Module 5.1 : First Trimester Normal Flashcards Preview

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Flashcards in Module 5.1 : First Trimester Normal Deck (70)
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1

pregnancy dates

- pregnancy dated by weeks from first day of last menstrual period (LMP) or (LMNP)
- 40 weeks completed gestation (41)
- 280 days
- 3 trimesters

2

1st trimester dates

0 - 13 6/7 weeks

3

2nd trimester dates

14 - 27 6/7 weeks

4

3rd trimester dates

28 - 40 weeks

5

embryo

- the conceptus is called an EMBRYO from conception up to 10 week LMP
- after 10 week called a FETUS

6

importance of ultrasound - first trimester

- confirm pregnancy
- confirm location ( intrauterine vs. extrauterine)
- confirm size of embryo agrees with LMP dating (CRL)
- confirm number of embryos
- confirm viability ( fetal heart rate with m-mode)

7

ovulation

- occurs at day 14 in ideal cycle
- LH must surge for ovulation to occur
- ovum ejected from follicle and propelled toward fallopian tube
- lives fro 12 - 24 hours

8

sperm

- 200 to 500 million sperm deposited near cervix on 300 to 500 reach ovum
- 100 mill / ml is normal
- under 20 million considered sterile
- usually survive for 24 hours

9

fertilization

1. sperm passes through the ZONA PELLUCIDA ( doesnt allow more sperm to fertilize ovum)
2. sperm head enlarges to become male pronucleus and tail breaks off
3. ovum completes second meiotic divison at this time to become female pronucleus
4. both pronuclei fuse and the chromosomes intermingle

10

zygote

union of sperm and ovum
+ also called conceptus

11

morula

- cluster of cells 12-16 BLASTOMERES
- morula remains the same size but the cells become smaller and smaller with each divisions

12

blastocyst

- secretions cross the zone pellucida enter the morula forming a fluid filled cavity

13

The Journey

1. the ovum travels 24 - 36 hours to reach the ampullae portion of the fallopian tube where fertilization occurs
2. the blastocyst enters the uterus 6-7 days after fertilization
3. implantation is complete by 11-12 days post ovulation or 9-10 days post fertilization

14

cleavage

- rapid cell division without a change in the size of the original zygote is CLEAVAGE

15

blastomeres

- chromosomes of the zygote arrange in the preparation for the 1st cleavage division the two daughter cells are called BLASTOMERES

16

blastocyst

- fluid enters the zygote and separates it into 2 parts
+ TROPHOBLAST
= outer cell to be placenta and chorion
+ EMBRYOBLAST
= inner cell mass ( forms embryo, you sac, amnion)
- once the zone pellucida disappears the blastocyst implants in the uterus

17

implantation

- blastocyst attaches to endometrial epithelium
- trophoblast differentiates in to 2 layers
+ SYNCYTIOTROPHOBLAST
+ CYTOTROPHOBLAST

18

syncytiotrophoblast

- PRODUCES HCG
- invasively erodes the endometrial stroma and blastocyst sinks into endometrium

19

lacunae

- the spaces eroded in the endometrium by the syncytiotrophoblast
- become intervillous spaces of the placenta

20

cytotrophoblast

- produces finger like projections that extend into the forming lacunar network called PRIMARY CHORIONIC VILLI

21

primary chorionic villi

- finger like projection of cytotrohphoblast
- form
+ chorion frondosum
= villi directly at implantation site
= early placenta
+ smooth chorion or chorion laeve
= all the remaining villi around gestational sac (become chorionic membrane)

22

decidua (endometrium) reaction in the uterus

- decidua cells of the endometrium increase in size and content for implantation due to progesterone
- the endometrium will undergo a decidua reaction with an ectopic pregnancy as well regulating in pseudo sac
- if pregnancy occur in bicornuate uterus the decidua reaction will occur in the non pregnant horn making it look like twins
- trophoblastic cells of embryo produce hCG regardless of location of implantation supporting the corpus luteum on ovary

23

decidua layers of uterus

BCP
- decidua BASALIS
- decidua CAPSULARIS
- decidua PARIETALIS ( VERA)

24

decidua basalis

- part of decidua underlying the conceptus
- eventually becoming the maternal side of the placenta

25

decidua capsularis

- part that covers over the gestational sac

26

decidua parietalis ( vera)

- all remaining decidua

27

double decidual sign

- sonographic descriptor
- opposed layers of decidua parietalis and capsularis can be identified on early ultrasound
- should always try to identify this to rule out pseudo gestational sac before embryo can be seen

28

gift wrap

- in real pregnancy with gestational sac the layers of decidua will be easily indented and uniform in concentric layers
- in pseudo sac the layers are not uniform and har to see

29

fusion of decidua

- the decidua vera and capsularis fuse
- prior to this fusion there is potential space between the 2 layers this might cause some light bleeding

30

amniotic cavity

- small spaces occur between the inner cell mass and the trophoblast
- by day 9 from conception these form the amniotic cavity
- THE BLASTOCYST CAVITY NOW CALLED THE PRIMITIVE YOLK SAC ( not seen on ultrasound)