early embryonic stage of the first trimester

aneuploidy

this means extra chromosome

chorionic villi sampling

diagnostic genetic testing is offered through (x) between 13 and 14wks

gestational age

the first day of the last menstrual period (LMP) as the beginning of gestation

zygote

for 12 days after conception, during the implantation process, the conceptus is called a

secondary yolk sac

the (x) is the yolk sac seen sonographically throughout the first tri

amniotic cavity

the embryo is located within the

5wks

the gestational sac should be visible by TV at how many wks

5.5wks

yolk sac should be visible from how many wks in the first trimester

6wks

the embryo is usually seen at

7wks

the amnion is visualized at approx.

35mm

the CRL measures how many mm by the end of the 10th wk

10wks

gestational sac size and hCG lvls increase proportionally until how many wks

45mm

at 10 wks the gestational sac is how many mm MSD (mean sac diameter)

45mm

at what MSD of the gestational sac should the embryo be EASILY detected

greater than 1000 to 2000

a NL gestational sac is expected to be visible when the hCG lvls are

3.5

the NL IUP at less than 7 wks demonstrates doubling of quantitative maternal serum hCG lvls every how many days

plateau and decline

at 9 to 10 wks, hCG lvls…while gestation continues

plateau later and decrease much more slowly

in pregnancies where the fetus is trisomy 21, the hCG lvls…

round or oval

shape of gestational sac

fundal or middle portion of UT; center position

position of gestational sac

smooth

contour of gestational sac

echogenic

wall of gestational sac is

>12mm

yolk sac is typically present when gestational sac is measuring

>25mm

embryo is present when gestational sac is measuring

>10mm

embryo can be seen TV when MSD is

12wk

intestines should fully return to the abdomen by which wk

chorionic cavity

the anechoic center of the gestational sac represents what cavity

decidua basalis

the portion of the gestational sac on the myometrial or burrowing side of the conceptus is known as the

decidua capsularis

the villi covering the developing embryo are referred to as the

gestational sac

the … is eccentrically placed in relation to the endometrial cavity, secondary to its implantation

yolk sac

what is the first structure that is seen sonographically within the gestational sac with an MSD >6mm or at 5.5wks

provision of nutrients to the developing embryo, hematopoiesis, development of embryonic endoderm which forms the primitive gut

the essential functions of the secondary yolk sac

10-15mm, 20mm

TA studies have shown that the yolk sac should be seen within MSDs of (range) and should ALWAYS be seen with MSD of

0.1

when the MSD measures less than 15mm, the growth rate of the yolk sac is approx. Xmm/mL of growth of the MSD

0.03

the growth of the yolk sac is Xmm/mL of growth of the MSD through the first tri

5.5 to 6wks, CRL 3mm

early embryo is often not identified with TV until heart motion is detected at approx. how many wks and what CRL

6mm

the NL diameter of the yolk sac should not exceed

embryonic period

the time between 4 and 10 wks of gestation is considered the

6th wk

the spine closes at approx. the

parallel echogenic lines at 6 wks

the developing spine may be visualized as

prosencephalon, mesencephalon, rhombencephalon

by 8 wks, 3 primary vesicles are seen within the fetal brain:

rhombencephalon

which vesicle in the fetal brain is seen early

9th wk

by what wk the maxilla and the mandible are noted as brightly echogenic structures

the heart

what is the first organ to function within the embryo

35d, 5.5-6wks

the embryonic heart starts beating at approx how many D and wks

8th wk

complex embryogenesis occurs to fully develop all cardiac structures by what wk

gestational age during first trimester, CRL

what is the most accurate pregnancy dating and parameter

menstrual age during early pregnancy

mean gestational sac size correlates closely with

the first 8wks

the gestational sac size remains accurate through

6wks

CRL measurements can be obtained as early as

absence of the fetal nasal bone

what is associated with trisomy 21