Ultrasound Machine

Risks and Safety

Part: 1 | 2 | 3 | 4 | 5

Part of the ultrasound machine safety guide....

Why be anxious about left-handed boys?

If the only determined finding of neonatal 3D 4D ultrasound is more left-handed boys, why worry?

There are two main answers to this question.

Firstly, statistics show that left-handedness is linked to a number of cognitive and developmental problems varying from learning difficulties to autism to epilepsy.

ultrasound risk

Secondly, a number of researchers suggest that a rising number of left-handedness may mean that other types of minor brain damage also arise. According to a medical reporter, the rise in left-handedness associated with exposure to ultrasound in the womb could be the result of subtle brain damage. He suggests that this subtle damage may actually cause people who ought genetically to be right-handed to become left-handed.

These findings were based on health data regarding children whose mothers underwent lower-voltage scanning in the late 1970s and early 1980s. But average ultrasound machine exposure levels had risen significantly by the mid-1990s. In 2003, the ECMUS Safety Committee commented that time-averaged values of intensity in the most commonly used ultrasound scanning mode, “are now up to 1000 times greater than those reported in the 1970s.”

It is now necessary for scientists to repeat the left-handedness studies, along with studies of other possible effects, on this younger, more intensively exposed population. As yet, no such follow up studies have been undertaken. Therefore, claims that “there has never been a harmful effect shown” simply cannot be used with regard to today’s ultrasound equipment.

FDA Reduces Oversight Whilst Increasing Risk Levels

In 1993, the FDA raised the maximum output of ultrasound machines used in obstetrics by eight times what it was previously, from 94 up to 720 milliwatts per square centimeter.

The FDA was persuaded that prenatal sonogram operators needed more flexibility, particularly when confronting life-and-death situations such as determining blood flows in tiny coronary arteries during an ongoing heart attack.

Ultrasound Machine Questions

At the time, questions were raised regarding the exposure ceiling. The FDA began requiring that manufacturers add two on-screen safety indexes. One measuring the heating of bone or tissue; the other “mechanical” effects, including cavitation caused by the expansion of gas bubbles, sheering forces within tissues, and induced flows within fluids.

The FDA expected that well trained sonographers using the on-screen safety indexes in the correct manner would not subject patients to higher levels of ultrasound exposure than they did under the previous system of regulation. However the FDA failed to ensure that sonographers were properly trained.

Ultrasound machine experts suggest that the training actually received by sonographers training is entirely inadequate. Dr. Jacques Abramowicz, Professor of Obstetrics and Gynecology and Radiation at the University of Chicago, stated, “Only two to three percent of the population doing ultrasound really know what the thermal index and the mechanical index mean.”

Even trained operators are baffled by the complex nature of interactions between sound waves and human tissues, the ways various ultrasound modes affect exposure, and the differing responses caused in various parts of the body. For instance, bones respond differently than muscles.

Bone is particularly sensitive to ultrasound heating: the skull of a third-trimester fetus heats up fifty times more quickly than brain tissue during exposure to 3D ultrasound. Therefore brain structures which lie near to the skull, such as the pituitary and the hypothalamus, are at particular risk of secondary heating from the ultrasound machine.

Continue to part four...

Return from Ultrasound Machine to Main Page