Yolk Sac Enlargement: Significance of 5.6mm

Normal Yolk Sac Parameters

• The yolk sac typically measures less than 6mm according to the Society of Radiologists in Ultrasound consensus guidelines 1, 2, 3
• The yolk sac is visualized at approximately 5½ weeks gestational age as a thin-rimmed circular structure eccentrically located within the gestational sac 1, 2, 3

Clinical Significance of Yolk Sac Measurement

• A yolk sac measuring 5.6mm is within normal limits and typically measures less than 6mm in viable early pregnancies, though the upper limit can extend to approximately 8mm 1, 2, 3
• Normal range: <6mm (your measurement) 1, 2, 3
• The yolk sac should always be located outside the amniotic cavity 1, 3

Important Considerations for Yolk Sac Evaluation

• Your 5.6mm measurement requires correlation with: presence or absence of embryo and its crown-rump length 2
• Your 5.6mm measurement requires correlation with: presence or absence of cardiac activity 2
• Your 5.6mm measurement requires correlation with: yolk sac morphology (should be thin-rimmed, circular, normal shape) 1
• Your 5.6mm measurement requires correlation with: gestational age based on last menstrual period or prior ultrasound 1