what is normal to see in 1st trimester and when

blastocyst enters the uterus

4–5 days after fertilization

by 12 days after fertilization

implantation is complete

-no longer zygote phase, embryo phase begins after time of implantation

early ga sac becomes visible

~4-5 Gestational weeks

when does secondary yolk usually come visible (earliest structure seen inside GA sac)

5-5.5 weeks

Cardiac activity becomes visible when

5.5-6.5 weeks

during the beginning of the ___ week, embryo folds into a ______ structure

6th, c-shape

limb buds may be detected, embryonic head can be identified

7 weeks onward

Midgut herniation is normal between what weeks of gestation?

8-12 weeks

midgut herniation begins.

yolk sac separates from the embryo as the amniotic cavity expands

(midgut herniates into base of umbilical cord)

~week 8

from ____ to _____ weeks, _______ in the posterior cranium is normal.

8-10

cystic rhombencephalon

hcg plateaus and begins to decline when

9-10 weeks

long bone calcification makes limbs easier to identifty when

~10 weeks

NT examination window

11 weeks- 13 weeks 6 days

Yolk sac usually no longer visible by week

12

bowel returns to abdomen

week 12

CRL remains the dating measurement through when?

why is it no longer usable

through 12 weeks and 6 days

because the baby starts bending and not straight to measure ish

amnion and yolk sac may for double bled sigh seen by TVUS when

5-7 weeks

At approximately how many days menstrual age is the primary yolk sac pinched off by extra embryonic celom, forming secondary yolk?

23

Between 5 and 10 weeks, a normal YS has a diameter of what?

5.5

Cardiac anomaly seen as early as ____ weeks where the chambers of the heart and great vessels are checked to see if they are developing correctly.

• There is a strong relationship between increased NT and cardiac defects

12
four chambers view and great vessels

A blood hCG test should be positive at how many days post conception?

7-10

By the end of what week of gestation has the heart obtained its adult configuration?

8

What is the best way to scan and evaluate the amnion?

Between 5 and 7 weeks with TVUS. You will see a double bleb sign

The heart starts beating at approximately what time/

35 days, 5-5.5 weeks

Embryonic cardiac activity should always be seen by 46 menstrual days or when crown rump length is over how many mm?

>4mm

ges sac size is accurate for the first ____ weeks of pregnancy

8