What Does 1.50 Cm Fetus Mean?

Hii doctor i m manju from singapore..19 jan my doc did u/s and he can c heartbeat but can not hear outside and his measurement was 0.59cm but yesterday he did u/s fetus was 1.50cm but can not c and can not hear heartbeat and showing 7w3d.what can be the reason for this pls guie me..my doc ask me for d&c