[Vaginal ultrasonography in the first trimester. II. Quantitative parameters]

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Embryology

Context:

• First-trimester ultrasound is crucial for monitoring early pregnancy development.
• Accurate dating of pregnancy is essential for appropriate prenatal care and management.
• Variability in early embryonic growth necessitates established normative data.

Purpose:

• To establish normative growth curves for multiple gestational parameters during the first trimester (4-13 weeks).
• To determine the reliability of various sonographic measurements in estimating gestational age.
• To provide reference ranges for chorionic cavity diameter, trophoblast thickness, yolk sac diameter, crown-rump length, amniotic cavity diameter, biparietal diameter, abdominal diameter, and femur length.

Summary:

• Vaginal sonographic measurements from 259 normal singleton pregnancies were analyzed to create growth curves for key parameters.
• Normal values and 90% confidence limits were established for chorionic cavity diameter, trophoblast thickness, yolk sac diameter, crown-rump length, amniotic cavity diameter, biparietal diameter, abdominal diameter, and femur length.
• Embryonic heart rate progression was also documented.

Impact:

• Provides clinicians with validated reference data for assessing early pregnancy progression and dating.
• Crown-rump length offers the most accurate gestational age estimation (±6 days), followed by biparietal/abdominal diameters (±8 days) and mean chorionic diameter (±9 days).
• Enhances the accuracy of first-trimester pregnancy dating, aiding in clinical decision-making and risk assessment.