What Is Blighted Ovum?

Blighted ovum—also known as anembryonic pregnancy or empty sac—is a type of early pregnancy loss, in which the pregnancy implants and there is a gestational sac, but the embryo doesn't grow.

Additionally, both the placental tissue and sac continue to produce pregnancy hormones, even after the embryo has stopped developing, so pregnancy tests are likely to come back positive when the embyro is no longer growing. In those cases, a person may not find out that the pregnancy is not progressing until their first ultrasound.

Signs and Symptoms of Blighted Ovum

A blighted ovum occurs when a fertilized egg does not develop, despite the formation of a gestational sac.

In some cases, there are no signs or symptoms of blighted ovum, resulting in a missed miscarriage. If symptoms do occur, they can look similar to those of an ectopic pregnancy, and can include:

• Mild cramps in the lower abdomen
• Light bleeding from the vagina (spotting)

Causes

There are approximately 200,000 cases of blighted ovum in the United States every year. In fact, blighted ovum causes one out of every two miscarriages that occur in the first trimester.

Typically, when a person becomes pregnant, the fertilized egg starts dividing within hours of conception, resulting in an embryo around 8 to 10 days later that implants on the uterine wall. After that, the placenta starts to form, and the pregnant person's hormones spike. But in the case of blighted ovum, the fertilized egg either never gets to the point of being an embryo, or if it does, it stops developing soon after implantation.

Though the specific cause is unknown, most of the time, blighted ovum is the result of chromosomal abnormalities in the fertilized egg. Other possible causes—or factors that increase the risk of blighted ovum—can include:

• An infection
• An autoimmune disease in the pregnant person
• An endocrine disease in the pregnant person
• Tissue that divides the inside of the uterus into sections (septum)
• Other malformations of the uterus
• Hormonal factors (such as low levels of progesterone)
• Endocrinological disorders (thyroid autoimmunity and thyroid dysfunction) 
• Polycystic ovarian syndrome
• Being overweight
• Advanced age

Diagnosis

Diagnosis for blighted ovum—which typically happens between the eighth and thirteenth weeks of pregnancy—varies. In some cases, the pregnant person may not be aware that they're pregnant. In other cases, pregnancy and other blood tests will come back indicating that everything is progressing normally, when, in fact, it's not.

That's because a hormone called human chorionic gonadotropin (hCG)—which is produced by the placenta during pregnancy—will continue not only to be present but also to increase over time as the placenta develops, with or without a healthy embryo. As a result, someone might think they are pregnant until their routine ultrasound (either transabdominal or transvaginal) which indicates that the gestational sac is empty.

Treatments

Following a pregnancy loss—even one that occurs this early in the gestational period—the body has to pass the placenta and gestational sac. There are three ways this can happen:

• Expectant management: Also known as the "watch and wait" method, it involves closely monitoring the formerly pregnant person once it is established that they are dealing with blighted ovum. No action is taken using this technique: the person waits until the placenta and gestational sac naturally pass through the vagina—potentially resembling the clots that some experience during a heavy menstrual period.
• Medical management: In the event that the physician and/or patient wants to speed up the process and control when the passing of the tissue occurs, a medicine called misoprostol may be administered orally or vaginally.
• Surgical treatment: In other cases, a healthcare provider may recommend a procedure called a dilation and curettage (D&C). After giving the patient medication to control the pain and help them relax, a tube that is attached to a vacuum device is inserted through the opening of the vagina and cervix. Depending on the size and location of the tissue, a tool called a curette may be used to help loosen tissue in the uterus first. Then the suction of the vacuum helps remove the tissue.

Once the placental and sac tissue has passed or been removed, another ultrasound is performed to ensure that there is none remaining in the uterus. In the event that there is, a D&C procedure may need to be done to retrieve the residual tissue. This is important because tissue left in the uterus could cause an infection, potentially resulting in a serious complication called a septic miscarriage.

Possible Complications

Though serious complications from the treatment of blighted ovum are uncommon, they are possible, and can include:

• Excess bleeding/hemorrhage
• Infection (including sepsis)
• Scar tissue
• Perforation (a tear in the uterus)

Coping

Though everyone's pain tolerance is different and the loss of the pregnancy can occur over the course of a few weeks, it is important to ensure that anyone who has experienced blighted ovum receive the care they need—both physically and emotionally.

Physically, this means following the usual post-miscarriage care guidelines:

• Taking over-the-counter pain medication such as acetaminophen or ibuprofen to help deal with cramps
• Wearing pads (not tampons) for as long as the bleeding continues

While the heavy bleeding should stop within a day or two, spotting may continue to occur for several weeks.

Going through a pregnancy loss—regardless of the circumstance—can be distressing, so the formerly pregnant person should have access to counseling or other resources to help them cope following the miscarriage.

A Word From Verywell

Whether or not a person even realized they were pregnant in the first place, dealing with a miscarriage as a result of blighted ovum can be difficult. It's not uncommon for people to mourn the loss of their baby and future family, and they should be given the time and space to do so.

It's important to keep in mind that there's no evidence that anything a pregnant person does—in terms of health behaviors or physical accidents during pregnancy—causes blighted ovum. So while they may experience feelings of guilt and shame after the loss, they should know that this is in no way their fault, and nothing they could have done (or avoided) could have prevented this.