It is happen to me for the 2nd time after 9 years

EMPTY SAC???

A complete spontaneous abortion at about six weeks from conception

An empty sac is a condition where the gestational sac develops normally, while the embryonic part of the pregnancy is either absent or stops growing very early. Other terms for this condition are blighted ovum and anembryonic pregnancy.

An anembryonic gestation (aka blighted ovum) is a pregnancy in which the very early pregnancy appears normal on an ultrasound scan, but as the pregnancy progresses a visible embryo never develops. In a normal pregnancy, an embryo would be visible on an ultrasound by six weeks after the woman's last menstrual period.
An anembryonic gestation is characterized by a normal-appearing gestational sac, but the absence of an embryo. It likely occurs as a result of early embryonic death with continued development of the trophoblast. When small, the sac cannot be distinguished from the early normal pregnancy, as there may be a yolk sac, though a fetal pole is not seen. For diagnosis, the sac must be of sufficient size that the absence of normal embryonic elements is established. A pregnancy is anembryonic if a transvaginal ultrasound reveals a sac with a mean gestational sac diameter (MGD) greater than 13 mm and no yolk sac, or an MGD >18 mm with no embryo.

Reference:-
http://en.wikipedia.org/wiki/Miscarriage