What is the correct way to measure abdominal circumference?

The correct way to measure abdominal circumference during an ultrasound is at the level of the junction of the umbilical vein and the portal sinus. This specific location is essential because it allows for a standardized measurement that accurately reflects fetal growth and development. The junction of the umbilical vein and portal sinus is typically well-defined and correlates with the internal abdominal cavity of the fetus. This anatomical landmark provides a reliable structure when assessing the abdominal circumference for evaluating potential growth issues or anomalies.

Measuring abdominal circumference at other levels, such as the diaphragm, iliac crests, or fetal bladder, does not offer an accurate representation of the fetal abdomen. Each of these locations measures different parts of the body rather than a consistent cross-section of the fetal abdomen, which is crucial for proper assessment in prenatal care. The established protocol for fetal measurements ensures that any growth assessments are both accurate and consistent, facilitating better monitoring of the fetus's well-being throughout pregnancy.