OBG - Fetal Age Flashcards
1
Q
What is the first sign of pregnancy? When is it seen?
A
Early gestational sac; as early as 16-21 days post-conception on U/S
2
Q
When can the early embryo be identified on U/S?
A
By the 6th menstrual week
3
Q
At 6 weeks, what is the best estimation of GA?
A
Crown rump length
4
Q
In the first trimester, the ___ is accurate to within 3-5 days for gestational age determination.
A
Crown-rump length
5
Q
After 13-14 weeks, what measurements are used for dating?
A
- Biparietal diameter
- Head circumference
- Abdominal circumference
- Femur length
6
Q
What are the most accurate measures in the second trimester?
A
Biparietal diameter
Femur length
7
Q
After 26 weeks, all measurements are less accurate. What is used in the third trimester?
A
Serial exams are helpful, as the variation in both biparietal diameter and femur measurements is +/- 14-24 days
