Ultrasound markers of fetal chromosomal abnormality: a survey of policies and practices in UK maternity ultrasound departments

Prevalence of defined ultrasound findings of unknown significance at the second trimester fetal anomaly scan and their association with adverse pregnancy outcomes: the Welsh study of mothers and babies population-based cohort

OBJECTIVE

The aim of this article was to estimate the population prevalence of seven defined ultrasound findings of uncertain significance ('markers') in the second trimester and the associated risk of adverse pregnancy outcomes.

METHOD

A prospective record-linked cohort study of 30 078 pregnant women who had second trimester anomaly scans between July 2008 and March 2011 in Wales was conducted.

RESULTS

The prevalence of markers ranged from 43.7 per 1000 singleton pregnancies for cardiac echogenic foci [95% confidence interval (CI): 38.8, 51.1] to 0.6 for mild-to-moderate ventriculomegaly (95% CI: 0.3, 1.0). Isolated echogenic bowel was associated with an increased risk of congenital anomalies [risk ratio (RR) 4.54, 95% CI: 2.12, 9.73] and preterm birth (RR 2.30, 95% CI: 1.08, 4.90). Isolated pelvicalyceal dilatation was associated with an increased risk of congenital anomalies (RR 3.82, 95% CI: 2.16, 6.77). Multiple markers were associated with an increased risk of congenital anomalies (RR 5.00, 95% CI: 1.35, 18.40) and preterm birth (RR 3.38, 95% CI 1.20, 9.53).

CONCLUSIONS

These data are useful for counselling families and developing clinical guidance and care pathways following the detection of markers in clinical practice, particularly the need for follow-up scans to monitor placental function and growth in pregnancies with isolated echogenic bowel, and further investigation for multiple markers. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.

The Welsh study of mothers and babies: protocol for a population-based cohort study to investigate the clinical significance of defined ultrasound findings of uncertain significance

BACKGROUND

Improvement in ultrasound imaging has led to the identification of subtle non-structural markers during the 18 - 20 week fetal anomaly scan, such as echogenic bowel, mild cerebral ventriculomegaly, renal pelvicalyceal dilatation, and nuchal thickening. These markers are estimated to occur in between 0.6% and 4.3% of pregnancies. Their clinical significance, for pregnancy outcomes or childhood morbidity, is largely unknown. The aim of this study is to estimate the prevalence of seven markers in the general obstetric population and establish a cohort of children for longer terms follow-up to assess the clinical significance of these markers.

METHODS/DESIGN

All women receiving antenatal care within six of seven Welsh Health Boards who had an 18 to 20 week ultrasound scan in Welsh NHS Trusts between July 2008 and March 2011 were eligible for inclusion. Data were collected on seven markers (echogenic bowel, cerebral ventriculomegaly, renal pelvicalyceal dilatation, nuchal thickening, cardiac echogenic foci, choroid plexus cysts, and short femur) at the time of 18 - 20 week fetal anomaly scan. Ultrasound records were linked to routinely collected data on pregnancy outcomes (work completed during 2012 and 2013). Images were stored and reviewed by an expert panel.The prevalence of each marker (reported and validated) will be estimated. A projected sample size of 23,000 will allow the prevalence of each marker to be estimated with the following precision: a marker with 0.50% prevalence to within 0.10%; a marker with 1.00% prevalence to within 0.13%; and a marker with 4.50% prevalence to within 0.27%. The relative risk of major congenital abnormalities, stillbirths, pre-term birth and small for gestational age, given the presence of a validated marker, will be reported.

DISCUSSION

This is a large, prospective study designed to estimate the prevalence of markers in a population-based cohort of pregnant women and to investigate associations with adverse pregnancy outcomes. The study will also establish a cohort of children that can be followed-up to explore associations between specific markers and longer-term health and social outcomes.

Facts first, then reaction--expectant fathers' experiences of an ultrasound screening identifying soft markers

BACKGROUND

expectant fathers often attend pregnancy ultrasound but their needs are poorly examined, especially in connection with adverse findings.

OBJECTIVE

to explore men's expectations of routine ultrasound and experiences when soft markers were discovered.

DESIGN/SETTING

a qualitative study at Uppsala University Hospital in Sweden where semi-structured, in-depth interviews were conducted with 17 expectant fathers 6-12 weeks after the discovery of a soft marker at the routine ultrasound scan.

FINDINGS

five major themes emerged: (1) 'immediate reaction: frustration and thoughts about consequences', (2) 'need for facts to gain control', (3) 'concern about the partner', (4) 'in retrospect: almost okay but routines need changing' and (5) 'amniocenteses or not: a joint decision with several considerations'.

CONCLUSIONS AND IMPLICATIONS FOR PRACTISE

these findings contribute important knowledge about men's needs related to pregnancy ultrasound with unexpected findings, and their role in decision-making concerning fetal diagnostics. Our results show that men enter a role of a kind of fact manager and have both a psychological need as well as the capacity to perceive important information during the process following the detection of a soft marker in the fetus. Practitioners conducting pregnancy ultrasound should therefore have relevant knowledge to be able to provide immediate information about soft markers, including risk assessment for chromosomal defects. In addition to this, written information about soft markers should be available to expecting parents in this situation.

Did I really want to know this? Pregnant women's reaction to detection of a soft marker during ultrasound screening

OBJECTIVE

To investigate women's expectations of routine ultrasound and experiences when soft markers were discovered: what the disclosure meant, how it affected them, how they experienced the information given and why they did or did not choose amniocentesis.

DESIGN

Semi-structured, in-depth interviews were conducted with 11 women 25-30 weeks into the pregnancy, 7-13 weeks after the discovery of a soft marker.

FINDINGS

Women lacked knowledge about the potential of the scan and detection of soft markers created strong emotional reactions that women thought could have been alleviated by prior information about potential findings. Information in connection with the scan was perceived as insufficient. Decision about amniocentesis was affected by attitudes to disability, anxiety about fetal loss due to the procedure, need for certainty by a diagnostic test, and partner's opinion.

CONCLUSIONS

Women were shocked by the unexpected and sometimes unwanted information on elevated risk for a chromosomal aberration for which they lacked any preparation. Because this event often has long-lasting effects on the pregnancy, models of information that are efficient in promoting informed decisions are imperative.

PRACTICE IMPLICATIONS

Both women and their partners need relevant information before and in connection with ultrasound scan to be able to make informed choices.

Second trimester prenatal ultrasound for the detection of pregnancies at increased risk of Down syndrome

OBJECTIVE

To determine the association between second trimester ultrasound findings (genetic sonogram) and the risk of Down syndrome.

METHODS

Prospective population-based cohort study of women who were at increased risk of chromosome abnormality based on serum screening.

RESULTS

Overall 9244 women with singleton pregnancies were included, including 245 whose fetuses had Down syndrome. Overall, 15.3% of the women had an abnormal genetic sonogram, including 14.2% of pregnancies with normal fetuses and 53.1% of those with Down syndrome. If the genetic sonogram were normal, the risk that a woman had a fetus with Down syndrome was reduced (likelihood ratio 0.55 [95% CI 0.49, 0.62]) However, if the normal genetic sonogram were used to counsel these high-risk women that they could avoid amniocentesis, approximately half of the cases of Down syndrome (115 of 245) would have been missed. The isolated ultrasound soft markers were the most commonly observed abnormality. These were seen in a high proportion of Down syndrome fetuses (13.9%) and normal fetuses (9.3%). In the absence of a structural anomaly, the isolated ultrasound soft markers of choroid plexus cyst, echogenic bowel, renal pyelectasis, clenched hands, clinodactyly, two-vessel umbilical cord, short femur, and short humerus were not associated with Down syndrome. Nuchal fold thickening was a notable exception, as a thick nuchal fold raised the risk of Down syndrome even when it was seen without an associated structural anomaly.

LIMITATIONS

All women included in this study were at high risk of Down syndrome based on serum screening, and thus the results of this study cannot be used as a basis to modify maternal age-related risk.

CONCLUSIONS

The accuracy of the genetic sonogram is less than previously reported. The genetic sonogram should not be used as a sequential test following serum biochemistry, as this would substantially reduce the prenatal diagnosis of Down syndrome cases. In contrast to prior reports, most isolated soft markers were not associated with Down syndrome.

Ultrasound screening in pregnancy: advancing technology, soft markers for fetal chromosomal aberrations, and unacknowledged ethical dilemmas

Fetal ultrasound screening has become routine practice in many western countries. During the last decade, such screening has led to frequent situations characterised by clinical uncertainty due to the disclosure of soft markers in the unborn child. Soft markers are minor anatomical variations indicating a somewhat increased likelihood that the fetus has a chromosomal aberration, most frequently trisomy 21 (Down syndrome). This paper presents the results of a comprehensive literature search of the National Library of Medicine with emphasis on the chronological development of scientific knowledge in relation to soft markers and the link between advancing imaging technology and clinical counselling dilemmas. An analysis of the literature makes evident that many ultrasound examiners have counselled individual pregnant women on the basis of insufficient data. Moral dilemmas have thus emerged as a direct result of advancing medical technology, and healthy fetal lives prove to have been lost due to invasive diagnostic testing aimed at resolving clinical uncertainty. Ultrasound examiners have warned against a policy of disclosing all findings of soft markers to expectant parents, but no exploration of experiential aspects linked to the disclosure of fetal soft markers has yet been published in the medical literature. The emotional reactions of mothers are important to consider given their potential impact on the biological development of the fetus. In conclusion, this paper stresses the need for paying close attention to the crucial distinction between technology development and technology implementation in relation to prenatal testing. Furthermore, it provides strong arguments for scrutinising the interface between prenatal testing and human experience.

Use of genetic sonography for adjusting the risk for fetal Down syndrome

Systematic evaluation of ultrasound findings known to be associated with trisomy 21, at an appropriate gestational age, has been referred to as a genetic sonogram. A number of high-risk centers performing genetic sonography have reported detection of ultrasound abnormalities in the majority of fetuses with fetal Down syndrome. However, nonspecific markers are more commonly observed than structural abnormalities, which are detected in less than 20% of cases in a nonselected population. Also, the actual sensitivity of a genetic sonogram will depend on various factors including the markers sought, gestational age, reasons for referral, and of course the quality of the ultrasound. Appropriate use of a genetic sonogram can help to modify the risk of fetal Down syndrome by decreasing the risk when the ultrasound is normal, or increasing the risk when specific ultrasound markers are detected. The postultrasound risk can be estimated by applying specific likelihood ratios, reflecting the strength of individual markers, with the a priori risk based on maternal age alone, or combined with biochemical markers when known. We review this approach of age-adjusted ultrasound risk assessment for fetal Down syndrome and illustrate how the risk can be estimated. Individual sonographic markers are also discussed.

Antenatal detection of a single umbilical artery: does it matter?

The presence of a single umbilical artery is recognised as a soft marker for congenital anomalies, aneuploidy, earlier delivery and low birthweight. Most of the available data are derived from case series or highly selected populations and are therefore likely to be unrepresentative. In this retrospective case-comparison study, we firstly aimed to determine the incidence of a single umbilical artery in an unselected population and secondly to examine the clinical significance of this soft marker. Over a 40-month period, 107 cases were identified from a cohort of 35 066 births giving an incidence of 3.1 per 1000 total births and late pregnancy losses. The antenatal detection rate was only 30%. Compared to fetuses with normal cord vasculature, fetuses with a single umbilical artery were more likely to be delivered at an earlier gestation and to weigh less, were 1.7 times more likely to be delivered by a Caesarean section and 19% of the cases had a congenital anomaly. The perinatal mortality was 49.0 per 1000 total births, which was 6 times higher than the background hospital rate. The presence of a single umbilical artery is associated with a poorer perinatal outcome compared to that in fetuses with three vessels in the cord. Unfortunately, the antenatal detection rate is poor. Recognising the importance of this soft marker in counselling and management of pregnancies should provide the stimulus to improve detection rates.

Psychological impact of the detection of soft markers on routine ultrasound scanning: a pilot study investigating the modifying role of information

OBJECTIVES

To determine the impact on maternal anxiety of detecting a soft marker, and the association between anxiety and the information given during the scan.

METHODS

Routine 20-week fetal anomaly scans were audiotaped in the obstetric ultrasound unit of a London teaching hospital, across a four month study period. The study sample comprised 28 pregnant women: 14 in whom a soft marker was detected and a comparison group of 14 women in whom no marker was identified. Telephone interviews were conducted within one week of the scan, at 30 weeks' gestation, and one month after the birth of their children. The main outcome was anxiety, assessed using a standardized scale. Information provided during the scan was coded from transcripts.

RESULTS

In the week following the scan, women with soft markers had clinically significant levels of anxiety. At 30 weeks' gestation and one month post-partum their levels were within the normal range. Women who were told during their scan that their baby would probably be all right, compared with women not told this, were significantly less anxious and worried about their baby.

CONCLUSIONS

Results from this small longitudinal study suggest that the detection of soft markers on routine prenatal ultrasound causes considerable short-term anxiety for women and that providing reassurance during the scan may prevent some of this anxiety.