When a woman has blighted ovum, what does it mean?

Blighted Ovum. Blighted ovum is a condition wherein a pregnancy occured but the fetus did not develop. In other words, it is an empty sac. It generally can be caused by chromosomal abnormalities, an infectious agent, or an immune reaction.
A blighted ovum. The term "blighted ovum" is really a misnomer. The condition occurs in early pregnancy where the fetus fails to develop. There is a gestational sac and a placenta, but no fetus.
This is an early pre. This is an early pregnancy failure. In fact it is not a good description of what happens. The actual term to use is anembryonic pregnancy, that is when the fertilized egg does not develop an embryo, but just develops a so called gestational sac without the embryo forming. This is actually what is meant by a "blighted ovum".