Lesson 4A (Part 2)

Question 1

What does the yolk sac help you visualize?

Answer 1

To confirm the true gestational sac

Question 2

How do you take a measurement of the yolk sac?

Answer 2

Inner to inner AP measurement

Question 3

How big is the yolk sac normally when you first see it?

Answer 3

2.3 mm

Question 4

How much does the yolk sac grow each day?

Answer 4

0.1mm

Question 5

What is the max diameter of the yolk sac?

Answer 5

5. 6mm

- 10 weeks

Question 6

What are yolk sac pathologies associated with?

Answer 6

Large yolk sac

Question 7

What are the functions of the yolk sac? (4)

Answer 7

1. Providing nutrients to the early embryo
2. Vitelline duct (arteries and veins) connect yolk sac to embryo
3. Production of albumin, alphafetoprotein (AFP) and other proteins
4. Embryonic hematopoiesis
   - formation of blood cells

Question 8

What happens as the placenta takes over the embryonic needs?

Answer 8

The yolk sac will slowly lose functionality

Question 9

When does the embryo develop?

Answer 9

6-10 weeks

Question 10

What is the embryo also known as?

Answer 10

Fetal pole

Question 11

When does the embryo appears adjacent to the yolk sac?

Answer 11

6 weeks

Question 12

What first appears at 6 weeks?

Answer 12

Embryo

- focal thickening

Question 13

What does it mean if the MSD is larger than 66mm without an embryo?

Answer 13

May be a sign of early pregnancy failure

Question 14

CRL

Answer 14

Crown rump length

Question 15

Crown rump length

Answer 15

The main measurement used in 1st trimester

- the most accurate estimate of gestational age

Question 16

Why is the crown rump length the most accurate estimate of gestational age?

Answer 16

Because there is little biological variability for CRL in the first trimester

Question 17

What is crown rump length?

Answer 17

The length of the embryo or fetus from the top of its head (crown) to bottom (rump)

Question 18

What can be seen by 7-8 weeks?

Answer 18

Cephalad-caudad orientation

Question 19

What can be seen by 8-9 weeks?

Answer 19

Limb buds may be seen

Question 20

What can be seen by 9-10 weeks?

Answer 20

Movement may be visualized

Question 21

What is the 1st organ to function in the embryo?

Answer 21

The primitive (tubular) heart

Question 22

When does the primitive (tubular) heart begin to beat?

Answer 22

5 weeks

- 36-37 days

Question 23

When can cardiac activity be seen on an embryo?

Answer 23

> 5mm

Question 24

When must you be able to see cardiac activity for an embryo?

Answer 24

If the fetal pole is 7mm

Question 25

What is the heart rate of the a fetus at 5 weeks?

Answer 25

100-115 bpm

Question 26

What is the heart rate of the a fetus at 9 weeks?

Answer 26

170-180 bpm

- decreases soon after to 160-170 bpm

Question 27

What is the heart rate of the a fetus between the 2nd and 3rd trimester?

Answer 27

160-170 bpm

Question 28

Trachycardia

Answer 28

Abnormally rapid hear rate

Question 29

Bradycarida

Answer 29

Abnormally slow heart rate

Question 30

When is the amniotic cavity seen?

Answer 30

7-8 weeks

- will slowly increase in size as fluid accumulates within the cavity

Question 31

Why does the amniotic cavity increase rapidly after 9 weeks?

Answer 31

Fetal urine starts to be produced

- at 12 weeks, increase can be 5mm/day