Diagnostic ultrasound is a powerful, non-invasive medical tool.
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The basis of operation for diagnostic ultrasound is the transmission into the body of sound (or acoustic radiation) at frequencies 100 - 500 times higher than can be heard. Images are then created by reception, processing, and display of echoes reflected from structures, tissues and flowing blood. The technique is similar to how bats, whales, and dolphins use echolocation, or how submarines use SONAR.
Ultrasound is used for real time imaging of the fetus, internal organs of the body, veins, arteries and blood flow. Ultrasound can be used as a form of physiotherapy treatment and as a surgical tool for destroying abnormal tissue growths or tumours.
Ultrasound is also used extensively in industrial, commercial, military and home applications such as ultrasonic drilling, welding, cleaning, alarms, and animal repellants.
There are concerns about the safety of ultrasound because it is a form of energy which, above certain thresholds, can cause destructive heating and/or interaction effects with microscopic bubbles in the body. A cautious approach should therefore be taken in its use.
Health Canada recommends that diagnostic fetal ultrasound should be done only when the expected medical benefits outweigh any foreseeable risk.
Diagnostic fetal ultrasound
Diagnostic fetal ultrasound provides medical information that will help your health care professional care for you and your baby.
Fetal ultrasound creates images of the unborn baby in the womb. The procedure uses very short bursts of sound vibrations that travel as waves through the body in a series of focused beams. Echoes from the beams are converted into real-time images that show the movement, surface features, internal organs and, with special techniques, even the blood flow of the fetus. The images are viewed on a monitor and can be stored on CDs. When the procedure is used to obtain images for medical purposes, it is called diagnostic fetal ultrasound.
Diagnostic fetal ultrasound provides important medical information, such as the size, age and state of health of the baby in the womb. It can also detect twins and can diagnose certain birth defects. The clinical use of fetal ultrasound has grown rapidly and it has an excellent safety record. There have been millions of these examinations over the past few decades with no confirmed health risks for the baby or the mother. This finding is consistent with the majority of scientific studies on the effects of ultrasound.
Although this is very reassuring, there is also suggestive evidence that there may be a biological effect on the fetus even during diagnostic use. Research is ongoing to ensure the continued safety of diagnostic fetal ultrasound.
Diagnostic fetal ultrasound is done only on referral from a licenced health care provider. It is performed in a clinical setting by highly qualified professionals. Discuss any concerns you have with your health care provider so that you can make an informed decision about the use of fetal ultrasound during your pregnancy.
Fetal ultrasound for keepsake videos
Some businesses promote the use of fetal ultrasound machines for the sole purpose of making videos of babies in the womb as a keepsake for parents. In this setting, the ultrasound provides no information about the baby's health.
When fetal ultrasound is done for a keepsake video, no medical information is provided to justify exposing the baby to ultrasound. Health Canada recommends that you have fetal ultrasound only on referral from a licenced health care provider.
Health Canada's role
Health Canada regulates diagnostic ultrasound devices under the Food and Drugs Act, the Radiation Emitting Devices Act, and the Medical Devices Regulations. This ensures the safety and effectiveness of the devices when they are used for their licenced diagnostic purposes and according to guidelines for safe use.
Health Canada has established Guidelines for the Safe Use of Diagnostic Ultrasound. The Guidelines state that ultrasound should not be used for any of the following activities:
- to have a picture of the fetus, solely for non-medical reasons
- to learn the sex of the fetus, solely for non-medical reasons
- for commercial purposes, such as trade shows or producing pictures or videos of the fetus
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