9wks, something in the sac other than baby?

I went to my obgyn yesterday to have my first ultra sound. Everything went great, the heart rate was 179 & the fetus actually looks like a little baby in the photos. Left feeling blessed & relieved nothing was wrong... until I got home. I received a phone call from the ob that did my exam but not my ultra sound photos, she explained that the lady who had done my ultra sound saw something in the gestational sac other than the baby & she would like for me to come in for further opinion from a specialist. She told me to enjoy my weekend & they would see me Monday & that these things normally resolve themselves? This worries me although they told me not to worry but I can't help it? What could this be in the sac with the baby? Please help ):