What is the maximum inner-to-inner diameter of the yolk sac in early pregnancy ultrasound?

What is the maximum inner-to-inner diameter of the yolk sac in early pregnancy ultrasound?

• A. 4 mm
• B. 6 mm
• C. 8 mm
• D. 10 mm

Answer: (B)

In early pregnancy ultrasound, the yolk sac size is a quick indicator of viability. You measure the inner-to-inner diameter across the yolk sac in the longest axis, making sure to exclude surrounding chorionic tissue. The yolk sac normally grows to a maximum inner diameter of about 6 millimeters. A yolk sac measurement near or exceeding this size can be a sign of potential problems with viability or chromosomal issues, so 6 mm is the practical upper limit for a normal yolk sac when assessing a very early pregnancy. Values smaller than that, like 4 mm, can still be normal, while 8 or 10 mm would be larger than what’s typically seen in a viable early pregnancy.

In early pregnancy ultrasound, the yolk sac size is a quick indicator of viability. You measure the inner-to-inner diameter across the yolk sac in the longest axis, making sure to exclude surrounding chorionic tissue. The yolk sac normally grows to a maximum inner diameter of about 6 millimeters. A yolk sac measurement near or exceeding this size can be a sign of potential problems with viability or chromosomal issues, so 6 mm is the practical upper limit for a normal yolk sac when assessing a very early pregnancy. Values smaller than that, like 4 mm, can still be normal, while 8 or 10 mm would be larger than what’s typically seen in a viable early pregnancy.