What is blighted ovum?
Blighted ovum or anembryonic pregnancy happens when a fertilised egg begins to implant in the wall of the uterus, but an embryo either doesn't develop in the sac at all, or stops developing very early. It is thought to be responsible for around 50% of first trimester miscarriages and often takes place before a woman even realises that she is pregnant.
Women who have been trying for a baby and are on the look out for pregnancy signs, or take a test at the earliest time, are most likely to be aware of blighted ovum. As the placenta begins to develop and release the pregnancy hormone human chorionic gonadtrophin (hCG), a pregnancy test will give a positive result even though the pregnancy is not 'valid'. Because of this, and the fact that a natural miscarriage may not take place for a number of weeks, blighted ovum is not usually diagnosed until either a miscarriage occurs, or until an ultrasound shows that the embryonic sac is empty.
What are the signs of Blighted Ovum?
If you are experiencing a blighted ovum then you may have spotting, bleeding and abdominal cramps. If hCG produced common pregnancy symptoms such as sore breasts, nausea, tiredness and an aversion to certain foods and smells, then these will fade as the hCG level falls. In cases where the woman wasn't aware of the pregnancy she may experience blighted ovum as a heavier-than-usual period.
Quite often there are no signs that the pregnancy is not developing normally and the blighted ovum detected at your first scan, usually around 12 weeks.
What causes blighted ovum?
Blighted Ovum is believed to be caused by chromosomal abnormalities in the embryo which prompt the body to end the pregnancy because it can't develop into a healthy baby. Chromosomal abnormalities may be the result of an inferior egg or sperm, or occur in the early stages of cell division.
Blighted ovum is NOT caused by you having done something wrong.
How is blighted ovum managed?
In many cases blighted ovum requires no management as the pregnancy naturally ends either in miscarriage or with the body simply reabsorbing the fertilised egg. However, if an ultrasound reveals that the embryonic sac is empty, then it is usually up to the woman to decide whether to have a D&C (Dilation and Curettage) or ERPC, (Evacuation of the Retained Products of Conception)- simple surgical procedures to remove the empty sac - or to wait for a natural miscarriage. A natural miscarriage may take several weeks but should happen before the end of the first trimester. A woman diagnosed with a blighted ovum pregnancy who hasn't yet miscarried will be advised to have a D&C if she is in a lot of pain or is suffering excessive bleeding, or if there are signs of an infection, such as a fever.
Can blighted ovum be misdiagnosed?
It is possible that an ultrasound in the first two months of pregnancy could misdiagnose a blighted ovum, particularly if you have a retroverted, or tilted, uterus. A tilted uterus can make it harder for ultrasound technicians to produce an accurate ultrasound. However, most women in the UK don't have an ultrasound until around 12 weeks, at which time a misdiagnosis is extremely unlikely.
In the UK a blighted ovum is not usually diagnosed until the pregnancy sac is at least 20mm long. This is because a smaller sac may be an indication that you are simply not as far along in your pregnancy as you thought. A second scan a week or two later can confirm whether there is an embryo or not, or whether the embryonic sac is growing at the expected rate, if the sac is not growing properly it is an indication that there is no fetus developing in the sac.
Coping with blighted ovum
Losing a pregnancy through blighted ovum is every bit as upsetting as any other cause of miscarriage. You may hear some people try to console you with the idea that there never really was a baby to lose, however this usually isn't helpful. If you had a blighted ovum then the egg was fertilised and you were truly pregnant, even if only for a short time.
See this article for help in coping after a miscarriage.
Does having one blighted ovum raise the likelihood of another?
No, having had one blighted ovum pregnancy doesn't raise the chance that you will miscarry again, but of course miscarriage is a risk in any pregnancy.
After suffering a miscarriage with a blighted ovum you'll usually be advised by your doctor to wait for two to three cycles before trying for a baby again. This is to give yourself time to recover physically and emotionally from the trauma of a miscarriage.