A blighted ovum, also called an anembryonic pregnancy, occurs when an early embryo never develops or stops developing, is resorbed and leaves an empty gestational sac. The reason this occurs is often unknown, but it may be due to chromosomal abnormalities in the fertilized egg.
A blighted ovum usually occurs early in pregnancy — sometimes before you even know you're pregnant. However, you may be aware of your early pregnancy because of a positive pregnancy test or missed menstrual period. A pregnancy test may be positive because the early embryo secretes a pregnancy hormone — human chorionic gonadotropin (HCG) — until the embryo stops developing and fails to implant.
You may have symptoms of early pregnancy, such as breast tenderness, nausea and vomiting. But when the embryo stops growing and hormone levels decrease, pregnancy symptoms subside. At this point, minor abdominal cramping and light spotting or bleeding are possible. An ultrasound will show an empty gestational sac.
A blighted ovum eventually results in miscarriage. Some women choose to wait for the miscarriage to happen naturally, while others take medication to trigger the miscarriage. In some cases, a procedure called dilation and curettage (D&C) is used to remove the placental tissues.
Most women who've had a blighted ovum go on to have successful pregnancies. If you experience multiple consecutive miscarriages, talk with your doctor or other care provider to identify any underlying causes.