A Good Way To Detect Submarines, But Babies? – Ultrasound
26 Aug 2008
“Will repeated ultrasound examinations (US) harm my baby?” This is a question readers often ask. It’s a timely question since millions of obstetrical diagnostic exams are done every year in North America. As well many expectant families want to record this historic moment by obtaining a high-resolution 3-D video of it. How safe are these procedure?
Ultrasonography was invented during World War II to prevent German submarines from sinking Allied ships. Later, Dr. Ian Donald, a Scottish doctor, used this technique to diagnose abdominal tumours. Its use quickly spread to pregnancies.
Ultrasound uses high frequency sound waves that create images on a screen. This can be extremely useful in helping doctors to determine the cause of bleeding in early pregnancy, or in detecting twins, or abnormal positions of the fetus. No one questions its use for diagnostic purposes.
Ultrasound waves affect living tissue in two ways. The sonar beam heats the examined area to about 1 degree centigrade (2 degrees fahrenheit). This temperature increase is believed to be safe. The second effect is known as, cavitation, in which small pockets of gas within tissues vibrate, intense heat is generated and the cavity collapses. The significance of this process in human tissue is unknown. However, studies on cells grown in laboratories showed that abnormalities caused by exposure to US persisted for several generations.
Newborn rats that are at the same stage of development as humans at four to five months have been subjected to US. One study showed that US can damage the myelin sheath that covers nerves, possibly indicating that the nervous system may be susceptible to damage by this technique.
Another study on animals reported in New Scientist showed that exposing mice to dosages typical of obstetrical US caused a 22 percent reduction in the rate of cell division and a doubling of cell death in cells of the small bowel.
But does this apply to humans? Some researchers relate miscarriage, low birth weight, dyslexia, delayed speech development and less right-handedness to obstetrical US. They question whether this is the result of damage to the developing brain.
An Australian study revealed that babies exposed to five or more ultrasounds were 30 percent more likely to develop intrauterine growth retardation. However, two long-term studies comparing exposed and unexposed children eight to nine years of age showed no measurable effect from obstetrical US. But these studies were done many years ago and scanning time was only three minutes. Today Doppler US exposure levels are higher and with the use of vaginal US there is less tissue shielding the baby from the U.S probe.
The other concern is the wide range of doses possible from a single machine. Years ago I discovered that X-ray machines were sometimes delivering 90 times the normal dose of radiation needed, often reaching near lethal limits. Studies show there can be a wide range of doses a fetus receives from US equipment, depending on the age of the equipment and the skill of the technician.
What concerns me is the use of 3-D high intensity ultrasound strictly for entertainment purposes by private clinics. It’s another money-making marketing ploy. The enticement is that families can see for 30 minutes or longer a video of little Johnnie or Mary bobbing around in amniotic fluid, yawning and sucking its thumb. Happy parents can see the eyebrows, ears and other features. Some clinics even suggest it provides a chance to see who the baby looks like, which is really stretching the truth.
These clinics also stress that 3-D videos create bonding with the baby. This is absolute nonsense. A similar marketing ploy brought fathers into the delivery room to cement family bonding. As yet I haven’t heard of any decrease in the divorce rate.
To be sure no one has proven beyond a shadow of a doubt that long exposure to 3-D ultrasound is harmful. But hell would freeze over before I would allow any of my children to be exposed to the potentially damaging effects of US vibration and heat. To me it’s just another form of medical technology gone rampant. Families should have more enduring priorities.
