Ch. 9 Normal First Trimester Flashcards

1
Q

How many hours after ovulation does fertilization occur?

A

24-36 hours

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2
Q

Where does normal fertilization occur?

A

In the ampulla of the fallopian tube

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3
Q

What is the normal number of chromosomes?

A

46 chromosomes, 23 pairs

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4
Q

The embryonic stage that is the male and female reproductive cell, ie. ovum or spermatozoa

A

Gamete

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5
Q

The embryonic stage that is a single celled fertilized ovum prior to miotic division

A

Zygote

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6
Q

a dividing fertilized ovum at 2 cell and 4 cell stages, located within the ampulla of the fallopian tube

A

Blastomere

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7
Q

a mass of dividing cells (resembling a mulberry) located in the isthmus of oviduct and enters the uterus 4 days after fertilization

A

Morula

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8
Q

Organized collection of cells which implants into the endometrium 7 days after fertilization

A

Blastocyst

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9
Q

What is the function of the trophoblast or the outer layer of cells around the blastocyst

A

Trophoblast cells produce hCG to extend the life of the corpus luteum. The trophoblast cells will eventually form into the placenta

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10
Q

The corpus luteum produces ——– which assures retention of the ——

A

Progesterone, endometrial lining

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11
Q

The inner fluid-filled cavity of a blastocyst that will become the yolk sac, embryonic disc, and amnion is known as

A

Blastocele

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12
Q

At what gestation are all three germ cell layers formed

A

by five weeks after LMP

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13
Q

Germ cell layer that becomes GI and respiratory systems

A

Endoderm

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14
Q

Germ cell layer that becomes the brain, nervous system, and skin

A

Ectoderm

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15
Q

Germ cell layer that becomes the musculoskeletal and circulatory systems

A

Mesoderm

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16
Q

Between what weeks do all major internal and external structures begin to form?

A

6-10 weeks

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17
Q

The primordial heart begins beating at what gestational age

A

6 weeks (think of the heartbeat bill, other organ function remains normal)

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18
Q

The embryonic period ends at

A

the end of the 10th menstrual week

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19
Q

When does the fetal period occur

A

at the beginning of the 11th menstrual week

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20
Q

hCG is initially produced by the ——- and later in pregnancy by the ———–

A

trophoblastic cells, placenta

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21
Q

With an IUP, hCG becomes detectable in the bloodstream how many days after ovulation?

A

7-10 days after ovulation or 3 weeks after LMP

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22
Q

hCG doubles every

A

48 hours or 2-3 days

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23
Q

When does hCG naturally plateau?

A

around 8-9 weeks and then declines afterwards

24
Q

A ways of measuring hCG levels with either a positive or negative result

A

qualitative (ie. Urine results, over the counter pregnancy tests)

24
Q

A ways of measuring hCG levels with either a positive or negative result

A

qualitative (ie. Urine results, over the counter pregnancy tests)

25
Q

A ways of measuring hCG levels that provides a specific level or number that is within the bloodstream

A

Quantitative

26
Q

What is the most common method used to detect quantitative hCG

A

3rd IRP (International reference preparation)

27
Q

Elevated levels of hCG are seen with which type of cases

A

incorrect dates (further than expected)
gestational trophoblastic disease
multiple gestations

28
Q

Decreased levels of hCG are seen in what types of cases

A

incorrect dates (not as far along as expected)
ectopic pregnancy
embryonic demise
abnormal IUP

29
Q

When does the blastocyst implant into the endometrium

A

by the end of the 3rd week

30
Q

List the three distinct layers of the decidualized endometrium

A

Decidua basalis, decidua capsularis, decidua parietalis/decidua vera

31
Q

Layer of the decidualized endo that develops where the blastocyst implants: the maternal contribution to the placenta

A

decidua basalis

32
Q

Maternal component of the placenta

A

decidua basalis

33
Q

fetal component of the placenta

A

trophoblast/chorion frondosum

34
Q

What is the chorion

A

The chorion becomes the fetal contribution to the placenta

35
Q

What is the amnion

A

The amnion forms the inner cell mass. The amniotic cavity expands to fill the chorionic cavity.

36
Q

When should the amnion and chorion fuse

A

Fusion is complete by 12-16 weeks

37
Q

Define a chorionic bump

A

Is thought to represent a resolving hematoma. It’s significance on the pregnancy outcome is uncertain as it may be associated with an increased risk of pregnancy loss

38
Q

Describe the normal doppler waveform of trophoblastic tissue

A

high velocity, low resistance flow (bc its providing the embryo with nutrients and oxygen

39
Q

By how many weeks should a gestational sac be visualized on US

A

> 5 weeks

40
Q

Normal sono findings of a gestational sac on US

A

round, oval or teardrop shaped. located toward the fundus or mid-uterus, DOUBLE DECIDUAL SIGN, GROWS 1MM A DAY, yolk sac present when MSD is > than or = to 8mm on TV US

41
Q

What is the MSD formula

A

MSD=length + height + width/ 3. MSD should be measured inner to inner.

42
Q

At what gestation should the secondary yolk sac be seen with TV US

A

5.5 weeks LMP

43
Q

At what gestation should the secondary yolk sac be seen with transabdominal US

A

7 weeks LMP

44
Q

The secondary yolk sac should be seen on TV US when the MSD reaches

A

8mm

45
Q

The secondary yolk sac should be seen on transabdominal US when the MSD reaches

A

20mm

46
Q

Name the structure that attaches the secondary yolk sac to the embryo

A

vitelline duct

47
Q

The yolk sac should be measured inner to inner and should not exceed

A

6 mm or <5.6mm

48
Q

What is the most accurate method of dating a pregnancy sonographically

A

CRL measurement (measured from top of the head to the bottom of the rump, excluding the legs)

49
Q

The embryo should be seen TV when the gestational sac measures

A

16mm

50
Q

The embryo should be seen transabdominally when the gestational sac measures

A

25mm

51
Q

The embryo grows at a rate of

A

1 mm per day

52
Q

CRL (mm) + —— = GA (days)

A

42

53
Q

Anechoic, cystic structure seen in the posterior portion of the embryonic/ fetal brain

A

Rhombencephalon

54
Q

When is the rhombencephalon seen

A

from 8-11 weeks

55
Q

Normal midgut herniation aka physiologic omphalocele occurs at around —– weeks and should return to the abdominal cavity by —- weeks

A

9 weeks, 12 weeks