Effectiveness of 12-13-week scan for early diagnosis of fetal congenital anomalies in the cell-free DNA era

OBJECTIVES

The main aim of this study was to assess the proportion and type of congenital anomalies, both structural and chromosomal, that can be detected at an early scan performed at 12-13 weeks' gestation, compared with at the 20-week structural anomaly scan offered under the present screening policy. Secondary aims were to evaluate the incidence of false-positive findings and ultrasound markers at both scans, and parental choice regarding termination of pregnancy (TOP).

METHODS

Sonographers accredited for nuchal translucency (NT) measurement were asked to participate in the study after undergoing additional training to improve their skills in late first-trimester fetal anatomy examination. The early scans were performed according to a structured protocol, in six ultrasound practices and two referral centers in the north-east of The Netherlands. All women opting for the combined test (CT) or with an increased a-priori risk of fetal anomalies were offered a scan at 12-13 weeks' gestation (study group). All women with a continuing pregnancy were offered, as part of the 'usual care', a 20-week anomaly scan.

RESULTS

The study group consisted of 5237 women opting for the CT and 297 women with an increased a-priori risk of anomalies (total, 5534). In total, 51 structural and 34 chromosomal anomalies were detected prenatally in the study population, and 18 additional structural anomalies were detected after birth. Overall, 54/85 (63.5%) anomalies were detected at the early scan (23/51 (45.1%) structural and all chromosomal anomalies presenting with either an increased risk at first-trimester screening or structural anomalies (31/34)). All particularly severe anomalies were detected at the early scan (all cases of neural tube defect, omphalocele, megacystis, and multiple severe congenital and severe skeletal anomalies). NT was increased in 12/23 (52.2%) cases of structural anomaly detected at the early scan. Of the 12 cases of heart defects, four (33.3%) were detected at the early scan, five (41.7%) at the 20-week scan and three (25.0%) after birth. False-positive diagnoses at the early scan and at the 20-week scan occurred in 0.1% and 0.6% of cases, respectively, whereas ultrasound markers were detected in 1.4% and 3.0% of cases, respectively. After first- or second-trimester diagnosis of an anomaly, parents elected TOP in 83.3% and 25.8% of cases, respectively.

CONCLUSIONS

An early scan performed at 12-13 weeks' gestation by a competent sonographer can detect about half of the prenatally detectable structural anomalies and 100% of those expected to be detected at this stage. Particularly severe anomalies, often causing parents to choose TOP, are amenable to early diagnosis. The early scan is an essential part of modern pregnancy care. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Prevalence, diagnosis and outcome of cleft lip with or without cleft palate in The Netherlands

OBJECTIVE

To examine the accuracy and timing of diagnosis of fetal cleft lip with or without cleft palate (CL ± P) in the years following the introduction of a national screening program, and to assess the completeness and accuracy of information in The Netherlands Perinatal Registry.

METHODS

A list was obtained of cases with a prenatal or postnatal diagnosis of CL ± P from two fetal medicine units between 2008 and 2012. All cases of CL ± P were included irrespective of the presence or absence of additional anomalies. Cases were included if the estimated date of delivery was between 1 January 2008 and 31 December 2012.

RESULTS

During the study period, 330 cases of CL ± P were identified, with a prevalence of 15 per 10 000 pregnancies. The number of cases that were detected before 24 weeks' gestation increased during the study period, while the rate of termination of pregnancy did not change significantly (P = 0.511). CL ± P was isolated in 217 (66%) cases and karyotype was abnormal in 69 (21%) cases. In 5% of the cases in which CL ± P seemed to be isolated during the 18-23-week anomaly scan, postnatal array comparative genomic hybridization (array-CGH) revealed an abnormal karyotype and 50% of these cases had major additional anomalies. Examination of data from The Netherlands Perinatal Registry demonstrated that in 37% of cases CL±P was not recorded in the pregnancy records.

CONCLUSION

CL ± P is increasingly being diagnosed prenatally, without a significant effect on the rate of pregnancy termination. Further improvement in the diagnostic accuracy may be achieved by advocating prenatal array-CGH to reduce the frequency of unexpected anomalies being diagnosed after birth. It is important that healthcare providers register accurately the presence or absence of anomalies in the birth records to ensure that, in the future, data from The Netherlands Perinatal Registry can be relied upon to monitor prevalence. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Timing of detection of anencephaly in The Netherlands

OBJECTIVE

The objective of this study is to assess the gestational age at detection and prevalence of anencephaly in the North of The Netherlands over a 5-year period.

METHODS

A case list of all cases of anencephaly from two fetal medicine units was compiled. Cases were included if the estimated due date was between 1 August 2008 and 31 July 2013.

RESULTS

Overall prevalence of anencephaly was 5.4 per 10.000 pregnancies (n = 110). The majority of cases (69%) was detected before 18 weeks' gestation. Factors determining successful early diagnosis were competence level of the sonographers, with a significantly higher detection rate when scans were performed by a sonographer licensed by the Fetal Medicine Foundation (FMF) for nuchal translucency measurement (p = 0.001), and gestational age at or beyond 11 weeks of gestation (p = 0.024).

CONCLUSION

Improving detection of anencephaly in the first trimester requires ultrasound screening at or after 11 weeks of gestation, performed by experienced sonographers trained in recognizing fetal anomalies. Sonographers should be instructed that the goal of the first trimester scan is not only to measure nuchal translucency thickness but also to exclude major anomalies.

Impact of introduction of mid-trimester scan on pregnancy outcome of open spina bifida in The Netherlands

OBJECTIVE

To examine the impact of introduction of the mid-trimester scan on pregnancy outcome in cases of open spina bifida in two regions of The Netherlands.

METHODS

This was a retrospective cohort study of 190 cases of open spina bifida diagnosed pre- or postnatally, with an estimated date of delivery between 2003 and 2011.

RESULTS

With implementation of the mid-trimester scan the percentage of cases of open spina bifida detected before the 24(th) week of pregnancy increased from 43% to 88%. The rise in prenatal detection rate was associated with a significant increase in the number of terminated pregnancies and a decrease in the rate of perinatal loss; the percentage of children born alive did not change significantly. In the subgroup that underwent a scan between 18 and 24 weeks of pregnancy, cranial signs were present in 94.4% of cases.

CONCLUSION

Introduction of the mid-trimester scan has led to an increase in early identification of pregnancies complicated by open spina bifida. Pregnancies previously destined to end in perinatal loss are now terminated whilst pregnancies with a relatively good prognosis are frequently continued; the number of children with open spina bifida who are born alive has not changed significantly. Our study confirms that prenatal diagnosis is usually triggered by visualization of a lemon-shaped skull or a banana-shaped cerebellum.