Understanding the Causes of a Blighted Ovum

What makes this form of pregnancy loss unique

Pregnant woman having ultrasound scan
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The term blighted ovum sounds more than a little strange and confusing. After all, the word "blight" is a pretty strongly negative word and ovum isn't a common word for most people.

A blighted ovum is a type of miscarriage in which the baby either never develops or stops growing at a very early stage in pregnancy and then disintegrates -- but a gestational sac does develop and the body does not recognize that the baby is missing.

Causes

Doctors believe that blighted ovums are the result of chromosomal abnormalities in the fertilized egg. One 1993 study looked at the genetics of blighted ovum miscarriages and found abnormal chromosomes in 67 percent of the samples. There is no evidence that blighted ovums are ever caused by anything the mother does or does not do.

Symptoms

A blighted ovum can be a type of missed miscarriage; a woman might have no miscarriage symptoms and may even have full-blown pregnancy symptoms at the time of diagnosis. A blighted ovum can also be miscarried naturally, in which case the woman would have typical miscarriage symptoms.

How a Blighted Ovum Is Diagnosed

Blighted ovum might be discovered when investigating a mother's miscarriage symptoms in the first trimester or via first-trimester ultrasound for other reasons. If the woman does not have any signs of miscarriage, the diagnosis might not come until in the early second trimester when the baby's heartbeat does not become audible on a heart rate monitor.

The method of diagnosis is usually ultrasound; hCG levels may rise the same as in a normal pregnancy.

Blighted Ovum Treatment

Many women who have been diagnosed with a blighted ovum may choose to have a D & C in order to get the physical part over with, given that a blighted ovum without miscarriage symptoms could mean weeks of waiting.

Others prefer natural miscarriage; women choosing this option might need to be monitored by a doctor until the miscarriage is complete.

Coping

Blighted ovum can be a traumatic diagnosis when it comes unexpected; like in chemical pregnancy, it can sound like there was never a baby. Friends and relatives may not understand why a woman grieves a blighted ovum. In a blighted ovum, it is true that the baby did not develop enough to be visible on ultrasound, but a conception did occur and the pregnancy did exist -- and it is OK to grieve the loss of the baby.

Chance of Misdiagnosis

With a blighted ovum, a slim chance exists for misdiagnosis if the pregnancy is early along and the dates are not certain.

The beginnings of a developing baby typically become visible on a transvaginal ultrasound around five to six weeks of pregnancy and on an abdominal ultrasound as late as six to seven weeks of pregnancy. And if the dates of the pregnancy are even a little bit off, a viable pregnancy could theoretically be misdiagnosed as a blighted ovum.

If you are diagnosed with a blighted ovum in the E.R. and feel that there is any chance at all that your dates might be off, consider postponing any treatment decisions until you check with your regular doctor. If your doctor feels there is any uncertainty about the diagnosis, the doctor will most likely ask you to return for a followup ultrasound in a few days or a week. Obviously this wait for a verdict can be excruciating and stressful, but it is a good way for doctors to avoid the possibility of misdiagnosis.

Sources:

Minelli, E., C. Buchi, P. Granata, E. Meroni, R. Righi, P. Portentoso, A. Giudici, A. Ercoli, M.G. Sartor, A. Rossi, et al. "Cytogenetic findings in echographically defined blighted ovum abortions." Ann. Genet. 1993. Accessed 7 Feb 2008.

U.W.O. Undergraduate Medical Radiology, "Obstetrics and Gynecology." Normal Obstetrical Studies. Aug 2001. Accessed 7 Feb 2008.

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