Blighted Ovum: Understanding Gestational Sacs & Early Pregnancy

It is possible to have a blighted ovum (BO) even if an ultrasound showed a gestational sac (GS) and a "little dot." While the presence of a GS and embryo (the little dot) is typically a positive sign of pregnancy, it does not guarantee a viable pregnancy.

In the early stages of pregnancy, a BO may appear on an ultrasound as a GS without a developing fetus. This occurs when an egg is fertilized, implants in the uterus, and begins to form the gestational sac, but there is no development of an embryo. Instead of a normal pregnancy, the sac remains empty or contains only a small amount of tissue.

Here's how to distinguish a blighted ovum from a viable pregnancy based on ultrasound findings:

1. Empty Gestational Sac: If the ultrasound shows a GS without any visible embryonic structures or a yolk sac, it may be a sign of a BO. A normal pregnancy should show an embryo or a yolk sac within the GS by a certain stage of development.

2. Size of the Gestational Sac: In some cases, a blighted ovum can have a GS that appears larger than expected for the gestational age. This is known as an anembryonic sac or an empty sac syndrome.

3. Absence of Embryonic Structures: If the ultrasound does not show any signs of an embryo, including the yolk sac or fetal pole, it may be an indication of a blighted ovum.

4. Shape of the Gestational Sac: In a blighted ovum, the GS may appear flattened or collapsed compared to a normal, round or oval-shaped GS.

It's important to note that ultrasound findings alone may not always be conclusive in diagnosing a blighted ovum. Your healthcare provider may order additional tests, such as blood tests to measure pregnancy hormone levels (hCG), or perform a repeat ultrasound at a later date to confirm the diagnosis.