Hello doctor. I had an ultrasound and the doctor concluded that the gestational sac was 20.6mm, CRL 16mm, the gestational sac was smaller than the gestational age. So doctor, can you tell me if a gestational sac being smaller than the gestational age is dangerous?

This is my first pregnancy check-up. I had a private black and white ultrasound. The doctor said I'm 5 weeks pregnant but only has an 11mm gestational sac and nothing has been detected yet. Doctor, can you tell me what the size of the gestational sac indicates about the condition of the embryo?