Early ultrasound linked to improved fetal anomaly detection

Serious structural issues in fetuses can be identified sooner by first-trimester screening, according to a recent study published in PLOS Medicine on November 25, 2025.¹

Congenital anomalies are often detected during a second-trimester ultrasound at 20-weeks’ gestation, but advances in imaging have allowed for earlier screening. However, earlier evaluations are currently not recommended by policy in England.¹

“With advancing ultrasound technology much earlier detection of serious fetal conditions is now feasible; our guidance must catch up to these developments so families can benefit,” said Jehan Karim, MBBS, MSc, lead researcher and junior research fellow at the University of Oxford.¹

Survey distribution and trust classification

The study was conducted to determine whether first-trimester fetal anatomy screening impacts the timing of major fetal anomaly diagnoses.² In the first part of the study, a nationwide survey of first-trimester ultrasound practices was distributed to maternity units in England.²

Domains of the survey included current first-trimester ultrasound protocols, local policies, inclusion of an early assessment of fetal anatomy, and availability of resources. The reliability and validity of the survey was confirmed through a multi-stage validation and piloting process.²

Finalized surveys were provided to maternity units electronically on January 25, 2019, with reminders sent out in February 2019. Trusts were classified into 4 groups based on their survey responses:²

1. Group A with no formal first-trimester fetal anatomy assessment through ultrasound
2. Group B with a basic anatomical assessment
3. Group C with an advanced anatomical protocol
4. Group D with an extended anatomical protocol

Linking survey data to anomaly registries

Survey data was linked to information about the number of babies diagnosed with a congenital anatomy and diagnosis timing through the National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) database. Anomalies were coded in the NCARDRS database based on the International Classification of Diseases 10th revision.²

Anomalies of interest included 12 structural anomalies that are monitored in the second-trimester Fetal Anomaly Screening Program, alongside 2 anomalies considered important in the early anatomy scan. Categories of gestational age at diagnosis included before 16-weeks’ gestation, 16- to 23-weeks’, and after 24-weeks’ but before birth.²

Responses from 110 maternity trusts were included in the final analysis, 27 of which were classified as Group A, 22 as Group B, 45 as Group C, and 16 as Group D. Additionally, 67% were district general hospitals, 32% university-affiliated and academic centers, and 11% tertiary care units, highlighting the variety of settings.²

Some type of first-trimester anatomy assessment was reported in 75% of responding trusts, with rates of 100% for tertiary care centers, 80% for university and academic centers, and 69% of district general hospitals. Across these trusts, care was provided to 1,030,224 pregnancies.²

Anomaly detection outcomes

A congenital anomaly was identified in 5895 fetuses, 32.7% of which were suspected or diagnosed before 16-weeks’ gestations. Group A reported the lowest rate of anomaly detection at 27.7%, followed by Group B at 31.2%, Group C at 33.2%, and Group D at 40.4%.²

This data highlighted significant variation in first-trimester ultrasound practices. According to investigators, there is a need for more detailed screening protocols linked to increased earlier detection rates.²

“A single, focused first-trimester ultrasound scan brings the diagnosis of major fetal conditions forward by weeks; this gives families time to consider and expand clinical options,” said Aris Papageorghiou, MBChB, MRCOG, study lead and professor at the University of Oxford.¹ “However, the lack of guidance has led to variation in practice.”

References

1. Routine first trimester ultrasounds lead to earlier detection of fetal anomalies. PLOS. November 25, 2025. Accessed December 4, 2025. https://www.eurekalert.org/news-releases/1106411.
2. Karim JN, Broughan JM, Aldridge N, Pandya P, McHugh A, Papageorghiou AT. Impact of first-trimester ultrasound on early detection of major fetal anomalies: Nationwide population-based study of over 1 million pregnancies. PLOS Medicine. 2025. doi:10.1371/journal.pmed.1004709