A patient expecting their first child recently asked me about prenatal ultrasounds.  Allow me to “sound off” on this “ultra-important” topic.

Prenatal ultrasounds have become commonplace in the United States, even to the point of the popularization of “ultrasound parties” and “3-D ultrasound bonding services” which seem to treat this technology with the kind of blithe naiveté that we once treated x-rays.  This is despite the fact that the American Academy of Obstetricians and Gynecologists have officially recommended against routine prenatal ultrasounds (OBGYN 5, Aug.1997).

Some of you may be old enough to remember that shoe stores used to have x-ray machines in them as a gimmick to optimally analyze the proper size and shape of the foot.  No maximum exposure limits were set on the devices, and kids could, and did flock to the shoe store to look at their feet under x-rays as they wiggled their toes.  Pregnant patients were routinely x-rayed (for example, Dr. Julieta was exposed while in the womb.  She and her twin were subsequently born extremely premature and barely survived).

That kind of radiation today would be criminal, because we now know how dangerous and damaging x-ray radiation can be.  Ultrasound is a different kind of radiation, but it is, however, listed in the FDA website under “Radiation-Emitting Products and Procedures” and, like any medical technology, not without risks.  Let’s look at some Ultrasound facts:


Of some concern is the fact that, like x-rays of old, There are currently no standards  to prevent overexposure to Ultrasound radiation.

The ultrasound’s ability to effectively screen for abnormalities has been notoriously poor.  Ob-Gyns in Michigan found that preterm labor rates were DOUBLE in women with weekly US vs Pelvic exam only (Lorenz et. Al. 1990).  A large, randomized study in Helsinki of 9,000 women found 20 miscarriages  in the scanned group and 0 in the control group.  Another study of 4,000 women scanned at 16-20 weeks found 250 cases of placenta previa (where the placenta is attached close to the cervix) and only 4 cases where the placenta did not self correct by delivery.  The same number of women in the un-scanned group presented with placenta previa at delivery, and there was no difference in outcome between the groups.  In other words, the proposed intention and benefit to the mother and baby was not supported by the data.  Another study published in the medical journal Lancet concluded that detection of placenta previa with ultrasound was no safer than detection in labor.

Here is what the FDA has to say about ultrasounds:

Even though there are no known risks of ultrasound imaging, it can produce effects on the body. When ultrasound enters the body, it heats the tissues slightly. In some cases, it can also produce small pockets of gas in body fluids or tissues (cavitation). The long-term effects of tissue heating and cavitation are not known. (my emphasis)

Because of the particular concern for fetal exposures, national and international organizations have advocated prudent use of ultrasound imaging. Furthermore, the use of diagnostic ultrasound for non-medical purposes such as fetal keepsake videos has been discouraged.

All of this is not to suggest that there is no use or place for prenatal Ultrasounds, but only to remind patients that Ultrasounds are radiation-emitting devices that have known as well as unknown risks to the fetus and the mother.  Therefore, a prudent, evidence-based risk/benefit analysis should be conducted before allowing this procedure to be performed on any particular patient.  I recommend being very skeptical about any physician who endorses the routine administration of ultrasounds without clear clinical indication of need and benefit which outweighs the risk.  It is our opinion that in the case of the vast majority of healthy pregnancies, this tool is contraindicated and ultrasounds should be avoided at all costs.  If an ultrasound is recommended, we suggest the physician to produce compelling epidemiological evidence to support the risk of the procedure.  And in all cases, we urge patients to NEVER participate in the use of ultrasound for the purposes of bonding, determination of gender, or other social justifications.

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