Parents warned over 'souvenir' baby scans Print
While ultrasound scans are “entirely justifiable and safe, the Health Protection Agency (HPA) is concerned about ‘boutique’ scanning”.

This is the appropriate sound advice at the current time. Ultrasound has been used for diagnostic purposes for 50 years quite safely and is an important tool in many areas of medicine. However, with the increasing demand for unnecessary souvenir pictures (i.e. not the routine antenatal scans) using ultrasound, unknown risks may be introduced. The HPA states, further research is needed to clarify these risks.  In the meantime, parents should consider carefully whether these unknown risks justify having a keepsake enhanced photo of their developing baby.

 
What is ultrasound?
Ultrasound images are produced from echoes formed when high frequency sound waves bounce off body organs.  Different tissues in the body are characterised by differences in amplitude, arrival times and frequency of echoes, with highly reflective structures such as bone giving the brightest spots on the ultrasound scan.

Where has this advice come from?

The advice regarding souvenir keepsake images or ‘real time’ ultrasound scans that have no diagnostic benefit has been issued by the Health Protection Agency (HPA).

Their advice is based on a review of the evidence on the health effects of ultrasound (frequency above 20 kilohertz) and infrasound (frequency below 20 kilohertz). It eas carried out by the independent Advisory Group on Non-Ionising Radiation (AGNIR), which reports to the HPA.

The main finding is that there is no evidence that ultrasound increases the risk of mortality or cancer to the developing foetus. However, there are some unconfirmed reports that ultrasound could affect the developing nervous system, potentially affecting what would be the child’s natural handedness (i.e. whether they are right or left-handed).

Unlike diagnostic scans which provide a basic image and opportunity for measurements of the baby’s growth and development, ‘souvenir scans’ show detailed 3D facial images or recordings of the baby’s movement in the womb and require a longer and more intense ultrasound exposure.

 
What is contained in the AGNIR report?

The main points of the report are:

    * When used for diagnostic medical purposes, which are generally infrequent and for short periods of time, ultrasound does not cause heating or cavitation damage (formation of cavities) in tissues, which can occur with higher levels of exposure.
    * A single study in pregnant mice has observed that ultrasound used at similar levels to those used in medical practice affected the developing nerve cells in the unborn mouse brain. However, the significance of these changes is not known and the study has not been repeated.
    * Ultrasound evidence in humans has mainly been concerned with exposures within the womb. No evidence that ultrasound affects mortality around the time of pregnancy or birth or has any effect on childhood cancers has been found in these studies. In randomised-controlled trials there has been ‘weak evidence’ that it may affect whether a child is right or left handed.  This may be the result of confounding, rather than actual causation.
    * When looking at the available evidence for the health effects of low frequency infrasound, (produced by aircraft, trains, thunderstorms, wind, waves and certain machines) there is sparse research. There are also no confirmed biological effects, although at levels above 140dB, hearing damage can occur, i.e. ear pain or ear drum rupture. Infrasound also has no clear physiological or behavioural effects on humans. Overall, the researchers consider there to be little evidence that infrasound exposure affects humans and no information on its long-term effects.
    * Although there are recognised adverse effects from overexposure to ultrasound and infrasound, guidelines and protocols are in place to minimise or avoid this when it is used for medical purposes. Despite there being “no established evidence of specific hazards” however, there is too little evidence to draw firm conclusions about its long-term effects.
    * When regarding diagnostically unnecessary souvenir foetal imaging scans, the unconfirmed reports of possible neurological effects mean there is a need for further research into possible adverse effects.

 
What are the conclusions?

AGNIR state there is no conclusive evidence that ultrasound is dangerous to the developing baby. However, it is recognised further research is needed to determine if there are any long-term adverse health effects. The chairman of AGNIR, Professor Anthony Swerdlow said, ‘Ultrasound has been widely used in medical practice for 50 years, and there is no established evidence of specific hazards from diagnostic exposures. However, in the light of the widespread use of ultrasound in medical practice, its increasing commercial use for souvenir foetal imaging, and the unconfirmed indications of possible neurological effects on the foetus, there is a need for further research on whether there are any long-term adverse effects of diagnostic ultrasound.'

In response, the HPA said, “parents-to-be should not hesitate to continue taking advantage of ultrasound scans for diagnostic purposes. However they should consider the uncertainties when deciding whether to have ultrasound scans that do not have a defined diagnostic benefit and provide only keepsake images or ‘real time" scans’.”

 
Conclusion

Ultrasound has a long history of use in medical, surgical and antenatal care.  In pregnancy, ultrasound remains the safest way of looking at the developing baby without using radiation and the associated risks.

As the HPA says, there is little evidence of the longer-term health effects of ultrasound exposure to developing babies. However, the fact that antenatal ultrasounds have been used for several decades without any apparent ill effects is encouraging. The evidence of a neurological effect of ultrasound comes from a few animal and human studies that are viewed as inconclusive and not exhaustive enough by the HPA.

Expectant parents can be reassured that routine diagnostic ultrasound scans (performed at 10-13 and 18-20 weeks of pregnancy) are safe. They can provide the baby’s definite gestational age, identify multiple pregnancies, inform about the baby’s growth, placental health, and identify any potential problems and developmental or structural abnormalities. Outside of pregnancy, people should also not be concerned when undergoing ultrasounds to help with the diagnosis of medical conditions. However, ‘souvenir scans’, which provide detailed life-like images of the developing baby as keepsakes for the parents, serve no diagnostic or clinical purpose. Compared to diagnostic scans, whether as part of antenatal or medical care, ‘souvenir scans’ require prolonged and more intense ultrasound exposure. As such, they represent an increased, potential risk to the developing baby that cannot be weighed against any necessary medical benefit.

The HPA advises that although there is no clear evidence that souvenir scans are harmful to the foetus: “parents-to-be must decide for themselves if they wish to have souvenir scans and balance the benefits against the possibility of unconfirmed risks to the unborn child”. This is sensible advice and the most appropriate offered at the current time.

Research into the safety of ultrasound is continuing, both in the UK and internationally.