A pregnancy loss at any point can be heartbreaking. In particular, the first trimester’s newness, excitement, and hope can be shattered instantly due to miscarriage. Maybe you walked into your first ultrasound eager to see your baby and hear its heartbeat, only to instead hear the devastating news that there is no baby. Or maybe you have experienced unexpected bleeding only to be later told you have had a blighted ovum.
While you may not be able to prevent or rescue a blighted ovum from happening to you, understanding more about what happened may help to process your grief and move forward.
What is a Blighted Ovum?
A blighted ovum is a type of first-trimester miscarriage. It can also be called an “anembryonic pregnancy” because it refers to a fertilized egg that implants but never progresses to an embryo.1
Because the fertilized egg has implanted into the uterus, the placenta begins to form, and pregnancy hormones still secrete. This may cause you to experience early pregnancy symptoms. A gestational sac forms and sometimes even a yolk sac, but the embryo ceases to develop.1,2
What Causes a Blighted Ovum?
It can be difficult to identify the cause of a blighted ovum because it happens so early in pregnancy. A woman may not even have received an ultrasound yet before she experiences symptoms of miscarriage. Otherwise, a blighted ovum may be found unexpectedly at a first-trimester dating ultrasound.1
Even if you have an early pregnancy ultrasound, the products of conception may be tiny, making it difficult to obtain and test genetic material. However, experts believe chromosomal or genetic abnormalities most often cause blighted ova. These chromosomal abnormalities, such as trisomy of a particular chromosome, can cause structural issues with the embryo that prevent it from implanting or developing.1
Structural issues within the uterus, including adhesions or an unusually shaped uterus that a woman is born with, can also affect long-term implantation and contribute to miscarriage. These uterine structural issues may be genetic or can result from scar tissue from prior uterine surgeries or infections.1
Immune disorders in the mother can also cause her body to reject the newly implanted egg and cause it to cease growing.1
Finally, hormonal disorders such as low progesterone or thyroid dysfunction may contribute to early pregnancy loss and blighted ovum.1
Risk Factors for a Blighted Ovum
A blighted ovum can happen to anyone, but certain risk factors make women more susceptible to them.
Obesity
Women with obesity are more likely to experience miscarriage. Although most miscarriages are thought to be related to chromosomal abnormalities, obese women are more likely than women with a lower body mass index to miscarry a genetically normal embryo.3
Advanced Maternal Age
As women age, the number of eggs remaining decreases because she is born with all the eggs she will ever have and loses some of them every month beginning at puberty. In addition to having fewer eggs, the quality of the eggs and the genetic material decreases — the remaining eggs are more likely to be chromosomally abnormal. If fertilized, these chromosomally abnormal eggs may cause structural abnormalities that prevent an embryo from implantation and development, causing a blighted ovum.4
How is a Blighted Ovum Diagnosed?
Your medical provider can diagnose a blighted ovum via ultrasound. Once the gestational sac reaches a certain size, but you cannot visualize an embryo within, practitioners can feel confident the embryo will not develop from there.1
If there is uncertainty about whether an embryo is present, your medical provider can perform a repeat ultrasound 11 to 14 days after the first. If there has been no growth of an embryo, your provider can diagnose a blighted ovum at that point.1
What are the Symptoms of a Blighted Ovum?
A provider may suspect or diagnose a blighted ovum because of a pregnant woman’s presenting symptoms. These symptoms may include abdominal cramping and vaginal bleeding, but there also may be no symptoms. This means a blighted ovum is often not discovered until an ultrasound is performed.1
How Common is a Blighted Ovum?
First-trimester miscarriage happens in about 15 percent of clinically recognized pregnancies, and blighted ova cause about half of those miscarriages. Therefore, 7 to 8 percent of pregnancies may have a blighted ovum.1
How Do You Treat a Blighted Ovum?
Once a provider diagnoses a blighted ovum, three primary treatment options exist.
Expectant Management
Expectant management means watching and waiting to see if the body passes the pregnancy tissue spontaneously. You may be monitored with hCG blood draws or ultrasounds to ensure you pass all the pregnancy tissue and your pregnancy hormone levels return to baseline, but expectant management means no interventions.1
If a miscarriage does not occur on its own, or if not all the pregnancy tissue passes, you may become at risk of infection. To help the miscarriage progress, interventions such as medication or surgery may become necessary.
Medical Management
Medical management means using a medication called misoprostol to induce the passing of the products of conception. Your doctor can prescribe this medication. It causes uterine cramping and vaginal bleeding as if a miscarriage were to happen independently, but you have control over where and when it occurs.1
Surgical Management
Surgery can remove a blighted ovum from the uterus. Typically, this is done by dilating the cervix and then using a vacuum or an instrument to empty the uterus.2
Future Pregnancies Can Be Healthy
Blighted ova are usually random events due to an issue with the egg or sperm that joined at conception. They occur due to factors determined at or even before conception. Unfortunately, you cannot prevent a blighted ovum, nor can it progress to a healthy pregnancy. However, most women or couples who experience one have a successful, healthy pregnancy later.2
Regardless of whether an embryo ever fully develops, you were still pregnant. You had hopes and dreams for this pregnancy and baby. Miscarriage is no less tragic because it was early. You may have feelings of sadness, frustration, and even guilt. However, nothing you did can cause a blighted ovum, so it is not your fault. Allow yourself time to grieve and talk to your doctor if you have questions about your treatment options, what happened to you, or how to proceed.
