Does ultrasound have any risks? Ultrasound is safe for you and your baby when done by your health care provider. Because ultrasound uses sound waves instead of radiation, it’s safer than X-rays. Providers have used ultrasound for more than 30 years, and they have not found any dangerous risks.
Ultrasound is safe for you and your baby when done by your health care provider. Because ultrasound uses sound waves instead of radiation, it’s safer than X-rays. Providers have used ultrasound for more than 30 years, and they have not found any dangerous risks. However, some people are concerned about a possible link between ultrasound and autism spectrum disorders (ASD). The research is inconclusive, but there are enough concerns that the American College of Obstetricians and Gynecologists advises doctors not to use routine ultrasounds in pregnancy unless medically necessary.
Ultrasounds are safe. Ultrasounds are safe for both you and your baby when done by a health care provider. In fact, ultrasound has been used for more than 30 years and there have not been any dangerous risks found.
Your ultrasound is safe for both you and your baby. Ultrasound uses sound waves instead of radiation, so it’s safer than X-rays. And because ultrasound has been used over 30 years, there hasn’t been any evidence found of harmful effects to either you or your baby.
An ultrasound is a safe procedure for you and your baby. Ultrasound uses sound waves instead of radiation, so it’s safer than x-rays. To date, no major risks have been found by using ultrasound during pregnancy.
Are Too Many Ultrasounds Bad For Baby
An ultrasound is a procedure that uses soundwaves to create images of your baby while it’s in the uterus (womb). During the scan, gel is placed on your abdomen (tummy) and a probe called a transducer is placed against your skin. Pulses of sound waves are then sent from the probe to your baby, creating echoes that are turned into images by computer. You can see these images on a monitor.
In some situations, your doctor might prefer a transvaginal ultrasound to get better pictures of your baby. In this case, you will be covered with a sheet while the probe is inserted into your vagina. The probe would be moved around in the vagina to take pictures of your baby. It may be a little uncomfortable, but it shouldn’t hurt
Why do I need an ultrasound scan?
Ultrasounds are a simple, pain-free way to check how your pregnancy is progressing, and to provide helpful information on how your baby is developing. For example, they can:
- confirm your pregnancy (and check for multiple pregnancies, for example, twins)
- check your baby’s age and estimated due date
- see how your baby’s organs and other structures are developing
- check your baby’s position in your uterus
- examine your cervix and the placenta
- check the amniotic fluid around your baby
What routine scans might be offered during pregnancy?
Several types of scan are routinely recommended during pregnancy.
Dating scan: This ultrasound is usually done in the first trimester, between 6 and 10 weeks of pregnancy, to help date your pregnancy, and estimate your baby’s due date. It can also confirm how many babies you are carrying, check that your baby is growing well in your womb, and is not ectopic (outside the uterus).
Nuchal translucency scan: This ultrasound can be done between 11 weeks, 3 days and 13 weeks, 6 days of pregnancy. It measures the amount of fluid behind your baby’s neck. This measurement, known as the ‘nuchal translucency’, is used — together with your age, weight and blood test results — to calculate the risk that your baby may have a chromosomal abnormality, such as Down syndrome.
Morphology scan: A morphology scan (also known as a ‘fetal anomaly scan’) is an ultrasound done between 18 and 20 weeks of your pregnancy. It checks your baby’s body organs, specifically looking at their structure and growth, while their age can be estimated based on these measurements. This scan can also check your baby’s heart rate and rhythm, show whether you have more than one baby in your uterus, and where your placenta is lying. Depending on your baby’s position, the scan may also reveal the sex.
Why else might I need an ultrasound during pregnancy?
In some cases, your doctor might recommend a third trimester ultrasound scan to assess your baby’s wellbeing and growth. The third trimester ultrasound also gives your healthcare team information about the location of your placenta and helps assess your cervix.
Can an ultrasound scan hurt my baby?
Ultrasound is a safe and pain-free test, and there is no increased risk of miscarriage or harm to your baby. The sound waves used are at very low volume and so they will not hurt you or your baby and your baby will not be able to hear them.
Do I need to have ultrasound scans?
Your doctor is likely to recommend you have one or more ultrasound scans during your pregnancy so they can check how your baby is developing, but you’re still free to choose whether or not you have the scan.
Talk to your doctor or midwife about tests and scans to understand why they might be offered to you.
Questions you might want to ask your doctor
Here are some questions you might want to ask your midwife or doctor:
- Why are you offering me this test?
- What does the procedure involve, do I need to do anything on the day?
- When will I get the results?
- Who will contact me to give me the results?
- Do I need to do anything to care for myself after the procedure?
Who performs an ultrasound scan?
Some medical specialists, such as obstetrician, have had specialised training and are certified to carry out ultrasound scans. In other cases, your doctor may refer you to an imaging clinic where a trained ultrasound operator known as a sonographer will check your baby. You might have your ultrasound in a community clinic, an imaging centre or in a hospital.
Ask your health team if you can have printed copies of your baby’s ultrasound images to take home.
How do I prepare for an ultrasound scan?
The ultrasound clinic will tell you how to best prepare for your scan. Some clinics will ask you to drink 3 glasses of water 1 hour before the appointment and to not go to the toilet or empty your bladder until you’ve had your scan. This is because a full bladder makes it easier to see the images. Other clinics recommend eating and drinking normally, but ask that you do not empty your bladder within 30 minutes of your appointment.
Please check with your clinic what they prefer when you book your appointment what they would prefer you to do.
How much does an ultrasound cost?
Medicare will cover part of the cost of your ultrasound scans. Ask your doctor if you should expect any out-of-pocket costs for your specific situation.
When will I get the results of my ultrasound scan?
The results from the scan will be available on the same day as you have it. A copy of the report will be sent to your referring doctor. If there are any abnormalities found in the scan, a specialist doctor will contact you to discuss what they mean.
One of the aims of having ultrasound scans in pregnancy is to offer a safe, accessible test that can provide you with more information about your unborn baby. While these scans can reassure you that your baby is developing normally, you may also learn that your baby has an abnormality. For this reason, before you have the test it’s a good idea to think about why you are choosing to do it, and how you will feel once you get the results. Consider also who you might want to discuss any important decisions with. Your partner, a friend or family member, or a health professional such as your GP or midwife are all good options.
If the results of your ultrasound bring up any concerns about genetic conditions, you can talk to your doctor or midwife about other diagnostic tests, such as chorionic villus sampling or amniocentesis, for these conditions.
How Many Ultrasounds Are Safe During Pregnancy
In the last article in this series on natural childbirth, I reviewed evidence suggesting that routine prenatal ultrasound does not improve birth outcomes for mothers or babies, and that organizations like the American College of Obstetricians & Gynecologists recommend ultrasound scans only for specific reasons.
In this article I’m going to review evidence on the safety of routine ultrasound and Doppler scanning, and make recommendations based on that research.
The potential adverse effects of ultrasound
- Acoustic streaming
The sonar beam can cause heating in the tissues beings scanned. During normal pregnancy, increases in whole-body temperature of up to 4.5 degrees F (2.5 C) are presumed to be safe, and research suggests that elevations of tissue temperature up to 1.8 – 2.7 degrees F (1.0 to 1.5 C) caused by ultrasound are also safe.
The degree to which ultrasound machines raise temperatures in the tissues depend on which tissues are scanned. Bone heats more than soft tissue, which in turn heats more than fluid. Heating is also dependent upon exposure time, the intensity of the machine, and whether the transducer is held stationary or moved frequently.
Doppler ultrasound, which uses continuous rather than pulsed waves, has been shown to cause significant heating – especially in the baby’s developing brain. A recent study suggests that heating in late-pregnancy fetal tissues exposed to normal pulsed and continuous Doppler ultrasound may be higher than what is regarded as safe: 2.5 to 10.4 degrees F (1.4 – 5.8 C) respectively.
A 1997 study found that significant temperature increases can occur at or near to bone in the fetus starting in the second trimester, if the beam is held stationary for more than 30 seconds in some pulsed Doppler applications. This in turn can lead to heating of sensory organs incased in bone.
Though both animal and human studies have shown that temperature elevations can cause abnormal development and birth defects, so far human studies have not shown a direct causal relationship between diagnostic ultrasound exposure during pregnancy and adverse effects to the developing baby.
However, it must be pointed out that all human epidemiological studies were conducted with commercially available devices predating 1992, with acoustic outputs not exceeding an intensity of 94 mW/cm2.
Current limits in the U.S. have risen dramatically, and now allow intensities of up to 720 mW/cm2 – more than 7 times the limit in 1992. This means we have no large, population-based studies examining the effects of ultrasound at the much higher intensities commonly used today.
This is highly problematic, because, according to a 2001 review called “Guidelines and Recommendations for Safe Use of Doppler Ultrasound in Perinatal Applications“:
When modern sophisticated equipment is used at maximum operating settings for Doppler examinations, the acoustic outputs are sufficient to produce obvious biological effects, e.g. significant temperature increase in tissue or visible motion of particles due to radiation pressure streaming effects. The risk of inducing thermal effects is greater in the second and third trimesters, when fetal bone is intercepted by the ultrasound beam and significant temperature increase can occur in the fetal brain.
A 2007 study reached a similar conclusion:
(1) thermal rather than nonthermal mechanisms are more likely to induce adverse effects in utero, and (2) while the probability of an adverse thermal event is usually small, under some conditions it can be disturbingly high.
Cavitation occurs in tissues with significant pockets of gas (such as the lung and the intestine) after birth. There is no consensus on the significance of cavitation effects in human fetal tissue, but some evidence suggests that mammalian tissue may contain microbubbles that are susceptible to cavitation effects.
Acoustic streaming involves a jet of fluid created by the ultrasound wave, which causes a mechanical shearing force at the cell surface. While the effect of this force is not fully understood, research suggests that it may change cell permeability and have adverse effects on both early and late prenatal and postnatal development.
Animal studies suggest diagnostic levels of ultrasound may cause harm
One study found brain hemorrhages in mouse pups exposed in the womb to pulsed ultrasound at doses similar to those used on human babies.
Another study found exposing adult mice to dosages typical of obstetric ultrasound caused a 22 percent reduction in rate of cell division and a doubling of the rate of apoptosis of cells in small intestine.
Other research has found that ultrasound induces bleeding in the lungs among other mammals, including newborns and young animals.
There exists abundant peer-reviewed published scientific research that clearly and convincingly documents that ultrasound at commercial diagnostic levels can produce lung damage and focal haemorrhage in a variety of mammalian species…. The degree to which this is a clinically significant problem in humans is not known.
I want to be clear: we can’t extrapolate the results of these animal studies to humans, and so far, many longer-term human studies have not shown harm to the fetus from diagnostic ultrasound exposure. However, when the stakes are this high (i.e. the health of our children), I believe the animal study results warrant caution and further study before plowing ahead with ultrasound technology.
Some human studies also suggest harm…
Single or small studies on humans exposed to ultrasound have shown that possible adverse effects include premature ovulation, preterm labor or miscarriage, low birth weight, poorer condition at birth, perinatal death, dyslexia, delayed speech development, and less right-handedness.1
This is especially true for Doppler ultrasound, which is used in specialized scans, fetal monitors and handheld fetal stethoscopes (sonicaids). Ordinary scans use pulses of ultrasound that last only a fraction of a second. The machine uses the interval between pulses to interpret the echo returns. Doppler, on the other hand, uses continuous waves – leading to much higher levels of exposure than with pulsed ultrasound.
A large UK study found that healthy mothers and babies that received two or more Doppler scans to check the placenta had more than 2 times the risk of perinatal death compared to babies unexposed to Doppler.
An Australian study found babies that received more than 5 Dopplers were 30% more likely than babies that received routine (pulsed) ultrasound to develop intrauterine growth retardation (IUGR). This is ironic because Doppler is often used specifically to detect IUGR.
A randomized clinical trial published in 1996 split 2,743 women into two groups: one that received a single doppler at 18 weeks and further scans only when clinically indicated, and another that received 5 Doppler readings during pregnancy. When compared with the regular group, and after adjusting for other confounding variables, babies in the intensive group tended to be shorter when measured at birth and at 2-3 days of age. There were also reductions in the circumferences of the chest, abdomen and mid-arm, and in the skin-fold thicknesses of the triceps, parascapular and subscapular regions – although these differences weren’t statistically significant.
A later study in Lancet found a similar effect on fetal growth in women receiving repeated ultrasound exams, although measures of growth and development later in childhood (up to age eight) were similar in both groups.
A case control study of 72 children who had undergone a formal language evaluation found that children with delayed speech had a higher rate of ultrasound exposure in utero than normal controls. Their findings suggested that a child with delayed speech was twice as likely to have been exposed to prenatal ultrasound. (Note that this is a correlation and doesn’t prove causation.)