Blighted Ovum OR Anembryonic pregnancy

What is the blighted ovum?

The blighted ovum syndrome (or anembryonic pregnancy) is defined as the condition in which the amniotic sac does not contain fetal elements (fetal pole), as would be expected in a normal pregnancy. In other words, a fertilized egg implants in the uterus, but then its normal development does not follow.

The amniotic sac is the structure within which the fetus grows during pregnancy. It consists of a thin membrane that is in contact with the wall of the endometrial cavity and it is part of the placenta. In normal conditions, as the fetus grows, it occupies the entire cavity of the uterus. Inside the sac, in addition to the fetus, there is a watery fluid, the amniotic fluid. However, in the case of the blighted ovum syndrome, the amniotic sac grows, without to contain a fetus (with or without the presence of a yolk sac).

When can the blighted ovum syndrome occur and what are its causes?

The syndrome appears in the first trimester of pregnancy and it is the most common cause of miscarriage during this period. The causes of the syndrome have not been precisely determined. It usually occurs due to chromosomal abnormalities of the fertilized egg. Other factors such as hormonal imbalances, anatomical anomalies of the uterus, genetic factors have been blamed for its appearance, but without being scientifically documented.

Signs that may indicate blighted ovum syndrome

Although no embryo has been developed inside the amniotic sac, pregnancy-related hormones are released normally. The release of hormones causes early signs of pregnancy, which usually include the following:

• Positive pregnancy test
• Nausea
• Morning sickness
• Breast tenderness

In addition to the above symptoms that indicate pregnancy, the syndrome can also manifest itself with miscarriage symptoms. In particular, a woman with the blighted ovum syndrome may experience vaginal bleeding or pelvic cramps.

How is the diagnosis made?

The diagnosis of the syndrome is made after the fifth week of pregnancy through transvaginal ultrasound. After the end of the fifth week, the fetus should be clearly visible inside the amniotic sac, which does not happen in the blighted ovum syndrome.

The yolk sac can be detected very quickly within the first 2 weeks after a missed period by ultrasound.

How is it treated?

In the majority of cases, the blighted ovum syndrome results in a spontaneous miscarriage. If this does not happen, then the patient should undergo medical or surgical evacuation ofthe endometrial cavity.

A possible miscarriage due to the syndrome in no way excludes a future pregnancy. After two menstrual periods and as soon as the couple recovers psychologically, they can try again to achieve pregnancy and also search for the possible causes through their gynecologist.

The Obstetrician-Gynecologist Melina Stasinou has been a Research Associate at the Imperial College Extracorporeal and has extensive experience in assisted reproduction. The physician, knowing how important the role of the gynecologist is in trying to achieve pregnancy, stands next to all women. Each failed attempt needs individualized treatment in order to find the possible causes.