Delphi Consensus Standardizes First-Trimester Fetal Ultrasound for Early Detection of Structural Abnormalities

How can early fetal structural abnormalities be reliably detected across diverse healthcare settings? As first-trimester ultrasound screening becomes more prevalent, clinicians face challenges in standardizing protocols and ensuring quality. A comprehensive Chinese expert consensus, developed via the Delphi method and published in the Archives of Gynecology and Obstetrics, offers new, practical guidance for anatomical ultrasound examinations between 11+0 and 13+6 weeks of gestation.

Consensus Development and Methodology

Expert Panel & Delphi Process: This guidance was shaped by 35 core and 122 additional experts representing 27 institutions across China. Using the Delphi method—a systematic, multi-round survey technique—the panel refined a consensus on anatomical ultrasound standards for early pregnancy.

Extensive Literature Review: The team synthesized recent evidence and international guidelines to inform their recommendations, ensuring both scientific rigor and local applicability.

Tiered Classifications for Examinations

Three Categories: The consensus divides first trimester fetal ultrasound anatomical exams into basic (Class I), detailed (Class II), and targeted (Class III) levels.

Basic (Class I): For general screening in low-risk pregnancies, suitable for county-level hospitals.

Detailed (Class II): For enhanced screening in low-risk cases, performed at municipal-level hospitals with additional sub-items and measurements.

Targeted (Class III): For high-risk pregnancies or suspected anomalies; requires advanced imaging and is limited to specialized diagnostic centers.

Key Examination Features

Mandatory vs. Suggested Items: Through expert agreement (≥75%), each anatomical plane or measurement is categorized as recommended (mandatory) or suggested (optional, based on technical feasibility).

Core Structures: All exams focus on crucial fetal organs and biometric parameters. Detailed and targeted exams include more specific planes (e.g., for the CNS, cardiac system, or craniofacial anomalies).

Equipment & Safety: Examinations must use high-resolution Doppler systems, adhere to ALARA principles (minimizing ultrasound exposure), and strictly limit scan times.

Implications for Clinical Practice

Standardization: These guidelines harmonize protocols across institutions, reducing variability and improving detection rates for conditions such as anencephaly, cardiac malformations, and cleft palate.

Early Detection & Intervention: Standardized early screening allows more time for genetic counseling, advanced diagnostics, and, if needed, timely interventions.

Quality Control: The consensus calls for robust image storage, structured reporting, and ongoing quality assurance, including multidisciplinary consultations when anomalies are suspected.

Limitations and Future Directions

The consensus reflects Chinese clinical practice and infrastructure; regional adaptation may be needed elsewhere.

Some malformations manifest only later in pregnancy, reinforcing the need for serial follow-up.

Ongoing research and periodic updates are essential to integrate emerging imaging technologies and broader clinical data.

Conclusion

This Delphi-based consensus provides clinicians with a scientifically robust, tiered framework for first trimester fetal anatomical ultrasound. By standardizing examination content and quality across levels of care, it aims to improve early detection of fetal abnormalities and support consistent, evidence-based prenatal screening.

Key Points

The consensus introduces a three-tiered classification for first trimester ultrasound exams: basic, detailed, and targeted.

Mandatory and suggested planes are clearly defined, improving consistency in fetal anomaly detection.

Advanced targeted exams (e.g., for CNS or cardiac anomalies) are reserved for high-risk pregnancies at specialized centers.

Quality control measures—including structured reporting and multidisciplinary collaboration—are emphasized to minimize missed or incorrect diagnoses.

Early standardized screening facilitates prompt genetic counseling and intervention, ultimately supporting better pregnancy outcomes.

Citation:

Lyu G, Liao R, Jiang Q, He X, Weng Z. Chinese Expert Consensus on ultrasound anatomical examination of fetuses at 11+0 to 13+6 weeks of gestation based on the Delphi method. Archives of Gynecology and Obstetrics. 2025;312:1937–1954. doi:10.1007/s00404-025-08231-z