Acog ultrasound dating

Can ultrasound dating be used to calculate the estimated due date (EDD)?

However, ultrasound dating, in particular first trimester sonography, has greatly improved our ability to calculate the estimated due date (EDD). There will be times that dating based on LMP does not match the ultrasound date.

When is a pregnancy without a dating ultrasound ‘suboptimally dated’?

Consider a pregnancy without a dating ultrasound prior to 22 0/7 weeks ‘suboptimally dated’ (refer to Related ObG Topics below) The age of the embryo is subtracted from the number of days between ovulation to delivery (280-14 = 266). For example, if the embryo is 3 days at transfer, the due date is 263 days from the date of transfer.

When should I change the date of delivery for an ultrasound?

Dating changes for smaller discrepancies are appropriate based on how early in the first trimester the ultrasound examination was performed and clinical assessment of the reliability of the LMP date Table 1. For instance, before 9 0/7 weeks of gestation, a discrepancy of more than 5 days is an appropriate reason for changing the EDD.

Why is my LMP not matching my ultrasound date?

There will be times that dating based on LMP does not match the ultrasound date. Clinical determination of EDD, 280 days after the last menstrual period ( LMP) still plays a role but may not always be accurate due to variability in length of an individual woman’s cycle length or timing of ovulation.

When should the EdD be changed to correspond with ultrasound dating?

If ultrasound dating before 14 0/7 weeks of gestation differs by more than 7 days from LMP dating, the EDD should be changed to correspond with the ultrasound dating.

Can an ultrasound predict a different due date?

It is common for each ultrasound throughout pregnancy to predict a different due date. Earlier ultrasounds are more accurate in terms of predicting the due date, so thats why doctors will usually use the dates and measurements from the first ultrasound of the pregnancy as a reference.

How is the estimated due date (EDD) determined?

As soon as data from the last menstrual period, the first accurate ultrasound examination, or both are obtained, the gestational age and the estimated due date (EDD) should be determined, discussed with the patient, and documented clearly in the medical record.

What is a dating scan and when is my due date?

I have read and agree to the Terms of Use and Privacy Policy is required . A dating scan is an ultrasound scan to determine how many weeks pregnant you are and your due date. Read on for more information about what a dating scan offers.

Compare the results If the margin of error is bigger than the difference in days between the due dates, use the LMP date as your due date. If the margin of error is smaller than the difference, use the ultrasound date as your due date. Can your due date change? Yes, your estimated due date can change, but it’s nothing to worry about.

When is a pregnancy without a dating ultrasound ‘suboptimally dated’?

What if my scan date differs from my LMP date?

“If the scan date differs from your LMP dates, then the scan dates will be used, but do discuss with your midwife if you are concerned. The best time to establish this date is at the scan you are offered between 11 weeks and 2 days and 14 weeks plus 1 day,”

Can ultrasound dating be used to calculate the estimated due date (EDD)?

However, ultrasound dating, in particular first trimester sonography, has greatly improved our ability to calculate the estimated due date (EDD). There will be times that dating based on LMP does not match the ultrasound date.

When is a pregnancy without a dating ultrasound ‘suboptimally dated’?

Consider a pregnancy without a dating ultrasound prior to 22 0/7 weeks ‘suboptimally dated’ (refer to Related ObG Topics below) The age of the embryo is subtracted from the number of days between ovulation to delivery (280-14 = 266). For example, if the embryo is 3 days at transfer, the due date is 263 days from the date of transfer.

When should I redate my LMP date?

There will be times that dating based on LMP does not match the ultrasound date. ACOG recommends redating as follows: Clinical determination of EDD, 280 days after the last menstrual period ( LMP) still plays a role but may not always be accurate due to variability in length of an individual woman’s cycle length or timing of ovulation.