How to know if the baby is down syndrome or mosaic down without blood test?

Difficult issue: Prior to the availability of chromosome(chm) and chm banding studies, these kids were usually classified by physical features.Errors happened occasionally.Many features are quite consistent among DS kids, yet they are also found occasionally in normal kids & some DS kids have few if any typical features.Separating the regular DS from a mosaic is impossible without testing.

Why do you ask?: You're going to need labs to determine this. Please forgive my frankness. Having a child with possible Down's is an extremely serious business and anyone who would trivialize this by saying, "Let's skip the labs that will establish the diagnosis" is doing both the child and the family a grave disservice.