What Does Hypoechoic Mass In Posterior Wall Of 45.9mmx48.9mm Mean?

hi doc i've been ultrasound in my pelvic this may 3 and the sonologist add a comment on my result that there is a hyphoechoic mass in the posterior wall measures 45.9mm x 48.9mm.. what does this mean? im so curious about it and nervous that it can affect my pregnancy