Ultrasound Safety
	Ultrasound is a form of energy produced from high frequency waves, or pulses of sound lasting less than one ten-thousandth of a second. These pulses of sound, the equivalent of acoustical radiation, are beyond the range of human hearing. If ultrasound is defined as sound that lies beyond the range of human hearing, how can a fetus hear an ultrasound scan? "This is really a secondary effect," explained by Dr. Fatemi of the Acoustical Society of America in Fort Lauderdale, Florida. "Ultrasound is not audible, but, the ultrasound energy produces a tapping force on any organ or object that it intercepts. When that tapping force is repeated, it produces a vibration sililar to that produced by sound. As the ultrasound beam moves during examination of the fetus, the focal point of the beam can pass over the fetal head. When this happens, the sensitive hearing structure of the fetus receives vibrations at a rate equal to the number of pulses per second from the ultrasound beam. The radiation force of these vibrations produces a localized "noise" that might range from 85 decibels to 120 decibels if it were traveling through air. This is equivalent to the level of sound produced by an approaching subway train. However, because sound is focused on a tiny, square-millimeter spot, and the sound diminishes rapidly from that spot, the fetus could quickly adjust its position to avoid the loudness. Knowint the intensity, we know how much force and pressure it will produce at a localized point. Unlike sound, however, this force is confined to a very sharp focal area and even a 1-centimeter change in focus significantly reduces the acoustic vibrations "heard" by the fetus." Obstetric ultrasound can cause a heating effect on tissue, up to 2 degrees F, and the bubbling motion of cells (known as cavitation) can produce toxic gasses that have an unknown effect on the growing baby. What does the medical community have to say about the use of ultrasound? The American College of Obstetrics and Gynecology (ACOG), Federal Drug Administration (FDA), American Medical Association and the American Institute for Ultrasound in Medicine all recommend against routine ultrasound, and have deemed the non-medical use of ultrasound fo psycho social or entertainment purposes to view the fetus, obtain a picture, or determine gender without a medical indication as inappropriate and contrary to responsible medical practice. Is a sonogram accurate? The diagnosis of fetal abnormalities is often inaccurate. The use of ultrasound to determine the due date can be just as accurate using the last menstrual period, and using an ultrasound to determine birth weight is often very inaccurate. Even a sonogram to diagnose placenta previa carries no greater accuracy than discovering a previa in labor. What are the benefits of ultrasound? Ultrasound can be used to diagnose developmental abnormalities in the baby that would influence where the baby should be born and what preparations need to be made beforehand. Abnormalities of the heart, lung, and intestinal development can, if detected early, alert parents and healthcare providers to deliver the baby in a facility equipped to begin management immediately after birth. Sometimes this early recognition and early treatment can be lifesaving. Diagnosis of a malformation may also help some parents emotionally prepare for the birth of an impaired child, or parents may suffer a prolonged and devastating upset through such information when it is discovered that there was no abnormality. What are the risks of ultrasound? Measuring the risk of any intervention in pregnancy is very complicated because there are so many things to look at. Intelligence, personality, growth, sight, hearing susceptibility to infection, allergies and subsequent fertility are but a few issues which, if affected, could have serious long-term implications. Because a baby grows rapidly, exposing it to ultrasound at 8 weeks can have different effects than exposure at, for example, 10, 18 or 24 weeks. The rapid development of each new variation of ultrasound has not been accompanied by similar careful evaluation by controlled, large-scale trials. Thus the full risks of ultrasound in humans is not well studied and difficult to prove equivocally in humans. There have been literally thousands of studies done on the safety of ultrasound, and while there is no definite evidence of risk, there is some good evidence that it can cause permanent cellular changes in the brain of a developing fetus as supported by an increase in left-handedness, and there is good research to indicate it can cause intrauterine growth restriction. What is a doppler? A doppler is a hand-held device used to detect the heartbeat of the fetus. An ultrasound machine used to view a sonogram and a doppler both use ultrasound, however a doppler uses a continuous beam of ultrasound instead of an intermittent wave. One minute of doppler use is the equivalent of 35 minutes of a visual sonogram. It is customary in homebirth midwifery to use a stethoscope or fetoscope to detect heart tones, which sometimes takes patience. A doppler may be used during labor or prenatally if heart tones cannot be heard with a stethoscope or fetoscope due to baby's position, noise, gestational age, etc., but always with consent only. A sonogram is not recommended unless there is a clear medical indication that birth at home may be inadvisable in the presence of certain complications, and an ultrasound may potentially give a definitive diagnosis. You should consider your options thoroughly regarding ultrasound use, and examine your motives carefully if you feel the need to obtain a sonogram for any other reason, or for routine use of the doppler. References "Fetal Effects of Ultrasound: A Growing Controversy," by Doris Haire, Journal of Nurse-Midwifery, 29:4, p241 "Sonograms Aren't Safe...Dopplers Are Worse" by Tracy West-Lauer, AAMI "Ultrasound in Controversy," by Jay Hathaway Guide to Effective Care in Pregnancy, 1st ed., p48-56 Mothering #102, p58-61 Midwifery Today #50, p 30; #51, p31-33, #64, p28 Understanding Lab Work in the childbearing Year, 4th ed., p402-406 www.birthlove.com/pages/sarah/ultrasound.html www.fda.gov/fdac/features/2004/104_images.html www.fetalsure.com/fetal-doppler-safety.html www.ob-ultrasound.net www.plus-size-pregnancy.org/Prenatal%20Testing/prenataltest-ultrasoundsafety.htm www.unhinderedliving.com/pultra.html
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