WEEK 2: WORKSHOP: ANTENATAL ULTRASOUND

Question 1

State the 5 Uses of Antenatal US.

Answer 1

• Confirming a viable pregnancy
  – Normal IUP vs. abnormal IUP vs. ectopic
  pregnancy
• Dating the pregnancy
• Detecting multiple gestations
• Evaluating the foetal anatomy
  – Detection of anomalies
• Evaluating the placenta and umbilical cord

Question 2

What is ultrasound (US)?

Answer 2

Imaging with sound

Question 3

How does it work?

Answer 3

• Emit sound wave
• Listen for echos
• Emit sound wave
• Listen for echos
• Etc.

Question 4

What produces echos?

Answer 4

– Difference in tissues (tissue planes)
* Different tissue – different acoustic impedance
* Echo at interface

Question 5

What do the following measure:

– Time to echo return

– Loudness of return

– Shadowing

Answer 5

– Time to echo return
* Measure of depth

– Loudness of return
* Measure of difference in acoustic impedance

– Shadowing
* Complete reflection of sound at an interface
– Calcifications
– Air

Question 6

Why is the bladder dark?

Answer 6

No tissue planes.
Anechoic

Question 7

How many weeks is the second trimester?

State the 4 exam purposes in second trimester.

Answer 7

– 14-28 wks.
– Exam usually 18-22 wks.
* Exam purpose

1. Gestational age/growth (foetal biometry)
2. Foetal number (and type if twin)
3. Assess for foetal anomalies
4. Placenta position and pathology

Question 8

State the 4 Foetal Biometry in 2nd Trimester.

What are they used for?

Answer 8

1. Biparietal diameter
2. Head circumference
3. Abdominal circumference
4. Femur length

Used to determine gestational age.

Question 9

What do we look for in the placenta?

Answer 9

• Position
  – Anterior/posterior/lateral
  – Relation with cervix
• Maturity

Question 10

What 4 specific findings are evaluated for Foetal Anatomy in 2nd Trimester?

Answer 10

Evaluation of specific findings
– Cranial contents
– Thoracic-abdominal contents
– Spine
– Extremities