Symptoms of a blighted ovum, or anembryonic pregnancy, include abdominal cramps, vaginal spotting, bleeding and a heavier-than-normal period, according to WebMD. These symptoms occur after signs of early pregnancy including a missed period and a positive pregnancy. The American Pregnancy Association explains that pregnancy hormones may continue to rise, even after a blighted ovum, because the placenta continues to grow despite the failed egg.
An ultrasound diagnoses blighted ovum by viewing the placenta without the normal, developing fetus. WebMD states that the pregnancy sac appears empty in the image within the first 12 weeks, or first trimester, of pregnancy. Blighted ovum is an early pregnancy failure, or an early miscarriage, due to the timing of the egg failure.
Causes of a blighted ovum include abnormal cell division in the fetus, a deformed egg or malfunctioning sperm. Chromosomal abnormalities are generally associated with a blighted ovum, according to the American Pregnancy Association. The woman's uterus realizes the baby will not develop normally, and the mother's body aborts the process naturally. The disorder is responsible for 50 percent of all failed pregnancies that occur in the first trimester.
Mayo Clinic explains that some women take medication to induce a miscarriage once the empty placenta is detected. A procedure called dilation and curettage also removes placental tissues. Other women choose to let the miscarriage occur naturally. Most women with a blighted ovum have successful pregnancies after the uterus heals. Having more than one such miscarriage may be the sign of a more complicated health issue that requires further investigation.