Soft markers: where are we now?

Abstract 

With high resolution ultrasound, it is possible to examine fetal anatomy in great detail. The quality of images obtained today is such that minor deviations from normal can often be clearly identified. Whilst the relationship of major anomalies with genetic syndromes and karyotypic abnormalities is clear, the importance of more subtle ultrasound findings – which are often so common as to be considered a normal variant – has remained confusing. These subtle findings, or soft markers, frequently resolve as gestation increases. The degree to which such markers increase the risk of aneuploidy has always been controversial, the lack of clarity being primarily related to the initial reports of associations in high-risk cases, with the strength of association usually weakened or indeed negated in studies of low-risk populations. The National Screening Committee in England has recently provided guidance on this issue, and this review offers practical advice on management of pregnancies where soft markers are detected. Isolated soft markers, with the exception of increased nuchal fat pad, should not be used to adjust the a priori risk of Down’s syndrome.

Keywords: aneuploidy, anomaly, chromosomes, fetal, ultrasound