What is Ultrasound?
Ultrasound is a screening device used to view the fetus during pregnancy. Also known as a sonogram, it has been used for many purposes including underwater navigation for submarines since World War I. Physical therapists have relied on ultrasound since the 1940s for its heating effects which can reduce inflammation, increase local blood flow and breakdown scar tissue. Since the 1960s, ultrasound has replaced X-rays as the primary method of fetal imaging in pregnancy. We now know X-rays are considered dangerous to the fetus and are rarely used during pregnancy. Initially ultrasound was a screening device to look for high risk conditions. However now it has become routine regardless if a woman has any risks.
Ultrasound is an ultra high frequency sound wave which generates an image to view the fetus in utero. The sound waves are above the range of human hearing. From a transducer or a probe placed deep within the vagina (in early pregnancy) or on the surface of the abdomen (second and third trimesters), sound waves are emitted at millions of cycles per second. A pattern of echo waves creates a picture from a variety of surfaces from fluid and soft tissues to a boney skeleton. Modern ultrasound energy intensities are higher than compared to earlier decades. In obstetrics the following ultrasounds and energy exposures are used:
•Standard scan. The standard scan is used on the abdomen after early pregnancy. Provides a brief pulse ultrasound of lower exposure
•Trans Vaginal ultrasound. Used in early pregnancy. High exposure levels due to close proximity of probe to early developing fetus. .Uncomfortable procedure been called “diagnostic rape” by some women. .
•Doppler ultrasound. Used by many obstetricians and midwives provides relatively low exposure level.
•Fetal monitors: used in late pregnancy and during labor to monitor baby and heart level. High level of exposure.
•3-D Ultrasound. To generate 3-D images of the developing fetus.
•4-D or Dynamic 3-D Ultrasound: Uses specially designed scanners to look at the face and movements of the baby.
•Fetal Echocardiography: Uses ultrasound waves to assess the baby's heart in suspected congenital heart defects.
Reasons to consider ultrasound
•Confirm early pregnancy using a vaginal ultrasound
•Detect multiple births
•Calculate due date through measurements of fetus’ skull, femur, or crown-rump length (done in second trimester)
•Inspect fetal organs for growth and development
•Verify fetal position and breech presentation
•Inspect the placenta and placement.
•Many expectant parents are excited to see the ultrasound including the 4D sonogram technology that makes it possible to clearly see a baby close up.
Risks of ultrasound
•“The long term effects of repeated ultrasound exposures on the fetus are not fully known. It is recommended that ultrasound only be used if medically indicated.” (American Pregnancy Association)
•40% pf abnormalities are missed or go undetected according to a recent study in Brisbane.
•Causes anxiety and stress for parents who are given abnormal results or false positive findings.
•Ultrasound heats the tissue and researchers suspect that the waves cause small local gas pockets which vibrate and collapse called cavitation. The gas can reach up to temperatures of thousands of degrees (Celsium) leading to production of potentially toxic chemical reactions.
•Studies done on mice have shown intestinal bleeding caused by changes in the cells. Scientists conclude that there would be similar effects in humans.
•Ultrasound has been linked to the following abnormalities:
-Left handedness in children who are supposed to be right-handed. Although there is nothing inherently wrong with being left handed, the change is attributed to a subtle damage to the brain. Males are more affected than female fetuses, probably because the male brain develops later.
-Early labor, premature birth, miscarriage, low birth weight, poorer health at birth, and perinatal death.
-Increased learning disabilities, epilepsy, delayed speech development, dyslexia
Ultrasound is used routinely and considered harmless by the medical profession, and for this reason risks are not discussed. In fact, it is presumed that use of ultrasound and the information it provides is considered valuable and desired by every woman. As with many of the tests and procedures during pregnancy, consider the risks, benefits and implications of the test. Ultrasound is an elective test, it is not mandatory. According to Beverley Beech, the chairman of the Association for Improvements in Maternity Services, "I am not sure at all that the benefits of ultrasound scans outweigh the downsides. We should be advising women to think very, very carefully before they have scans at all."
During my pregnancies, I declined all ultrasound and Doppler tests deferring instead to the old-fashioned obstetric stethoscope which meant my midwife could hear my baby’s heartbeat by my 20th week – late by modern standards! However, living in our modern world, most pregnant women will undergo a minimum number of ultrasounds. If you are having an ultrasound consider the following:
•Use ultrasound sparingly, avoid unnecessary scans.
•Minimize use of ultrasound before 20 weeks of pregnancy. The most sensitive time for development of brain defects is between 10 and 17 weeks of gestation.
•Work with an experienced ultrasonography technician at a reputable site.
•Use a scan machine that provides the least exposure in the shortest amount of time.
Kieler H, Cnattingius S, Haglund B, Palmgren J, Axelsson O.. Sinistrality--a side-effect of prenatal sonography: a comparative study of young men. SourceDepartment of Women's and Children's Health, Obstetrics and Gynecology, Uppsala University, Sweden.
"Prenatal exposure to ultrasound waves impacts neuronal migration in mice," Proceedings of the National Academy of Sciences, 2006 103: 12903-12910.
Newnham, J.P., Evans, S.F., Michael, C.A., Stanley, F.J., & Landau, L. I. (1993). Effects of Frequent Ultrasound During Pregnancy: A Randomized Controlled Trial. The Lancet, 342(Oct.9), 887-891.
Campbell, J.D., Elford, R.W. & Brant, R.F. (1993). Case-Controlled Study of Prenatal Ultrasound Exposure in Children with Delayed Speech. Canadian Medical Association Journal, 149(10), 1435-1440.