Glossary — Abdominal circumference (AC)

Abdominal circumference (AC)

The distance around the fetal abdomen. Abdominal circumference is one of the standard biometric measurements used in fetal growth assessment.

The abdominal circumference is measured by sonogram from outer skin surface to outer skin surface.

The appropriate transverse plane for measurement of the fetal abdominal circumference (AC) should include the umbilical vein at the level where the umbilical vein enters the liver. The ossification centers of the spine should be aligned.

Ultrasound image showing umbilical vein and spine for AC measurement
Key landmarks: UV = Umbilical vein; S = Spine.
Ultrasound image demonstrating abdominal circumference tracing
Example of abdominal circumference (AC) tracing on an appropriate transverse plane of the fetal abdomen.
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