What is a blighted ovum?

Blighted ovum: A blighted ovum is defined as a empty gestational sac. During the first trimester an intrauterine gestational sac is seen, but there is no evidence of a fetus. This most often is due to a chromosomal abnormality with the fetus.

Empty sac: 'blighted ovum' is an older, less precise name for anembryonic pregnancy. It refers to a first trimester pregnancy in which a gestational sac/intrauterine pregnancy is seen but with no embryonic pole (baby.) it's also called an 'empty sac.'.