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A few days ago, Y.L. came to see me in the office. She’s a 26 year old woman, recently married, and she was thrilled to report a positive urine pregnancy test at home.
I wanted to see her right away for a number of reasons, among them early diagnosis of threats to her pregnancy, such as tobacco, alcohol, certain and medications, and also to get her started on prenatal vitamins, if she isn’t already taking them. The extra folic acid in prenatal vitamins helps reduce the risk of neural tube defects, and is ideally started several months before the onset of pregnancy.
I also wanted to confirm, if possible, the viability and location of the pregnancy. That’s important because roughly one in every four pregnancies is destined to miscarry, and 2% of pregnancies are located in the wrong place, also known as an ectopic pregnancy.
First, I confirmed the positive pregnancy test. Her last menstrual period was 7 weeks ago, and she had noticed the pregnancy symptoms of fatigue, and occasional waves of nausea. This is her first pregnancy and they had been trying for a pregnancy for two months before conceiving. She had been taking multivitamins for women with appropriate folic acid supplementation since she initiated her efforts for a pregnancy.
After examining her, I could feel that the uterus was enlarged and soft. We have an ultrasound machine in our office, so I turned it on and began scanning, using the transvaginal probe. I was expecting to find a 7-week size sac measuring about 21 mm in diameter. The gestational sac normally grows about 1 mm a day for each day past the 4th week since her LMP. I was also expecting to see a 7 mm fetus with a visible heartbeat. The fetus normally grows about 1 mm a day in crown rump length, starting at the 6th week since her LMP.
Instead of these normal findings, I found a 12 mm sac, without anything inside it…no fetus and no rhythmic cardiac activity. I strongly suspected a “missed abortion”, one that is destined to occur, but has not yet occured.
I finished the scan and then sat down to talk with her. I explained that I could see the pregnancy in the right place, but it was measuring smaller than I expected. I showed her on the ultrasound images to help her better understand the size differences. I told her that about one in every four pregnancies will end up as a miscarriage, and that I was suspicious that this pregnancy would be one of them. I explained that I was not 100% sure of this, based on a single ultrasound scan, because occasionally there are other explanations for the discrepancy, for example a pregnancy that is not as far along as we would think, based on the LMP. To be 100% certain, I would need to take another look in about a week. If the pregnancy were normal, then in one week, the 14 mm sac should grow to 21 mm, and the absent fetus should grow to 7 mm and have a heartbeat. We arranged to have her return in a week with her husband.
I then explained to her that about two-thirds of miscarriages occur because of chromosome abnormalities, and that is not something that can be fixed. Another 1/3 (about) are associated with malformations of the placenta, and that cannot be changed. There are a small number, 10% or less, of miscarriages that are caused by a variety of problems, including virus infections and catastrophic maternal trauma, but that at this stage of pregnancy, if a miscarriage is in the works, there nothing that can be done to salvage it. I wanted her to understand that she has no control over whether a miscarriage occurs or not. She cannot cause it and she cannot prevent it. They are random occurrences that have no impact on the future. Every time a woman becomes pregnant, she will have about a one in four chance of having a miscarriage, even if she’s had one before.
I discussed the natural course of miscarriages, that she would continue to have pregnancy symptoms and a positive pregnancy test for a while, because those are caused by the placental tissue producing pregnancy hormone.
Eventually, those symptoms will disappear and she will begin to experience some vaginal bleeding and cramping. This usually is intermittent over the course of days to weeks, but eventually the bleeding and cramping become as intense as a bad menstrual period, following which, she will expell the pregnancy tissue. It will not be recognizeable to her as usually, a fetus never forms. After she passes the tissue, the bleeding usually stops and the cramping stops. She does need to be examined at that point, however, since sometimes (though infrequently) some of the pregnancy tissue remains inside the uterus, provoking further bleeding, and requiring minor surgery, a D&C, to complete.
Most of the time, though, the pregnancy tissue passes uneventfully, normal menses resume in about a month, and she can again try for a pregnancy, again with a one in four chance for a miscarriage.
An alternative to awaiting spontaneous abortion is to perform minor surgery, a D&C, to surgically remove the pregnancy. The disadvantage to this approach is that it requires surgery and anesthesia and the small risks associated with them. The advantage is the quick resolution of an emotionally draining problem for the woman, with a predictable end. For example, some of my patients with small children at home, do not want to run the risk of being called away in the middle of the night to go to the hospital to deal with a miscarriage, and they often prefer to schedule a D&C at a time when they can set up child care arrangements.
When she returns with her husband next week, I don’t know what the scan will say, but usually it shows slight growth of the sac, like a couple of mm, but not normal growth, and usually there is no visible fetus, even though it should have grown 7 mm, and no heartbeat.
