PART 4: Determination of Gestational
Age / CRL / Multiple Gestations
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS 100%
CORRECT!!!
Q: What are two key sonographic measurements used to determine gestational
age?
A: Crown-Rump Length (CRL) and Gestational Sac Size (also known as Mean
Sac Diameter, or MSD).
Q: Up to how many weeks is gestational sac size considered a reliable
indicator for dating a pregnancy?
A: It remains accurate up to 8 weeks of gestation.
Q: How is the Mean Sac Diameter (MSD) calculated on ultrasound?
A: By averaging the gestational sac’s length, width, and height:
(Length + Width + Height) ÷ 3
Q: From what gestational age can CRL (Crown-Rump Length) be measured
using ultrasound?
A: Starting at approximately 5½ weeks using transvaginal sonography.
Q: The appearance of embryonic cardiac activity is an indicator for the start of
which measurement?
A: Crown-Rump Length (CRL) measurements.
CRLs considered most accurate method for dating through ______ weeks of
gestation
12 weeks
After 12 weeks; fetus begins to "____", making CRL measurements of length
more difficult
Age / CRL / Multiple Gestations
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS 100%
CORRECT!!!
Q: What are two key sonographic measurements used to determine gestational
age?
A: Crown-Rump Length (CRL) and Gestational Sac Size (also known as Mean
Sac Diameter, or MSD).
Q: Up to how many weeks is gestational sac size considered a reliable
indicator for dating a pregnancy?
A: It remains accurate up to 8 weeks of gestation.
Q: How is the Mean Sac Diameter (MSD) calculated on ultrasound?
A: By averaging the gestational sac’s length, width, and height:
(Length + Width + Height) ÷ 3
Q: From what gestational age can CRL (Crown-Rump Length) be measured
using ultrasound?
A: Starting at approximately 5½ weeks using transvaginal sonography.
Q: The appearance of embryonic cardiac activity is an indicator for the start of
which measurement?
A: Crown-Rump Length (CRL) measurements.
CRLs considered most accurate method for dating through ______ weeks of
gestation
12 weeks
After 12 weeks; fetus begins to "____", making CRL measurements of length
more difficult
