Dedicated First‐Trimester Anomaly Scan in a National Prenatal Screening Program and Timing of Diagnosis: The Prospective IMITAS Cohort Study

BJOG An International Journal of Obstetrics & Gynaecology, vol. 133, pp. 1373–1380

Abstract

OBJECTIVE: To determine the diagnostic yield of a nationally implemented first-trimester anomaly scan (FTAS), compared to standard obstetric care with a second-trimester anomaly scan. DESIGN: Prospective observational cohort study. SETTING: Nationwide prenatal screening program in the Netherlands. POPULATION: Pregnant women referred for suspected fetal anomalies with subsequent abnormal diagnostic scans in 2021-2022. METHODS: All fetal diagnoses < 18 weeks' gestational age (GA) were registered: 8 months before (BEFORE) and 1 year after (AFTER) FTAS implementation. BEFORE-cohort: referrals after routine scans (e.g., dating scans). AFTER-cohort: all referrals, including FTAS. Corrections were made for missing referrals < 12 + 3 weeks in the AFTER-cohort. Time adjustment was made in the BEFORE-cohort. Anomalies were categorised as: First-Trimester Major Anomalies (FTMA), often detectable anomalies and other anomalies. MAIN OUTCOME MEASURES: Number of fetal anomalies, time to final diagnosis, GA at termination of pregnancy (TOP). RESULTS: Abnormal diagnostic scans increased from 750 to 1261 (BEFORE vs. AFTER) with definitive diagnoses in 609 vs. 940. Time to diagnosis and GA at TOP in c-BEFORE were comparable to c-AFTER (11 vs. 13 days and GA 14 + 6 vs. 15 + 1, respectively). FTAS increased the detection of often detectable and other anomalies (53 vs. 124 and 248 vs. 474, respectively). FTMA slightly increased (308 vs. 342). CONCLUSIONS: FTAS substantially increases detection of fetal anomalies, primarily often detectable and other anomalies. Overall GA at diagnosis or TOP increased marginally, but some cases required an extended period of diagnostic evaluation.

Authors 18

1. Kim Bronsgeest Aachen Department of Obstetrics and Gynaecology Leiden University Medical Centre Leiden the Netherlands

   Leiden University · Leiden University Medical Center

   Affiliation as printed

   Department of Obstetrics and Gynaecology Leiden University Medical Centre Leiden the Netherlands

2. Eline E R Lust

   University Medical Center Utrecht

   Affiliation as printed

   Department of Obstetrics and Gynaecology University Medical Centre Utrecht Utrecht the Netherlands

3. Lidewij Henneman

   Amsterdam UMC Location Vrije Universiteit Amsterdam

   Affiliation as printed

   Department of Human Genetics and Amsterdam Reproduction and Development Research Institute, Amsterdam UMC Location Vrije Universiteit Amsterdam Amsterdam the Netherlands

4. Neeltje M. T. H. Crombag

   University Medical Center Utrecht

   Affiliation as printed

   Department of Obstetrics and Gynaecology University Medical Centre Utrecht Utrecht the Netherlands

5. Caterina M. Bilardo

   Amsterdam University Medical Centers

   Affiliation as printed

   Department of Obstetrics and Gynaecology Amsterdam UMC Amsterdam the Netherlands

6. Robert‐Jan H. Galjaard

   Erasmus MC

   Affiliation as printed

   Department of Clinical Genetics Erasmus University Medical Centre Rotterdam the Netherlands

7. Esther Sikkel

   Radboud University Nijmegen · Radboud University Medical Center

   Affiliation as printed

   Department of Obstetrics and Gynaecology Radboud University Medical Centre Nijmegen the Netherlands

8. Nan van Geloven Aachen Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Leiden University Medical Center

   Affiliation as printed

   Department of Biomedical Data Sciences Leiden University Medical Centre Leiden the Netherlands

9. Audrey B. C. Coumans

   Maastricht University Medical Centre

   Affiliation as printed

   Department of Obstetrics and Gynaecology Maastricht UMC+, GROW—Research Institute for Oncology and Reproduction Maastricht the Netherlands

10. Ayten Elvan‐Taşpınar

    University Medical Center Groningen

    Affiliation as printed

    Department of Obstetrics and Gynaecology University Medical Centre Groningen Groningen the Netherlands

11. Sander Galjaard

    Erasmus MC

    Affiliation as printed

    Department of Obstetrics and Gynaecology Erasmus University Medical Centre Rotterdam the Netherlands

12. Attie T. J. I. Go

    Erasmus MC

    Affiliation as printed

    Department of Obstetrics and Gynaecology Erasmus University Medical Centre Rotterdam the Netherlands

13. Elisabeth van Leeuwen

    Amsterdam University Medical Centers

    Affiliation as printed

    Department of Obstetrics and Gynaecology Amsterdam UMC Amsterdam the Netherlands

14. Gwendolyn T. R. Manten

    Isala

    Affiliation as printed

    Department of Obstetrics and Gynaecology Isala Zwolle the Netherlands

15. Eva Pajkrt

    Amsterdam University Medical Centers

    Affiliation as printed

    Department of Obstetrics and Gynaecology Amsterdam UMC Amsterdam the Netherlands

16. Mireille N. Bekker

    University Medical Center Utrecht

    Affiliation as printed

    Department of Obstetrics and Gynaecology University Medical Centre Utrecht Utrecht the Netherlands

17. Monique C. Haak corresponding Aachen Department of Obstetrics and Gynaecology Leiden University Medical Centre Leiden the Netherlands

    Leiden University · Leiden University Medical Center

    Affiliation as printed

    Department of Obstetrics and Gynaecology Leiden University Medical Centre Leiden the Netherlands

18. the IMITAS study group