Prenatal Ultrasound

Through a comprehensive review of the literature it has been found that on its own prenatal ultrasound exposure is not a cause of autism. Although previously performed studies reported a link between autism and ultrasound exposure the results have not been replicated. More recently performed studies have found that those exposed to ultrasound prenatally have the same risk of developing autism as those unexposed. Based on the results of such research studies as Grether et al. and Stalberg et al. it is recommended that prenatal ultrasound use be continued for medical reasons during pregnancy. The minimal number of scans necessary should be performed to ensure the pregnancy is progressing normally.
While the majority of studies found no link between prenatal ultrasound exposure and ASD further research is still needed into the topic. Most of the studies discussed were performed in the late nineteen nineties with follow-ups on the children being done more recently. The output capabilities of ultrasound machines as well as medical guidelines for ultrasound use have changed since then. Ultrasound use should remain limited in pregnancy with only necessary scans being performed until this research has been completed. In addition to the research discussed another risk of ultrasound exposure is tissue heating which
can be a cause of concern associated with prenatal ultrasounds. Most cavitational and thermal effects that cause increased tissue heating are relatively negligible with medical scans. However, with the increasing popularity of keepsake ultrasounds these effects may become more of a problem. Keepsake ultrasound scans consist of long ultrasound scans to capture the fetus in many positions and sometimes can include up to a 2 hour long video. This increased scan time causes increased tissue heating and cavitational effects, which can cause adverse effects to the patient. The FDA warns expectant mothers to avoid these keepsake ultrasound scans as well as other at home Doppler heartbeat monitors. The unregulated use of ultrasound is discouraged and scans should be only be performed by trained professionals.
While discussing possible harmful effects of prenatal ultrasound exposure, one study suggested that ultrasound might not be a cause, but a determining factor in the development of ASD.
Ultrasound may become the stressor that causes development of ASD if exposure occurs during a specific time period of vulnerability during pregnancy to a genetically susceptible fetus (Williams and Casanova, 2010). This concept is important because if it can be proved legitimate we can then narrow down the specific window of time where fetuses are most susceptible to teratogenic effects from ultrasound and then ensure that ultrasounds are not given during this time
period.
Another important point is faulty transducer use and the need to better educate end-users. Surveys of end users found that 82 % lacked adequate understanding of the thermal index, 96% failed to demonstrate appropriate understanding of the mechanical index and only 20% knew where these safety indices were located on the machines (Williams and Casanova, 2012). This poses considerable risks to patient safety and more training regulations must be put into place to ensure patients are receiving the lowest necessary doses of exposure and that users know how to achieve this. Studies performed on transducer error rates found that all companies who provided machines had an error rate of at least 20%, with some being much higher (Williams and Casanova, 2014). Transducer errors can affect image quality causing the end-user to increase the intensity (Williams and Casanova, 2012). Faulty equipment can lead to exposures reaching harmful levels, which can cause adverse effects to the patient, in this case fetus.