Blighted Ovum FAQ
What is a blighted ovum?
A blighted ovum is a fertilized egg that implants but does not develop. The gestational sac continues to grow but the baby does not grow within the sac. If the case is a true blighted ovum, the yolk and fetal pole will not be present.
My doctor told me I have an anembryonic pregnancy, what is that?
An anembryonic pregnancy is the same thing as a blighted ovum.
So, there was never a baby?
Unfortunately after women suffer through a blighted ovum, they often hear comments about there never having been a baby. This is just not true. An egg has been fertilized just as in every pregnancy. The baby just does not develop beyond implantation. If you've had a blighted ovum, you were no less pregnant than any other pregnant woman at that same stage and you have every right to mourn the baby that only shared your body for a couple weeks.
How common is a blighted ovum?
Approximate estimates indicate that 15% of all clinically recognized pregnancies end in miscarriage*. Estimates vary little and approximate blighted ovums account for 45 to 55% of all miscarriages**.
What causes a blighted ovum?
There is just so much we do not know about the blighted ovum. Although the blighted ovum is mentioned frequently in medical literature, not many research papers dedicated to understanding the blighted ovum can be found. General concensus seems to indicate that a blighted ovum is due to a chromosomal abnormality possibly related to trisomies 16 and 22***. Some research seems to indicate that a blighted ovum may be more common in older mothers and is usually a problem with the egg rather the sperm. Generally, a blighted ovum is considered a one-time event and fluke of nature. However, miscarriage is a risk in any pregnancy. Just because you've had one blighted ovum does not mean you will not miscarry again, but your risk is not heightened because of the blighted ovum.
Can anything be done to prevent a blighted ovum?
Unfortunately, no, nothing can be done to prevent a blighted ovum. However, several online sites do believe that low progesterone may be a factor in early pregnancy loss and progesterone supplements have been shown to lower the miscarriage risk in some women with recurrent miscarriages****. The research seems to be divided on the importance of progesterone supplements in early pregnancy but the many stories found online seem to indicate that progesterone supplements have saved some pregnancies. If you believe progesterone may be a problem, have your progesterone tested as early as possible in the pregnancy. If your doctor is not open to testing your levels you may benefit from finding another physician.
What standards do doctors use for diagnosing a blighted ovum?
According to the Encyclopedia of Medical Imaging, the criteria for a diagnosis of blighted ovum are:
1) failure to identify an embryo in a gestational sac measuring at least 20 mm via transabdominal ultrasound.
2) Failure to identify an embryo in a gestational sac measuring approximately 18mm or more via transvaginal ultrasound.
3) Failure to identify a yolk sac in a gestational sac measuring 13mm or more.
Additionally, the outline of the sac may be irregular, incomplete or absent decidual reaction and/or fluid found in the gestational sac.
Are these criteria for finding a blighted ovum set in stone?
No, we at the Misdiagnosed Miscarriage do not believe so. We have seen a number of cases where either the baby or the yolk sac is not found within the gestational sac until the sac was bigger than these measurements.
What would account for the discrepancy?
We believe, based on the numerous stories that have found their way into the Misdiagnosed stories forum, that having a retroverted uterus may alter when you may see your baby via ultrasound.
What are the new UK guidelines for diagnosing a blighted ovum?
The UK recently went through a 'misdiagnosed miscarriage' scandal and have changed the way they diagnose miscarriages. You can read more by clicking the 'New Blighted Ovum Guidelines' link above but, in a nutshell, if you have a growing gestational sac and there are no complications, doctors should wait until the sac is at least 25mm before diagnosing. Even then, it may be just a bit too early. Still, these new guidelines would prevent a lot of the misdiagnosed miscarriages we see on this site including my own.
What is a retroverted uterus?
A retroverted uterus, also known as a tipped or tilted uterus, is a uterus that tilts back toward the rectal area. In most women the uterus will tilt slightly forward toward the belly. Actually, having a retroverted uterus is quite common. Reports vary but approximately 20% to 40% of all women have a retroverted uterus. Because this is so common, doctors rarely mention if you have a tilted uterus unless you ask.
Why do you believe it is so difficult to find the baby via ultrasound?
Actually only during the early first trimester do we believe it may be a little more difficult to find the baby via transvaginal ultrasound. After talking to women and their ultrasound techs we've concluded that the positioning is more awkward when the uterus is retroverted and this makes viewing a bit trickier. There may be a possibility that when the baby lies parallel to the ultrasound beam, measurments may be off and the baby will appear smaller than he actually is. However, in the second trimester, measurements are generally more accurate in women with a tilted utersus.
I'd like to wait to end my pregnancy but is it safe?
According to the 'Journal of Family Practice' and other medical organizations, a woman can safely wait to miscarry naturally (or until she knows for sure there is absolutely no hope) if she:
1) does not have a fever
2) has stable vital signs
3) has no excessive pain
4) has no excessive bleeding
If you meet these four criteria, waiting before having a D&C or to have a natural miscarriage is a reasonable option. If you do not meet these criteria, you could be at risk for infection. Seek help immediately.
Okay, I can safely wait, but how long will I have to wait?
We've seen women who were diagnosed with a blighted ovum who only had to wait a week or two before miscarrying or finding their babies and others who needed to wait three or more weeks. We do know with some certainty that waiting only one week, especially if you are eight weeks or less is not enough time to be certain you have a blighted ovum.
But, doctors would never misdiagnose something as important as a miscarriage, would they?
Unfortunately, the answer is yes and we can say that with reasonable certainty because we get several cases a month on the website where a woman was misdiagnosed. In many of these cases, the misdiagnosed woman has already turned down the D&C at least once.
How often do you think a blighted ovum is misdiagnosed?
Honestly, the vast majority of diagnosed miscarriages are in fact miscarriages. We do believe, though, that a fairly large number of women who are diagnosed with a blighted ovum AND have a retroverted uterus are misdiagnosed especially if they are diagnosed at eight weeks or before.
They finally found my baby at 10 weeks but are telling me I am only 7 or 8 weeks but I know this is impossible. How can this be?
The measurements taken by transvaginal ultrasound are very accurate during the first trimester and used by physicians to date the pregnancy. However, they are subject to human error and, we believe, they are not quite as accurate if your uterus is tilted. We've had a number of women who knew exactly when they conceived but did not see their babies until 8 to 12 weeks (or even more) and, when finally found, their doctors insisted their dates were off by weeks. Even if the woman only had sex one time, they'll insist she got pregnant weeks later. We believe that with the awkward positioning during the ultrasound coupled with the tilted uterus, dates are skewed during the first trimester. And, in fact, most of these women report the dates as being accurate again at their 20 week (or second trimester ) ultrasound.
Do you have research to back this up?
The sad answer is no but we are hopeful the research will be done soon. Just because the research has never been done does not make this an impossibility. Nobody has even looked into this link (that we can find) but with the word getting out there, we think it is a matter of time before doctors are forced to reexamine how they determine a woman has a blighted ovum. In the meantime just remember, this lack of research does not mean it doesn't happen. We see at least a few misdiagnosed cases a month and in each case the woman has declined a D&C or just decided to wait it out.
What is the purpose of the Misdiagnosed Miscarriage site
With a growing number of women waiting out their diagnoses and finding their babies later than most, we know the word is getting out there. We believe women deserve to know without a doubt whether they are indeed going to miscarry or if, instead, there is a chance they have been misdiagnosed as well.
*Luise C, et al. Outcome of expectant management of spontaneous first trimester miscarriage: observational study.
British Medical Journal. April 13, 2002; 324:873-5.
** American Pregnancy Association http://www.americanpregnancy.org/pregnancycomplications/blightedovum.html
*** Minelli E, et al. Cytogenetic findings in echographically defined blighted ovum abortions.
Ann Genet. 1993;36(2):107-10.
**** Oates-Whitehead, et al. Progesterone for preventing miscarriage.
Cochrane Database Syst Rev. 2003;(4)