Unit 5 - 1st Trimester Measurements: 69-83

_____ _____ is most accurate time for dating pregnancy with ultrasound for GS

1st Trimester

What is the 2 parameters for sonographic gestational dating?

• Crown- rump length [CRL]

• Gestational sac size [GS]

What is the most accurate type of dating?

Crown-rump length

• [+/- week]

How do you measure the crown-rump length?

• Longest length

  • Top of head to rump

What is not included in CRL

yolk sac

The crown-rump length can be used until week ___.

12

What is the formula for Gestational Age?

CRL [mm] + 42 = GA [days]

• Convert to weeks/days / 7

What is this image?

Crown-rump length

What is this image?

Crown-rump length

What is this image?

Crown-rump length

What is this image?

Crown-rump length

What is this image?

Crown-rump length

What is this image?

Crown-rump length

What is the formula for Mean Sac Diameter (MSD)?

L + W + H [mm] / 3

What is the Menstrual Age [days] formula?

MSD + 30

Menstrual age [days] divided by 7 =

Menstrual age [weeks]

During a transvaginal exam, a gestational sac can be seen with hCG levels of …

500

During a transabdominal exam, a gestational sac can be seen with hCG levels of …

>1800

During a transvaginal exam, a gestational sac should always be seen with hCG levels of …

> 2000-3000

What is the discriminatory level for viewing a gestational sac?

3000

What is this image?

Gestational sac

What is this image?

Gestational sac

What is this image showing?

Gestational sac

What is this image?

Longitudinal Gestational Sac Measurement

What is this image?

Longitudinal Gestational Sac Measurement

What is this image?

Longitudinal Gestational Sac Measurement

What is this image?

Transverse Gestational Sac Measurement

What is this image?

Transverse Gestational Sac Measurement

what is the formula for finding the LMP?

EDC + 3 months - 7 days