Module 4 Unit A

Question 1

How would you determine an EDB and current gestational age for a patient who presents for initial prenatal care in the second trimester?

What if the person was sure of their LMP

What if they had no idea about LMP

What other ways could you corroborate the EDB

Answer 1

Start by using the same history-taking approach we use during the first trimester.
Then use decision-making process that you used in the first trimester as to whether a dating ultrasound is clinically superior to using menstrual-based dates.

Use LMP date

Use u/s date

onset of pregnancy symptoms
date of any positive home pregnancy tests
date of quickening
fundal height

Question 2

Which fetal structures are used for dating ultrasounds in the second trimester

Answer 2

Biparietal diameter (BPD)
Head circumference (HC)
Abdominal circumference (AC)
femur length (FL)

Question 3

Why are earlier dating u/s more accurate than later dating ultrasounds

Answer 3

Because all conceptuses begin at the same size but fetal growth becomes more and more variable as pregnancy progresses. …so we must be cautious about changing an EDB in the second trimester…fact is…it should not be changed…

Question 4

How would you decide whether to change a due date at different gestational ages in the second trimester?

Answer 4

Weeks…………………Menstrual date to U/S date
14-15 6/7 weeks ……if more than 7 days
16-21 6/7 weeks ……if more than 10 days
22-27 weeks…………..if more than 14 days
28 weeks and beyond…if more than 21 days

Question 5

Imagine a patient is unhappy with the EDB you have set. How will you respond

Answer 5

by providing clinical appropriate and factual information with validating the person’s feelings and experience.

The bottom line is that you should not change a due date unless it meets the guidelines but you will want to be supportive and kind, providing individualized and respectful education and listening carefully to the patient’s concerns