Should I be worried

Paula • 31🎉, Wife💍👫, 💗EGR👼🏻 6/3/18, 🌈👶🏼 💗 ELR 11/16/19🥰

I went for my 20 week anatomy scan. Baby girl is measuring great and right along time. They said everything was great besides a 3.3 mm spot of fluid by her heart. They want be to have another more detailed ultrasound. Has anyone else went through this and Baby been okay and it go away? My dr didn’t seem too worried. Thanks