Tuesday, November 25, 2008
Ultrasound was invented by an English physician by the name of Ian Donald. It was first tested in 1957 & one year later, was used on a pregnant woman. I won’t go into the history, but if you are a history buff, you might like this link: http://www.ob-ultrasound.net/history1.html (I like history about as much as I like eating sand after being in the desert for two days with no water)..
A prenatal ultrasound test uses high-frequency sound waves, inaudible to the human ear, to transmit through the abdomen via a device called a transducer to look at the inside of the abdomen. With prenatal ultrasound, the echoes are recorded and transformed into video or photographic images of your baby.
There are several reasons why an ultrasound is done, and they can be quite beneficial. However, (I didn’t say BUT!) I’m finding a lot of women are having them done a LOT - and there is really not a benefit to this in most cases. Let me explain.
Ultrasounds are often done at around 20 weeks, with another one in the third trimester. Depending on the doctor, it might be around 32 weeks, or 36-37 weeks. They are looking for lots of things. More than one baby, size of the baby for dates, placental location and various problems and/or deformities of the baby.
I mentioned that the use of ultrasounds is on the rise. Some doctors are using them at each prenatal visit. I know three people who just had to sign a form at their doctors’ office saying that they had to consent to *at least* three ultrasounds during their care. To add fuel to my fire, all three of these pregnant mothers, signed this form AFTER already having three ultrasounds. Many doctors do an ultrasound on the first visit to confirm pregnancy! What happened to a good ol’ blood test or a urine test?
A short story of my own: With my fourth child, I had my first prenatal at 9 weeks. A vaginal ultrasound was done to confirm pregnancy. I went back in at 13 weeks for my second prenatal. The doctor could not get fetal heart tones using her Doppler. (Back then, I was not aware that this was not uncommon for this gestational age - especially with a mother with ..ahem “padding”). Another vaginal ultrasound was done immediately to see if there was in fact a beating heart. I had a routine ultrasound at 20 weeks. (So far three ultrasounds). I had a history of preterm labor with all my children, so my doctor thought it would be wise to share my care with a perinatolgist. During these visits they would do an ultrasound to check for funneling and cervical effacement. I had an ultrasound once a week from weeks 25-28. They didn’t catch anything. At 28 weeks and 6 days I went in for my regular OB prenatal, and I was found to be 1cm dilated and 90% effaced. She sent me to the hospital (though I was not contracting at the time). BUT, before I was to go to labor and delivery, she ordered...an ultrasound. She said she wanted to know how big baby was according to gestational age. I hope that wasn’t all that she wanted, because I had 7 ultrasounds so far, with the last one just a few days earlier. I didn’t know any better. I just did what the doctor told me - because they are the ones who went to school. My son is autistic. I will live the rest of my life wondering if these ultrasounds, along with 40 minutes a day of external fetal heart monitoring for two weeks straight, had a role in the cause for his autism.
My concern is that we do not have enough research to prove the safety of ultrasounds. They have been done for 30 years, but what are the long term effects? How could they know? According to a report in an edition of Proceedings of the National Academy of Science, exposure to ultrasound can affect fetal brain development.. When pregnant mice were exposed to ultrasound, a small number of nerve cells in the developing brains of their fetuses failed to extend correctly in the cerebral cortex."These disorders range from mental retardation and childhood epilepsy to developmental dyslexia, autism spectrum disorders and schizophrenia.” The researchers also said “Our study in mice does not mean that use of ultrasound on human fetuses for appropriate diagnostic and medical purposes should be abandoned," -Pasko Rakic, chairman of the neurobiology department at Yale University School of Medicine.
So what DO we know about ultrasounds?
1) Ultrasounds cause heat
2) Ultrasounds cause “cavitation”. Cavitation is the development of bubbles which expand and collapse.
3) In 1993 the FDA raised the maximum output of ultrasound machines used in obstetrics eightfold, from 94 up to 720 milliwatts per square centimeter. The higher the milliwatts the higher chance of heat and cavitation.
We also know that ultrasounds are not always accurate. When they measure the baby, it can be off by as much as one pound in either direction. This can sometimes mean a difference between a preterm or term baby, or even an overdue baby. Sometimes there is uncertainty in what is seen; maybe the normal structure was not seen well, or something out of the ordinary was missed. Case in point - 2% of ultrasounds are wrong about the sex of the baby! Often, a mother worries over something that was “seen” in an ultrasound that turns out to be completely normal. And most of these cases had to be confirmed with another ultrasound (sometimes later in pregnancy) with a consult to a specialist. Sometimes the specialist can not confirm the ‘problem’ anyway.
I can understand one or two routine ultrasounds during pregnancy. I can see the need for one or two more in such cases as something like placental previa (to see if the placenta moves up away from the cervix). I don’t understand why they should increase ultrasounds for the rest of the women.
3-D, 4-D ultrasounds anyone? Your doctor may let you have one of these. If not, you can go to a shopping mall around the corner, and pay out of pocket for one! When the FDA raised the milliwatts per square centimeter they also required manufacturers to add two on-screen safety indexes. One measures the heating of bone or tissue; the other “mechanical” effects, including cavitation caused by the expansion of gas bubbles, sheering forces within tissues, and induced flows within fluids. My point is that the FDA expected sonographers to be well trained in using the on-screen safety indexes properly. These safety features would help keep patients from getting greater levels of ultrasound exposure than under the previous system of regulation. According to ultrasound experts, the actual state of sonographer training is dismally inadequate. Dr. Jacques Abramowicz, Professor of Obstetrics and Gynecology and Radiation at the University of Chicago, said, “Only two to three percent of the population doing ultrasound really know what the thermal index and the mechanical index mean.” In other words, going down the road to “Ultrasounds R Us” may not be such a good idea after all. The other problem with 3 and 4D ultrasounds is the time that it takes. Research shows that there is damage to fetal mice brains after ultrasound exposure of 30 minutes or more. Common sense tells *me* that I probably don’t want to take any risks, or have an ultrasound longer than necessary -no matter how much I want to see my baby.
I get wanting to see our babies! I’m sure women from the dawn of time have wished there was a window to their uterus. Ultrasounds are a pretty close second. Can they help women connect to their babies? You bet. We can ad this to our list of pros. We all have to decide what risks we are willing to take, and for what reason. There is no clear cut evidence - but I don’t see studies being done here in the US to make sure that the other studies are right or wrong. I wonder if there is just too much money in ultrasounds?
Here are some more links if you want to research this further. I do not provide them as true evidence - just food for thought.