4 doctors weighed in:
How accurate are doctors in knowing the date of conception once a woman has had an ultrasound?
4 doctors weighed in

Dr. Nikolaos Zacharias
Obstetrics & Gynecology - Maternal Fetal Medicine
2 doctors agree
In brief: Depends.
+/-3-5 days by ultrasound before 10 weeks.
+/-5-7 days by ultrasound between 10-14 weeks. +/-7-10 days by ultrasound between 14-20 weeks. +/-10-14 days by ultrasound between 20-24 weeks. +/-14-21 days after 25 weeks.

In brief: Depends.
+/-3-5 days by ultrasound before 10 weeks.
+/-5-7 days by ultrasound between 10-14 weeks. +/-7-10 days by ultrasound between 14-20 weeks. +/-10-14 days by ultrasound between 20-24 weeks. +/-14-21 days after 25 weeks.
Dr. Nikolaos Zacharias
Dr. Nikolaos Zacharias
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Dr. Helayne Merkin
Obstetrics & Gynecology
1 doctor agrees
In brief: Within 3 days
If the ultrasound is done in the 1st trimester it is very accurate in dating the pregnancy usually within 3 days of accuracy.
The later in pregnancy the ultrasound is done, the larger the windows of accuracy of the ultrasound.

In brief: Within 3 days
If the ultrasound is done in the 1st trimester it is very accurate in dating the pregnancy usually within 3 days of accuracy.
The later in pregnancy the ultrasound is done, the larger the windows of accuracy of the ultrasound.
Dr. Helayne Merkin
Dr. Helayne Merkin
Thank
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