The normal first trimester

Question 0

what is gestational age?

Answer 0

used by clinicians and sonographers

aka menstrual age

1st day of pregnancy is 1st day of LMP

adds 2 weeks (14 days) to conceptual age

Question 1

What is conceptional age?

Answer 1

used by embryologists

aka embryologic age

1st day of pregnancy is conception

Question 2

what is the ovum?

Answer 2

egg released from ruptured graffian follicle

Question 3

what is the zygote?

Answer 3

fertilized ovum

for 12 days after conception during implantation process

Question 4

what is the morula?

Answer 4

16 stage cell and greater

Question 5

what is a blastocyst?

Answer 5

enters uterus at day 4-5 after fertilization

implants into the endometrial lining lining begins 7-9 days after fertilization

Question 6

What is the baby call the Embryo?

Answer 6

from implantation until end of 10th week

Question 7

When is ovulation

Answer 7

day 14 of 28 day cycle

Question 8

fertilization occurs when?

Answer 8

within 1-2 days after ovulation

in distal Fallopian tube

fertilized ovum becomes ZYGOTE - zona pellucida forms around zygote prevents sperm from penetrating

Question 9

What happens when the ruptured graffian follicle becomes corpus luteum

Answer 9

secretes progesterone and estrogen

Question 10

What is the job of the morula?

Answer 10

continues cellular proliferation

becomes blastocyst - fluid filled cavity

Question 11

What does the blastocyst consist of?

Answer 11

blastocyst

trophoblast

inner cell mass

Question 12

What happens during the blastocyst stage?

Answer 12

Contains trophoblastic cells (cells that make up the placenta)

secretes hCG (causes endometrium to convert to decidua)

form chorion and placenta

“inner cell mass” become future embryo, yolk sac and amnion

enters uterus 4-5 days after fertilization

Question 13

When is implantation completed?

Answer 13

6-9 days post fertilization (super complete by day 12)

Question 14

What do trophoblast produce?

Answer 14

enzymes

create lacunae (blood pools formed by eroded maternal capillaries)
which nourish trophoblastic cells

Question 15

What happens during implantation?

Answer 15

Enzymes produced by trophoblast

blood exchange network formed between mother and blastocyst

mature into placental/maternal circulation

when complete zygote buried in one wall of uterus

may cause light vaginal bleeding (implantation bleeding)

When complete trophoblast forms primary villi which encircle early gestational sac

Question 16

What produces the hCG?

Answer 16

trophoblastic cells

Question 17

What is the outer membrane of the gestational sac?

Answer 17

chorion

Question 18

what is chorion frondosum?

Answer 18

early chorionic villi

attaches to endo becomes fetal side of placenta

Question 19

is the chorion laeve involved with implantation?

Answer 19

no

Question 20

what creates the “double bubble?”

Answer 20

the decidua capsularis + decidua vera parietalis = decidua vera (double bubble)

the white reaction around the gestational sac

Question 21

What does the deciduas basalis turn into?

Answer 21

the placenta

maternal component of placental attachment

Question 22

Do we ever see the primary yolk sac?

Answer 22

no we only see the secondary

Question 23

When does the secondary yolk sac form?

Answer 23

approx day 23 (9 days after fertilization) primary yolk sac is “pinched off”

Question 24

What happens with the secondary yolk sac during early gestation development?

Answer 24

seen sonographically in first trimester Function: transfer of nutrients, hematopoiesis (forming blood cells), angiogenesis ( forming of blood vessels), formation of digestive tract amniotic and chorionic cavities develop at the same time period

Question 25

What happens around 5 weeks?

Answer 25

gastrulation - creating 3 germ cell layers cardiovascular formation begins - begins to form immediately after gastrulation is complete in 5-8 weeks (normal FHR 120-160bpm) neurulation - formation of neural tube - complete closure by 7 weeks

Question 26

When is the embryonic phase?

Answer 26

week 6-10

Question 27

What happens in the embryonic phase?

Answer 27

organogenesis - main feature all major internal and external structures begin to develop embryo changes from flat dislike appearance to C-shaped structure, then human like appearance CRL rapid development - 35mm by 10th week most susceptible to teratogens nearly all congenital malformation originate before or during limb buds form brain growth midgut herniation

Question 28

When is the embryo most susceptible to teratogens?

Answer 28

during the embryonic phase radiation, drugs, viruses, poor nutrition, toxins, alcohol, smoking etc

Question 29

When is the beginning of the fetal period?

Answer 29

weeks 11 and 12

Question 30

What happens in the fetal period?

Answer 30

organ and structures continue to grow and develop fetal head disproportionately large almost 50% of the baby fetal anatomy fully developed in late 1st trimester

Question 31

in maternal biochemistry what kind of relationship is there between quantitative bHCG and sonographic findings?

Answer 31

Direct relationship

Question 32

What is PAPP-A?

Answer 32

a pregnancy marker associated plasma protein - A insulin like growth factor in pregnancy associated with growth processes bone and tissue formation decreased levels in early pregnancy - marker for trisomy 21 levels may be linked with preterm labor and preeclampsia

Question 33

What is the TA sonographic technique and evaluation?

Answer 33

overall view of pelvic sturctures/anatomic relationships/pelvic masses

Question 34

What is the sonographic technique for TV?

Answer 34

more detailed evaluation of pelvic anatomy/pathology sagittal and coronal/semicoronal planes more detailed evaluations of gest. sac and contents, fetus

Question 35

Why would you use the transperineal sonographic techinque?

Answer 35

visualize cervix - sometimes done in first trimester...usually done in second can be done if patient refuses tv

Question 36

Why would you use 3D evaluation in first trimester?

Answer 36

clinical value not really established

Question 37

Pulsed doppler should be used in first trimester?

Answer 37

only if absolutely necessary....use M-Mode.

Question 38

Who sets the standards for OB sonography?

Answer 38

ACR AIUM ACOG

Question 39

What major components are scanned in the first trimester?

Answer 39

Uterus and adnexa - presence of gestational sac sonographic measurements of embryo and or gestational sac presence/absence of fetal cardiac activity fetal number and chronicity of multiple gestations uterus, adnexa, cul-de-sac, ovaries

Question 40

What are the normal sonographic features of the gestational sac?

Answer 40

round or oval fundal position eccentrically placed smooth contours decidual wall thickness > 3mm

Question 41

if there is implantation in the LUS what are the placenta issues?

Answer 41

placenta accreta placenta previa

Question 42

What is MSD?

Answer 42

mean sac diameter

Question 43

What is the measurement of the yolk sac between 5 - 5 1/2 weeks gestation?

Answer 43

> 12 mm MSD embryo - > 18mm MSD Gest Sac grows 1mm/day in early pregnancy

Question 44

Where do you find the yolk sac?

Answer 44

within the chorionic sac

Question 45

what is the earliest intragestational sac that you can see?

Answer 45

yolk sac - normally seen from 5 weeks gestation

Question 46

how is the yolk sac initially attached to the embryo?

Answer 46

yolk stalk

Question 47

What is the typical size of the yolk sac?

Answer 47

2-6 mm over 6mm = abnormal

Question 48

When is the baby called a fetus?

Answer 48

after the first 10-12 weeks

Question 49

What is the zygote or conceptus?

Answer 49

undergoes rapid cellular division forms 16-18 cell morula

Question 50

What is Decidua?

Answer 50

glycogen rich mucosa - nourishes early pregnancy

Question 51

What is the decidua capsularis?

Answer 51

layer of endo that heals over the implanted gestational sac

Question 52

What is decidua vera parientalis?

Answer 52

endo not in direct contact with gestational sac

Question 53

What is the lab values when the gestational sac is visualized transvaginally?

Answer 53

500-1000 mIU/ml

Question 54

What is the lab value for visualization of the gestational sac transabdominally?

Answer 54

1800 mIU/ml

Question 55

What should happen to the hCG levels every 48 hours in the first 6 weeks?

Answer 55

it should double hCG levels plateau and then decline at 9-10 weeks

Question 56

What is suspected when hCG levels do not increase normally?

Answer 56

pregnancy is abnormal possible ectopic or trisomy 21

Question 57

What two values are used in combination in 1st trimester (9-11 weeks) as a marker for trisomy 21 (downs syndrome)

Answer 57

hCG level and PAPP-A

Question 58

when can the amniotic cavity and membrane, chorionic cavity, yolk sac and embryo be seen?

Answer 58

5.5 - 6 weeks

Question 59

What happens to the yolk sac at approximately 8 weeks gestation?

Answer 59

with amniotic cavity expansion, the yolk sac, which lies between amniotic and chorionic membranes detaches from the yolk stalk

Question 60

When is the yolk sac resorb and no longer seen?

Answer 60

Sonographically by 12 weeks persistent yolk sac does occur persistent yolk sac my be visualized at placental umbilical cord insertion where amniotic and chorionic membranes fused

Question 61

At the beginning of the 5th week bilaminar embryonic disk undergoes gastrulation and converts into what?

Answer 61

trilaminar (three germ layer) embryonic disk

Question 62

What does visualization of the yolk sac predict?

Answer 62

viable pregnancy in 90% of cases

Question 63

When the yolk sac typically no longer seen?

Answer 63

by 12 weeks