needs surgery now. For a suspicious mass the only way to be sure is to remove the mass and have it checked by a pathologist. Hope this helps.