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Published on: February 14, 2022
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Amniotic sac diameter reference interval in early pregnancy between 7 and 10 weeks' gestation
S A Solangon1, S Nijjar1, L V De Braud1
1EGA Institute for Women's Health, Faculty of Population Health Sciences, University College Hospital, London, UK.
Summary
This study establishes normal reference intervals for amniotic sac diameter (ASD) in early pregnancy. These findings provide crucial data for assessing gestational sac diameter (GSD) and embryo crown-rump length (CRL) in routine clinical practice.
Area of Science:
- Obstetrics and Gynecology
- Fetal Medicine
- Diagnostic Ultrasound
Background:
- Accurate dating and assessment of early pregnancy are crucial for optimal fetal outcomes.
- Establishing normative data for early pregnancy ultrasound measurements aids in identifying potential developmental abnormalities.
- Amniotic sac diameter (ASD) is a key parameter, but comprehensive reference intervals relative to gestational sac diameter (GSD) and crown-rump length (CRL) are needed.
Purpose of the Study:
- To establish normal reference intervals for amniotic sac diameter (ASD) between 7 weeks 0 days and 9 weeks 6 days of gestation.
- To determine the relative size of ASD in relation to gestational sac diameter (GSD) and embryo crown-rump length (CRL).
- To provide data for routine clinical application in early pregnancy assessment.
Main Methods:
- Prospective, cross-sectional study of 360 singleton pregnancies with normal early scans.
- Data collected between 7 weeks 0 days and 9 weeks 6 days of gestation.
- Regression analyses performed to establish reference intervals and assess inter- and intraobserver variability.
Main Results:
- Good inter- and intraobserver agreement was found for ASD measurements.
- Statistically significant associations were identified between GSD, ASD, and CRL.
- Regression equations were derived to quantify ASD and GSD/ASD ratios across a range of CRL values and gestational ages, with R² values up to 90% for ASD and CRL.
Conclusions:
- Comprehensive reference intervals for amniotic sac size in early pregnancy have been established.
- These reference intervals can be utilized in routine clinical practice for enhanced early pregnancy assessment.
- The study provides valuable normative data for ultrasound dating and monitoring of early fetal development.
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