A 23-year-old female asked:
when 1st trimester ultrasounds date pregnancy how do they base the gestational age? do they assume conception occured on cd14?
1 doctor answer
Dr. Gerard Honore answered
28 years experience Fertility Medicine
US: First trimester ultrasound is based on biometric measurements only, the embryonic crown-rump length, which is extremely reliable when done by a skilled sonographer. No assumptiosn need be made at all. The ega is however reported correctly, by convention, from the first day of a hypotehtical last menstrual period; so in that regard it 'assumes' conception on cd 14.
Answered on Feb 20, 2014
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more. Get help now:
People also searched for:
Connect by text or video with a U.S. board-certified doctor now — wait time is less than 1 minute!