The Obstetric special issue

Abstract

This obstetric special issue features seven of the best papers on the subject published in Ultrasound prior to 2010 and will be of interest to all members involved in the scanning of pregnant women. The publication dates of the papers range from May 2006 to November 2008 and cover topics ranging from early embryonic heart detection and the role of ultrasound in early pregnancy detection, through fetal heart imaging, vasa praevia, and placenta accreta to overviews of neural tube defects and the value of obstetric ultrasound. The range and depth of subject matter covered provides not only an excellent aide memoire for the experienced sonographer but also an opportunity to reflect on the changes in practice that have taken, and continue to take place, within the specialty. A word of warning, therefore, for readers who are students or relatively new to obstetric ultrasound – clinical practice in Norway in 2006 should not be taken as representative of routine practice in the UK either in 2006 or indeed 2010. In addition, the publication of the Fetal Anomaly Screening National Standards in January this year has changed the interpretation of appearances previously known as soft markers. These two papers in particular allow us all to reflect on the importance of assessing information within its appropriate context and at the time of its writing. The natural tendency to accept the printed word without question when published in a high quality journal such as Ultrasound is, as we know (or hope), an anathema to the reflective health professional. The articles by Meire, Daly-Jones et al. and Coady should encourage the reader to reflect on the contribution that diverse views and strong opinions make to the ultrasound community. Each paper expresses statements which the reader may find challenging, infuriating, incorrect or at odds with his or her own opinions and/or clinical practice. Acharya’s paper provides a wide ranging overview of neural tube defects (NTD), concentrating principally on open spina bifida. The discussion on prenatal diagnosis includes both ultrasound imaging and amniocentesis, the authors’ views on the latter being, I would suggest, a reflection of clinical practice in Norway rather than those of the UK in 2006. It is refreshing to be given a brief overview of the genetic factors underlying the condition and its recurrence risks, together with new methods being used to define the molecular basis of NTD. As Ramsey and Shilitto comment, it is indeed surprising that, 12 years after the RCOG/RCR published guidelines for early pregnancy ultrasound, so few reports of primary studies investigating heart activity in the very early embryo have been published. The authors attempt to address this shortfall with the study of 95 embryos scanned between approximately 5 weeks 2 days and 6 weeks 3 days. Cardiac activity was seen across a crown rump length (CRL) range of 1.4–6.0 mm. Miscarriage was subsequently confirmed in all embryos in which no cardiac activity was seen (CRL range of 1.2–6.0 mm). The authors concluded that cardiac activity should be identified in all live embryos as soon as the embryo can be reliably identified and that, conversely, the absence of heart activity is indicative of pregnancy demise, irrespective of the CRL. Although this is a comparatively small study, their conclusions are of practical significance in early pregnancy management. The early pregnancy theme continues with Coady’s detailed interpretation of early pregnancy issues, her article being an extension of the question and answer session held at the BMUS Annual Scientific Meeting (ASM) in 2007. Twelve questions were posed at the ASM and their answers form the basis of the paper’s discussion. The ultrasound features, significance and clinical management of subchorionic haemorrhage, secondary yolk sac, embryonic heart activity and pregnancy of unknown location are discussed and illustrated with 19 informative ultrasound images. Coady has firm views which she expresses clearly and succinctly. The management pathway which is alluded to may be familiar to some and questioned by others, providing an ideal topic for further local discussion. The overview of vasa praevia authored by Daly-Jones et al. provides invaluable reading for any sonographer unfamiliar with this condition. The outcome of undiagnosed vasa praevia is likely to result in fetal exsanguination or death due to asphyxiation. Although it is a relatively rare condition, vasa praevia can be excluded by identifying the cord insertion within the body of the placenta and excluding any placental tissue in the proximity of the cervix. The authors present a simple algorithm which includes imaging the lower uterus and cervix with colour Doppler, to exclude the presence of fetal vessels close to or crossing the cervix. They further recommend incorporating this algorithm into routine practice – a recommendation that has subsequently been incorporated into the Society and College of Radiographers’ Guidelines for Professional Working Standards.