What Is a Blighted Ovum?

A blighted ovum is a term to explain an empty gestational sac, explains Octavia Cannon, D.O., an OB-GYN with Arboretum Obstetrics & Gynecology in Charlotte, North Carolina,. This type of pregnancy can also be called an anembryonic pregnancy because a woman is fully pregnant but without an actual embryo.

Here's what happens: An egg is fertilized, prompting the body to pave the way for a baby by pumping out pregnancy hormones and forming the gestational sac. For some reason, though, the egg never develops into an embryo. This leaves the woman with a fully formed gestational sac and all the symptoms of pregnancy—but no developing embryo.

Read on to learn more about blighted ovum causes, signs, and statistics.

Blighted Ovum Causes

A blighted ovum may result from a poor-quality sperm or egg, or it may occur due to abnormal cell division. But in many cases, Dr. Cannon says, an anembryonic pregnancy is caused by a chromosomal abnormality in the fetus's gene. There isn't always a clear explanation, but blighted ovums don't result from anything a father or mother did.

How Common is a Blighted Ovum?

Blighted ovums are actually quite common. Dr. Cannon notes that a blighted ovum is the cause behind a staggering 50 percent of first trimester miscarriages. And considering that 15-20% of all known pregnancies end in miscarriage—and more than 80% happen in the first trimester—that's not a small number.

Blighted Ovum Symptoms

If it occurs early enough, the woman might not show any signs of blighted ovum, and therefore won't even know it happened. Yet others with this condition have typical symptoms of pregnancy, such as a positive pregnancy test, missed period, morning sickness, and sore breasts.

Most people learn about a blighted ovum when the fetal ultrasound shows an empty gestational sac. Others might experience heavy period-like bleeding and cramping, which are common signs of miscarriage.

Blighted Ovum Ultrasound and Diagnosis

Your doctor will confirm a blighted ovum miscarriage on an ultrasound, where it's indicated by an empty gestational sac. In the case of an early pregnancy, a doctor might advise the woman to wait a week and then do a repeat ultrasound, just to make sure that no embryo has formed.

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Dr. Cannon explains that whether a blighted ovum diagnosis is confirmed for a woman's first pregnancy or after she already had a healthy baby, it should not be cause for alarm. "Many times, a patient will have already had a normal pregnancy and then have a blighted ovum," she says. "If it happens more than once consecutively, I urge the patient to allow additional testing to try to find a reason for the recurrent miscarriage."

In very rare cases, a pregnancy may also develop outside the uterus or womb, either as an ectopic pregnancy in one of the fallopian tubes or somewhere else in the body, such as on the ovaries or attached to the bowel. In these cases, the woman may need a special medication called methotrexate, which causes the tissue to stop growing and allows the body to expel the non-viable pregnancy. This medication must be administered in the hospital and may cause lower abdominal pain, fatigue, nausea, vomiting, and muscle soreness.

Blighted Ovum Treatment

An anembryonic pregnancy will be treated differently for every woman, depending on the pregnancy. Many women complete the blighted ovum miscarriage naturally without intervention. If a woman has already started bleeding but is stable, a doctor may offer to do a D&C (dilation and curettage) to clear the uterine lining of tissue. She might also take medication to help pass the products of conception at home. "I carefully counsel patients on what to expect when there is no need to stay in the hospital," explains Dr. Cannon. "Many times it helps to be at home."

No matter what process you choose, your doctor will most likely order you to have weekly blood tests to track your hCG (Human chorionic gonadotropin, or the pregnancy hormone produced by the placenta). HCG levels may increase when your body thinks it's pregnant, but they'll eventually begin to fall. Soon enough, your blighted ovum hCG levels will return to their pre-pregnancy state.

An important thing to note: If you miscarry naturally at home, you won't physically see an embryo or anything that resembles a baby. Some women may see a formed sac, but more likely, the miscarriage will only look like blood clots and thick tissue. This is important to recognize, because some women might struggle with never seeing physical "evidence" of the pregnancy, so they may need other physical signs of closure as they move through their grieving process.

Healing from a Blighted Ovum Miscarriage

In general, Dr. Cannon recommends that women healing after a miscarriage continue taking their prenatal vitamins and abstain from sex, douching, and tampons for at least a month after passing the tissue, no matter if the loss happened surgically, medically, or naturally. Women may expect the return of their menstrual cycle in about one month, and the initial cycle may be heavier than normal.

Many doctors used to advise women to wait two to three menstrual cycles before trying to conceive again, but newer recommendations from The American College of Obstetricians and Gynecologists have found no evidence of any benefits to delaying conception. So a woman can try to conceive again as soon as she feels comfortable, although you may want to wait until after you've had a menstrual period so calculating the due date of your next pregnancy is easier.

The emotional healing from a pregnancy loss can be a very difficult journey, and with a blighted ovum, it's especially important for a woman to realize that she has every right to acknowledge the full weight of her loss. "I always stress to my patients that although there was no embryo, it was still a pregnancy," she explains. "Therefore, it is a miscarriage and she has every right to grieve."

She also notes that some women can experience postpartum depression after a pregnancy loss, so it's important to be aware of the symptoms and to talk openly and honestly with a partner who can monitor for any signs of postpartum depression as well.