Pregnancy is a time of excitement and anticipation. While most pregnancies progress without complication, understanding common early concerns can be helpful.
Understanding HCG’s Role in Pregnancy
Human Chorionic Gonadotropin (HCG) is a hormone produced by the placenta shortly after a fertilized egg implants in the uterus. This hormone plays a significant role in maintaining early pregnancy by signaling the corpus luteum to continue producing progesterone. Progesterone is necessary to support the uterine lining, which sustains the developing pregnancy. HCG is detected by home pregnancy tests and clinical blood tests, confirming pregnancy.
What is a Blighted Ovum?
A blighted ovum, also called an anembryonic pregnancy, occurs when a fertilized egg implants in the uterus and the gestational sac forms, but an embryo fails to develop. The sac and placenta grow, but there is no fetal pole or visible embryo. Chromosomal abnormalities in the fertilized egg are often the reason for this type of early pregnancy loss. It is a common cause of miscarriage during the first trimester.
HCG Levels with a Blighted Ovum
With a blighted ovum, HCG levels often rise, mimicking a normal early pregnancy initially because the placenta develops after implantation. This can lead to a positive pregnancy test and typical pregnancy symptoms like nausea or breast tenderness.
The rise in HCG might be slower than in a typical pregnancy, or it might plateau. Normal HCG levels have been detected until the 14th week in some cases, even with a blighted ovum. Research suggests HCG levels may start to show lower values around 6 to 8 weeks in anembryonic pregnancies.
A single HCG reading is generally not enough for a diagnosis due to wide variability and potential miscalculations of conception dating.
Confirming a Blighted Ovum Diagnosis
Because HCG levels can be misleading, a blighted ovum is primarily diagnosed through an ultrasound. An ultrasound reveals an empty gestational sac without a visible embryo or yolk sac at a point when one should be seen, typically around 6 to 7 weeks, or if an embryo is visible but lacks cardiac activity.
In some situations, especially if the pregnancy is very early, multiple ultrasounds over time might be recommended to confirm the diagnosis before definitive action is taken. While HCG levels provide supporting information, they are not the sole diagnostic tool for a blighted ovum.