Hi,im In 22week In My Pregnancy.yesterday I Had My Tiffa

Hi,im in 22week in my pregnancy.yesterday i had my tiffa scan and the reports says that i have posterior placenta and that lower end of placenta there is a cystic like structure of 50×45mm and my dr suggested me proluton depo injection once in every week for one month.im very much worried about the scanning reports says..can u please help me