1M - Fetal Imaging

Question 1

Upon ultrasound, the results show an 80mm fetus with identifiable features and internal organs. What trimester is the fetus in?

Answer 1

1st trimester

Question 2

What is the first sign of early pregnancy on ultrasound?

Answer 2

Gestational sac

Question 3

When can we first see the gestational sac?

Answer 3

3-5 weeks gestation

The mean sac diameter is 2-3mm

Question 4

Where can we see the true gestational sac and the pseudo gestational sac?

Answer 4

True gestational sac can be seen in the eccentrically in the endometrium while the pseudo gestational sac can be seen centrally within the uterine cavity

Question 5

at 4.5-5 weeks, what is most helpful sign of pregnancy sonographically?

Answer 5

Double decidual sign

Question 6

What is the possible hcg levels within the first 5 weeks of pregnancy that coincides with the presence of gestational sac?

Answer 6

1000-2000 IU/L

Question 7

A sonographic
measurement of the gestational sac which is usually
first seen at around 3 weeks after conception (5 weeks
after the last menstrual period), when it measures 2-3
mm

Answer 7

Mean sac diameter

Question 8

What measurement of MSD with absent fetal pole is indicative of pregnancy failure or missed miscarriage?

Answer 8

> 25mm

Question 9

What measurement of MSD is suspicious of pregnancy failure if an embryo is not found?

Answer 9

16-24mm

Question 10

What measure of MSD should yolk sac be already visible?

Answer 10

8mm

Question 11

First anatomical structure identified within the gestational sac?

Answer 11

Yolk sac

Question 12

This structure play a critical role in embryonal development by providing nutrients and serving as the site of initial hematopoiesis?

Answer 12

Yolk sac

Question 13

This is characterized a a structure with a round bright ring measuring <6mm sonographically

Answer 13

Yolk sac

Question 14

When does the yolk sac involute?

Answer 14

At 11 weeks

Question 15

When does the yolk sac become unidentfiable?

Answer 15

at 14-20 weeks

Question 16

Appears as a circular thick-walled echogenic structure

with an anechoic center within the gestational sac, but outside the amniotic membrane

Answer 16

Yolk sac

Question 17

This is the first direct imaging manifestation of the fetus? Seen as a thickening on the margin of the yolk sac
during early pregnancy. It is often used
synonymously with the term “embryo”.

Answer 17

Fetal pole

Question 18

When can we first identify the fetal pole?

Answer 18

6.5 weeks with TAS

6 weeks with TVS

Question 19

Upon TVS what is the MSD if the fetal pole already present?

Answer 19

> or = 16mm

TAS - > or = 25mm

Question 20

When a fetal pole measures > or = 5mm what what other thing should be detected?

Answer 20

fetal heartbeat

Question 21

it is the length of the
embryo or fetus from the top of its head to bottom of
torso?

Answer 21

Crown rump length

the largest dimension of the embryo excluding the yolk sac and extremities

Question 22

It is the most accurate estimation of gestational age in early pregnancy?

Answer 22

Crown rump length

This is due to the small biological variability

Question 23

This is the primary measure of gestational age from 7-13 weeks?

Answer 23

Crown rump length

accurate to within 5-7 days

Question 24

What measure of CRL should cardiac activity be present?

Answer 24

7mm

Question 25

What is the definitive sign of intrauterine pregnancy at 5 weeks?

Answer 25

Gestational sac and yolk sac

Question 26

if the yolk sac or embryo is not yet visualized, what can be an alternative sign of intrauterine pregnancy?

Answer 26

Double decidual sign

Question 27

What are the outer and inner parts of the double decidual sign?

Answer 27

Outer - decidua Inner - chorion seen as round oval fluid filled collection surrounded by 2 echogenic rings

Question 28

Visualization of a gestational sac containing a yolk sac and amniotic sac giving an appearance of two small bubbles where the embryonic disc is located between the 2 bubbles?

Answer 28

Double bleb sign

Question 29

How many days of gestation should we first see intradecidual sign and when is the last discriminatory day of gestation should it start be seen to confirm intrauterine pregnancy?

Answer 29

Should be seen at 24 days (threshold level) but not later than 47 days (discriminatory level) to confirm intrauterine pregnancy

Question 30

This is a frequent cause of first and second trimester hemorrhage caused by blood collecting between the uterine wall and the chorionic membrane

Answer 30

sub chorionic hemorrhage

Question 31

This is the normal fluid-filled subcutaneous space identified at the back of the fetal neck during the late first trimester and early second trimester (11 weeks 3 days to 13 weeks 6 days).

Answer 31

Nuchal transluency nuchal fold - seen at second trimester

Question 32

What does increase in nuchal translucency indicate?

Answer 32

dilated lymphatic vessels and fetal abnormalities

Question 33

When do we check for nuchal translucency?

Answer 33

11-13 weeks

Question 34

What are the 3 factors used to calculate for risk of trisomies?

Answer 34

Nuchal translucency Crown rump length fetal heart rate

Question 35

Most accurately reflects gestational age, with a | variation of 7 to 10 days in the second trimester

Answer 35

bi parietal diameter measurement of the shape of the fetal head

Question 36

What view is needed to see the biparietal diameter?

Answer 36

Axial view at the level of the thalamus

Question 37

How to measure biparietal diameter?

Answer 37

From the outer edge of the near cranium to the inner edge of the far cranium

Question 38

What is the condition if BPD is high for gestational age?

Answer 38

Brachycephaly

Question 39

What is the condition if BPD is low for gestational age?

Answer 39

dolicocephaly

Question 40

To correctly measure the head circumference and biparietal diameter, what structures must be included?

Answer 40

cavum septum pellucidum, thalamus, and choroid plexus in the atrium of the lateral ventricles

Question 41

What measurements reflects growth of the fetal brain?

Answer 41

Head circumference and biparietal diameter

Question 42

This is a perimeter measurement of the fetal cranium excluding subcutaneous soft tissues.

Answer 42

Head circumference

Question 43

This measurement reflects the growth of intraabdominal organs and fetal weight and sized? It is the peripheral measurement of the fetal abdomen including the subcutaneous tissue

Answer 43

Abdominal circumference

Question 44

What are the landmarks in measuring the abdominal circumference?

Answer 44

Portal section of the UV Stomach Spine

Question 45

Serves to monitor growth of long bones?

Answer 45

Femur length

Question 46

The normal growth and development of the fetus are dependent upon the normal function and integrity of this structure?

Answer 46

Placenta

Question 47

When can the placenta be first visualized sonographically by TVS

Answer 47

8 weeks as a focal thickening along the periphery of the gestational sac evident by 12 weeks

Question 48

This protects the fetus from injury and allows growth and fetal movement. This is also essential for lung maturation.

Answer 48

Amniotic fluid

Question 49

This measure the vertical height of the deepest fluid pocket in 4 quadrants?

Answer 49

amniotic fluid index

Question 50

What is the normal range for amniotic fluid index?

Answer 50

5-20 cms

Question 51

If AFI is below 5 cms, what is the condition?

Answer 51

Oligohydramnios

Question 52

What are the causes of oligohydramnios?

Answer 52

Post term PROM IUGR urinary tract abnormalities

Question 53

If AFI is more than 20 cms, what is the condition?

Answer 53

polyhydramnios

Question 54

What are the causes of polyhydramnios?

Answer 54

Gestational diabetes - most common GI and CNS abnormalities lethal skeletal dysplasia chromosomal abnormalities