Sneaking a peek of your unborn baby probably rates as one of the most exciting things about being pregnant.
For those who have struggled with fertility or miscarriage, ultrasounds can provide a sense of comfort and relief.
Pregnancy Ultrasounds – Risks and Benefits
Most pregnant women will have at least two routine ultrasounds during pregnancy.
Women who are under the care of a private obstetrician might have one at each antenatal visit, depending on their doctor.
Ultrasounds have become so routine during pregnancy that we do not question whether they’re necessary – or even safe.
History Of Ultrasound
Ultrasound was first used for medical purposes in the 1950s, when a Scottish surgeon discovered different body tissues gave off different sound wave echo. It wasn’t long before ultrasound was used to detect and investigate potential problems in pregnancy.
Originally, ultrasound was not used routinely, but in cases where there was a suspicion of breech, twins, or if early bleeding indicated miscarriage.
Since the 1970s, ultrasound has become routine for almost every pregnant woman.
What Is Ultrasound Used For?
These days ultrasound is a routine part of the pregnancy package. Most women will have at least two scans during pregnancy (at around 12 and 20 weeks). It’s also common to do an extra scan very early, to ‘date’ the pregnancy, and give an estimated date of delivery (EDD).
The nuchal translucency ultrasound happens between 11-14 weeks. It is done to:
- Check your baby is in the right place in your uterus
- Discover if there is more than one baby
- Look at developmental growth
- Perform the nuchal translucency test (to see if your baby is at risk of chromosomal conditions such as Down syndrome).
The anomaly ultrasound happens between 18-20 weeks. It is done to:
- Look at your baby’s body and organs in detail
- Check where the placenta is
- Check for any obvious development or growth problems, such as spina bifida, or heart defects
- Find out your baby’s gender.
Later in pregnancy, ultrasound might be used to assess certain indicators for high-risk problems, such as premature labour, or increasing or decreasing levels of amniotic fluid.
How Is Ultrasound Performed?
Pregnancy ultrasounds are done by radiographers who have undertaken specialised training in sonography. They have qualifications in medical ultrasound, and are trained in the procedures, risks, and interpretation of sonography.
The sonographer will put some gel on your stomach which helps to transmit the ultrasound waves. A hand-held device called a transducer is placed directly onto your skin, and pressed while being moved. This procedure is painless, but can be uncomfortable, depending on the pressure used, or if you have a full bladder.
The transducer emits ultrasound waves which pass into your body and bounce off your baby, creating images that you can view on a screen. Bone and hard tissue appear white; soft tissue appears grey. The sonographer will interpret the shades and intensity to determine how your baby is growing and developing.
Occasionally, if it is difficult to get a clear image of the baby, the sonographer will suggest a vaginal ultrasound. The transducer used in vaginal scans is narrow, and is lubricated with gel so that it can be inserted easily. The transducer doesn’t need to be inserted deeply, and it shouldn’t cause you any pain or discomfort.
If there are specific concerns about your baby’s growth or development, you might need to have a scan done by a doctor trained in maternal fetal medicine.
Is Ultrasound Safe?
Routine ultrasound is so much a part of antenatal care, women rarely question its safety.
Ultrasound introduces energy into the body. This can heat body tissue, and can also produce small pockets of gas in body tissue or fluids (cavitation). It is not known what the long-term consequences of these effects might be for women and their unborn babies.
Human studies have not yet shown a direct association between pregnancy ultrasound and adverse effects on unborn babies. However all human studies were done before 1992, when ultrasound was used at a much lower intensity than it is today.
Currently there are no human studies looking at the effects of today’s levels, which are seven times higher than the limit used prior to 1992.
A number of organisations, including the American Institute of Ultrasound in Medicine, recommend ultrasound should be used only by trained health care providers, for specific diagnostic purposes, and exposure time should be limited as much as possible.
While ultrasound is considered safe for low-risk women, there is a concern that risk increases with unnecessary, prolonged exposure to ultrasound energy.
The use of ultrasound for non-diagnostic purposes or non-medical reasons, such as fetal ‘keepsake’ videos, is not recommended, because of the additional length of time required, and the potential exposure to ultrasound energy for much longer periods.
Does Ultrasound Have Any Benefits?
If you are being offered ultrasound as a routine procedure, it’s worth asking your care provider about the possibilities of inaccurate or false positive results. As with all tests, ultrasounds can provide results that need further verification, such as amniocentesis (amniotic fluid test).
Ultrasound can be used to detect problems when your doctor or midwife has concerns about your baby’s growth or development, or if you appear to be experiencing premature labour. Using ultrasound for non-diagnostic reasons doesn’t improve outcomes for either mother or baby.
Should I Have Any Ultrasounds?
Although most women have at least one ultrasound during pregnancy, you can choose not to have any scans at all.
If your midwife or doctor recommends you have an ultrasound, make sure you know the risks and benefits before you decide. Your care provider should tell you why it’s needed, how it will be done, and what risks might be involved.
Ultrasound has become a widely used procedure that has the potential to provide medical information to pregnant women. However, ultrasound isn’t without potential risk, and should be used carefully to ensure that babies and mothers benefit from the information it provides.
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