This project investigates circulating tumor DNA (ctDNA) in patients with suspected ovarian malignancy. We hypothesize that measurement of ctDNA in women with suspected ovarian cancer can improve the diagnostic efficiency for preoperative differentiation between benign and malignant masses. Specifically, we hope to determine the diagnostic efficiency of ctDNA alone and ctDNA in combination with imaging modalities (ultrasonography, MRI, PET-CT) and CA 125 for preoperative differentiation between benign and malignant adnexal masses. Based on this, we hope to develop an improved diagnostic algorithm. The mutational profile and relation to tumour type, stage, treatment response and prognosis will be explored. Analyses of blood and tissue samples will be used to examine the disease development and biology. Blood samples, tumour tissue and data on imaging modalities as well as CA 125 will be collected prospectively in consecutive women referred to Aarhus University Hospital.