CS Ch.20 PP (OB basics)

Gestational Age

the age of the pregnancy measured in weeks (GA)

Embryo

an early pregnancy less than 10 weeks GA

Fetus

a pregnancy greater than 10 weeks GA

1st Trimester

from conception to 13 weeks 6 days GA

2nd Trimester

from 14 weeks - 27 weeks 6 days GA

3rd Trimester

from 28 weeks - 40+ weeks GA

Fetal Biometry

a series of specific measurements that are taken of a fetus that are used to calculate approximate size, weight and growth rate of the fetus

Gestational Sac (GS)

a fluid filled cavity that encompasses the embryo/fetus during the first trimester

what is one of the first signs of pregnancy?

a gestational sac

Mean Sac Diameter (MSD)

-age determining measurement of the gestational sac

what is the average of the GS diameter taken in?

3 different planes

Yolk Sac (YS)

nutrient filled sac within the gestational sac that feeds the embryo/fetus throughout the first trimester until the placenta is fully formed

YS Diameter

a measurement of the size of the inner lumen of the YS

an abnormally enlarged YS can indicate what?

a problem with the pregnancy

Crown Rump Length (CRL)

-a measurement of the length of the embryo/fetus; from the top of the head (crown) to the middle of the buttocks (rump)

-obtained during first trimester

What is the most accurate measurement that can be obtained throughout the pregnancy to generate gestational age and calculate estimated due dates?

Crown rump length (CRL)

How are embryonic/fetal heart rates obtained? And why?

By using M-mode to reduce the potential bioeffects related to higher intensity sound waves that are used for PW Doppler

What can heart rates that are exceeding or lower than the normal average for that GA indicate?

A problem with the pregnancy