Unit 5- Sono Eval Embryo

In the embryonic cranium, what is shown in the 6th week of gestation?

• Prosencephalon

• Mesencephalon

• Rhombencephalon

What is the Rhombencephalon?

• Cystic rhomboid fossa

• Imaged routinely from 8-11 weeks

What are these images showing?

Rhombencephalon

What is this image showing?

Rhombencephalon

What is the embryonic cranium?

• 9 weeks gestation

• Cerebral hemispheres

  • Divided by cerebral fill

• Lateral ventricles completely fill cerebral vault

• Echogenic chorid plexus fills lateral ventricles

What should be seen on ultrasound at 10-12 weeks?

• Head and trunk well defined

• Arms and legs formed

• Amniotic cavity expanding

• Yolk sac usually disappears by 12 weeks

• External genitalia appear similar regardless of gender

• May see a functional hernia at abdominal cord insertion

What is this image showing?

Gestation age 9 W 6 D

When does a physiologic herniation of bowel occur?

Bowel normally migrates into the base of the umbilical cord between 8 + 12 menstrual weeks

What is the US of physiologic bowel herniation?

• Echogenic mass at base of umbilical cord

  • Mass should not measure >7mm at any gestational age

  • Mass should never measure <4mm

When does a physiologic bowel herniation return to abdomen?

• Bowel returns to abdominal cavity by 12 menstrual weeks

  • Echogenic mass no longer visualize

What is this image showing?

Physiologic Herniation of Bowel

What is this image showing?

Early midgut herniation

What can a physiologic herniation of bowel be confused with?

• Omphalocele

• Gastroschisis

What is the first organ to function?

Heart

When does the heart start beating?

• Starts beating at approximately 35 days (5 weeks)

At what week does the heart have its adult configuration?

End of 8th week

When should cardiac activity always be seen?

49 menstrual(gestational) days

• TV- 5mm CRL (5-6 weeks)

• TA- 9mm CRL (7 weeks)

• 7mm(TV) is discriminatory size

What is the range of heart rates throughout pregnancy?

• 90 - 170 bpm

  • 140 bpm average

What is this image showing?

10 week fetus/yolk sac

What is this image showing?

10 weeks

What are these images showing?

12 week fetus

What is this image showing?

12 weeks