Question 1

why are early ultrasounds more accurate when it comes to dating a pregnancy?

Accepted Answer

Yes: Yes the best and safe procedure

Question 2

how accurate are ultrasounds for dating pregnancy what's the margin of error. if my due date is oct 31, what are the dates i could have gotten pregnant?

Accepted Answer

What year?: It would seem that you would have to conceive on feb.. 8, 2014 to give birth on 10/31. If the question is of historical interest, i would need to know when the ultrasound was done. Otherwise, you might want to check the dates you provided.

Question 3

can the first 2 ultrasounds of pregnancy taken a month apart with the same accuracy of gestational age in the second trimester be off by +- 25 days ?

Accepted Answer

Ultrasound: The earlier an ultrasound is done the more accurate it is. The due date should never be changed to the date received on a later ultrasound.

Question 4

are ultrasounds done at 13 weeks pregnant accurate? what is the margin error of dating scans performed at this stage of the pregnancy?

Accepted Answer

Yes, fairly accurate: The margin of error on a dating scan at 13 weeks is approximately 7 days.

Question 5

how accurate are first trimester ultrasounds? how accurate are ultrasounds done during the first trimester of pregnancy? i had one done and the doc told me that i'm 8 weeks pregnant, but how off could he be? is there a week or 2 margin of error?

Accepted Answer

The : The earlier an ultrasound is performed during pregnancy the more accurate it is likely to be. Here's a general rule of thumb: a due date given during the first trimester should be within 1 week of the true due date; during the second trimester it is within 2 weeks; and during the third trimester it is within 3 weeks. 
An 8 week ultrasound is quite accurate and if it differs more than 1 week from your due date based on your last menstrual period, then your obstetrician will assume the ultrasound to be more accurate. In your case, if you were told that you were 8 weeks along you could have actually been between 7 weeks and 9 weeks and your due date also has a +/- 1 week range of error. You will probably have another ultrasound during your second trimester. The technologist will recalculate a due date; this will have a larger margin of error but should be within 2 weeks of the initial due date you were given (remember the rule of thumb described above). Because the earliest ultrasound is considered the most accurate, the due date given at the first ultrasound is usually not changed by the obstetrician.

Question 6

how accurate are ultrasounds during early pregnancy? i had one at the er are the ones given in the obgyn office more accurate? thoughts? transvaginal

Accepted Answer

Both are accurate: Er and ob/gyn are both accurate for gestational age; typically transvaginal is more accurate than transabdominal.
Ultrasound performed in the er in early pregnancy are typically ordered to confirm whether or not you are pregnant, and how far along you are. 
The scans typically performed by your ob/gyn are often are more detailed to determine how your fetus and its anatomy are developing.

Question 7

are abdominal ultrasounds as accurate for dating as vaginal around 11 weeks of pregnancy? what is the margin of error for abdominal at this gestation?

Accepted Answer

Depends: If a woman is thin and the doctor has a good image of the fetus, then abdominal can be just as accurate as vaginal.  Margin of error at this gestation is still +/- 5 days. After 14 weeks that number increases to +/- 10 days.

Question 8

accuracy at 11wks. pregnant, going by the actual age of pregnancy can it be possible for the ulstrasound to date me 10 days before i even had sex with second partner and 1 day after my first partner?

Accepted Answer

: Evidence suggests that ultrasounds more accurately predict your due date than using your last menstrual period—but only in the first trimester and early second trimester (until roughly 20 weeks). Early ultrasound due dates have a margin of error of roughly 1.2 weeks. After 20 weeks, your Dr will measure your fundal height to see if the baby's growth is keeping on track with the EDD.

Question 9

how accurate is a ultra sound for the fetal age in early pregnancy?

Accepted Answer

Depends: Ultrasound are very accurate particularly in the 1st trimester, and are often only 1-2 days off, if at all, from the estimated due date. The later along in pregnancy you get your ultrasound done, however, the less accurate the dating will be. Congrats on your pregnancy and best wishes!

Question 10

how common are partial molar pregnancies among caucasians? can they be picked up on a an ultrasound at 5 weeks gestation? possible signs?

Accepted Answer

Molar pregnancies: Molar pregnancies are more common in Asian individuals and can be sometimes suspected by a rapid rise in the size of the uterus relative to known LMP gestational age. At 5 weeks of gestation it is very difficult to confirm a partial molar pregnancy as the ultrasound if done will show only early gestational material. A chorionic villus or amniocentesis sampling later in pregnancy will be abnormal.

Get Virtual Care

For Businesses

About Us

HealthTap Online Primary Care Doctors Accepting New Patients

Doctor answers about:

Ultrasound accurate determine pregnancy

A member asked:

Why are early ultrasounds more accurate when it comes to dating a pregnancy?

A member asked:

How accurate are ultrasounds for dating pregnancy what's the margin of error. if my due date is oct 31, what are the dates i could have gotten pregnant?

A member asked:

Can the first 2 ultrasounds of pregnancy taken a month apart with the same accuracy of gestational age in the second trimester be off by +- 25 days ?

A member asked:

Are ultrasounds done at 13 weeks pregnant accurate? what is the margin error of dating scans performed at this stage of the pregnancy?

A member asked:

How accurate are first trimester ultrasounds? how accurate are ultrasounds done during the first trimester of pregnancy? i had one done and the doc told me that i'm 8 weeks pregnant, but how off could he be? is there a week or 2 margin of error?

A member asked:

How accurate are ultrasounds during early pregnancy? i had one at the er are the ones given in the obgyn office more accurate? thoughts? transvaginal

A member asked:

Are abdominal ultrasounds as accurate for dating as vaginal around 11 weeks of pregnancy? what is the margin of error for abdominal at this gestation?

A member asked:

Accuracy at 11wks. pregnant, going by the actual age of pregnancy can it be possible for the ulstrasound to date me 10 days before i even had sex with second partner and 1 day after my first partner?

A member asked:

How accurate is a ultra sound for the fetal age in early pregnancy?

A member asked:

How common are partial molar pregnancies among caucasians? can they be picked up on a an ultrasound at 5 weeks gestation? possible signs?

HealthTap Online Primary Care Doctors Accepting New Patients

Telemedicine

Primary Care

Manage Your Conditions

Women's Health

Children's Health

Men's Health

Senior Health

Wellness, Prevention & Lifestyle

Sexual Health

Mental & Behavioral Health

Travel Medicine

Urgent Care

Didn't find what you're looking for?

More of what we treat

Allergies

Antibiotics

Asthma

High Blood Pressure

Prescriptions

Type 2 Diabetes

For Businesses

Company

Health Content

Join Us

Download HealthTap

Questions?