Ultrasound is being increasingly used for non-medical reasons, however, in the first 10 weeks of pregnancy it should be performed only when clinically indicated, advises a new Scientific Impact Paper (SIP) published today by the Royal College of Obstetricians and Gynaecologists (RCOG).
SIPs are produced by the Scientific Advisory Committee at the RCOG and are up-to-date reviews of emerging or controversial scientific issues of relevance to obstetrics and gynaecology.
Ultrasound is the most widely used medical imaging method during pregnancy and has become central in the management of the problems of early pregnancy, particularly in the management of women after assisted conception, those where miscarriage is feared and those in whom ectopic pregnancy is suspected.
The opinion paper addresses the issues of ultrasound exposure in the first 10 weeks of gestation, known as the embryonic period, in light of the most current evidence and guidance from national and international ultrasound safety committees and organisations. Both medical and non-medical use are considered.
The paper highlights that there is no evidence that repeated exposure to ultrasound has cumulative and/or detrimental effects. However, the first 10 weeks of gestation is a time of potential vulnerability as the embryo is very small and cell division is most rapid during this period. Additionally, fetal blood flow is limited as the fetal-placental circulation is established after 11 weeks of gestation, meaning a potential vulnerability to thermal stress.
With a lack of epidemiological data, the authors adopt a precautionary approach and state that they do not endorse the use of ultrasound in this early stage of pregnancy unless clinically indicated or within the context of a research study.
The paper highlights the various types of ultrasound, including B-mode (the most commonly used form of ultrasound in obstetrics), colour and pulse wave Doppler. Colour and pulsed wave Doppler involve greater average intensity and power outputs than B-mode and are not recommended at all during the embryonic period of development conclude the authors.
Additionally, there has been a move to perform 3D and 4D ultrasound scans earlier in pregnancy, states the paper. 4D ultrasound is ‘real time’ 3D and is associated with higher power outputs than 2D as the scanning time is longer, typically by several minutes. However, 3D ultrasound allows the rapid acquisition of a ‘volume’ for later off line analysis and may in fact be associated with lower exposure time.
The authors of the paper do not recommend the use of ultrasound including 4D for the sole purpose of souvenir images or video recordings in the embryonic period.
The authors of the SIP also call for inclusion of the safety aspects of ultrasound in all educational activities concerning ultrasound diagnosis.
Dr Christoph Lees, Reader in Obstetrics and Fetal Medicine at Imperial College London and lead author of the paper said:
“Ultrasound scanning in the embryonic period is an invaluable resource in several important scenarios where the embryo is at possible risk.
“While there are presently no grounds for questioning the safety of diagnostic ultrasound in this context, ultrasound imaging is increasingly being used without obvious medical justification and the possibility of subtle long-term adverse effects should be kept in mind, particularly in the first weeks of gestation when the embryo is potentially the most vulnerable.”
Dr Sadaf Ghaem-Maghami, Chair of the RCOG’s Scientific Advisory Committee, added:
“B-mode ultrasound used for clinical reasons from conception to 10 weeks of gestation is safe and the benefits outweigh any theoretical risks. We are adopting a precautionary approach and are highlighting the small but possible risks to women so that they can make informed choices.
“We also emphasise that any healthcare professional involved in the use of ultrasound is aware of the safety principles of ultrasound. These have now been included within the RCOG ultrasound curriculum.”
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Read the Ultrasound Scientific Impact Paper key messages.
About RCOG Scientific Impact Papers
RCOG Scientific Impact Papers (formerly SAC Opinion papers) are produced by the Scientific Advisory Committee. They are up-to-date reviews of emerging or controversial scientific issues of relevance to obstetrics and gynaecology, together with the implications for future practice. These documents have been rebranded to raise awareness of the issues in obstetrics and gynaecology discussed in the documents and to more accurately reflect their content and remit of the Committee.