Yolk sac volume assessed by three-dimensional ultrasonography using the VOCAL method

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Fetal Development

Background:

• The yolk sac plays a crucial role in early embryonic development.
• Establishing normative data for yolk sac volume (YSV) is important for assessing early pregnancy viability.
• Three-dimensional ultrasonography (3D-US) offers advanced volumetric assessment capabilities.

Purpose of the Study:

• To establish normative data for yolk sac volume (YSV) between 7-10 weeks of gestation.
• To assess YSV using transvaginal 3D-US with the Virtual Organ Computer-aided AnaLysis (VOCAL) method.
• To analyze the correlation between YSV and gestational age (GA) or crown-rump length (CRL).

Main Methods:

• A cross-sectional study of 62 normal pregnancies.
• YSV measurements performed using transvaginal 3D-US with a volumetric transducer.
• VOCAL method with a 30-degree rotation angle used for volumetric calculations.

Main Results:

• Normative reference limits for first-trimester YSV were generated.
• A poor correlation was observed between YSV and GA (R²=0.188) or CRL (R²=0.203).
• Mean YSV increased from 0.063 cm³ at 7 weeks to 0.164 cm³ at 10 weeks.

Conclusions:

• Reference limits for first-trimester YSV using 3D-US were established.
• The study confirmed a weak correlation between YSV and GA or CRL.
• These normative data can aid in the early assessment of pregnancy.