A new study of Polish BRCA1 carriers showed that screening through transvaginal ultrasound was not effective or reliable in detecting ovarian cancer early. Consequently, preventive oophorectomy remains the only proven method to lower ovarian cancer risks and increase survival.
Check out the article at: https://www.ncbi.nlm.nih.gov/pubmed/31500890.
Check out the NCCN ovarian cancer screening recommendations for BRCA1 and other gene mutation carriers: https://www.nccn.org/store/login/login.aspx?ReturnURL=https://www.nccn.org/professionals/physician_gls/pdf/genetics_bop.pdf