What is a missed abortion?

Monday September 14 2020
By Dr Vincent Karuhanga

I know someone who had a positive pregnancy test but following a scan, she was told that she had had a missed abortion. What is a missed abortion and how can it be prevented ?–Naula
Dear Naula,
After fertilisation, the fertilised egg takes 30 minutes to start dividing into cells that will make a baby and associated tissue, including the placenta.
The placenta makes most Human chorionic gonadotropin (HCG) that is detected in both urine and blood during urine and blood pregnancy tests.
Sometimes, the embryo can die or not develop as expected, leaving the placenta tissue-making HCG hormones with a likelihood of the pregnancy tests being positive without the embryo in what is called a missed miscarriage, (missed abortion) or anembryonic pregnancy. In these circumstances, the pregnancy test will be positive and ultrasound scans will show an empty sac with no embryo as is usually indicated by a flickering of or pumping of the heart.
A foetal heartbeat may first be detected by a vaginal ultrasound at about six weeks after fertilisation and absence of the heart but only an embryonic sac after seven weeks will most likely indicate a missed abortion. Sometimes, however, the heart may not be detected if scans are done earlier which calls for another check after a week or two to confirm the diagnosis. 
A missed miscarriage is appropriately tagged a silent miscarriage because women may not have symptoms such as vaginal bleeding, cramps or expulsion of blood clots. However, even when the said symptoms do or do not occur and the usual pregnancy symptoms such as breast pain, nausea, or fatigue, disappear, this may be indicative of a missed abortion. 
Though the causes of missed abortion are mostly obscure, many may happen because the embryo has abnormal chromosomes, especially in numbers. That said, one may be at a higher risk for missed miscarriage because of hormonal problems, if one is a heavy smoker or has autoimmune problems. 
Taking folic acid every day at least three months before pregnancy, eating healthy before and during pregnancy, exercising regularly, managing stress, keeping healthy weight and avoiding smoking are some of the factors that may help prevent missed abortions.